DE102023108872A1 - GAS TURBINE ENGINE WITH STAGED COMBUSTION SYSTEM - Google Patents

Abstract

The present application discloses a gas turbine engine (10) for an aircraft (1), comprising: a staged combustion system (64) with pilot injection nozzles (313) and main injection nozzles (314), the staged combustion system (64) being in an operating range with only pilot injection and one Operating range can be operated with pre- and main injection. The gas turbine engine further includes a fuel supply controller (306) arranged to control the supply of fuel (F) to the pilot and main injectors (313, 314), and a fuel characteristic determination module (330) so is configured to determine one or more fuel characteristics of the fuel (F) supplied to the staged combustion system (64). The gas turbine engine further includes a controller (42) configured to determine a stage point that defines the point at which the staged combustion system (64) is switched between operation with pilot injection only and operation with pilot and main injection , wherein the stage point is determined based on the determined one or more fuel characteristics, the controller (42) being configured to control the staged combustion system (64) according to the determined stage point. Also disclosed is a method (4038) for operating a gas turbine engine and an aircraft (1).

Description

The present disclosure relates to a gas turbine engine for an aircraft and a method of operating a gas turbine engine for an aircraft. The present disclosure further relates to a computer-implemented method for determining one or more fuel loading parameters for an aircraft, a system for determining fuel loading parameters, a method for determining fleet-wide fuel allocation for a plurality of missions, and a system for determining fleet-wide fuel allocation. The present disclosure further relates to a method for loading fuel into the aircraft and a plurality of aircraft performing the plurality of missions.

The aviation industry is expected to see a trend toward using fuels that are different from the traditional kerosene fuels currently in common use.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen für Kraftstoff, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist; und
• einen Kraftstoff-Zufuhrregler, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen steuert, wobei der Kraftstoff-Zufuhrregler so angeordnet ist, dass er Kraftstoff von einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, erhält, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet,
• wobei der Kraftstoff-Zufuhrregler so angeordnet ist, dass er den Voreinspritzdüsen während mindestens eines Teils des Betriebsbereichs nur mit Voreinspritzung Kraftstoff zuführt, der ein anderes Kraftstoffmerkmal aufweist als der Kraftstoff, der den Voreinspritzdüsen und/oder den Haupteinspritzdüsen während mindestens eines Teils des Betriebsbereichs mit Vor- und Haupteinspritzung zugeführt wird.

According to a first aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors for fuel, the staged combustion system being operable in an operating range with pilot injection only and an operating range with pilot and main injection; and
• a fuel supply regulator arranged to control the supply of fuel to the pilot and main injectors, the fuel supply regulator arranged to supply fuel from a first fuel source containing a first fuel having a first fuel characteristic , and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first,
• wherein the fuel supply controller is arranged to deliver fuel to the pilot injectors during at least a portion of the pilot-only operating range that has a different fuel characteristic than the fuel supplied to the pilot injectors and/or the main injectors during at least a portion of the pilot-only operating range - and main injection is supplied.

The inventors have found that it may be advantageous to supply fuel from different fuel sources with different fuel characteristics to the fuel supply regulator, and to supply fuel to the pilot and main injectors such that fuel with different characteristics is provided in different operating regions of the combustion chamber. This more flexible supply of fuel to the combustion chamber can make it possible to use fuel with favorable combustion properties, which is only available to a limited extent, where these favorable properties have a greater effect.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel supplied to the pilot injectors during at least a portion of the pilot only operating range may be associated with nvPM production that is less than that of the fuel supplied to one or both of the pilot injectors and main injectors during at least a portion of the pilot operating range - and main injection is supplied.

The fuel supply controller may be configured to deliver fuel from the first fuel source to the pilot injectors during operation in both the pilot injection only operating range and the pilot and main injection operating range and fuel from the second fuel source to the main injectors during operation in the operating range with pilot and main injection.

The fuel delivery controller may be configured to deliver fuel from the first fuel source to the pilot injectors during operation in at least a portion of the pilot injection only operating range and to deliver fuel from the second fuel source to the pilot injectors during the pilot and main injection operating range .

The fuel delivery controller may be configured to switch the delivery of fuel to the pilot injectors between fuel from the first fuel source and fuel from the second fuel source at one or more operating points within the pilot-only operating range or at a boundary of this range.

The fuel delivery controller may be configured to switch the delivery of fuel to the pilot injectors between fuel from the first fuel source and fuel from the second fuel source in accordance with a mode signal indicative of a change in the operating range of the staged combustion system. The switchover can take place at the transition point between the operating range with pilot injection only and the operating range with pilot and main injection.

The fuel delivery controller may be configured to switch the delivery of fuel to the pilot injectors between fuel from the first fuel source and fuel from the second fuel source at a threshold within the pilot only operating range. Fuel from the second source may be delivered to the pilot injectors at flow rates below the threshold, and fuel from the first source is delivered to the pilot injectors at flow rates between the threshold and the limit of the pilot-only operating region.

The threshold may be a flow rate at which the production of nvPM by the gas turbine engine exceeds a threshold of nvPM produced by the gas turbine engine during operation in which the pilot injectors are supplied with fuel with the second fuel characteristic

Additionally or alternatively, the threshold may be a predefined threshold fuel flow rate that is less than the fuel flow rate at the boundary between pilot injection only operation and pilot and main injection operation by a predefined amount. The predefined fuel flow rate threshold may be either a percentage of the fuel flow rate at the step point or an absolute value of the fuel flow rate that is less than that at the step point.

The fuel supply controller may include a fuel mixer arranged to receive fuel from both the first and second fuel sources and output fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof. The fuel mixer may be arranged to deliver fuel to the pilot injectors.

The fuel mixing device may be configured to supply a mixture of fuel from the first fuel source and fuel from the second fuel source to the pilot injectors at least during a portion of the operating range with pilot injection only.

The fuel mixing device may be configured to supply the pilot injectors with a fuel mixture having a varying mixing ratio of fuel from the first fuel source and fuel from the second fuel source, wherein the mixing ratio can be varied within the operating range with pilot injection only according to the fuel flow rate.

The proportion of fuel from the first fuel source compared to that from the second fuel source can be reduced as the flow rate decreases within the operating range with pilot injection only.

The dependence of the proportion of fuel from the first fuel source compared to that from the second fuel source on the flow rate is determined depending on a desired nvPM level at a specific fuel flow rate and can be set so that the nvPM does not exceed a predetermined threshold or that nvPM generation is minimized over an operating period of the gas turbine engine. nvPM generation can be minimized over the LTO cycle.

The fuel mixer may be configured to mix fuel to achieve a desired nvPM level at one or more operating conditions of the gas turbine engine within the pilot injection only operating range.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Ort (z. B. Längen- und Breitengrad) der nvPM-Produktion;
• iii) Wetter- und/oder Witterungsbedingungen an einem Ort der nvPM-Produktion;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion;
• v) Masse und/oder Größe der einzelnen erzeugten nvPM-Partikel;
• vi) mögliche Kondensstreifenproduktion und/oder Kondensstreifenmerkmale;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) nvPM-Masse und/oder -Nummer.

The fuel controller may be configured to deliver fuel to the pilot injectors to minimize a cost function that depends on one or more nvPM influencing parameters. The one or more nvPM influence parameters may include one or more of the following parameters:

• i) height above ground at which nvPM production takes place;
• ii) location (e.g. longitude and latitude) of nvPM production;
• iii) Weather and/or weather conditions at a nvPM production location;
• iv) climate impacts associated with the location of nvPM production;
• v) mass and/or size of each nvPM particle produced;
• vi) possible contrail production and/or contrail features;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) nvPM mass and/or number.

1. a) die für einen geplanten Flug verfügbare Kraftstoffmenge mit der ersten Kraftstoffzusammensetzung (z. B. Schätzung oder Messung der Kraftstoffmenge in den Kraftstofftanks, die die erste und zweite Kraftstoffquelle bilden);
2. b) die Menge des gesamten Kraftstoffbedarfs für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Kraftstoffzusammensetzung (z. B. Zertifizierungsgrenze, für die Betankung verfügbare Kraftstoffzusammensetzung, Luftfahrzeug-/Triebwerksgrenzen).

The mixing ratio provided by the fuel mixing device can be determined at least in part according to one or more of the following criteria:

1. a) the amount of fuel available for a planned flight with the first fuel composition (e.g. estimation or measurement of the amount of fuel in the fuel tanks that form the first and second fuel sources);
2. (b) the amount of total fuel demand for the pilot injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. (c) a fuel composition limit parameter (e.g. certification limit, fuel composition available for refueling, aircraft/engine limits).

• Regelung der Kraftstoffzufuhr zu den Vor- und Haupteinspritzdüsen aus einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet,
• wobei die Regelung der Kraftstoffzufuhr das Zuführen von Kraftstoff zu den Voreinspritzdüsen während mindestens eines Teils des Betriebsbereichs nur mit Voreinspritzung umfasst, der ein anderes Kraftstoffmerkmal aufweist als der Kraftstoff, der an eine oder beide der Vor- und Haupteinspritzdüsen während mindestens eines Teils des Betriebsbereichs mit Voreinspritzung geliefert wird.

According to a second aspect, a method for operating a gas turbine engine for an aircraft is provided, wherein the gas turbine engine comprises a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in an operating range with pilot injection only and an operating range with pilot and main injection, wherein the procedure includes:

• Controlling the fuel supply to the pilot and main injectors from a first fuel source containing a first fuel with a first fuel characteristic and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first,
• wherein controlling the fuel delivery includes supplying fuel to the pilot injectors during at least a portion of the pilot-only operating range that has a different fuel characteristic than the fuel delivered to one or both of the pilot and main injectors during at least a portion of the pilot-injected operating range is delivered.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel supplied to the pilot injectors during at least a portion of the pilot-only operating range may be associated with nvPM production that is less than that of the fuel supplied to one or both of the pilot injectors and main injectors during at least a portion of the pilot-injected operating range is supplied.

The control of the fuel supply can include the supply of fuel from the first fuel source to the pilot injectors during operation both in the operating range with pilot injection only and in the operating range with pilot and main injection and of fuel from the second fuel source to the main injectors during operation in the operating range Include pilot and main injection.

Controlling the fuel delivery may include supplying fuel from the first fuel source to the pilot injectors during operation in at least a portion of the pilot injection only operating range and supplying fuel from the second fuel source to the pilot injectors during the pilot injection only operating range.

The control of the fuel supply may include switching the fuel supply to the pilot injectors between fuel from the first fuel source and fuel from the second fuel source at one or more operating points within the pilot-only operating range or at a boundary of this range.

The control of the fuel supply may consist of switching the supply of fuel to the pilot injectors between fuel from the first source and fuel from the second source in accordance with a mode signal indicative of a change in the operating range of the staged combustion system.

Controlling the fuel delivery may further include switching the fuel delivery to the pilot injectors between fuel from the first fuel source and fuel from the second fuel source at a threshold within the pilot injection only operating range.

The threshold may be a fuel flow rate at which the production of nvPM by the gas turbine engine exceeds a threshold amount of nvPM produced by the gas turbine engine during operation in which the pilot injectors are supplied with fuel of the second fuel characteristic become.

Additionally or alternatively, the threshold value may be a predefined flow rate that is lower than the flow rate by a predefined amount at the boundary between operation with pilot injection only and operation with pilot and main injection.

• Mischen eines Vorrats an Kraftstoff aus der ersten und der zweiten Kraftstoffquelle, um einen gemischten Kraftstoff zu bilden, der aus Kraftstoff aus der ersten Kraftstoffquelle, Kraftstoff aus der zweiten Kraftstoffquelle oder einer Mischung davon besteht; und
• Leiten des gemischten Kraftstoffs zu den Voreinspritzdüsen.

Fuel supply control may include:

• Mixing a supply of fuel from the first and second fuel sources to form a blended fuel consisting of power material consists of the first fuel source, fuel from the second fuel source or a mixture thereof; and
• Directing the mixed fuel to the pilot injectors.

The supply of the fuel mixture can consist of supplying a mixture of fuel from the first fuel source and fuel from the second fuel source to the pilot injectors at least during a part of the operating range with pilot injection only.

The supply of the mixed fuel may include supplying a fuel mixture to the pilot injectors with a varying mixing ratio of fuel from the first fuel source and fuel from the second fuel source, the mixture ratio being varied within the operating range with only pilot injectors according to the fuel flow rate.

The proportion of fuel from the first fuel source compared to that from the second fuel source can be reduced as the flow rate decreases within the operating range with pilot injection only.

The flow rate dependence of the proportion of fuel from the first fuel source compared to that from the second fuel source may be determined depending on a desired resulting nvPM level at a particular fuel flow rate, such that the nvPM does not exceed a predetermined threshold , or such that nvPM generation is minimized during a period of operation of the gas turbine engine.

The mixing of the fuel may consist of mixing the fuel such that a desired nvPM level is achieved in one or more operating conditions of the gas turbine engine within the operating range with pilot injection only.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Ort der nvPM-Produktion;
• iii) Wetter- und/oder Witterungsbedingungen am Ort der nvPM-Produktion;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion;
• v) Masse und/oder Größe der einzelnen erzeugten nvPM-Partikel;
• vi) mögliche Kondensstreifenproduktion und/oder Kondensstreifenmerkmale;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) nvPM-Masse und/oder -Nummer.

Controlling fuel delivery may include delivering fuel to the pilot injectors to minimize a cost function that depends on one or more nvPM influencing parameters. The one or more nvPM influence parameters may include one or more of the following parameters:

• i) height above ground at which nvPM production takes place;
• ii) location of nvPM production;
• iii) weather and/or atmospheric conditions at the location of nvPM production;
• iv) climate impacts associated with the location of nvPM production;
• v) mass and/or size of each nvPM particle produced;
• vi) possible contrail production and/or contrail features;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) nvPM mass and/or number.

1. a) die für einen geplanten Flug verfügbare Menge an Kraftstoff mit der ersten Kraftstoffzusammensetzung;
2. b) die Menge des gesamten Kraftstoffbedarfs für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Zusammensetzung des Kraftstoffs.

Mixing the fuel may include mixing the fuel in a mixing ratio determined at least in part by one or more of the following criteria:

1. (a) the quantity of fuel with the first fuel composition available for a planned flight;
2. (b) the amount of total fuel demand for the pilot injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. c) a limit parameter for the composition of the fuel.

According to a further aspect, an aircraft is provided that includes one or more gas turbine engines according to the first aspect and optionally one or more of the above-mentioned associated statements.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung, in dem Kraftstoff nur an die Voreinspritzdüsen geliefert wird, und in einem Betriebsbereich mit Voreinspritzung und Haupteinspritzung, in dem Kraftstoff an mindestens die Haupteinspritzdüsen geliefert wird, betreibbar ist; und
• einen Kraftstoff-Zufuhrregler, der so angeordnet ist, dass er die Kraftstoffzufuhr zu den Vor- und Haupteinspritzdüsen steuert, wobei der Kraftstoff-Zufuhrregler so angeordnet ist, dass er Kraftstoff von einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, empfängt, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet, wobei:
  • das gestufte Verbrennungssystem so angeordnet ist, dass es zwischen dem Betriebsbereich nur mit Voreinspritzung und dem Betriebsbereich mit Vor- und Haupteinspritzung an einem Stufenpunkt umschaltet, der einem stationären Reiseflugbetrieb des Triebwerks entspricht, wobei der Stufenpunkt eine Grenze zwischen einem ersten Reiseflug-Betriebsbereich und einem zweiten Reiseflug-Betriebsbereich des Triebwerks definiert; und
  • der Kraftstoff-Zufuhrregler so angeordnet ist, dass er den Voreinspritzdüsen während mindestens eines Teils des ersten Reiseflug-Betriebsbereichs Kraftstoff zuführt, der ein anderes Kraftstoffmerkmal aufweist als der Kraftstoff, der einem oder beiden der Vor- und Haupteinspritzdüsen während des zweiten Reiseflug-Betriebsbereichs zugeführt wird.

According to a third aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in a pilot injection only operating region in which fuel is delivered only to the pilot injectors and in a pilot injection and main injection operating region in which fuel is delivered to at least the main injectors ; and
• a fuel supply regulator arranged to control fuel supply to the pilot and main injectors, the fuel supply regulator arranged to supply fuel from a first fuel source containing a first fuel having a first fuel characteristic, and a second fuel source containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first, wherein:
  • the staged combustion system is arranged to switch between the operating region with pilot injection only and the operating region with pilot and main injection at a stage point that corresponds to a stationary cruise operation of the engine, the stage point defining a boundary between a first cruise operating region and a second Engine cruise operating range defined; and
  • the fuel supply controller is arranged to deliver fuel to the pilot injectors during at least a portion of the first cruise operating range that has a different fuel characteristic than the fuel supplied to one or both of the pilot and main injectors during the second cruise operating range .

The inventors have discovered that it may be advantageous to operate a staged combustion system to operate on pilot injection only during at least a portion of cruise operation, while selectively supplying fuel from two different sources to the combustion chamber during cruise operation. The inventors have found that certain engine emissions can be reduced and combustion efficiency can be improved by adjusting the step point so that cruise flight operation can take place with lower power in pure pilot injection mode. In conjunction with the selective use of fuels with different characteristics, the inventors have found that adverse emissions effects that would otherwise result from shifting the stage point can be mitigated. The combination of these factors therefore leads to an overall improvement in combustion efficiency and a reduction in emissions.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel delivered to the pilot injectors during the first cruise operating range may be associated with nvPM production that is less than that of the fuel delivered to one or both of the pilot injectors and main injectors during at least a portion of the second cruise operating range .

The first fuel characteristic may correspond to a greater SAF content in the respective fuel than the second fuel characteristic, and the fuel delivered during the first cruise operating range may have a higher SAF content than the fuel delivered during the second cruise operating range.

The first cruise operating range may correspond to operating the aircraft in a later portion of a cruise segment of a flight, and the second cruise operating range may correspond to operating the aircraft in a relatively earlier portion of the cruise segment.

The first cruise operating range may correspond to stationary subsonic cruise flight of the engine and the second cruise operating range may correspond to stationary supersonic cruise flight of the engine.

The fuel supply controller may include a fuel mixer arranged to receive fuel from both the first and second fuel sources and output fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof. The fuel mixer may be arranged to deliver fuel to the pilot injectors and optionally to the main injectors.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source may be determined according to a desired resulting level of nvPM production at a particular fuel flow rate within the first cruise operating range, such that the nvPM Generation does not exceed a predetermined threshold value, or that the nvPM generation is minimized during an operating period of the gas turbine engine.

1. a) die für einen vorgeschlagenen Flug verfügbare Menge an Kraftstoff mit dem ersten Kraftstoffmerkmal und dem zweiten Kraftstoffmerkmal;
2. b) die Menge des gesamten Kraftstoffbedarfs für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzwert für die Kraftstoffzusammensetzung.

The proportion of fuel delivered by the first fuel source compared to that from the second fuel source during the first cruise range of the engine may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel available for a proposed flight with the first fuel characteristic and the second fuel characteristic;
2. (b) the amount of total fuel demand for the pilot injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. c) a fuel composition limit.

• Regeln der Kraftstoffzufuhr zu den Vor- und Haupteinspritzdüsen aus einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet;
• Umschalten zwischen dem Betriebsbereich nur mit Voreinspritzung und dem Betriebsbereich mit Vor- und Haupteinspritzung an einem Stufenpunkt während eines stationären Reiseflugbetriebs des Triebwerks, um einen ersten Reiseflug-Betriebsbereichs und einen zweiten Reiseflug-Betriebsbereichs des Triebwerks zu definieren; und
• Zuführen von Kraftstoff zu den Voreinspritzdüsen während mindestens eines Teils des ersten Reiseflug-Betriebsbereichs mit einem Kraftstoffmerkmal, das sich von dem des Kraftstoffs unterscheidet, der zu einer oder beiden der Vor- und Haupteinspritzdüsen während des zweiten Reiseflug-Betriebsbereichs zugeführt wird.

According to a fourth aspect, a method of operating a gas turbine engine for an aircraft is provided, wherein the gas turbine engine has a staged combustion system with pilot injectors and main injectors wherein the staged combustion system is operable in a pilot injection only operating region in which fuel is delivered only to the pilot injectors and a pilot and main injection operating region in which fuel is delivered to at least the main injectors, the method comprising:

• controlling fuel delivery to the pilot and main injectors from a first fuel source containing a first fuel with a first fuel characteristic and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic different from the first;
• switching between the pilot injection only operating region and the pilot and main injection operating region at a stage point during steady cruise operation of the engine to define a first cruise operating region and a second cruise operating region of the engine; and
• Delivering fuel to the pilot injectors during at least a portion of the first cruise operating range with a fuel characteristic that is different from that of the fuel delivered to one or both of the pilot and main injectors during the second cruise operating range.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel supplied to the pilot injectors during the first cruise operating range may be associated with a level of nvPM generation that is less than that of the fuel to one or both of the pilot injectors and main injectors during at least a portion of the second cruise operating range is supplied.

The first fuel characteristic may correspond to a larger proportion of SAF in the respective fuel compared to the second fuel characteristic. The fuel delivered during the first cruise operating range may have a higher SAF content than the fuel delivered during the second cruise operating range.

The first cruise operating range may correspond to operating the aircraft in a later portion of a cruise segment of a flight, and the second cruise operating range may correspond to operating the aircraft in a relatively earlier portion of the cruise segment.

The first cruise operating range may correspond to stationary subsonic cruise flight of the engine and the second cruise operating range may correspond to stationary supersonic cruise flight of the engine.

The fuel delivery control may include delivering fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof using a fuel mixer. The fuel mixing device may be arranged to deliver fuel to the pilot injectors and optionally to the main injectors.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source may be determined according to a desired resulting nvPM level at a particular fuel flow rate within the first cruise operating range of the engine, such that the nvPM is a does not exceed a predetermined threshold value, or that the nvPM generation is minimized during an operating period of the gas turbine engine.

1. a) die Menge an Kraftstoff mit dem ersten Kraftstoffmerkmal und dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung steht;
2. b) die Menge des gesamten Kraftstoffbedarfs für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Kraftstofftzusammensetzung.

The proportion of fuel delivered by the first fuel source compared to the fuel delivered by the second fuel source during the first cruise operating range may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the second fuel characteristic available for a planned flight;
2. (b) the amount of total fuel demand for the pilot injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. c) a limit parameter for the fuel composition.

According to a further aspect, an aircraft is provided that includes one or more gas turbine engines according to the third aspect and optionally one or more of the above-mentioned associated statements.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung, in dem Kraftstoff nur an die Voreinspritzdüsen geliefert wird, und einem Betriebsbereich mit Vor- und Haupteinspritzung, in dem Kraftstoff an mindestens die Haupteinspritzdüsen mit einer relativen Rate geliefert wird, die durch ein Vor- und Haupteinspritzungs-Stufenverhältnis definiert ist, betrieben werden kann; und
• einen Kraftstoff-Zufuhrregler, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen steuert, wobei der Kraftstoff-Zufuhrregler so angeordnet ist, dass er Kraftstoff von einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, empfängt, wobei sich das zweite Kraftstoffmerkmal vom ersten unterscheidet, wobei:
  • das gestufte Verbrennungssystem ferner in einem Übergangs-Betriebsbereich zwischen dem Betriebsbereich mit nur Voreinspritzung und dem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist;
  • innerhalb des Übergangs-Betriebsbereich Kraftstoff sowohl den Vor- als auch den Haupteinspritzdüsen mit einem Übergangs-Stufenverhältnis zugeführt wird, das sich von dem Vor- und Haupteinspritzungs-Stufenverhältnis unterscheidet; und
  • der Kraftstoff-Zufuhrregler so angeordnet ist, dass er Kraftstoff an eine oder beide der Vor- und Haupteinspritzdüsen während des Übergangs-Betriebsbereichs mit einem Kraftstoffmerkmal liefert, das sich von dem des Kraftstoffs unterscheidet, der an eine oder beide der Vor- und Haupteinspritzdüsen während mindestens eines Teils des Betriebsbereichs mit Vor- und Haupteinspritzung geliefert wird.

According to a fifth aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors, the staged combustion system in one Pilot injection only operating region in which fuel is delivered only to the pilot injectors and a pilot and main injection operating region in which fuel is delivered to at least the main injectors at a relative rate defined by a pilot and main injection step ratio, can be operated; and
• a fuel supply regulator arranged to control the supply of fuel to the pilot and main injectors, the fuel supply regulator arranged to supply fuel from a first fuel source containing a first fuel having a first fuel characteristic , and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first, wherein:
  • the staged combustion system is further operable in a transitional operating region between the pilot injection only operating region and the pilot and main injection operating region;
  • within the transition operating range, fuel is delivered to both the pilot and main injectors at a transition staging ratio that is different from the pilot and main injection staging ratio; and
  • the fuel supply controller is arranged to deliver fuel to one or both of the pilot and main injectors during the transient operating range with a fuel characteristic that is different from that of the fuel delivered to one or both of the pilot and main injectors during at least part of the operating range is supplied with pilot and main injection.

The inventors have found that a transition region can be provided which enables a transition from the pure pilot injection (100:0) to the selected pilot and main injection. The inventors have found that by configuring the staged combustion system to operate in a transition region between pilot injection only operation and pilot and main injection operation, CO and HC emissions can be reduced in this range of engine power settings. The inventors have also found that any adverse change in engine emissions resulting from the transition region can be at least partially mitigated by using fuel with different fuel characteristics in the pilot and main injection operating region than in the pilot and main injection operating region.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel delivered to at least the pilot injectors during the transition region may be associated with an nvPM production that is less than that of the fuel delivered to one or both pilot injectors during at least a portion of the pilot and main injection operating region.

The first fuel characteristic may correspond to a higher proportion of SAF in the respective fuel compared to the second fuel characteristic. The fuel delivered during the transition region may have a higher proportion of SAF than the fuel delivered during at least a portion of the pilot and main injection operating region.

The transition stage ratio can have a continuous change in engine performance at least in part of the transition region.

The continuous change may be such that within the transition operating range, the proportion of the total fuel flow to the fuel injectors that is attributable to the fuel flow to the pilot injectors decreases with increasing engine power and the proportion of the total fuel flow to the fuel injectors decreases , which is due to fuel flow to the main injectors, increases as engine power increases.

The transition stage ratio may have a constant intermediate value, which differs from the pre- and main injection stage ratio, at least within a part of the transition range. The constant intermediate value can lie between that of the area with pilot injection only and that of the area with pilot and main injection.

The transition staging ratio may vary between a series of constant (i.e., different from each other) intermediate values, each distinct from the pre-injection and main injection staging ratios. Any intermediate value can lie between that of the pure pilot injection and that of the pilot and main injection.

The fuel supply regulator may include a fuel mixing device arranged to provide fuel supply from both the first th as well as from the second fuel source and outputs fuel from the first fuel source, fuel from the second fuel source or a mixture thereof. The fuel mixer may be arranged to deliver fuel to the pilot injectors and optionally to the main injectors.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source may be determined according to a desired resulting level of nvPM generation at a particular flow rate within the transient operating range, such that nvPM generation reaches a predetermined level Threshold value is not exceeded, or that nvPM generation is minimized over an operating period of the gas turbine engine.

1. a) die Menge an Kraftstoff mit dem ersten Kraftstoffmerkmal und dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung steht;
2. b) die Menge des gesamten Kraftstoffbedarfs für die Einspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Kraftstpffzusammensetzung.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source during the transition region of operation may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the second fuel characteristic available for a planned flight;
2. (b) the amount of total fuel demand for the injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. c) a limit parameter for the force composition.

• Regulieren der Kraftstoffzufuhr zu den Vor- und Haupteinspritzdüsen von einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet,
• Betreiben des gestuften Verbrennungssystems in einem Übergangs-Betriebsbereich zwischen dem Betriebsbereich nur mit Voreinspritzung und dem Betriebsbereich mit Voreinspritzdüsen und Haupteinspritzdüsen, in dem Kraftstoff sowohl an die Voreinspritzdüsen als auch an die Haupteinspritzdüsen mit einem Übergangs-Stufenverhältnis geliefert wird, das sich von dem Vor- und Haupteinspritzungs-Stufenverhältnis unterscheidet,
• wobei das Regulieren der Kraftstoffzufuhr das Zuführen von Kraftstoff zu einem oder beiden der Vor- und Haupteinspritzdüsen während des Übergangs-Betriebsbereichs umfasst, der ein Kraftstoffmerkmal aufweist, das sich von dem des Kraftstoffs unterscheidet, der zu einem oder beiden der Vor- und Haupteinspritzdüsen während zumindest eines Teils des Betriebsbereichs mit Vor- und Haupteinspritzung zugeführt wird.

According to a sixth aspect, there is provided a method of operating a gas turbine engine for an aircraft, the gas turbine engine comprising a staged combustion system with pilot injectors and main injectors, the staged combustion system in a pilot-only operating region in which fuel is delivered only to the pilot injectors, and a pilot and main injection operating region in which fuel is delivered to at least the main injectors at a relative rate defined by a pilot and main injection step ratio, the method comprising:

• regulating fuel delivery to the pilot and main injectors from a first fuel source containing a first fuel with a first fuel characteristic and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first,
• Operating the staged combustion system in a transitional operating region between the pilot injection only operating region and the pilot injector and main injector operating region in which fuel is delivered to both the pilot injectors and the main injectors at a transitional staging ratio that is different from the pilot and main injectors main injection stage ratio differs,
• wherein regulating fuel delivery includes delivering fuel to one or both of the pilot and main injectors during the transitional operating region having a fuel characteristic that is different from that of the fuel supplied to one or both of the pilot and main injectors during at least part of the operating range is supplied with pilot and main injection.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel delivered to at least the pilot injectors during the transition region may be associated with an nvPM production that is less than that of the fuel delivered to one or both pilot injectors during at least a portion of the pilot and main injection operating region.

The first fuel characteristic may correspond to a greater proportion of SAF in the respective fuel than the second fuel characteristic, and the fuel delivered during the pilot and main injection operating region may have a higher proportion of SAF than the fuel delivered during at least a portion of the pilot operating region - and main injection is delivered.

The transition stage ratio may exhibit a continuous change in engine performance at least in a portion of the transition operating range.

The continuous change can be such that within the transition operating range, the proportion of the total fuel flow to the injectors that is attributable to the fuel flow to the pilot injectors decreases with increasing engine power and the proportion of the total fuel flow to the injectors that due to fuel flow to the main injectors, increases with increasing engine power.

The transition stage ratio can have a constant intermediate value at least within a part of the transition operating range, which differs from the pre- and main injection ratio and optionally lies between that of the operating range with pre- and main injection and that of the operating range with pre- and main injection.

The transition step ratio may vary between a series of constant intermediate values, each different from the ratio between pilot and main injection and optionally between the ratio between pure pilot injection and pilot and main injection.

Regulating the fuel supply may include supplying fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof using a fuel mixer. The fuel mixing device may be arranged to deliver fuel to the pilot injectors and optionally to the main injectors.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source may be determined according to a desired resulting level of nvPM generation at a particular flow rate within the transient operating range. The proportion of fuel may be determined such that nvPM generation does not exceed a predetermined threshold or that nvPM generation is minimized over a period of operation of the gas turbine engine.

1. a) die Menge an Kraftstoff mit dem ersten Kraftstoffmerkmal und dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung steht;
2. b) die Menge des gesamten Kraftstoffbedarfs für die Einspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem der Kraftstoff von der ersten Kraftstoffquelle bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Kraftstoffzusammensetzung.

The proportion of fuel delivered from the first fuel source compared to that from the second fuel source during the transitional operating region may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the second fuel characteristic available for a planned flight;
2. (b) the amount of total fuel demand for the injectors during operation with pilot injection only for the entire flight in an operating range in which the fuel is provided by the first fuel source; and or
3. c) a limit parameter for the fuel composition.

According to a further aspect, there is provided an aircraft comprising one or more gas turbine engines according to the fifth aspect and optionally one or more of the above-mentioned related statements.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung, in dem Kraftstoff nur an die Voreinspritzdüsen geliefert wird, und einem Betriebsbereich mit Voreinspritzung und Haupteinspritzung, in dem Kraftstoff an mindestens die Haupteinspritzdüsen geliefert wird, betreibbar ist; und
• einen Kraftstoff-Zufuhrregler, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen steuert, wobei der Kraftstoff-Zufuhrregler so angeordnet ist, dass er Kraftstoff von einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, empfängt, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet, wobei:
  • das gestufte Verbrennungssystem so eingerichtet ist, dass es in einem Beschleunigungsmodus arbeitet, in dem eine Beschleunigung des Triebwerks aus einem stationären Betriebsmodus bewirkt wird; und
  • der Kraftstoff-Zufuhrregler angeordnet ist, um während des Betriebs in mindestens einem Teil des Beschleunigungsmodus Kraftstoff an eine oder beide der Vor- und Haupteinspritzdüsen zu liefern, der ein anderes Kraftstoffmerkmal aufweist als der Kraftstoff, der an eine oder beide der Vor- und Haupteinspritzdüsen während mindestens eines Teils des stationären Betriebsmodus geliefert wird.

According to a seventh aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in a pilot injection only operating region in which fuel is delivered only to the pilot injectors and a pilot injection and main injection operating region in which fuel is delivered to at least the main injectors; and
• a fuel supply regulator arranged to control the supply of fuel to the pilot and main injectors, the fuel supply regulator arranged to supply fuel from a first fuel source containing a first fuel having a first fuel characteristic , and a second fuel source containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first, wherein:
  • the staged combustion system is configured to operate in an acceleration mode in which the engine is caused to accelerate from a steady-state operating mode; and
  • the fuel supply controller is arranged to deliver fuel to one or both of the pilot and main injectors during operation in at least a portion of the acceleration mode, which has a different fuel characteristic than the fuel supplied to one or both of the pilot and main injectors during at least part of the stationary operating mode is delivered.

To reduce the generation of excessive amounts of nvPM during acceleration, it is known to switch to an "acceleration" operating mode of a gas turbine engine in which the step point is at a lower engine power setting. However, the inventors have found that switching to such a known acceleration mode can have a number of disadvantages. For example, there may be an increase in HC and CO emissions. In an acceleration mode of the present application, the fuel delivery controller is configured to deliver fuel to the fuel injectors (ie, the pilot and main injectors) that has a different fuel characteristic than the fuel that supplies the fuel injectors Fuel injectors (ie, the pilot and main injectors) are supplied during at least part of the steady-state operating mode. The inventors have determined that increased nvPM emissions when operating the engine in acceleration mode can be avoided or reduced by using a fuel with different fuel characteristics than steady-state operation. This allows the step point during acceleration mode to remain the same or similar to that of steady-state operation mode, thereby avoiding or reducing/limiting adverse increases in HC or CO emissions.

The first fuel feature may be associated with a level of nvPM production that is lower than that of the second fuel feature. The fuel delivered to at least the pilot injectors during acceleration mode may be associated with nvPM production that is less than that of the fuel delivered to one or both of the pilot injectors and main injectors during steady-state mode operation.

The first fuel characteristic may correspond to a greater proportion of SAF in the respective fuel than the second fuel characteristic, and the fuel delivered during the acceleration mode may have a higher proportion of SAF.

The staged combustion system can be set up to switch at a stage point between operation in the pilot injection only operating region and the pilot and main injection operating region.

The step point can be at the same or higher engine power in acceleration mode than in stationary mode.

The stage point may be at a lower engine power in acceleration mode than in stationary mode and may be at a higher power than a standard stage point by which the staged combustion system is controlled when fuel with other characteristics cannot be supplied to the combustion system.

The fuel delivery controller may be configured to deliver fuel to the pilot injectors during pilot-only operation in the acceleration mode that has different fuel characteristics than the fuel delivered to the main injectors during pilot-only and main-injection operation in the steady-state operating mode of the engine .

The fuel delivery controller may be configured to deliver fuel with a fuel characteristic determined based on a control parameter upon which nvPM generation by the engine depends during the pilot injection only operating range in acceleration mode.

The control parameter may be a fuel-air ratio in a combustion chamber of the staged combustion system.

As the air-fuel ratio is reduced, the proportion of fuel delivered to the pilot injectors, which have low nvPM production, can also be reduced.

The fuel delivery controller may be configured to switch fuel delivery to one or both of the main injectors and the pilot injectors to a fuel characteristic that is different at the beginning of a period of operation in the acceleration mode.

The fuel delivery controller can be set up to deliver fuel again with the same fuel characteristics as in steady-state mode after a transition to pilot and main injection operation.

The fuel delivery controller may be configured to deliver fuel to one or both pilot injectors and main injectors during acceleration mode at a rate greater than that sufficient to maintain steady-state operation of the engine.

• Regeln der Kraftstoffzufuhr zu den Vor- und Haupteinspritzdüsen aus einer ersten Kraftstoffquelle, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthält, und einer zweiten Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthält, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet;
• Betreiben des gestuften Verbrennungssystems in einem Beschleunigungsmodus, in dem eine Beschleunigung des Triebwerks aus einem stationären Betriebsmodus bewirkt wird; und
• Zuführen von Kraftstoff zu einer oder beiden der Vor- und Haupteinspritzdüsen während des Betriebs in mindestens einem Teil des Beschleunigungsmodus, der ein Kraftstoffmerkmal aufweist, das sich von dem Kraftstoff unterscheidet, der zu einer oder beiden der Vor- und Haupteinspritzdüsen während mindestens eines Teils des stationären Betriebsmodus zugeführt wird.

According to an eighth aspect, there is provided a method of operating a gas turbine engine for an aircraft, the gas turbine engine comprising a staged combustion system with pilot injectors and main injectors, the staged combustion system in a pilot-only operating region in which fuel is delivered only to the pilot injectors, and an operating range with pilot and main injection in which fuel is delivered to at least the main injectors, the method comprising:

• controlling fuel delivery to the pilot and main injectors from a first fuel source containing a first fuel with a first fuel characteristic and a second fuel source containing a second fuel with a second fuel characteristic, the second fuel characteristic different from the first;
• operating the staged combustion system in an acceleration mode that causes the engine to accelerate from a steady-state operating mode; and
• Delivering fuel to one or both of the pilot and main injectors during operation in at least a portion of the acceleration mode that has a fuel characteristic that is different from the fuel supplied to one or both of the pilot and main injectors during at least a portion of the steady state Operating mode is supplied.

The first fuel characteristic may be associated with a level of nvPM generation that is lower than that of the second fuel characteristic, and the fuel delivered to at least the pilot injectors during the acceleration mode may be associated with a level of nvPM generation that is lower is than that of the fuel supplied to one or both pilot injectors and the main injectors during steady-state mode operation.

The first fuel characteristic may correspond to a greater proportion of SAF in the respective fuel than the second fuel characteristic, and the fuel delivered during the acceleration mode may have a higher proportion of SAF.

The staged combustion system can be set up to switch at a stage point between operation in the pilot injection only operating region and the pilot and main injection operating region.

The step point can be at the same or higher engine power in acceleration mode than in stationary mode.

The stage point may be at a lower engine power in acceleration mode than in stationary mode and may be at a higher power than a standard stage point by which the staged combustion system is controlled when fuel with different fuel characteristics cannot be supplied to the combustion system.

During pilot-injection-only operation in acceleration mode, fuel with different fuel characteristics may be delivered to the pilot injectors than to the main injectors during pilot and main injection operation in the stationary mode of the engine.

The delivery of fuel to the injectors may include the delivery of fuel during the pilot injection only operating region in acceleration mode with fuel characteristics based on a control parameter on which the nvPM generation by the engine depends. The control parameter may be a fuel-air ratio in a combustion chamber of the staged combustion system. As the air-fuel ratio decreases, the proportion of fuel delivered to the pilot injectors that causes low nvPM generation may also be reduced.

The delivery of fuel to the injectors may consist of switching the delivery of fuel to one or both of the main injectors and the pilot injectors to a fuel characteristic that is different at the beginning of a period of operation in the acceleration mode.

The supply of fuel to the injectors can consist of supplying fuel with the same fuel characteristics as in stationary operation again after a transition to operation with pilot and main injection.

During acceleration mode, more fuel may be delivered to the injectors than is required to maintain steady-state operation.

According to a further aspect, an aircraft is provided that includes one or more gas turbine engines according to the seventh aspect and optionally one or more of the above-mentioned related statements.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen für Kraftstoff, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist; und
• einen Kraftstoff-Zufuhrregler, der die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen steuert;
• ein Kraftstoffmerkmal-Bestimmungsmodul, das so konfiguriert ist, dass es ein oder mehrere Kraftstoffmerkmale des Kraftstoffs, der dem gestuften Verbrennungssystem zugeführt wird, bestimmt; und
• eine Steuerung, die so konfiguriert ist, dass sie einen Stufenpunkt bestimmt, der den Punkt definiert, an dem das gestufte Verbrennungssystem zwischen einem Betrieb nur mit Voreinspritzung und einem Betrieb mit Vor- und Haupteinspritzung umgeschaltet wird, wobei der Stufenpunkt auf der Grundlage der bestimmten einen oder mehreren Kraftstoffmerkmale bestimmt wird, und die Steuerung so konfiguriert ist, dass sie das gestufte Verbrennungssystem gemäß dem bestimmten Stufenpunkt steuert.

According to a ninth aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors for fuel, the staged combustion system being operable in an operating range with pilot injection only and an operating range with pilot and main injection; and
• a fuel supply regulator that controls the supply of fuel to the pilot and main injectors;
• a fuel characteristic determination module configured to determine one or more fuel characteristics of the fuel supplied to the staged combustion system; and
• a controller configured to determine a stage point that defines the point at which the staged combustion system switches between pilot injection only operation and pilot and main fuel operation tion is switched, wherein the stage point is determined based on the determined one or more fuel characteristics, and the controller is configured to control the staged combustion system according to the determined stage point.

The inventors have discovered that the stage point at which a staged combustion system is controlled can be determined depending on the characteristics of the fuel supplied to the combustion chamber. As discussed above in connection with the third, fourth, seventh and eighth aspects, the stage point may be controlled in cases where fuel with different characteristics is available to reduce certain engine emissions.

One or more fuel characteristics may indicate that the fuel has lower nvPM production compared to fossil kerosene.

• (i) einen prozentualen Anteil an nachhaltigem Flugkraftstoff im Kraftstoff;
• (ii) den Gehalt an aromatischen Kohlenwasserstoffen im Kraftstoff; und/oder
• (iii) Naphthalin-Gehalt des Kraftstoffs.

Fuel characteristics may include one or more of the following:

• (i) a percentage of sustainable aviation fuel in the fuel;
• (ii) the aromatic hydrocarbon content of the fuel; and or
• (iii) Naphthalene content of the fuel.

The controller may be configured to determine the stage point such that a stage point associated with one or more fuel characteristics indicating that the fuel is associated with low nvPM production corresponds to a higher power setting of the engine compared to a step point associated with one or more fuel characteristics that indicate that the fuel is associated with relatively higher nvPM production.

The determined stage point may be a cruise stage point, and the controller may be configured to control the combustion system using the determined stage point during a cruise operating condition of the engine.

The controller may be configured to determine the stage point such that the staged combustion system is arranged to switch between the pilot injection only operating region and the pilot and main injection operating region at a stage point corresponding to a steady-state cruise operating mode of the Engine corresponds, wherein the step point defines a boundary between a first cruise operating range and a second cruise operating range of the engine.

The first cruise operating range may correspond to operating the aircraft in a later portion of a cruise segment of a flight, and the second operating range may correspond to operating the aircraft in a relatively earlier portion of the cruise segment.

The first cruise range may correspond to the stationary subsonic cruise operation of the engine, the second cruise range to the stationary supersonic cruise operation of the engine.

The determined stage point may be an engine acceleration stage point, and the controller may be configured to control the staged combustion system using the determined stage point during an acceleration operating state of the engine. The engine acceleration staging point may be determined to be identical to (e.g., set to be identical to) a cruise staging point depending on one or more fuel characteristics.

• Bestimmen eines oder mehrerer Kraftstoffmerkmale eines Kraftstoffs, der dem gestuften Verbrennungssystem zugeführt wird;
• Bestimmen eines Stufenpunktes, der den Punkt definiert, an dem das gestufte Verbrennungssystem zwischen einem Betrieb nur mit Voreinspritzung und einem Betrieb mit Vor- und Haupteinspritzung umgeschaltet wird, auf der Grundlage der bestimmten einen oder mehreren Kraftstoffmerkmale; und
• Steuerung des gestuften Verbrennungssystems entsprechend dem ermittelten Stufenpunkt.

According to a tenth aspect, a method for operating a gas turbine engine for an aircraft is provided, wherein the gas turbine engine comprises a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in an operating region with pilot injection only and an operating region with pilot and main injection, wherein the procedure includes:

• determining one or more fuel characteristics of a fuel supplied to the staged combustion system;
• determining a stage point that defines the point at which the staged combustion system is switched between pilot injection only operation and pilot and main injection operation based on the determined one or more fuel characteristics; and
• Control of the staged combustion system according to the determined stage point.

One or more fuel characteristics may indicate that the fuel has lower nvPM production compared to fossil kerosene.

• (i) einen prozentualen Anteil an nachhaltigem Flugkraftstoff im Kraftstoff;
• (ii) den Gehalt an aromatischen Kohlenwasserstoffen im Kraftstoff; und/oder
• (iii) Naphthalin-Gehalt des Kraftstoffs.

Fuel characteristics include one or more of the following:

• (i) a percentage of sustainable aviation fuel in the fuel;
• (ii) the aromatic hydrocarbon content of the fuel; and or
• (iii) Naphthalene content of the fuel.

Determining the stage point may include setting the stage point such that a stage point associated with one or more fuel characteristics indicating that the fuel is associated with low nvPM production corresponds to a higher power setting of the engine than a step point associated with one or more fuel characteristics that indicate that the fuel is associated with relatively higher nvPM production.

The determined stage point may be a cruise stage point, and the combustion system may be controlled using the determined stage point during a cruise operating condition of the engine.

The stage point may be set such that the staged combustion system is arranged to switch between the pilot injection only operating region and the pilot and main injection operating region at a stage point corresponding to a steady cruise operating mode of the engine. The step point may define a boundary between a first engine cruise operating range and a second engine cruise operating range.

The first cruise operating range may correspond to operating the aircraft in a later portion of a cruise segment of a flight, and the second cruise operating range may correspond to operating the aircraft in a relatively earlier portion of the cruise segment.

The first cruise range may correspond to the stationary subsonic cruise operation of the engine and the second cruise range may correspond to the stationary supersonic cruise operation of the engine.

The determined stage point may be an engine acceleration stage point, and the staged combustion system may be controlled using the determined stage point during an acceleration operating condition of the engine. The engine acceleration stage point may be determined to be the same as a cruise stage point depending on one or more fuel characteristics.

According to an eleventh aspect, there is provided an aircraft comprising one or more gas turbine engines according to the ninth aspect and optionally one or more of the above-mentioned related statements.

• ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen für Kraftstoff, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist;
• einen Kraftstoff-Zufuhrregler, der die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen steuert;
• ein Kraftstoffmerkmal-Bestimmungsmodul, das so konfiguriert ist, dass es ein oder mehrere Kraftstoffmerkmale des Kraftstoffs, der dem gestuften Verbrennungssystem zugeführt wird, bestimmt; und
• eine Steuerung, die so konfiguriert ist, dass sie ein Stufenverhältnis bestimmt, das das Verhältnis des Kraftstoffstroms der Voreinspritzdüse zum Kraftstoffstrom der Haupteinspritzdüse definiert, wobei das Stufenverhältnis gemäß den einen oder mehreren Kraftstoffmerkmalen bestimmt wird und die Steuerung so konfiguriert ist, dass sie das gestufte Verbrennungssystem gemäß dem bestimmten Stufenverhältnis steuert.

According to a twelfth aspect, there is provided a gas turbine engine for an aircraft, comprising:

• a staged combustion system with pilot injectors and main injectors for fuel, the staged combustion system being operable in an operating range with pilot injection only and an operating range with pilot and main injection;
• a fuel supply regulator that controls the supply of fuel to the pilot and main injectors;
• a fuel characteristic determination module configured to determine one or more fuel characteristics of the fuel supplied to the staged combustion system; and
• a controller configured to determine a staging ratio that defines the ratio of the pilot injector fuel flow to the main injector fuel flow, the staging ratio being determined according to the one or more fuel characteristics, and the controller configured to control the staged combustion system controls according to the specific step ratio.

The inventors have discovered that the step ratio can be determined based on one or more fuel characteristics to more effectively control engine emissions. In this way, for example, the stage ratio can be adjusted to reduce CO and HC production in a way that would otherwise result in high nvPM production, as explained above in connection with the fifth and sixth aspects.

One or more fuel characteristics may indicate that the fuel has lower nvPM production compared to fossil kerosene.

• (i) einen prozentualen Anteil an nachhaltigem Flugkraftstoff im Kraftstoff;
• (ii) den Gehalt an aromatischen Kohlenwasserstoffen im Kraftstoff; und/oder
• (iii) Naphthalin-Gehalt des Kraftstoffs.

Fuel characteristics may include one or more of the following:

• (i) a percentage of sustainable aviation fuel in the fuel;
• (ii) the aromatic hydrocarbon content of the fuel; and or
• (iii) Naphthalene content of the fuel.

• Steuern des gestuften Verbrennungssystems während des Betriebsbereichs mit Vor- und Haupteinspritzung gemäß einem Vor- und Haupteinspritzungs-Stufenverhältnis, und wobei das gemäß den einen oder mehreren Kraftstoffmerkmalen bestimmte Stufenverhältnis ein Übergangs-Stufenverhältnis ist; und
• Steuern des gestuften Verbrennungssystems, so dass es in einem Übergangs-Betriebsbereich zwischen dem Betriebsbereich nur mit Voreinspritzung und dem Betriebsbereich mit Vor- und Haupteinspritzung betrieben wird, wobei innerhalb des Übergangs-Betriebsbereichs das gestufte Verbrennungssystem gemäß dem Übergangs-Stufenverhältnis gesteuert wird, wobei das Übergangs-Stufenverhältnis von dem Vor- und Haupteinspritzungs-Stufenverhältnis verschieden ist.

The controller can be configured to:

• controlling the staged combustion system during the pilot and main injection operating region according to a pilot and main injection stage ratio, and wherein the stage ratio determined according to the one or more fuel characteristics is a transition stage ratio; and
• Controlling the staged combustion system to operate in a transitional operating range between the pilot injection only operating range and the pilot and main injection operating range, wherein within the transitional operating range the staged combustion system is controlled according to the transitional stage ratio, the transition -Stage ratio is different from the pre-injection and main injection step ratio.

The transition stage ratio can change continuously as engine performance changes within the transition range.

The continuous change may be such that the portion of the total fuel flow to the fuel injectors that is attributable to the fuel flow to the pilot injectors decreases as engine power increases, and the portion of the total fuel flow to the fuel injectors that is attributable to the fuel flow to the main injectors decreases , increases with increasing engine power within the operational transition area.

The transition staging ratio may vary between a series of constant intermediate values, each different from the pre-injection and main injection staging ratios. Any intermediate value can lie between that of the pure pilot injection and that of the pilot and main injection.

• Bestimmen eines oder mehrerer Kraftstoffmerkmale eines Kraftstoffs, der dem gestuften Verbrennungssystem zugeführt wird;
• Bestimmen eines Stufenverhältnisses, das das Verhältnis des Kraftstoffflusses der Voreinspritzdüse zum Kraftstofffluss der Haupteinspritzdüse definiert, wobei das Stufenverhältnis entsprechend einem oder mehreren Kraftstoffmerkmalen bestimmt wird; und
• Steuerung des gestuften Verbrennungssystems entsprechend dem ermittelten Stufenverhältnis.

According to a thirteenth aspect, there is provided a gas turbine engine having a staged combustion system with pilot injectors and main injectors, the staged combustion system operable in a pilot injection only operating region and a pilot and main injection operating region, the method comprising:

• determining one or more fuel characteristics of a fuel supplied to the staged combustion system;
• determining a step ratio that defines the ratio of the pilot injector fuel flow to the main injector fuel flow, the step ratio being determined according to one or more fuel characteristics; and
• Control of the staged combustion system according to the determined stage ratio.

One or more fuel characteristics may indicate that the fuel has lower nvPM production compared to fossil kerosene.

• (i) einen prozentualen Anteil an nachhaltigem Flugkraftstoff im Kraftstoff;
• (ii) den Gehalt an aromatischen Kohlenwasserstoffen im Kraftstoff; und/oder
• (iii) Naphthalin-Gehalt des Kraftstoffs.

Fuel characteristics may include one or more of the following:

• (i) a percentage of sustainable aviation fuel in the fuel;
• (ii) the aromatic hydrocarbon content of the fuel; and or
• (iii) Naphthalene content of the fuel.

Determining the step ratio may include determining a transition step ratio; and the control of the staged combustion system may consist of controlling the staged combustion system to operate in a transition region between the pilot injection only operating region and the pilot and main injection operating region. Within the transitional operating region, the staged combustion system may be controlled according to the transitional stage ratio, wherein the transitional stage ratio may be different from a pilot and main injection operating region according to which the staged combustion chamber is controlled during the pilot and main injection operating region.

The transition stage ratio can change continuously as engine performance changes within the transition range.

The continuous change may be such that the portion of the total fuel flow to the injectors that is attributable to the fuel flow to the pilot injectors decreases as engine power increases, and the portion of the total fuel flow to the injectors that is attributable to the fuel flow to the main injectors decreases , increases with increasing engine power within the transition area.

The transition step ratio can vary between a series of constant intermediate values, each of which differs from the ratio of the pilot and main injection. Any intermediate value can lie between that of the area with pilot injection only and that of the area with pilot and main injection.

According to a fourteenth aspect, there is provided an aircraft comprising one or more gas turbine engines according to the thirteenth aspect and optionally one or more of the above-mentioned related statements.

• das Luftfahrzeug umfasst eine erste Kraftstoffquelle, die geeignet ist, einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal zu enthalten, und eine zweite Kraftstoffquelle, die geeignet ist, einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal zu enthalten, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet;
• das Luftfahrzeug umfasst ein oder mehrere Gasturbinentriebwerke, die mit Kraftstoff aus der ersten und zweiten Kraftstoffquelle betrieben werden;
• die ein oder mehreren Gasturbinentriebwerke jeweils ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen umfassen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist;
• das eine oder die mehreren Gasturbinentriebwerke jeweils einen Kraftstoff-Zufuhrregler umfassen, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen von der ersten Kraftstoffquelle und der zweiten Kraftstoffquelle steuert,
• wobei das Verfahren umfasst:
  • Erhalten einer vorgeschlagenen Missionsbeschreibung mit einer Liste von Betriebspunkten für das eine oder mehrere Gasturbinentriebwerke während der Mission;
  • Ermitteln von nvPM-Einflussparametern (nichtflüchtige Partikel) für das eine oder die mehreren Gasturbinentriebwerke, wobei die Einflussparameter mit jedem Betriebspunkt der vorgeschlagenen Mission in Verbindung stehen, bei der Kraftstoff aus der ersten Kraftstoffquelle, Kraftstoff aus der zweiten Kraftstoffquelle oder eine Mischung daraus verwendet wird;
  • Berechnen eines optimierten Satzes von einem oder mehreren Kraftstoffmerkmalen für jeden Betriebspunkt der vorgeschlagenen Mission, die in der Missionsbeschreibung definiert ist, auf der Grundlage der nvPM-Einflussparameter; und
  • Bestimmen einer Kraftstoffzuteilung auf der Grundlage des optimierten Satzes von einem oder mehreren Kraftstoffmerkmalen.

According to a fifteenth aspect, there is provided a computer-implemented method for determining fuel allocation for an aircraft, wherein:

• the aircraft includes a first fuel source suitable for containing a first fuel having a first fuel characteristic and a second fuel source suitable for containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first;
• the aircraft includes one or more gas turbine engines operating on fuel from the first and second fuel sources;
• the one or more gas turbine engines each include a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in an operating region with pilot injection only and an operating region with pilot and main injection;
• the one or more gas turbine engines each include a fuel supply regulator arranged to control the supply of fuel to the pilot and main injectors from the first fuel source and the second fuel source,
• wherein the method includes:
  • Obtaining a proposed mission description including a list of operating points for the one or more gas turbine engines during the mission;
  • determining nvPM (non-volatile particulate matter) impact parameters for the one or more gas turbine engines, the impact parameters being associated with each operating point of the proposed mission using fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof;
  • calculating an optimized set of one or more fuel characteristics for each operating point of the proposed mission defined in the mission description based on the nvPM influence parameters; and
  • Determining a fuel allocation based on the optimized set of one or more fuel characteristics.

The inventors have discovered that by calculating fuel allocation in this manner, the fuel for a mission can be allocated in such a way that the aircraft can be provided with fuel with the necessary characteristics to enable it to carry out the proposed mission while mitigating the effects of the nvPM can be reduced. In this way, the properties of the available fuel can be better used to reduce the nvPM value than loading a specific amount of different types of fuel, regardless of the mission to be carried out with that fuel.

The first fuel feature may be associated with nvPM production that is lower than that of the second fuel feature.

Additionally or alternatively, the first fuel characteristic and the second fuel characteristic can be a percentage of SAF in the respective fuel.

Each operating point of the mission description may include one or more of the following: one or more operating conditions under which the gas turbine engines are to operate, one or more fuel flow rate values corresponding to an operating point, and/or a period of operation at one corresponding operating point.

The nvPM influence parameters may include an nvPM influence parameter that defines the amount of nvPM produced by the respective gas turbine engine under different fuel characteristics, including the first fuel, the second fuel, or a mixture thereof, at each operating point of the flight description.

• i) eine Kraftstoffmenge, die jeweils der ersten und der zweiten Kraftstoffquelle zugeordnet ist;
• ii) das erste Kraftstoffmerkmal;
• iii) das zweite Kraftstoffmerkmal; und/oder
• iv) ein Kraftstoff-Mischungsverhältnis.

Fuel allocation may include one or more of the following:

• i) an amount of fuel associated with each of the first and second fuel sources;
• ii) the first fuel feature;
• iii) the second fuel feature; and or
• iv) a fuel mixture ratio.

• i) eine Misch-Ablaufplanung, nach der Kraftstoff aus der ersten Kraftstoffquelle und der zweiten Kraftstoffquelle durch den Kraftstofflieferungsregler gemischt wird;
• ii) eine Umschalt-Ablaufplanung, nach der der Kraftstofflieferungsregler so konfiguriert ist, dass er zwischen der Lieferung von Kraftstoff aus der ersten Kraftstoffquelle und der zweiten Kraftstoffquelle umschaltet;
• iii) eine Aufteilung der im Luftfahrzeug vorhandenen Kraftstofftanks, um die erste Kraftstoffquelle und die zweite Kraftstoffquelle zu bilden; und/oder
• iv) eine Absperrventileinstellung für Kraftstofftanks, die die erste Kraftstoffquelle und die zweite Kraftstoffquelle bilden.

The method may further include determining one or more fuel consumption parameters corresponding to the fuel allocation. The fuel consumption parameters can be set how the fuel is to be used during the mission defined by the mission description. The one or more fuel consumption parameters may include one or more of the following parameters:

• i) a mixing schedule in which fuel from the first fuel source and the second fuel source is mixed by the fuel delivery controller;
• ii) a switching scheduling in which the fuel delivery controller is configured to switch between delivering fuel from the first fuel source and the second fuel source;
• iii) a division of the fuel tanks present in the aircraft to form the first fuel source and the second fuel source; and or
• iv) a shut-off valve setting for fuel tanks constituting the first fuel source and the second fuel source.

• i) der erreichbare Bereich von Kraftstoffmerkmalen, der durch den Kraftstofflieferungsregler bereitgestellt werden kann;
• ii) eine Gesamtmenge eines nicht standardmäßigen Kraftstoffs, die der Mission zugewiesen wurde;
• iii) einen Gesamtbedarf an Kraftstoff für die Mission;
• iv) das Fassungsvermögen der Kraftstofftanks des Luftfahrzeugs; und/oder
• v) Beschränkungen, wie die Kraftstofftanks des Luftfahrzeugs der ersten oder der zweiten Kraftstoffquelle zugeordnet werden können.

The optimized set of one or more fuel characteristics may be further determined based on one or more of the following criteria:

• i) the achievable range of fuel characteristics that can be provided by the fuel delivery controller;
• ii) a total amount of non-standard fuel allocated to the mission;
• iii) a total fuel requirement for the mission;
• (iv) the capacity of the aircraft's fuel tanks; and or
• v) Restrictions on how the aircraft's fuel tanks can be assigned to the first or second fuel source.

Calculating the optimized set of one or more fuel characteristics may include minimizing a cost function that depends on the one or more nvPM influencing parameters.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Ort der nvPM-Produktion;
• iii) Wetter- und/oder Witterungsbedingungen an einem Ort der nvPM-Produktion;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion;
• v) Masse/Größe der einzelnen erzeugten nvPM-Partikel;
• vi) mögliche Kondensstreifenproduktion und/oder Kondensstreifenmerkmale;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) Menge des produzierten nvPM (z. B. Masse und/oder Anzahl).

The one or more nvPM influence parameters may include one or more of the following parameters:

• i) height above ground at which nvPM production takes place;
• ii) location of nvPM production;
• iii) Weather and/or weather conditions at a nvPM production location;
• iv) climate impacts associated with the location of nvPM production;
• v) mass/size of each nvPM particle produced;
• vi) possible contrail production and/or contrail features;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) Amount of nvPM produced (e.g. mass and/or number).

• Bestimmung einer Zuteilung von Kraftstoff unter Verwendung des Verfahrens des fünfzehnten Aspekts und optional einer oder mehrerer der oben genannten zugehörigen Aussagen;und
• Beladung des Luftfahrzeugs mit Kraftstoff entsprechend der Kraftstoffzuteilung.

According to a sixteenth aspect, there is provided a method for loading fuel into an aircraft, comprising:

• Determining an allocation of fuel using the method of the fifteenth aspect and optionally one or more of the above associated statements; and
• Loading the aircraft with fuel according to the fuel allocation.

According to a seventeenth aspect, there is provided a non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform the method of the fifteenth aspect and, optionally, one or more of the above-mentioned associated statements.

According to an eighteenth aspect, there is provided a fuel allocation determination system for an aircraft, the fuel allocation determination system comprising a computing device configured to carry out the method of the fifteenth aspect and optionally one or more of the above-mentioned associated statements .

• das Luftfahrzeug eine erste Kraftstoffquelle umfasst, die einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal enthalten kann, und eine zweite Kraftstoffquelle, die einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal enthalten kann, wobei sich das zweite Kraftstoffmerkmal vom ersten unterscheidet;
• das Luftfahrzeug ein oder mehrere Gasturbinentriebwerke umfasst, die mit Kraftstoff aus der ersten und zweiten Kraftstoffquelle betrieben werden;
• die ein oder mehreren Gasturbinentriebwerke jeweils ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen umfassen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist;
• die ein oder mehreren Gasturbinentriebwerke jeweils einen Kraftstoff-Zufuhrregler umfassen, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen von der ersten und der zweiten Kraftstoffquelle steuert,
• wobei das System zur Bestimmung von Kraftstoff-Beladungsparametern umfasst:
  • ein Modul zum Erhalten einer Missionsbeschreibung, das so konfiguriert ist, dass es eine vorgeschlagene Missionsbeschreibung erhält, die eine Liste von Betriebsbedingungen für das eine oder die mehreren Gasturbinentriebwerke während der Mission umfasst;
  • ein Modul zur Ermittlung von Einflussparametern, das so konfiguriert ist, dass es nvPM-Einflussparameter für das eine oder die mehreren Gasturbinentriebwerke erhält, wobei die Einflussparameter jedem Betriebspunkt der vorgeschlagenen Mission unter Verwendung von Kraftstoffzusammensetzungen zugeordnet sind, die Kraftstoff aus der ersten Kraftstoffquelle, Kraftstoff aus der zweiten Kraftstoffquelle oder eine Mischung davon umfassen;
  • ein Kraftstoffmerkmal-Berechnungsmodul, das so konfiguriert ist, dass es einen optimierten Satz von einem oder mehreren Kraftstoffmerkmalen für jeden Betriebspunkt der vorgeschlagenen Mission, die in der Missionsbeschreibung definiert ist, auf der Grundlage der nvPM-Einflussparameter berechnet; und
  • ein Modul zur Bestimmung der Kraftstoffzuteilung, das so konfiguriert ist, dass es eine Kraftstoffzuteilung auf der Grundlage des optimierten Satzes von einem oder mehreren Kraftstoffmerkmalen bestimmt.

According to a nineteenth aspect, there is provided a fuel allocation determining system for an aircraft in which a fuel allocation is determined, wherein:

• the aircraft includes a first fuel source, which may include a first fuel with a first fuel characteristic, and a second fuel source, which may include a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first;
• the aircraft includes one or more gas turbine engines operating on fuel from the first and second fuel sources;
• the one or more gas turbine engines each have a staged combustion system Include pilot injectors and main injectors, wherein the staged combustion system is operable in an operating range with pilot injection only and an operating range with pilot and main injection;
• the one or more gas turbine engines each include a fuel supply regulator arranged to control the supply of fuel to the pilot and main injectors from the first and second fuel sources,
• wherein the system for determining fuel loading parameters comprises:
  • a mission description obtaining module configured to obtain a proposed mission description that includes a list of operating conditions for the one or more gas turbine engines during the mission;
  • an influence parameter determination module configured to obtain nvPM influence parameters for the one or more gas turbine engines, the influence parameters associated with each operating point of the proposed mission using fuel compositions that include fuel from the first fuel source, fuel from the second fuel source or a mixture thereof;
  • a fuel characteristic calculation module configured to calculate an optimized set of one or more fuel characteristics for each operating point of the proposed mission defined in the mission description based on the nvPM influence parameters; and
  • a fuel allocation determination module configured to determine a fuel allocation based on the optimized set of one or more fuel characteristics.

The first fuel feature may be associated with nvPM production that is lower than that of the second fuel feature.

Additionally or alternatively, the first fuel characteristic and the second fuel characteristic can be the percentage of SAF in the respective fuel.

Each of the operating points of the mission description received from the mission description obtaining module may include one or more of the following: one or more operating conditions under which the gas turbine engines are to be operated, one or more fuel flow rate values corresponding to an operating point, and /or a period of operation at a corresponding operating point.

The nvPM influence parameters obtained by the influence parameter determination module may include an nvPM influence parameter that defines the amount of nvPM produced by the gas turbine engines for various fuel characteristics that include the first fuel, the second fuel, or a mixture thereof at each operating point of the mission description include.

• i) eine Kraftstoffmenge, die jeweils der ersten und der zweiten Kraftstoffquelle zugeordnet ist;
• ii) das erste Kraftstoffmerkmal;
• iii) das zweite Kraftstoffmerkmal; und/oder
• iv) ein Kraftstoff-Mischungsverhältnis.

The fuel allocation determined by the fuel allocation determination module may include one or more of the following elements:

• i) an amount of fuel associated with each of the first and second fuel sources;
• ii) the first fuel feature;
• iii) the second fuel feature; and or
• iv) a fuel mixture ratio.

The fuel allocation determination system may further include a fuel consumption parameter determination module configured to determine one or more fuel consumption parameters corresponding to the fuel allocation, the fuel consumption parameters defining how the fuel is consumed during the fuel allocation the mission defined by the mission description is to be used.

• i) eine Misch-Ablaufplanung, nach der Kraftstoff aus der ersten Kraftstoffquelle und der zweiten Kraftstoffquelle durch den Kraftstofflieferungsregler gemischt wird;
• ii) eine Umschalt-Ablaufplanung, nach der der Kraftstofflieferungsregler so konfiguriert ist, dass er zwischen der Lieferung von Kraftstoff aus der ersten Kraftstoffquelle und der zweiten Kraftstoffquelle umschaltet;
• iii) eine Aufteilung der im Luftfahrzeug vorhandenen Kraftstofftanks, um die erste Kraftstoffquelle und die zweite Kraftstoffquelle zu bilden; und/oder
• iv) eine Absperrventileinstellung für Kraftstofftanks, die die erste Kraftstoffquelle und die zweite Kraftstoffquelle bilden.

The one or more fuel consumption parameters may optionally include one or more of the following parameters:

• i) a mixing schedule in which fuel from the first fuel source and the second fuel source is mixed by the fuel delivery controller;
• ii) a switching scheduling in which the fuel delivery controller is configured to switch between delivering fuel from the first fuel source and the second fuel source;
• iii) a division of the fuel tanks present in the aircraft to form the first fuel source and the second fuel source; and or
• iv) a shut-off valve setting for fuel tanks constituting the first fuel source and the second fuel source.

• i) der erreichbare Bereich von Kraftstoffmerkmalen, der durch den Kraftstofflieferungsregler bereitgestellt werden kann;
• ii) eine Gesamtmenge eines nicht standardmäßigen Kraftstoffs, die der Mission zugewiesen wurde;
• iii) den Gesamtbedarf an Kraftstoff für die Mission;
• iv) das Fassungsvermögen der Kraftstofftanks des Luftfahrzeugs; und/oder
• v) Beschränkungen, wie die Kraftstofftanks des Luftfahrzeugs der ersten oder der zweiten Kraftstoffquelle zugeordnet werden können.

The optimized set of one or more fuel characteristics derived from the fuel feature calculation module may further be determined based on one or more of the following criteria:

• i) the achievable range of fuel characteristics that can be provided by the fuel delivery controller;
• ii) a total amount of non-standard fuel allocated to the mission;
• iii) the total fuel requirements for the mission;
• (iv) the capacity of the aircraft's fuel tanks; and or
• v) Restrictions on how the aircraft's fuel tanks can be assigned to the first or second fuel source.

The fuel feature calculation module may be configured to calculate the optimized set of one or more fuel features by minimizing a cost function depending on one or more nvPM influencing parameters.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Ort der nvPM-Produktion;
• iii) Wetter- und/oder Witterungsbedingungen an einem Ort der nvPM-Produktion;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion;
• v) Masse der erzeugten nvPM-Partikel;
• vi) mögliche Kondensstreifenproduktion und/oder Kondensstreifenmerkmale;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) Menge des produzierten nvPM (z. B. Masse/Anzahl).

The one or more nvPM influence parameters may include one or more of the following parameters:

• i) height above ground at which nvPM production takes place;
• ii) location of nvPM production;
• iii) Weather and/or weather conditions at a nvPM production location;
• iv) climate impacts associated with the location of nvPM production;
• v) mass of nvPM particles generated;
• vi) possible contrail production and/or contrail features;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) Amount of nvPM produced (e.g. mass/number).

• eine erste Kraftstoffquelle, die geeignet ist, einen ersten Kraftstoff mit einem ersten Kraftstoffmerkmal zu enthalten, und eine zweite Kraftstoffquelle, die geeignet ist, einen zweiten Kraftstoff mit einem zweiten Kraftstoffmerkmal zu enthalten, wobei sich das zweite Kraftstoffmerkmal von dem ersten unterscheidet;
• ein oder mehrere Gasturbinentriebwerke, die mit Kraftstoff aus der ersten und zweiten Kraftstoffquelle betrieben werden, wobei:
  • die ein oder mehreren Gasturbinentriebwerke jeweils ein gestuftes Verbrennungssystem mit Voreinspritzdüsen und Haupteinspritzdüsen umfassen, wobei das gestufte Verbrennungssystem in einem Betriebsbereich nur mit Voreinspritzung und einem Betriebsbereich mit Vor- und Haupteinspritzung betreibbar ist;
  • das eine oder die mehreren Gasturbinentriebwerke jeweils einen Kraftstoff-Zufuhrregler umfassen, der so angeordnet ist, dass er die Zufuhr von Kraftstoff zu den Vor- und Haupteinspritzdüsen aus der ersten Kraftstoffquelle, der zweiten Kraftstoffquelle oder einer Mischung davon steuert; und
  • ein System zur Bestimmung der Kraftstoffzuteilung gemäß dem achtzehnten oder neunzehnten Aspekt und optional eine oder mehrere der oben genannten zugehörigen Aussagen.

According to a twentieth aspect, there is provided an aircraft comprising:

• a first fuel source suitable for containing a first fuel having a first fuel characteristic and a second fuel source suitable for containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first;
• one or more gas turbine engines operating on fuel from the first and second fuel sources, wherein:
  • the one or more gas turbine engines each include a staged combustion system with pilot injectors and main injectors, the staged combustion system being operable in an operating region with pilot injection only and an operating region with pilot and main injection;
  • the one or more gas turbine engines each include a fuel supply controller arranged to control the supply of fuel to the pilot and main injectors from the first fuel source, the second fuel source, or a mixture thereof; and
  • a system for determining fuel allocation according to the eighteenth or nineteenth aspect and optionally one or more of the above-mentioned related statements.

• Erhalten einer anfänglich vorgeschlagenen Kraftstoff-Zuweisung für jede der mehreren Missionen;
• Durchführen einer flottenweiten Optimierung, bei der die vorgeschlagene Kraftstoffzuteilung jeder der mehreren Missionen innerhalb der Beschränkungen des gesamten verfügbaren Standard- und/oder Nicht-Standard-Kraftstoffs von der Kraftstoffquelle modifiziert wird, um eine Summe von nvPM-Einflussparametern pro Mission über alle der mehreren Missionen zu minimieren, wobei jede der mehreren Missionen mit einem jeweiligen nvPM-Einflussparameter pro Mission verbunden ist, der gemäß einem Kraftstoffverbrauch für diese Mission bestimmt wird, wobei der Kraftstoffverbrauch definiert, wie die Kraftstoffzuteilung für die jeweilige Mission während dieser Mission zu verwenden ist; und
• Bestimmung der flottenweiten Kraftstoffzuteilung für die Vielzahl der Einsätze auf der Grundlage der flottenweiten Optimierung.

According to a twentieth aspect, there is provided a computer-implemented method for determining a fleet-wide fuel allocation for a plurality of missions conducted by a plurality of aircraft, the plurality of missions being fueled from a fuel source containing an amount of a standard fuel and a amount of a non-standard fuel, the fuel allocation indicating the amount of the non-standard fuel and the standard fuel to be allocated to each of the plurality of missions, the standard fuel and the non-standard fuel having one or more fuel characteristics that differ from one another, wherein the method includes:

• obtaining an initial suggested fuel allocation for each of the plurality of missions;
• Performing a fleet-wide optimization in which the proposed fuel allocation of each of the multiple missions is modified, within the constraints of the total available standard and/or non-standard fuel from the fuel source, by a sum of nvPM influence parameters per mission across all of the multiple missions to minimize, each of the plurality of missions being associated with a respective nvPM impact parameter per mission determined according to a fuel consumption for that mission, the fuel consumption defining how the fuel allocation for the respective mission is to be used during that mission; and
• Determine fleet-wide fuel allocation for the variety of missions based on fleet-wide optimization.

The inventors have determined that available fuel for a variety of missions can be intelligently divided between those missions to take advantage of different types of available fuel. This allows fuel, of which there is less available, to be divided between missions for more effective use, e.g. B. in such a way that the overall nvPM impact of the missions is reduced.

The non-standard fuel may be associated with lower nvPM production than the standard fuel.

The non-standard fuel may be formed from a mixture of a first fuel having a first fuel characteristic and a second fuel having a second fuel characteristic different from the first.

The first and second fuel characteristics may be a percentage of SAF in the respective fuel. The non-standard fuel may be a SAF-rich fuel and the standard fuel may be a relatively low-SAF fuel (i.e., having a lower SAF content compared to the SAF-rich fuel).

• i) Durchführen einer Optimierung in einer äußeren Schleife, bei der die Kraftstoffzuteilung einer oder mehrerer der mehreren Missionen variiert wird, um die Summe der nvPM-Einflussparameter pro Mission der mehreren Missionen zu verringern; und
• ii) Durchführen einer Optimierung in einer inneren Schleife, bei der der Kraftstoffverbrauch für jede der mehreren Missionen entsprechend den Einschränkungen der variierten Kraftstoffzuteilung ermittelt wird, um einen neuen vorgeschlagenen Kraftstoffverbrauch für jede der mehreren Missionen zu bestimmen.

Performing fleet-wide optimization may include:

• i) performing an outer loop optimization in which the fuel allocation of one or more of the plurality of missions is varied to reduce the sum of the nvPM influence parameters per mission of the plurality of missions; and
• ii) performing an inner loop optimization in which the fuel consumption for each of the multiple missions is determined according to the constraints of the varied fuel allocation to determine a new proposed fuel consumption for each of the multiple missions.

Steps i) and ii) can be repeated until an optimized fuel consumption is determined for each of the multiple missions, which corresponds to a minimized sum of the nvPM influence parameters per mission.

Optimization in the inner loop may consist of obtaining a prepared fuel consumption solution for a specific mission.

The proposed fuel allocation for each of the multiple missions may be determined by determining an optimized fuel consumption for the particular mission, determining how the fuel is to be used to minimize the per-mission nvPM impact parameter for that mission.

The optimized fuel consumption for each mission can be determined by optimizing per mission.

• Bestimmung des Typs und/oder der Betriebsfähigkeiten einer Verbrennungsanlage,
• die von dem jeweiligen Luftfahrzeug für den Einsatz verwendet wird;
• Bestimmung des gesamten Kraftstoffbedarfs für die jeweilige Mission; Bestimmung der Kraftstoffmenge, die für jeden Typ von Einspritzdüsen in der Brennkammer für den jeweiligen Einsatz erforderlich ist, wenn mehr als ein Typ von Einspritzdüsen vorhanden ist;
• Bestimmung der Abhängigkeit der nvPM-Emissionen für jeden Triebwerksbetriebspunkt der Mission unter Verwendung eines Kraftstoffs mit den Merkmalen des Standardkraftstoffs, eines Nicht-Standardkraftstoffs oder eines Gemischs davon; und
• Bestimmung eines optimierten Kraftstoffverbrauchs, der die gesamten nvPM-Emissionen für die jeweilige Mission minimiert.

Per-mission optimization can include the following for each individual mission:

• Determination of the type and/or operational capabilities of an incinerator,
• which is used by the respective aircraft for the mission;
• Determine total fuel requirements for each mission; determining the amount of fuel required for each type of injector in the combustion chamber for the particular application when more than one type of injector is present;
• Determination of the dependence of nvPM emissions for each engine operating point of the mission using a fuel with the characteristics of the standard fuel, a non-standard fuel or a mixture thereof; and
• Determine optimized fuel consumption that minimizes total nvPM emissions for the specific mission.

Determining a type of combustion system used by the aircraft may consist of determining whether the aircraft has a lean-burn combustor or a rich-burn combustor.

1. a) die Bestimmung der Kraftstoffmenge, die für die Voreinspritzdüsen während des Betriebs mit Vor- und Haupteinspritzung erforderlich ist; und/oder
2. b) Bestimmung einer Kraftstoffmenge, die für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung erforderlich ist; und/oder
3. c) Bestimmung der Kraftstoffmenge, die für die Voreinspritzdüsen erforderlich ist, die innerhalb eines Schwellenbereichs des Betriebs bei Durchflussraten unterhalb des Stufenpunkts arbeiten.

If it is a lean combustion chamber with pilot injectors and main injectors, the amount of fuel required for each type of injectors can be determined:

1. a) determining the amount of fuel required for the pilot injectors during operation with pilot and main injection; and or
2. b) determining an amount of fuel required for the pilot injectors during operation with pilot injection only; and or
3. c) Determine the amount of fuel required for the pilot injectors operating within a threshold range of operation at flow rates below the step point.

• einen Prozentsatz eines ersten Kraftstoffs mit einem ersten Kraftstoffmerkmal innerhalb des Standardkraftstoffs, der den geringstmöglichen Prozentsatz an Kraftstoff mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann; und/oder
• einen prozentualen Anteil des ersten Kraftstoffs mit dem ersten Kraftstoffmerkmal innerhalb des Nicht-Standardkraftstoffs, der den höchstmöglichen Prozentsatz des Kraftstoffs mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann; und/oder
• die Menge an nicht standardmäßigem Kraftstoff, die für die Vielzahl der Einsätze zur Verfügung steht.

Fleet-wide optimization can be based on the following factors:

• a percentage of a first fuel with a first fuel characteristic within the standard fuel that defines the lowest possible percentage of fuel with the first fuel characteristic that can be used for combustion; and or
• a percentage of the first fuel with the first fuel characteristic within the non-standard fuel that defines the highest possible percentage of the fuel with the first fuel characteristic that can be used for combustion; and or
• the amount of non-standard fuel available for the variety of missions.

• Bestimmen der Zuweisung von Kraftstoff für die Vielzahl von Missionen unter Verwendung des Verfahrens des einundzwanzigsten Aspekts und optional einer oder mehrerer der oben genannten zugehörigen Aussagen; und
• Beladen der Luftfahrzeuge mit Kraftstoff entsprechend der Kraftstoffzuteilung.

According to a twenty-second aspect, a method for loading fuel into a plurality of aircraft performing a plurality of missions is provided, the plurality of missions being supplied with fuel from a fuel source containing an amount of a standard fuel and an amount of a non-standard fuel comprises, the method comprising:

• determining the allocation of fuel for the plurality of missions using the method of the twenty-first aspect and optionally one or more of the above-mentioned associated statements; and
• Loading the aircraft with fuel according to the fuel allocation.

According to a twenty-third aspect, there is provided a non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform the method of the twenty-first aspect and, optionally, one or more of the above-mentioned associated instructions.

According to a twenty-fourth aspect, there is provided a fleet-wide fuel allocation determination system for determining fleet fuel allocation for a plurality of missions, the fleet-wide fuel allocation determination system comprising a computing device configured to implement the method of the twenty-first aspect and optionally a or performs more than one of the above-mentioned related statements.

• ein Modul zum Erhalten einer anfänglich vorgeschlagenen Kraftstoffzuteilung, das so konfiguriert ist, dass es eine anfänglich vorgeschlagene Kraftstoffzuteilung für jede der Vielzahl von Missionen erhält;
• ein flottenweites Optimierungsmodul, das so konfiguriert ist, dass es eine flottenweite Optimierung durchführt, bei der die vorgeschlagene Kraftstoffzuteilung jeder der mehreren Missionen innerhalb der Beschränkungen des gesamten verfügbaren Standard- und/oder Nicht-Standard-Kraftstoffs von der Kraftstoffquelle modifiziert wird, um eine Summe von nvPM-Einflussparametern pro Mission über alle der mehreren Missionen zu minimieren, wobei jede der mehreren Missionen mit einem jeweiligen nvPM-Einflussparameter pro Mission verbunden ist, der gemäß einem vorgeschlagenen Kraftstoffverbrauch für diese Mission bestimmt wird, wobei der Kraftstoffverbrauch definiert, wie die Kraftstoffzuteilung für die jeweilige Mission während dieser Mission zu verwenden ist; und
• ein Modul zur Bestimmung der flottenweiten Kraftstoffzuteilung, das so konfiguriert ist, dass es die flottenweite Kraftstoffzuteilung für die Vielzahl der Einsätze auf der Grundlage der flottenweiten Optimierung bestimmt.

According to a twenty-fifth aspect, a fleet-wide fuel allocation determination system is provided for determining fuel allocation for a plurality of missions conducted by a plurality of aircraft, the plurality of missions being supplied with fuel from a fuel source containing an amount of a standard fuel and an amount a non-standard fuel, the fuel allocation indicating the amount of the non-standard fuel and the standard fuel to be allocated to each of the plurality of missions, the standard fuel and the non-standard fuel having one or more different fuel characteristics, the system comprising :

• an initial proposed fuel allocation obtaining module configured to obtain an initial proposed fuel allocation for each of the plurality of missions;
• a fleet-wide optimization module configured to perform a fleet-wide optimization in which the proposed fuel allocation of each of the multiple missions is modified by a sum within the constraints of the total available standard and/or non-standard fuel from the fuel source of nvPM influence parameters per mission across all of the multiple missions, each of the multiple missions being associated with a respective nvPM influence parameter per mission determined according to a proposed fuel consumption for that mission, the fuel consumption defining how the fuel allocation for the respective mission is to be used during this mission; and
• a fleet-wide fuel allocation determination module configured to determine fleet-wide fuel allocation for the variety of missions based on fleet-wide optimization.

The non-standard fuel may be associated with lower nvPM production than the standard fuel.

The non-standard fuel may be formed from a mixture of a first fuel having a first fuel characteristic and a second fuel having a second fuel characteristic different from the first.

The first and second fuel characteristics may be a percentage of SAF in the respective fuel, where the non-standard fuel may be a SAF-rich fuel and the standard fuel may be a relatively low-SAF fuel.

• i) Durchführen einer Optimierung in einer äußeren Schleife, bei der die Kraftstoffzuteilung einer oder mehrerer der mehreren Missionen variiert wird, um die Summe der nvPM-Einflussparameter pro Mission der mehreren Missionen zu verringern; und
• ii) Durchführung einer Optimierung in einer inneren Schleife, bei der der Kraftstoffverbrauch für jede der mehreren Missionen gemäß den Einschränkungen der variierten Kraftstoffzuteilung ermittelt wird, um einen neuen vorgeschlagenen Kraftstoffverbrauch für jede der mehreren Missionen zu bestimmen.

The fleet-wide optimization module can be configured to perform the following steps:

• i) performing an outer loop optimization in which the fuel allocation of one or more of the plurality of missions is varied to reduce the sum of the nvPM influence parameters per mission of the plurality of missions; and
• ii) Performing an inner loop optimization in which the fuel consumption for each of the multiple missions is determined according to the constraints of the varied fuel allocation to determine a new proposed fuel consumption for each of the multiple missions.

The fleet-wide optimization module may be configured to repeat steps i) and ii) until an optimized fuel consumption is determined for each of the multiple missions, which corresponds to a minimized sum of the nvPM influencing parameters per mission.

The fleet-wide optimization module may be configured to perform inner loop optimization by obtaining a prepared fuel consumption solution for a specific mission.

The fleet-wide optimization module may be configured to determine the proposed fuel allocation for each of the multiple missions by determining an optimized fuel consumption for the respective mission, which determines how the fuel is to be used to determine the nvPM impact per mission parameter for to minimize this mission.

• Bestimmung des Typs und/oder der Betriebsfähigkeiten einer Verbrennungsanlage, die von dem jeweiligen Luftfahrzeug für den Einsatz verwendet wird;
• Bestimmung des gesamten Kraftstoffbedarfs für die jeweilige Mission;
• Bestimmung der Kraftstoffmenge, die für jeden Typ von Einspritzdüsen in der Brennkammer für den jeweiligen Einsatz erforderlich ist, wenn mehr als ein Typ von Einspritzdüsen vorhanden ist;
• Bestimmung der Abhängigkeit der nvPM-Emissionen für jeden Betriebspunkt des Triebwerks der Mission unter Verwendung eines Kraftstoffs mit den Merkmalen des Standardkraftstoffs, eines Nicht-Standardkraftstoffs oder einer Mischung davon; und Bestimmung eines optimierten Kraftstoffverbrauchs, der die gesamten nvPM-Emissionen für die jeweilige Mission minimiert.

The fleet-wide optimization module may be configured to determine the optimized fuel consumption for each mission by performing a per-mission optimization, where the per-mission optimization optionally includes for each respective mission:

• Determine the type and/or operational capabilities of an incinerator used by the particular aircraft for the mission;
• Determine total fuel requirements for each mission;
• determining the amount of fuel required for each type of injector in the combustion chamber for the particular application when more than one type of injector is present;
• Determination of the dependence of nvPM emissions for each operating point of the mission engine using a fuel with the characteristics of the standard fuel, a non-standard fuel or a mixture thereof; and determining optimized fuel consumption that minimizes total nvPM emissions for the specific mission.

Determining the type of combustion system used by the aircraft may consist of determining whether the aircraft has a staged lean combustion chamber or a rich combustion chamber.

• Bestimmung der Kraftstoffmenge, die für die Voreinspritzdüsen während des Betriebs mit Vor- und Haupteinspritzung erforderlich ist; und/oder
• Bestimmung der Kraftstoffmenge, die für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung erforderlich ist; und/oder
• Bestimmung der Kraftstoffmenge, die für die Voreinspritzdüsen benötigt wird, die innerhalb eines Schwellenbereichs des Betriebs bei Durchflussraten unterhalb des Stufenpunkts arbeiten.

If the combustion chamber is a lean burn chamber with pilot injectors and main injectors, determining the amount of fuel required for each type of injector may include:

• Determination of the amount of fuel required for the pilot injectors during operation with pilot and main injection; and or
• Determining the amount of fuel required for the pilot injectors during pilot-only operation; and or
• Determine the amount of fuel required for the pilot injectors operating within a threshold range of operation at flow rates below the stage point.

• einen Prozentsatz eines ersten Kraftstoffs mit einem ersten Kraftstoffmerkmal innerhalb des Standardkraftstoffs, der den geringstmöglichen Prozentsatz an Kraftstoff mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann; und/oder
• einen prozentualen Anteil des ersten Kraftstoffs mit dem ersten Kraftstoffmerkmal innerhalb des Nicht-Standardkraftstoffs, der den höchstmöglichen Prozentsatz des Kraftstoffs mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann; und/oder
• die Menge an nicht standardmäßigem Kraftstoff, die für die Vielzahl der Einsätze zur Verfügung steht.

The fleet-wide optimization module can be configured so that the basis of fleet-wide optimization is based on:

• a percentage of a first fuel with a first fuel characteristic within the standard fuel that defines the lowest possible percentage of fuel with the first fuel characteristic that can be used for combustion; and or
• a percentage of the first fuel with the first fuel characteristic within the non-standard fuel that defines the highest possible percentage of the fuel with the first fuel characteristic that can be used for combustion; and or
• the amount of non-standard fuel available for the variety of missions.

The present disclosure may apply to any relevant configuration of a gas turbine engine. Such a gas turbine engine may be, for example, a turbofan gas turbine engine, an open rotor gas turbine engine (where the propeller is not surrounded by a nacelle), a turboprop engine or a turbojet engine. Each of these engines can be equipped with an afterburner, but does not have to be.

A gas turbine engine according to any aspect of the present disclosure may include an engine core having a turbine, a combustor, a compressor, and a core shaft connecting the turbine to the compressor. Such a gas turbine engine may include a fan (with blades). Such a fan can be arranged upstream of the engine core. Alternatively, in some examples, the gas turbine engine may include a fan located downstream of the engine core, such as when the gas turbine engine is an open rotor or turboprop engine (in which case the fan may be referred to as a propeller).

If the gas turbine engine is an open rotor or a turboprop engine, the gas turbine engine may include two counter-rotating propeller stages that are attached to and driven by a free power turbine via a shaft. The propellers can rotate in opposite directions, so that one rotates clockwise and the other counterclockwise about the engine's axis of rotation. Alternatively, the gas turbine engine can consist of a propeller stage and a guide vane stage, which is connected downstream of the propeller stage. The vane stage can have a variable pitch. Accordingly, high-pressure, medium-pressure and free power turbines can drive high- and medium-pressure compressors or propellers via suitable connecting shafts. This allows the propellers to provide most of the propulsion thrust.

If the gas turbine engine is an open rotor engine or a turboprop engine, one or more of the propeller stages can be driven by a gearbox. The gearbox can be of the type described here.

An engine within the meaning of the present disclosure may be a turbofan engine. Such an engine may be a direct-drive turbofan engine, in which the fan is directly connected to the fan drive turbine, for example without a gearbox. With such a direct drive engine you can say that the fan rotates at the same speed as the turbine of the fan drive.

An engine within the meaning of the present disclosure can be a geared turbofan engine. In such an arrangement, the engine has a fan that is driven by a gearbox. Accordingly, such a gas turbine engine may include a gearbox that receives drive from the core shaft and delivers drive to the fan to drive the fan at a lower speed than the core shaft. The transmission can be driven directly from the core shaft or indirectly from the core shaft, for example via a face shaft and/or a gear. The core shaft can rigidly connect the turbine and compressor so that the turbine and compressor rotate at the same speed (with the fan rotating at a lower speed).

The gas turbine engine described and/or claimed herein may have any suitable general architecture. For example, the gas turbine engine may have any number of shafts connecting turbines and compressors, for example one, two or three shafts. By way of example only, the turbine connected to the core shaft can be a first turbine, the compressor connected to the core shaft can be a first compressor, and the core shaft can be a first core shaft. The engine core may further include a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor. The second turbine, the second compressor, and the second core shaft may be arranged to rotate at a higher speed than the first core shaft.

In such an arrangement, the second compressor can be arranged axially downstream of the first compressor. The second compressor may be arranged to receive the flow of the first compressor (e.g. directly, e.g. via a generally annular conduit).

The gearbox may be set up to be driven by the core shaft that rotates (e.g. during operation) at the lowest speed (e.g. the first core shaft in the example above). For example, the gearbox may be set up to be driven only by the core shaft that is configured to rotate (e.g. during operation) at the lowest speed (e.g. only the first core shaft and not the second core wave, as in the example above). Alternatively, the gearbox can be set up to be driven by one or more shafts, e.g. B. from the first and/or second wave in the example above.

The gearbox may be a reduction gearbox (ie the output to the fan has a lower speed than the input from the core shaft). Any type of gearbox can be used. The gearing may be, for example, a “planetary” or “star” gearing, as described in more detail elsewhere herein. Such a transmission can be single-stage. Alternatively, it can be a composite gear, e.g. B. a composite planetary gear (in which the input is on the sun gear and the output is on the ring gear and which is therefore also referred to as a “composite star gear”), which z. B. has two reduction levels.

The gearbox may have any reduction ratio (defined as the speed of the input shaft divided by the speed of the output shaft), for example greater than 2.5, for example in the range of 3 to 4.2, or 3.2 to 3.8, for example of the order of or at least 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4, 1 or 4.2. The gear ratio can e.g. B. lie between two of the values mentioned in the previous sentence. As a purely example, the gearbox can be a “star” gearbox with a reduction ratio in the range of 3.1 or 3.2 to 3.8. As another example, the gearbox may be a “star” gearbox with a reduction ratio in the range of 3.0 to 3.1. As another example, the gearbox may be a “planetary gearbox” with a reduction ratio in the range of 3.6 to 4.2. In some arrangements the gear ratio may be outside of these ranges.

In any gas turbine engine as described and/or claimed herein, fuel of a particular composition or mixture is supplied to a combustor which may be located downstream of the fan and compressor(s) with respect to the flow path (e.g B. axially downstream). The combustion system can, for example, be located directly downstream (e.g. at the outlet) of the second compressor if a second compressor is provided. Another example is that the flow at the exit of the combustion chamber can be fed to the inlet of the second turbine if a second turbine is present. The combustion system can be arranged upstream of the turbine(s).

The or each compressor (e.g., the first compressor and the second compressor as described above) may include any number of stages, e.g. B. several stages. Each stage may include a series of rotor blades and a series of stator blades, which may be variable stator blades (since their angle of attack may be variable). The row of rotor blades and the row of stator blades can be axially offset from one another. The gas turbine engine can be, for example, a directly driven turbofan gas turbine engine with 13 or 14 compressor stages (in addition to the fan). Such an engine can z. B. include 3 stages in the first (or “low pressure”) compressor and either 10 or 11 stages in the second (or “high pressure”) compressor. Another example is a "geared" gas turbine engine (where the fan is driven by a first core shaft via a reduction gear) with 11, 12 or 13 compressor stages (in addition to the fan). Such an engine may consist of 3 or 4 stages in the first (or "low pressure") compressor and 8 or 9 stages in the second (or "high pressure") compressor. Another example is a geared gas turbine engine that has 4 stages in the first (or "low pressure") compressor and 10 stages in the second (or "high pressure") compressor.

The or each turbine (e.g., the first turbine and the second turbine as described above) may include any number of stages, e.g. B. several stages. Each stage may include a series of rotor blades and a series of stator blades. The row of rotor blades and the row of stator blades can be axially offset from one another. The second turbine (or “high-pressure turbine”) may consist of two stages in any arrangement (e.g., regardless of whether the engine is geared or direct drive). The gas turbine engine may be a direct drive gas turbine engine including a first (or "low pressure") turbine with 5, 6 or 7 stages. Alternatively, the gas turbine engine may be a "geared" gas turbine engine that includes a first (or "low pressure") turbine with 3 or 4 stages.

Each airfoil can be defined to have a radial span extending from a root (or hub) at a radially inner gas-swept location or 0% span position to a 100% span tip. The ratio between the radius of the airfoil at the hub and the radius of the airfoil at the tip can be less than (or on the order of): 0.4, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, 0.27, 0.26, or 0.25. The ratio between the radius of the airfoil at the hub and the radius of the airfoil at the tip may be in a range limited by any two of the values mentioned in the previous sentence (ie the values may form upper or lower limits), for example in Range from 0.28 to 0.32 or 0.29 to 0.30. These ratios can be commonly referred to as hub-to-tip ratio become. The radius at the hub and the radius at the tip can both be measured at the leading edge (or axially forward part) of the blade. The hub-to-tip ratio of course refers to the gas-surrounded portion of the airfoil, that is, the portion that is radially outside of a platform.

The radius of the fan can be measured between the centerline of the engine and the tip of an airfoil at its leading edge. The diameter of the fan (which may simply be twice the radius of the fan) may be greater than (or on the order of) one of: 140cm, 170cm, 180cm, 190cm, 200cm, 210cm, 220cm , 230cm, 240cm, 250cm (about 100 inches), 260cm, 270cm (about 105 inches), 280cm (about 110 inches), 290cm (about 115 inches), 300cm (about 120 inches), 310 cm, 320 cm (approx. 125 inches), 330 cm (approx. 130 inches), 340 cm (approx. 135 inches), 350 cm, 360 cm (approx. 140 inches), 370 cm (approx. 145 inches), 380 cm (approx 150 inches), 390 cm (approximately 155 inches), 400 cm, 410 cm (approximately 160 inches) or 420 cm (approximately 165 inches). The diameter of the fan may be in a range limited by any two of the values mentioned in the previous sentence (i.e. the values may form upper or lower limits), for example in the range of 240 cm to 280 cm or 330 cm to 380 cm. Purely by way of example, the diameter of the fan can be in a range of 170 cm to 180 cm, 190 cm to 200 cm, 200 cm to 210 cm, 210 cm to 230 cm, 290 cm to 300 cm or 340 cm to 360 cm.

The speed of the fan can vary during operation. In general, the speed is lower for larger diameter fans. As a purely example, the speed of the fan in cruising flight can be less than 3500 rpm, e.g. B. less than 2500 rpm, e.g. B. be less than 2300 rpm. As another non-limiting example, the speed of the fan at cruise conditions for a geared gas turbine engine with a fan diameter in the range of 200 cm to 210 cm may be in the range of 2750 to 2900 rpm. As a further, non-limiting example, the speed of the fan in cruise flight for a geared turbofan gas turbine engine with a fan diameter in the range of 210 cm to 230 cm may be in the range of 2500 to 2800 rpm. As another non-limiting example, the speed of the fan at cruise conditions for a geared turbofan gas turbine engine with a fan diameter in the range of 340 cm to 360 cm may be in the range of 1500 to 1800 rpm. Purely by way of example, the speed of the fan can be in the range of 3600 to 3900 rpm in cruise flight conditions for a directly driven engine with a fan diameter in the range of 190 cm to 200 cm. As a further non-limiting example, the speed of the fan in cruise flight for a direct drive engine with a fan diameter in the range of 300 cm to 340 cm may be in the range of 2000 to 2800 rpm.

When the gas turbine engine operates, the fan (with the associated blades) rotates about an axis of rotation. This rotation causes the tip of the fan blade to move at a speed U _tip . The work done by the fan blades 23 on the flow leads to an increase in the enthalpy of the flow. The load on the fan tip can be defined as dH/U _tip ² , where dH is the enthalpy increase (e.g. the average 1-D enthalpy increase) across the fan and U _tip is the (translational) speed of the fan tip, e.g. B. at the leading edge of the tip (defined as the radius of the fan tip at the leading edge multiplied by the angular velocity). Fan tip load in cruise can be greater than (or on the order of): 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0, 35, 0.36, 0.37, 0.38, 0.39 or 0.4 (all values are dimensionless). The load on the fan tip can be in a range limited by any two of the values mentioned in the previous sentence (ie the values can form upper or lower limits), e.g. B. in the range of 0.28 to 0.31 or 0.29 to 0.3 (e.g. for a gas turbine engine with gearbox).

Gas turbine engines according to the present disclosure may have any bypass ratio, where the bypass ratio is defined as the ratio of the mass flow rate of flow through the bypass duct to the mass flow rate of flow through the core at cruise conditions. In some arrangements, the bypass ratio may be greater than (or on the order of) one of the following values: 9. 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5 , 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5 or 20. The bypass ratio can be in a comprehensive range limited by any two of the values mentioned in the previous sentence (i.e. the values can be upper or lower Form boundaries), for example in the range of 12 to 16, 13 to 15 or 13 to 14. By way of example only, the bypass ratio of a direct drive gas turbine engine according to the present disclosure can be in the range of 9:1 to 11:1. The bypass ratio of a geared gas turbine engine according to the present disclosure may range from 12:1 to 15:1, where the bypass channel is essentially an annular channel. The bypass channel can be located radially outside the engine. The radially outer surface of the bypass channel can be defined by a nacelle and/or a fan housing.

The total pressure ratio of a gas turbine engine described and/or claimed herein may be defined as the ratio between the stagnation pressure at the exit of the highest pressure compressor (before entering the combustion chamber) and the stagnation pressure before the fan. As a non-limiting example, the total pressure ratio of a gas turbine engine , as described and/or claimed herein, may be greater than (or on the order of) one of the following values at cruise: 35, 40, 45, 50, 55, 60, 65, 70, 75. The total pressure ratio can be in a range that is limited by any two of the values mentioned in the previous sentence (ie the values can form upper or lower limits), for example in the range from 50 to 70. Purely by way of example, the total pressure ratio in cruise flight of a gas turbine engine with gearbox and a fan -Diameters in the range of 200 cm to 210 cm are in the range of 40 to 45. The overall pressure ratio at cruise conditions of a geared gas turbine engine with a fan diameter in the range of 210 cm to 230 cm can be in the range of 45 to 55. The overall pressure ratio at cruise conditions of a geared gas turbine engine with a fan diameter in the range of 340 cm to 360 cm can be in the range of 50 to 60. The overall cruise pressure ratio of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm may be in the range of 50 to 60, which is an unrestricted example.

The specific thrust of an engine can be defined as the net thrust of the engine divided by the total mass flow through the engine. In some examples, the specific thrust at a particular thrust condition may depend on the specific composition of the fuel supplied to the combustion chamber. At cruise conditions, the specific thrust of an engine described and/or stressed herein may be less than (or of the order of magnitude) one of the following values: 110 Nkg ^-1 s, 105 Nkg ^-1 s, 100 Nkg ^-1 s, 95 Nkg ^-1 s, 90 Nkg ^-1 s, 85 Nkg ^-1 s or 80 Nkg ^-1 s. The specific thrust may be in a comprehensive range limited by any two of the values mentioned in the previous sentence (ie the values may be upper or lower Form limits), for example in the range from 80 Nkg ^-1 s to 100 Nkg ^-1 s or 85 Nkg ^-1 s to 95 Nkg ^-1 s. Such engines can be particularly efficient compared to conventional gas turbine engines. Purely as an example, the specific thrust of a gas turbine engine with a gearbox and a fan diameter of 200 cm to 210 cm can be in the range from 90 Nkg ^-1 s to 95 Nkg ^-1 s. Purely as an example, the specific thrust of a gas turbine engine with a gearbox and a fan diameter in the range of 210 cm to 230 cm can be in the range of 80 Nkg ^-1 s to 90 Nkg ^-1 s. The specific thrust of a geared gas turbine engine with a fan diameter in the range of 340 cm to 360 cm may range from 70 Nkg ^-1 s to 90 Nkg ^-1 s, which is an unlimited example. The specific thrust of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm may range from 90 Nkg ^-1 s to 120 Nkg ^-1 s, which is an unrestricted example.

A gas turbine engine as described and/or claimed herein may have any desired maximum thrust. By way of example only, a gas turbine described and/or claimed herein may be capable of producing a maximum thrust of at least (or on the order of) one of the following values: 100kN, 110kN, 120kN, 130kN, 140kN, 150kN, 160kN, 170kN , 180kN, 190kN, 200kN, 250kN, 300kN, 350kN, 400kN, 450kN, 500kN, or 550kN. The maximum thrust force may be within a broad range limited by any two of the values stated in the previous sentence (i.e. the values may form upper or lower limits). By way of example only, a gas turbine as described and/or claimed herein may be capable of producing a maximum thrust in the range of 330kN to 420kN, for example 350kN to 400kN. Purely as an example, the maximum thrust of a gas turbine engine with a gearbox and a fan diameter in the range of 200 cm to 210 cm can be in the range of 140kN to 160kN. The maximum thrust of a geared gas turbine engine with a fan diameter in the range of 210 cm to 230 cm may be in the range of 150 kN to 200 kN, which is an unrestricted example. The maximum thrust of a geared gas turbine engine with a fan diameter in the range of 340 cm to 360 cm may be in the range of 370 kN to 500 kN, which is an unlimited example. The maximum thrust of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm may be in the range of 370 kN to 500 kN, which is an unrestricted example. The above thrust may be the maximum net thrust at standard atmospheric conditions at sea level plus 15 degrees Celsius (ambient pressure 101.3 kPa, temperature 30 degrees Celsius) with the engine stationary.

During operation, the temperature of the flow at the inlet to the high-pressure turbine can be particularly high. This temperature, which can be referred to as TET, can be at the exit of the combustion chamber be measured, e.g. B. immediately upstream of the first turbine blade, which in turn can be referred to as a guide vane. In some examples, the TET for a particular thrust condition may depend on the specific composition of the fuel supplied to the combustion chamber. In cruise flight, the TET can be at least (or on the order of) one of the following values: 1400K, 1450K, 1500K, 1550K, 1600K or 1650K. As a purely example, the TET in cruise flight of a geared gas turbine engine with a fan diameter in the range of 200 cm to 210 cm can be in the range of 1540K to 1600K. As a purely example, the TET in cruise flight of a gas turbine engine with a gearbox and a fan diameter in the range of 210 cm to 230 cm can be in the range of 1590 K to 1650 K. As a purely example, the TET in cruise flight of a gas turbine engine with a gearbox and a fan diameter in the range of 340 cm to 360 cm can be in the range of 1600 K to 1660 K. Purely by way of example, the TET in cruise flight of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm can be in the range of 1590 K to 1650 K. As a purely example, the TET in cruise flight of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm can be in the range of 1570 K to 1630 K.

The cruise TET may lie in a broad range limited by any two of the values specified in the previous sentence (i.e. the values may form upper or lower limits). The maximum TET during operation of the engine can, for. B. be at least (or on the order of) one of the following values: 1700K, 1750K, 1800K, 1850K, 1900K, 1950K, 2000K, 2050K or 2100K. Purely by way of example, the maximum TET of a gas turbine engine with a gearbox and a fan diameter in the range of 200 cm to 210 cm can be in the range of 1890K to 1960K. Purely by way of example, the maximum TET of a gas turbine engine with a gearbox and a fan diameter in the range of 210 cm to 230 cm can be in the range of 1890 K to 1960 K. Purely by way of example, the maximum TET of a gas turbine engine with a gearbox and a fan diameter in the range of 340 cm to 360 cm can be in the range of 1890 K to 1960 K. The maximum TET of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm may range from 1935 K to 1995 K, which is a non-limiting example. By way of example only, the maximum TET of a direct drive gas turbine engine with a fan diameter in the range of 300 cm to 340 cm can be in the range of 1890 K to 1950 K. The maximum TET can be in a range limited by any two of the values mentioned in the previous sentence (i.e. the values can form upper or lower limits), for example in the range from 1800 K to 1950 K. The maximum TET can e.g. B. at a high thrust condition, e.g. B. occur at a maximum start state (maximum take-off - MTO).

A fan blade (fan blade) and/or an airfoil of a fan blade as described and/or claimed herein may be made from any suitable material or a combination of materials. For example, at least part of the fan blade and/or the airfoil can be at least partially made of a composite material, for example a metal matrix composite material and/or an organic matrix composite material, such as. B. carbon fiber composite material. As another example, at least a portion of the fan blade and/or airfoil may be made at least in part from a metal, such as a titanium-based metal or an aluminum-based material (such as an aluminum-lithium alloy) or a steel-based material. The fan blade can consist of at least two areas that are made of different materials. For example, the fan blade may include a protective leading edge made of a material that is more resistant to impact (e.g., from birds, ice, or other material) than the rest of the blade. Such a front edge can e.g. B. made of titanium or a titanium alloy. For example, the fan blade may have a carbon fiber or aluminum (such as aluminum-lithium alloy) body with a titanium leading edge.

A fan as described and/or claimed herein may include a central portion from which the fan blades may extend, for example in a radial direction. The fan blades can be attached to the central section in any desired manner. For example, each fan blade can have a fastener that can engage a corresponding slot in the hub (or disk). As an example, such an attachment can be in the form of a dovetail, which can be inserted and/or snapped into a corresponding slot in the hub/disc in order to attach the fan blade to the hub/disc. As a further example, the fan blades can be formed in one piece with a central section. Such an arrangement can be referred to as a blade disk or blade ring. Any suitable method can be used to produce such a blade disk or blade ring. For example, at least some of the fan blades can be made from a block and/or at least some of the fan blades may be attached to the hub/disc by welding, such as linear friction welding.

The gas turbine engines described and/or claimed herein may or may not be equipped with a variable area nozzle (VAN). With such a nozzle with a variable cross section, the exit area of the bypass channel can be varied during operation. The general principles of the present disclosure may apply to engines with or without VAN.

The gas turbine fan as described and/or claimed herein may have any number of fan blades, for example 14, 16, 18, 20, 22, 24 or 26 fan blades. If the fan blades have a carbon fiber composite body, there may be 16 or 18 fan blades. If the fan blades have a metal body (e.g. made of aluminum-lithium or titanium alloy), there can be 18, 20 or 22 fan blades.

The terms idle, taxi, takeoff, climb, cruise, descent, approach and landing used herein have the usual meaning and will be readily understood by those skilled in the art. Thus, for a particular gas turbine engine for an aircraft, the person skilled in the art would immediately recognize that each term refers to a phase of operation of the engine in the context of a specific use of an aircraft for which the gas turbine engine is intended.

In this context, the term “idle” can refer to a phase of engine operation in which the aircraft is stationary and in contact with the ground, but the engine must be running. During idle, the engine can produce between 3% and 9% of the engine's available thrust. In further non-limiting examples, the engine may produce between 5% and 8% of available thrust. In further non-limited examples, the engine may produce between 6 and 7% of available thrust. Taxiing may refer to a phase of engine operation in which the aircraft is moved over the ground using the thrust generated by the engine. While taxiing, the engine can produce between 5% and 15% of available thrust. In further non-limited examples, the engine may produce between 6% and 12% of available thrust. In further non-limited examples, the engine may produce between 7% and 10% of available thrust. The term “takeoff” may refer to a phase of engine operation during which the aircraft is propelled by the thrust produced by the engine. In the initial phase of takeoff, the aircraft can be propelled while touching the ground. At a later stage of the takeoff phase, the aircraft can be propelled while not in contact with the ground. During takeoff, the engine can produce between 90% and 100% of available thrust. In further non-limiting examples, the engine may produce between 95% and 100% of available thrust. In other non-limited examples, the engine can produce 100% of the available thrust.

Climb can refer to a phase of engine operation in which the aircraft is propelled by the thrust produced by the engine. During climb, the engine can produce between 75% and 100% of available thrust. In further non-limiting examples, the engine may produce between 80% and 95% of available thrust. In further non-limiting examples, the engine may produce between 85% and 90% of available thrust. In this context, climb can refer to the operational phase of an aircraft between takeoff and reaching cruise conditions. Additionally or alternatively, the term climb may refer to a nominal point in an aircraft flight cycle between takeoff and landing at which a relative gain in altitude is required, which may require additional engine thrust.

The term “cruise flight conditions” used here has the usual meaning and is readily understandable to those skilled in the art. Thus, for a particular gas turbine engine for an aircraft, one skilled in the art would immediately recognize that cruise conditions mean the operating point of the engine mid-cruise of a particular mission (which may be referred to in the industry as an "economic mission") of an aircraft at which the Gas turbine engine should be attached. In this context, mid-cruise is the point in an aircraft's flight cycle at which 50% of the total fuel burned between the highest point of climb and the start of descent has been burned (represented by the midpoint - in terms of time and/or distance - can be approximated between the highest point of the climb and the start of the descent). Cruise conditions thus define an operating point of the gas turbine engine that delivers thrust ensuring steady-state operation (i.e. maintaining a constant altitude and a constant Mach number) in the middle of the cruise flight of an aircraft for which it is designed, the number of engines for this aircraft is taken into account. For example, if an engine is designed to be mounted on an aircraft with two engines of the same type is set, the engine in cruise flight delivers half of the total thrust that would be required for stationary operation of the aircraft in mid-cruise.

In other words, for a particular gas turbine engine for an aircraft, cruise conditions are defined as the operating point of the engine that provides a specific thrust (which - in combination with other engines in the aircraft - is sufficient for the steady-state operation of the aircraft for which it is designed a certain Mach number is required at mid-cruise) at the atmospheric conditions at mid-cruise (defined by the international standard atmosphere according to ISO 2533 at cruise altitude). For any aircraft gas turbine engine, the mid-cruise thrust, atmospheric conditions, and Mach number are known, so that the operating point of the engine at cruise conditions is clearly defined.

As a purely example, the forward speed in cruise flight can be any point in the range from Mach 0.7 to 0.9, e.g. B. 0.75 to 0.85, e.g. B. 0.76 to 0.84, e.g. B. 0.77 to 0.83, e.g. B. 0.78 to 0.82, e.g. B. 0.79 to 0.81, e.g. B. be on the order of Mach 0.8, on the order of Mach 0.85 or in the range from 0.8 to 0.85. Any individual speed within these ranges can be part of the cruise flight. For some aircraft, cruise conditions may be outside these ranges, e.g. B. below Mach 0.7 or above Mach 0.9.

Purely by way of example, the cruise flight conditions can correspond to the standard atmospheric conditions (according to International Standard Atmosphere, ISA) at an altitude that is in the range from 10,000 m to 15,000 m, for example in the range from 10,000 m to 12,000 m, for example in the range from 10,400 m to 11,600 m (approximately 38,000 ft). , e.g. in the range from 10500m to 11500m, e.g. in the range from 10600m to 11400m, e.g. in the range from 10700m (about 35000 ft) to 11300m, e.g. in the range from 10800m to 11200m, e.g. in the range from 10900m to 1 1100m, for example in the order of magnitude from 11000m. Cruise conditions may correspond to standard atmospheric conditions at any altitude in these areas.

By way of example only, the cruise conditions may correspond to an operating point of the engine that has a known required thrust level (e.g. a value in the range of 30kN to 35kN) at a forward Mach number of 0.8 and standard atmospheric conditions (according to the international standard atmosphere) at an altitude of 11582 m (38000 ft). As another example, cruise conditions may correspond to an engine operating point that has a known required thrust (e.g. a value in the range of 50kN to 65kN) at a forward Mach number of 0.85 and standard atmospheric conditions (according to the international standard atmosphere) in a altitude of 10668m (35000ft).

In operation, a gas turbine engine described and/or claimed herein may operate under cruise conditions defined elsewhere herein. Such cruise conditions may be determined by the cruise conditions (e.g., mid-cruise conditions) of an aircraft to which at least one (e.g., 2 or 4) gas turbine engines may be mounted to generate propulsive thrust.

Furthermore, one skilled in the art would immediately recognize that the descent or landing approach refers to an operational phase within an aircraft flight cycle between cruise and landing of the aircraft. During descent or approach, the engine can produce between 20% and 50% of available thrust. In further non-exhaustive examples, the engine can produce between 25% and 40% of available thrust. In further non-limiting examples, the engine may produce between 30% and 35% of available thrust. Additionally or alternatively, the term "descent" may refer to a nominal point in an aircraft's flight cycle between takeoff and landing at which a relative drop in altitude is required, which may require less engine thrust.

According to one aspect, an aircraft having a gas turbine engine as described and/or claimed herein is provided. The aircraft according to this aspect is the aircraft to which the gas turbine engine is intended to be mounted. Accordingly, cruise conditions in accordance with this aspect correspond to the mean cruise of the aircraft, as defined elsewhere herein.

In one aspect, a method of operating a gas turbine engine as described and/or claimed herein is provided. Operation may occur at any suitable condition, which may be as defined elsewhere herein (e.g., with respect to thrust, atmospheric conditions, and Mach number).

According to one aspect, a method of operating an aircraft having a gas turbine engine as described and/or claimed herein is provided. Operation according to this aspect may include (or be) operation in any suitable state, for example in the Mid-cruise of the aircraft, as defined elsewhere herein.

Those skilled in the art will understand that a feature or parameter described in relation to any of the above aspects may also be applied to any other aspect, provided they are not mutually exclusive. In addition, any feature or parameter described herein may be applied to any aspect and/or combined with any other feature or parameter described herein, provided they are not mutually exclusive.

• 1 ist eine Seitenschnittansicht eines Gasturbinentriebwerks;
• 2 ist eine Seitenschnittgroßansicht eines stromaufwärtigen Abschnitts eines Gasturbinentriebwerks;
• 3 ist eine zum Teil weggeschnitte Ansicht eines Getriebes für ein Gasturbinentriebwerk;
• 4 ist eine schematische Darstellung eines Luftfahrzeugs mit zwei Kraftstoffquellen;
• 5 ist eine schematische Darstellung des Verbrennungssystems eines Gasturbinentriebwerks, das an zwei Kraftstoffquellen angeschlossen ist;
• 6 zeigt den Zusammenhang zwischen der Durchflussrate des Kraftstoffs und der nvPM-Zahl;
• 7 zeigt die Abhängigkeit der nvPM-Zahl von der Durchflussrate des Kraftstoffs für verschiedene Kraftstoffzusammensetzungen;
• 8 zeigt eine alternative Abhängigkeit der nvPM-Zahl von der Durchflussrate des Kraftstoffs für verschiedene Kraftstoffzusammensetzungen;
• 9 zeigt eine schematische Darstellung eines anderen Verbrennungssystems;
• 10 veranschaulicht die Abhängigkeit der nvPM-Zahl von der Kraftstoff-Durchflussrate für die Anordnung aus 9;
• 11 veranschaulicht ein Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 12 zeigt eine schematische Ansicht eines anderen Verbrennungssystems;
• 13 zeigt die Abhängigkeit der nvPM-Zahl von der Kraftstoff-Durchflussrate für die Anordnung aus 12;
• 14 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 15 zeigt ein weiteres Beispiel für die Abhängigkeit der nvPM-Zahl von der Kraftstoff-Durchflussrate für die Anordnung aus 12;
• 16 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 17 zeigt eine schematische Darstellung eines anderen Verbrennungssystems;
• 18 veranschaulicht die Abhängigkeit der nvPM-Zahl von der Kraftstoff-Durchflussrate für die in 17 dargestellte Anordnung;
• 19 zeigt den Bereich der möglichen nvPM-Zahlen in Abhängigkeit von der Kraftstoff-Durchflussrate für die in 17 dargestellte Anordnung;
• 20 zeigt eine weitere Abhängigkeit der nvPM-Zahl von der Kraftstoff-Durchflussrate für die in 17 dargestellte Anordnung;
• 21 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 22 veranschaulicht die Abhängigkeit des Emissionsindexes für Kohlenmonoxid (CO) und unverbrannte Kohlenwasserstoffe (HC) von der Leistungseinstellung des Triebwerks;
• 23 zeigt die Abhängigkeit des Emissionsindexes von Kohlenmonoxid (CO) und unverbrannten Kohlenwasserstoffen (HC) von der Leistungseinstellung des Triebwerks bei einem Stufenpunkt (SP), der so eingestellt ist, dass ein erster und ein zweiter Reiseflugbereich definiert werden;
• 24 veranschaulicht die Abhängigkeit des nvPM-Emissionsindex von der Leistungseinstellung des Triebwerks;
• 25 zeigt die Abhängigkeit des nvPM-Emissionsindexes von der Leistungseinstellung des Triebwerks, um das Ergebnis der selektiven Verwendung von Kraftstoff mit anderen Merkmalen während eines ersten Reiseflugs des Triebwerks zu veranschaulichen;
• 26 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 27 zeigt die Abhängigkeit des CO- und HC-Emissionsindex (EI) von der Leistungseinstellung des Triebwerks, um die Auswirkungen eines Übergangsbereichs zwischen einem Betrieb nur mit Voreinspritzung und einem Betrieb mit Vor- und Haupteinspritzung zu verdeutlichen;
• 28 zeigt die Abhängigkeit des nvPM-Emissionsindex von der Leistungseinstellung des Triebwerks, um die Auswirkungen des Übergangsbereichs zu verdeutlichen;
• 29 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 30 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 31 zeigt eine schematische Darstellung eines anderen Verbrennungssystems;
• 32 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 33 veranschaulicht ein weiteres Verfahren zum Betrieb eines Gasturbinentriebwerks;
• 34 veranschaulicht ein Verfahren zur Bestimmung eines oder mehrerer Kraftstoff-Beladungsparameter;
• 35 veranschaulicht ein Verfahren zum Laden von Kraftstoff in ein Luftfahrzeug;
• 36 zeigt eine schematische Darstellung eines Systems zur Bestimmung der Kraftstoff-Beladungsparameter;
• 37 veranschaulicht ein Verfahren zur Bestimmung einer optimierten flottenweiten Kraftstoffzuteilung für eine Vielzahl von Flügen;
• 38 veranschaulicht eine flugbezogene Optimierung zur Ermittlung eines optimierten Kraftstoffverbrauchs;
• 39 veranschaulicht ein Verfahren zum Laden von Kraftstoff in eine Vielzahl von Luftfahrzeugen;
• 40 zeigt eine schematische Darstellung eines flottenweiten Systems zur Bestimmung der Kraftstoffzuteilung; und
• 41 zeigt eine schematische Ansicht einer Datenverarbeitungsanlage.

Examples of embodiments are described below using the figures in which:

• 1 is a side sectional view of a gas turbine engine;
• 2 is a close-up side sectional view of an upstream portion of a gas turbine engine;
• 3 is a partially cutaway view of a gearbox for a gas turbine engine;
• 4 is a schematic representation of an aircraft with two fuel sources;
• 5 is a schematic representation of the combustion system of a gas turbine engine connected to two fuel sources;
• 6 shows the relationship between fuel flow rate and nvPM number;
• 7 shows the dependence of the nvPM number on the fuel flow rate for different fuel compositions;
• 8th shows an alternative dependence of the nvPM number on the fuel flow rate for different fuel compositions;
• 9 shows a schematic representation of another combustion system;
• 10 illustrates the dependence of the nvPM number on the fuel flow rate for the arrangement 9 ;
• 11 illustrates a method of operating a gas turbine engine;
• 12 shows a schematic view of another combustion system;
• 13 shows the dependence of the nvPM number on the fuel flow rate for the arrangement 12 ;
• 14 illustrates another method of operating a gas turbine engine;
• 15 shows another example of the dependence of the nvPM number on the fuel flow rate for the arrangement 12 ;
• 16 illustrates another method of operating a gas turbine engine;
• 17 shows a schematic representation of another combustion system;
• 18 illustrates the dependence of the nvPM number on the fuel flow rate for the in 17 arrangement shown;
• 19 shows the range of possible nvPM numbers depending on the fuel flow rate for the in 17 arrangement shown;
• 20 shows a further dependence of the nvPM number on the fuel flow rate for the in 17 arrangement shown;
• 21 illustrates another method of operating a gas turbine engine;
• 22 illustrates the dependence of the emission index for carbon monoxide (CO) and unburned hydrocarbons (HC) on the engine power setting;
• 23 shows the dependence of the emission index of carbon monoxide (CO) and unburned hydrocarbons (HC) on the power setting of the engine at a step point (SP) set to define a first and a second cruise range;
• 24 illustrates the dependence of the nvPM emission index on the engine power setting;
• 25 shows the dependence of the nvPM emission index on the power setting of the engine to illustrate the result of the selective use of fuel with different characteristics during a first cruise flight of the engine;
• 26 illustrates another method of operating a gas turbine engine;
• 27 shows the dependence of the CO and HC emission index (EI) on the engine power setting to illustrate the effects of a transition region between pilot injection only operation and pilot and main injection operation;
• 28 shows the dependence of the nvPM emission index on the power setting of the engine to illustrate the effects of the transition region;
• 29 illustrates another method of operating a gas turbine engine;
• 30 illustrates another method of operating a gas turbine engine;
• 31 shows a schematic representation of another combustion system;
• 32 illustrates another method of operating a gas turbine engine;
• 33 illustrates another method of operating a gas turbine engine;
• 34 illustrates a method for determining one or more fuel loading parameters;
• 35 illustrates a method for loading fuel into an aircraft;
• 36 shows a schematic representation of a system for determining fuel loading parameters;
• 37 illustrates a method for determining optimized fleet-wide fuel allocation for a variety of flights;
• 38 illustrates flight-related optimization to determine optimized fuel consumption;
• 39 illustrates a method for loading fuel into a variety of aircraft;
• 40 shows a schematic representation of a fleet-wide system for determining fuel allocation; and
• 41 shows a schematic view of a data processing system.

1 illustrates a gas turbine engine 10 with a main axis of rotation 9. The engine 10 includes an air inlet 12 and a thrust fan 23 that generates two air streams: a core air stream A and a bypass air stream B. The gas turbine engine 10 includes a core 11 that receives the core air stream A. The engine core 11 includes, in axial flow order, a low-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a low-pressure turbine 19 and a core thrust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass channel 22 and a bypass thrust nozzle 18. The bypass air flow B flows through the bypass channel 22. The blower (fan) 23 is attached to the low-pressure turbine 19 via a shaft 26 and an epicycloid gear 30 and is driven by it.

During operation, the core air flow A is accelerated and compressed by the low-pressure compressor 14 and fed into the high-pressure compressor 15, where further compression takes place. The compressed air emerging from the high-pressure compressor 15 is passed into the combustion system 16, where it is mixed with fuel F and the mixture is burned. The combustion system 16 can be referred to as a combustion chamber 16, with the terms “combustion system 16” and “combustion chamber 16” being used synonymously here. The resulting hot combustion products then expand through and drive the high and low pressure turbines 17, 19 before being expelled through the nozzle 20 to produce some propulsion. The high-pressure turbine 17 drives the high-pressure compressor 15 via a suitable connecting shaft 27. Fan 23 generally provides most of the propulsion thrust. The planetary gear 30 is a reduction gear.

An exemplary arrangement for a geared fan gas turbine engine 10 is shown in 2 shown. The low-pressure turbine 19 (see 1 ) drives the shaft 26, which is coupled to a sun gear 28 of the epicycloidal gear assembly 30. Several planet gears 32, which are coupled to one another by a planet carrier 34, are located radially outside of the sun gear 28 and mesh with it. The planet carrier 34 restricts the planet gears 32 from rotating synchronously around the sun gear 28 while allowing each planet gear 32 to rotate about its own axis. The planet carrier 34 is coupled to the fan 23 via linkage 36 to drive its rotation about the engine axis 9. An external gear or ring gear 38, which is coupled to a stationary support structure 24 via linkage 40, is located radially outside of the planet gears 32 and meshes with it.

It is noted that the terms “low pressure turbine” and “low pressure compressor” as used herein may be construed to mean the lowest pressure turbine stage and the lowest pressure compressor stage, respectively (i.e. not including the fan 23) and/or the turbine and compressor stages interconnected by the lowest speed connecting shaft 26 in the engine (ie, not including the transmission output shaft that drives the fan 23). In some literature, the “low pressure turbine” and “low pressure compressor” referred to herein may alternatively be known as the “medium pressure turbine” and “medium pressure compressor”. When using such alternative nomenclature, the blower 23 can be referred to as one First compression stage or compression stage with the lowest pressure are referred to.

The epicycloid gear 30 is in 3 shown in more detail as an example. The sun gear 28, the planetary gears 32 and the ring gear 38 each include teeth around their periphery for meshing with the other gears. However, for the sake of clarity, only exemplary sections of the teeth are shown in 3 shown. Although four planetary gears 32 are illustrated, it will be apparent to those skilled in the art that more or fewer planetary gears 32 may be provided within the scope of the claimed invention. Practical applications of an epicycloidal gear 30 generally include at least three planet gears 32.

This in 2 and 3 Epicycloidal gear 30 shown as an example is a planetary gear in which the planet carrier 34 is coupled to an output shaft via linkage 36, with the ring gear 38 being fixed. However, any other suitable type of epicycloidal gear 30 may be used. As another example, the epicycloidal gear 30 may be a star arrangement in which the planet carrier 34 is held fixed while allowing the ring gear (or outer gear) 38 to rotate. With such an arrangement, the fan 23 is driven by the ring gear 38. As another alternative example, the transmission 30 may be a differential gear in which both the ring gear 38 and the planet carrier 34 are allowed to rotate.

It is understood that the in 2 and 3 The arrangement shown is merely exemplary and various alternatives are within the scope of the present disclosure. By way of example only, any suitable arrangement for positioning the transmission 30 in the engine 10 and/or for connecting the transmission 30 to the engine 10 can be used. As another example, the connections (e.g. the linkages 36, 40 in the example of 2 ) between the transmission 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) have some degree of rigidity or flexibility. As another example, any suitable arrangement of bearings between rotating and stationary parts of the engine (e.g., between the input and output shafts of the transmission and fixed structures such as the transmission housing) may be used and is not disclosed to the exemplary arrangement of 2 limited. For example, it will be readily apparent to those skilled in the art that the arrangement of output and support linkages and bearing positioning in a star arrangement (described above) of the transmission 30 is generally different from those exemplified in 2 shown would differ.

Accordingly, the present disclosure extends to a gas turbine engine with any arrangement of gear types (e.g., star or planetary), support structures, input and output shaft arrangements, and bearing positionings.

Optionally, the transmission can drive auxiliary and/or alternative components (e.g. the medium-pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present disclosure may apply may have alternative configurations. For example, such engines can have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As another example, this shows in 1 Gas turbine engine shown has a split flow nozzle 18, 20, which means that the flow through the bypass channel 22 has its own nozzle, which is separate from the engine core nozzle 20 and radially outward thereof. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are prior to (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. mixed or combined. One or both nozzles (whether mixed or split stream) may have a fixed or variable range.

Although the example described relates to a turbofan engine, the disclosure may apply to any type of gas turbine engine, e.g. B. for an open rotor (where the fan stage is not surrounded by a nacelle) or turboprop engine. In some arrangements, the gas turbine engine 10 may not include a transmission 30.

The geometry of the gas turbine engine 10 and its components is defined by a conventional axis system having an axial direction (aligned with the axis of rotation 9), a radial direction (in 1 from bottom to top) and a circumferential direction (perpendicular to the side in the view of 1 ). The axial, radial and circumferential directions are perpendicular to each other.

The fuel F supplied to the combustion system 16 may be a fossil hydrocarbon fuel such as kerosene. So the fuel F can contain molecules from one or more of the chemical families of n-alkanes, iso-alkanes, cycloalkanes and Include aromatics. Additionally or alternatively, the fuel F may consist of renewable hydrocarbons produced from biological or non-biological resources, also known as sustainable aviation fuel (SAF). In each of the examples mentioned, the fuel F may contain one or more trace elements, e.g. B. Sulfur, nitrogen, oxygen, inorganic substances and metals.

The functional performance of a particular composition or fuel mixture for a particular application may be defined, at least in part, by the ability of the fuel to service the Brayton cycle of the gas turbine engine 10. The parameters that define functional performance include, for example, specific energy, energy density, thermal stability and emissions, including particulate emissions. A relatively higher specific energy (i.e. energy per unit mass), expressed as MJ/kg, can at least partially reduce takeoff weight and thus potentially provide a relative improvement in fuel consumption. A relatively higher energy density (i.e., energy per unit volume), expressed as MJ/L, can at least partially reduce the starting fuel volume, which may be particularly important for volume-limited missions or military operations involving refueling. Relatively higher thermal stability (i.e., preventing decomposition or coking of fuel under thermal stress) may allow the fuel to maintain higher temperatures in the engine and injectors, which may result in a relative improvement in combustion efficiency. Lower emissions, including particulate matter, can reduce the formation of contrails while reducing the environmental impact of a given mission. Other properties of the fuel can also be crucial for its functionality. A relatively low freezing point (°C) can enable the flight profile to be optimized during long-haul missions; a minimum concentration of aromatics (%) can ensure sufficient swelling of certain materials used in the manufacture of O-rings and seals previously exposed to fuels with a high content of aromatics; and a maximum surface tension (mN/m) can ensure sufficient spray atomization and atomization of fuel.

The ratio between the number of hydrogen atoms and the number of carbon atoms in a molecule can affect the specific energy of a particular composition or mixture of fuel. Fuels with a higher ratio of hydrogen atoms to carbon atoms can have a higher specific energy when there is no bond stress. For example, fossil-based hydrocarbon fuels may consist of molecules of approximately 7 to 18 carbon atoms, with a significant portion of a given composition consisting of molecules of 9 to 15 carbon atoms, with an average of 12 carbon atoms.

A number of sustainable aviation fuel blends are already approved, containing between 10 and 50% sustainable fuel (the remainder being one or more fossil hydrocarbon fuels such as kerosene), with additional compositions awaiting approval. However, the aviation industry expects that sustainable aviation fuel blends containing up to 100% sustainable fuel (SAF) will eventually be approved for use.

Sustainable aviation fuels may contain one or more of the following elements: n-alkanes, iso-alkanes, cyclo-alkanes and aromatics. For example, they can be made from one or more of the following elements: synthesis gas (syngas), lipids (e.g. fats, oils and fats), sugars and alcohols. Sustainable aviation fuels may therefore have lower aromatics and sulfur content, or both, compared to fossil hydrocarbon fuels. Additionally or alternatively, sustainable aviation fuels may have higher iso-alkanes and cyclo-alkanes content compared to fossil hydrocarbon fuels. Thus, in some examples, sustainable aviation fuels can either have a density between 90% and 98% of the density of kerosene, or a calorific value between 101% and 105% of the calorific value of kerosene, or both.

Due at least in part to the molecular structure of sustainable aviation fuels, sustainable aviation fuels can offer the following advantages compared to fossil hydrocarbon fuels (e.g. when burned in the incinerator 16): a higher specific energy (despite a lower energy density in some examples), a higher specific heat capacity, higher thermal stability, higher lubricity, lower viscosity, lower surface tension, lower freezing point, lower soot emissions and lower CO ₂ emissions. Accordingly, sustainable aviation fuels may result in a relative decrease in specific fuel consumption or a relative decrease in maintenance costs compared to fossil hydrocarbon fuels such as kerosene.

Aircraft fuel system and fuel characteristics

4 shows an aircraft 1 with two gas turbine engines 10 according to one of the examples described here. In this example, the aircraft 1 includes two gas turbine engines 10, but in other examples may also include one or more gas turbine engines. The aircraft 1 further includes an aircraft fuel system located on board the aircraft and adapted to supply each of the gas turbine engines 10 with fuel F combusted in the engine's combustor 16 as described above. The aircraft fuel system is arranged to deliver fuel to an engine fuel system provided on each of the gas turbine engines 10. The engine fuel system and the aircraft fuel system together form the aircraft fuel supply system 1.

The aircraft fuel system includes two fuel sources, a first fuel source 302 and a second fuel source 304 (in 4 shaded differently). For purposes of this application, the term “fuel source” means either 1) a single fuel tank or 2) a plurality of fuel tanks that may or may not be interconnected. Each of the fuel sources is arranged to provide separate fuel sources, that is, the first fuel source may include a first fuel that has a different property or properties than a second fuel included in the second fuel source. The first and second fuel sources are therefore not fluidly connected to each other to separate the different fuels (at least under normal operating conditions, as described elsewhere herein).

The aircraft fuel system may include a plurality of fuel tanks that may be selectively connected together in various arrangements to form the first and second fuel sources. The fuel tanks may have associated isolation valves so that different combinations of tanks can be grouped together in different configurations. In such examples, there may be multiple ways to associate individual fuel tanks with the first fuel source and the second fuel source. In other examples, the assignment of fuel tanks to individual fuel sources may be fixed. In the present example, the total volume of the fuel tanks that form the first fuel source 302 is less than or equal to the volume of the fuel tanks that form the second fuel source 304. However, in other examples this is not necessarily the case.

In the present example, the first and second fuel sources 302, 304 include a plurality of wing fuel tanks 53, of which at least one wing fuel tank is located in the port wing and at least one wing fuel tank is located in the starboard wing, and a center fuel tank 55 located primarily in the fuselage of the aircraft 1. Both the center fuel tank 55 and the wing fuel tanks 53 may consist of a plurality of interconnected fuel tanks, which are not shown in the figures. Like the shading in 4 shows, the wing fuel tanks 53 form the first fuel source 302, while the second fuel source 304 in the present example is formed by the center fuel tank 55.

To compensate, one or more fuel tanks in the port wing can be connected to one or more fuel tanks in the starboard wing. This can be done either via a center fuel tank (if not part of the other fuel source) or bypassing the center fuel tank(s), or both (for maximum flexibility and safety).

In another example, the second fuel source 304 includes wing fuel tanks and a center fuel tank, while the first fuel source 302 includes another separate center fuel tank. Fluid communication may be provided between the wing fuel tanks and the center fuel tank of the second fuel source to balance the aircraft.

In some examples, the allocation of fuel tanks available on the aircraft may be restricted such that the first fuel source and the second fuel source 302, 304 are each arranged substantially symmetrically about the centerline of the aircraft. In cases where asymmetrical distribution of fuel tanks is permitted, an appropriate means of fuel transfer between the fuel tanks of the first fuel source and/or between the fuel tanks of the second fuel source is provided so that the position of the aircraft's center of mass remains within acceptable limits throughout the flight lateral boundaries can be maintained.

A trim fuel tank could be part of the first fuel source 302 in some examples or part of the second fuel source 304 in other examples. The assignment of fuel tanks to the first fuel source 302 and the The second fuel source 304 may be limited such that neither the first fuel source 302 nor the second fuel source 304 exclusively includes the trim fuel tank.

While the examples described in the present application only include a first and a second fuel source 302, 304, in other examples additional fuel sources may be provided so that fuel from any number of sources, each with different fuel characteristics or properties, can be supplied via the fuel delivery controller can be fed to the combustion chamber.

The first and second fuel sources 302, 304 may be used to store fuel with different characteristics. This allows the combustion system 16 to be supplied with fuel with different characteristics, as will be described in more detail in the various examples below.

1. i. den prozentualen Anteil an nachhaltigem Flugkraftstoff (SAF) im Kraftstoff oder die Angabe, dass es sich um einen fossilen Kraftstoff, z. B. fossiles Kerosin, oder um einen reinen SAF handelt;
2. ii. Parameter einer Kohlenwasserstoffverteilung des Kraftstoffs, wie z. B.:
   • • den Gehalt an aromatischen Kohlenwasserstoffen im Kraftstoff und gegebenenfalls auch / alternativ den Gehalt an multiaromatischen Kohlenwasserstoffen im Kraftstoff;
   • • das Wasserstoff-Kohlenstoff-Verhältnis (H/C) des Kraftstoffs;
   • • Angaben zur prozentualen Zusammensetzung für einige oder alle vorhandenen Kohlenwasserstoffe;
3. iii. das Vorhandensein oder der prozentuale Anteil eines bestimmten Elements oder einer bestimmten Art, wie z. B.:
   • • der prozentuale Anteil der stickstoffhaltigen Spezies im Kraftstoff;
   • • das Vorhandensein oder der prozentuale Anteil einer Tracer-Spezies oder eines Spurenelements im Kraftstoff (z. B. eine im Kraftstoff inhärent vorhandene Spurensubstanz, die von Kraftstoff zu Kraftstoff unterschiedlich sein kann und somit zur Identifizierung eines Kraftstoffs verwendet werden kann, und/oder eine absichtlich zugesetzte Substanz, die als Tracer wirkt);
   • • Naphthalin-Gehalt des Kraftstoffs;
   • • Schwefelgehalt des Kraftstoffs;
   • • Cycloparaffingehalt des Kraftstoffs;
   • • Sauerstoffgehalt des Kraftstoffs;
4. iv. eine oder mehrere Eigenschaften des Kraftstoffs bei der Verwendung in einem Gasturbinentriebwerk 10, wie z. B.:
   • • Höhe der nichtflüchtigen Partikelemissionen (nvPM) oder der CO-Emissionen₂ bei der Verbrennung (es kann ein Wert für einen bestimmten Kraftstoff angegeben werden, der unter bestimmten Bedingungen betrieben wird, um einen fairen Vergleich der Kraftstoffe zu ermöglichen - ein gemessener Wert kann auf der Grundlage der Eigenschaften und Bedingungen des Kraftstoffs entsprechend angepasst werden);
   • • Verkokungsgrad des Kraftstoffs;
5. v. eine oder mehrere Eigenschaften des Kraftstoffs selbst, unabhängig von der Verwendung in einem Triebwerk oder der Verbrennung, wie z. B:
   • • thermische Stabilität des Kraftstoffs (z. B. Temperatur des thermischen Durchbruchs); und
   • • eine oder mehrere physikalische Eigenschaften wie Dichte, Viskosität, Brennwert, Gefriertemperatur und/oder Wärmekapazität.

The term “fuel characteristics” as used herein refers to intrinsic or inherent fuel properties such as fuel composition and not to variable properties such as volume or temperature. Examples of fuel characteristics include one or more of the following characteristics:

1. i. the percentage of sustainable aviation fuel (SAF) in the fuel or the indication that it is a fossil fuel, e.g. B. fossil kerosene, or a pure SAF;
2. ii. Parameters of a hydrocarbon distribution of the fuel, such as. E.g.:
   • • the content of aromatic hydrocarbons in the fuel and, if applicable/alternatively, the content of multiaromatic hydrocarbons in the fuel;
   • • the hydrogen to carbon ratio (H/C) of the fuel;
   • • Percentage composition information for some or all hydrocarbons present;
3. iii. the presence or percentage of a particular element or species, such as: E.g.:
   • • the percentage of nitrogen-containing species in the fuel;
   • • the presence or percentage of a tracer species or trace element in the fuel (e.g. a trace substance inherent in the fuel, which may vary from fuel to fuel and thus can be used to identify a fuel, and/or a intentionally added substance that acts as a tracer);
   • • Naphthalene content of the fuel;
   • • Sulfur content of fuel;
   • • Cycloparaffin content of the fuel;
   • • Oxygen content of the fuel;
4. iv. one or more properties of the fuel when used in a gas turbine engine 10, such as. E.g.:
   • • Level of non-volatile particulate matter emissions (nvPM) or _CO2 emissions during combustion (a value can be provided for a specific fuel operating under specific conditions to allow a fair comparison of fuels - a measured value can be based on based on the properties and conditions of the fuel);
   • • degree of coking of the fuel;
5. v. one or more properties of the fuel itself, regardless of its use in an engine or combustion, such as: B:
   • • thermal stability of the fuel (e.g. thermal breakdown temperature); and
   • • one or more physical properties such as density, viscosity, calorific value, freezing temperature and/or heat capacity.

The aircraft 1 can be refueled using a refueling source 60, e.g. B. an airport fuel truck, a fixed fuel storage facility or a permanent pipeline, is connected via a fuel line 61 to a connection opening 62 of the aircraft. A desired amount of fuel can be transferred from the refueling source 60 into one or more tanks 53, 55 of the aircraft 1. In the present example, in which different tanks 53, 55 are to be filled with different fuels, several fuel line connections 62 are provided. The fueling source 60 therefore, in this example, holds two fuels with different fuel characteristics in separate containers 60a, 60b (e.g. a standard and a non-standard fuel, as described later) in separate tanks. In other examples, valves may be used to appropriately direct fuel as it comes from a single port.

• (i) physikalische und/oder chemische Erfassung eines oder mehrerer Kraftstoffmerkmale, entweder während des Betriebs des Luftfahrzeugs (z. B. am Flügel) oder während der Betankung des Luftfahrzeugs;
• (iii) Empfangen von Daten, z. B. von einer Eingabe an einer Benutzerschnittstelle, oder von Daten, die an das Luftfahrzeug 1 übertragen werden.

Fuel characteristics can be obtained by:

• (i) physical and/or chemical detection of one or more fuel characteristics, either during operation of the aircraft (e.g. on the wing) or during refueling of the aircraft;
• (iii) Receiving data, e.g. B. from an input on a user interface, or from data that is transmitted to the aircraft 1.

• • Der Aromaten- oder Cycloparaffingehalt des Kraftstoffs kann anhand von Messungen der Quellung einer Sensorkomponente aus einem Dichtungsmaterial wie z. B. einem Nitrildichtungsmaterial bestimmt werden.
• • Anhand von Spurenstoffen oder -arten, die entweder von Natur aus im Kraftstoff vorhanden sind oder als Tracer zugesetzt werden, können Kraftstoffmerkmale bestimmt werden, z. B. der prozentuale Anteil an nachhaltigem Flugkraftstoff im Kraftstoff oder ob der Kraftstoff Kerosin ist.
• • Messungen der Schwingungsmode eines piezoelektrischen Kristalls, der dem Kraftstoff ausgesetzt ist, können als Grundlage für die Bestimmung verschiedener Kraftstoffmerkmale dienen, einschließlich des Aromatengehalts des Kraftstoffs, des Sauerstoffgehalts des Kraftstoffs und der thermischen Stabilität oder des Verkokungsgrads des Kraftstoffs - z. B. durch Messung des Aufbaus von Oberflächenablagerungen auf dem piezoelektrischen Kristall, die zu einer Änderung der Schwingungsmode führen.
• • Verschiedene Kraftstoffmerkmale können bestimmt werden, indem Leistungsmerkmale des Gasturbinentriebwerks 10 während einer ersten Betriebsperiode (z. B. während des Starts) erfasst und dann während einer zweiten Betriebsperiode (z. B. während des Reiseflugs) mit den erwarteten Werten verglichen werden, wenn Kraftstoff mit bekannten Eigenschaften verwendet wird.
• • Verschiedene Kraftstoffmerkmale, einschließlich des Gehalts an aromatischen Kohlenwasserstoffen im Kraftstoff, können auf der Grundlage von Sensormessungen des Vorhandenseins, des Nichtvorhandenseins oder des Grades der Bildung eines Kondensstreifens durch die Gasturbine 10 während ihres Betriebs bestimmt werden.
• • Kraftstoffmerkmale, einschließlich des Gehalts an aromatischen Kohlenwasserstoffen, können auf der Grundlage einer UV-Vis-Spektroskopiemessung des Kraftstoffs bestimmt werden.
• • Verschiedene Kraftstoffmerkmale, darunter der Schwefelgehalt, der Naphthalin-Gehalt, der Gehalt an aromatischem Wasserstoff und das Wasserstoff-Kohlenstoff-Verhältnis, können durch Messung der in den Abgasen des Gasturbinentriebwerks 10 während seines Betriebs vorhandenen Stoffe bestimmt werden.
• • Der Brennwert des Kraftstoffs kann während des Betriebs des Luftfahrzeugs 1 auf der Grundlage von Messungen ermittelt werden, die während der Verbrennung des Kraftstoffs durchgeführt werden, z. B. anhand der Durchflussrate des Kraftstoffs und der Wellendrehzahl oder der Temperaturänderung in der Brennkammer 16.
• • Verschiedene Kraftstoffmerkmale können bestimmt werden, indem eine Betriebsänderung vorgenommen wird, die den Betrieb des Gasturbinentriebwerks 10 beeinflusst, eine Reaktion auf die Betriebsänderung erfasst wird und die ein oder mehreren Kraftstoffmerkmale des Kraftstoffs auf der Grundlage der Reaktion auf die Betriebsänderung bestimmt werden.
• • Verschiedene Kraftstoffmerkmale können im Verhältnis zu Kraftstoffmerkmalen eines ersten Kraftstoffs bestimmt werden, indem ein dem Gasturbinentriebwerk 10 zugeführter Kraftstoff von dem ersten Kraftstoff auf einen zweiten Kraftstoff umgestellt wird und die ein oder mehreren Kraftstoffmerkmale des zweiten Kraftstoffs auf der Grundlage einer Änderung des Verhältnisses zwischen T30 und einem der Werte T40 und T41 bestimmt werden (wobei das Verhältnis für den Temperaturanstieg in der Brennkammer 16 kennzeichnend ist). Die Merkmale können als relative Werte im Vergleich zu dem ersten Kraftstoff oder als absolute Werte unter Bezugnahme auf bekannte Werte für den ersten Kraftstoff bestimmt werden.

Fuel characteristics can be determined in various ways, both directly (e.g. from sensor data corresponding to the fuel characteristic in question) and indirectly (e.g. by inference or calculation from other characteristics or measurements). The characteristics can be determined as relative values compared to another fuel or as absolute values. For example, one or more of the following methods can be used for determination:

• • The aromatics or cycloparaffin content of the fuel can be determined by measuring the swelling of a sensor component made from a sealing material such as: B. a nitrile sealing material can be determined.
• • Fuel characteristics can be determined using trace substances or species that are either naturally present in the fuel or added as tracers, e.g. B. the percentage of sustainable aviation fuel in the fuel or whether the fuel is kerosene.
• • Measurements of the vibration mode of a piezoelectric crystal exposed to the fuel can serve as a basis for determining various fuel characteristics, including the fuel's aromatics content, the fuel's oxygen content, and the thermal stability or degree of coking of the fuel - e.g. B. by measuring the buildup of surface deposits on the piezoelectric crystal, which lead to a change in the vibration mode.
• • Various fuel characteristics can be determined by detecting performance characteristics of the gas turbine engine 10 during a first period of operation (e.g., during takeoff) and then comparing them to expected values during a second period of operation (e.g., during cruise) when fuel with known properties is used.
• Various fuel characteristics, including the aromatic hydrocarbon content of the fuel, may be determined based on sensor measurements of the presence, absence, or degree of contrail formation by the gas turbine 10 during its operation.
• • Fuel characteristics, including aromatic hydrocarbon content, can be determined based on a UV-Vis spectroscopy measurement of the fuel.
• • Various fuel characteristics, including sulfur content, naphthalene content, aromatic hydrogen content, and hydrogen-to-carbon ratio, can be determined by measuring the substances present in the exhaust gases of the gas turbine engine 10 during its operation.
• • The calorific value of the fuel can be determined during operation of the aircraft 1 based on measurements taken during combustion of the fuel, e.g. B. based on the flow rate of the fuel and the shaft speed or the temperature change in the combustion chamber 16.
• • Various fuel characteristics may be determined by making an operational change that affects the operation of the gas turbine engine 10, detecting a response to the operational change, and determining the one or more fuel characteristics of the fuel based on the response to the operational change.
• • Various fuel characteristics may be determined relative to fuel characteristics of a first fuel by switching a fuel supplied to the gas turbine engine 10 from the first fuel to a second fuel and the one or more fuel characteristics of the second fuel based on a change in the ratio between T30 and one of the values T40 and T41 can be determined (the ratio being characteristic of the temperature increase in the combustion chamber 16). The characteristics may be determined as relative values compared to the first fuel or as absolute values with reference to known values for the first fuel.

• • T30 = Hochdruckkompressor (HPC) Auslass-Temperatur;
• • T40 = Verbrennungsaustrittstemperatur; und
• • T41 = Hochdruckturbine (HPT) Rotor-Eintrittstemperatur.

As used herein and explained below, T30, T40 and T41 and all other numbered pressures and temperatures are defined using the station numbering listed in the SAE AS755 standard:

• • T30 = High Pressure Compressor (HPC) outlet temperature;
• • T40 = combustion exit temperature; and
• • T41 = High Pressure Turbine (HPT) rotor inlet temperature.

Incinerator

5 schematically shows further details of the combustion system 16 (which may simply be referred to as a “combustion chamber”) of the gas turbine engine 10. In this example, the combustion system is part of a staged combustion system 64 in which the fuel is injected via pilot and main injectors. Fuel is delivered to the injectors via a fuel delivery controller 306 controlled by an electronic engine controller (EEC) 42. The fuel is delivered to the fuel delivery controller by the fuel pumps 308a, 308b. In this example, fuel is supplied to fuel supply controller 306 from two different fuel sources (first fuel source 302 and second fuel source 304), as described above. The fuel from the first and second fuel sources 302, 304 is provided by a first fuel pump 308a and a second fuel pump 308b, respectively. Each of these fuel pumps can be driven mechanically via an additional gear. In alternative configurations, e.g. B. in a more electric engine (MEE) configuration, the fuel pump may be electrically powered. Those skilled in the art will understand that any known suitable configuration of fuel pumps or a combination of fuel pumps may be used to deliver fuel from the fuel tanks 53, 55 into the combustion chamber 16.

The high pressure fuel is directed through the fuel supply regulator 306 into a pilot distribution 309 and a main distributor 310. In the present example, the staged combustion system includes a plurality of fuel nozzles 311 configured as dual injectors (also referred to as internally staged). In the present example, 16 circumferentially spaced fuel nozzles are arranged around an annular combustion chamber 312. Depending on the size of the engine and the design requirements, more or fewer fuel nozzles can be provided. In addition, different burner configurations can be used, e.g. B. cannula-shaped, in a container, etc.

The fuel from the pilot distribution 309 and the main distributor 310 is delivered to all fuel nozzles 311 for injection into the combustion chamber 312. In the present example, a central pilot injector 313 produces a pilot injector spray in a primary zone of the combustion chamber 312, while a concentric main injector 314 produces a main fuel spray.

The supply of fuel via the pilot and main injectors 313, 314 is staggered, i.e. H. At low powers (and therefore low air mass flows), fuel is supplied from the central pilot injector 313 with a rich fuel-air ratio (i.e. with an equivalence ratio greater than one) to improve flame stability. In the present example, as power and mass flow increase, a stage point (SP) is reached at which fuel is delivered from some or all of the main fuel injectors, thereby supplementing the fuel flow from the pilot injectors. The main injectors 314 are configured to inject fuel at a lean fuel-to-air ratio (i.e., with an equivalent ratio less than one). At this point, the airflow is such that the equivalence ratio immediately downstream of the pilot injectors is also lean. In this example, fuel is injected from all main injectors at higher power.

The staged combustion system is therefore characterized by an operating range “pilot-only” and an operating range “pilot-and-main”. The two areas are separated by the staging point. When operating “with pilot injection only”, the entire fuel flow within the combustion chamber is provided exclusively by the pilot injection nozzle(s). In operation “with pilot and main injection”, the fuel in the combustion chamber is provided by the pilot injector(s) and the main injector(s) or only by the main injector(s). The fuel supply controller 306 is therefore arranged to deliver fuel to the main injectors or to both the main and pilot injectors during pilot and main injection modes. The fuel supply controller may be configured to supply fuel to both the pilot and main injectors during pilot and main injection operation, rather than shutting off the pilot injectors in the event of a rapid emergency operation to keep the combustion chamber operating. When operating with pilot injection only, the fuel supply regulator only supplies fuel to the pilot injectors.

For a specific operating condition, such as B. the altitude or the ambient air pressure, the step point SP is usually defined by a threshold value of an engine parameter that is representative of the power setting of the engine, such as. B. T30 (total air temperature at the compressor outlet) or calculated T40 (total air temperature at the combustion chamber outlet) or the fuel-air ratio (FAR) of the combustion chamber. It becomes clear that different threshold values may apply for different operating conditions.

Professionals are familiar with the operation of staged combustion systems to achieve lean burn at high outputs while maintaining flame stability limits at lower outputs. In addition, they are also familiar with other staged combustion configurations, such as: B. those with separate pilot and main injectors (as opposed to duplex or internally staged systems), which can be arranged in parallel (radially separated, axially aligned) or in series (axially separated, radially aligned). It is understood that the principles disclosed herein can be applied to any staged combustion system having pilot and main injectors.

The balance of injection of fuel through the pilot injectors 313 and the main injectors 314 is controlled by the engine electronic controller 42, which provides control signals to the fuel supply controller 306 indicating the total fuel to be injected in the form of a flow rate ( _WF ) and ratio from pilot injector to main injector (stage ratio). The fuel flow controller 306 is configured to use these control signals to deliver the required flow rate of fuel in accordance with the required total fuel flow and the ratio of the pilot and main fuel flows. In alternative examples, the electronic engine controller 42 may instead be configured to provide control signals to the fueling controller 306 indicating the flow rate of fuel during pilot-only operation (W _FVor ) and the flow rate of fuel during main operation (W _FMain ). . It goes without saying that the information provided is equivalent.

In prior art systems, fuel may simply be routed from a single source to a fuel delivery regulator so that fuel with the same fuel characteristics (i.e., same fuel composition) is delivered to both pilot and main injectors at all operating points of the combustion chamber. However, in the present application, the fuel delivery controller 306 is configured to selectively deliver fuel from two different fuel sources to the main and pilot manifolds, as described below.

Staged combustion using fuel from more than one source

In state-of-the-art staged combustion systems, only a single fuel source is available, which is used in both the pilot and main injection operating range. Fuel with the same fuel characteristics is therefore delivered from the injectors to the combustion chamber regardless of the flow rate. The inventors have found that it may be advantageous to supply fuel from different fuel sources with different fuel characteristics to the fuel supply regulator and to supply the pilot and main injectors with fuel with different characteristics so that fuel with different characteristics is provided in different operating regions of the combustion chamber . Related to the in 5 In the staged combustion system shown, the fuel supply controller 306 is therefore set up to supply fuel with different fuel characteristics than the pilot injectors 313 and the main injectors 314 or both, at least during a portion of the operating range with pilot injection only (ie the operating mode), to the pilot injectors 313 or both be supplied with fuel during part of the operating range with pilot and main injection. The different fuel feature may be provided through the use of fuel from the first fuel source 302, fuel from the second fuel source 304, or a mixture thereof.

An advantage of this more flexible supply of fuel to the combustion chamber 16 is that fuel with favorable combustion properties, which is only available to a limited extent, can be used where these favorable properties have a greater effect.

nvPM emissions with staged combustion

6 illustrates the relationship between the fuel flow rate W _F and the soot particle emission rate (represented as the “non-volatile particle number (nvPM)” and referred to herein as the “nvPM number”) for a typical lean burn chamber (e.g. a staged burner system). Any reference to carbon black in this document may also apply to other types of nvPM.

6 shows a first area to the left of the stage point SP (at a lower fuel flow rate than at the stage point) in which only the pilot injectors of the combustion chamber are in operation and in which nvPM number increases rapidly with increasing fuel flow rate W _F. Operation in this first range is referred to as operation in the “pilot injection only” operating range.

6 shows a second region to the right of the stage point SP (at higher fuel flow rate than at the stage point) in which both the pilot injectors and the main injectors operate and in which nvPM number is much lower and increases only slowly (if at all) with increasing W _F . Operation in this second area is referred to as the “with pilot and main injection” operating area. Although in 6 a non-zero value of nvPM number is shown in the operating range with pre- and main injection, in some lean-burn combustion chambers the nvPM number in the operating range with pre- and main injection can be essentially equal to zero.

It goes without saying that the in 6 The curve shape shown is just an example for illustrative purposes. In general, the nvPM number in pilot injection only operation is significantly higher than in pilot and main injection operation, and there is a sharp boundary between the two operating ranges. Some of the examples listed below make additional use of the positive slope of the curve when operating with pilot injection only, but here too the exact shape of the curve is different 6 The curve shown is just an example of the dependence between W _F and nvPM number.

The position of the step point SP can be chosen so that the fuel flow rate is to the right of the step point SP during most or all cruise conditions, i.e. H. in a range of operation with pilot and main injection that corresponds to very low (or perhaps even essentially zero) values of nvPM number. Conversely, operations can occur at many other times during a flight, e.g. B. during taxiing, approach and descent, correspond to operation “only with pre-injection” in which the nvPM (soot) emissions are comparatively high.

It goes without saying that the step point SP varies under different flight conditions, e.g. B. in height, can be at different values of W _F. For example, during cruise flight, where the air density is low and therefore the mass flow rate of the working fluid through the gas turbine core is also low, the stage point SP may correspond to a significantly lower fuel flow rate than on the ground, where the air density is significantly higher.

The stage point SP applicable to a particular flight condition may be defined as the absolute value of the fuel flow rate or as a predetermined percentage of the maximum value W _F applicable to the flight condition. Other definitions of step point may also be used as understood by those skilled in the art.

The present applications relate to the nvPM number (or nvPM number) and its dependence on _WF , as in 6 shown. However, it goes without saying that a corresponding relationship for the nvPM mass and its dependence on W _F could also be considered and that the devices and methods described here could be adapted accordingly.

Control of nvPM emissions

The level of nvPM emissions from a gas turbine engine depends on the characteristics of the fuel used. For example, some aircraft fuels may have lower levels of certain components known to cause soot emissions than typical fossil kerosene and therefore may produce a lower amount of soot for the same fuel flow rate in the combustion chamber.

Although the nvPM emissions of a gas turbine engine could be effectively reduced by using fuels with a low nvPM production index, this is not always possible. For example, it may be that such fuel is not available for the entire duration of the flight. There may also be other technical, regulatory or cost limitations to the use of such low nvPM fuels in large quantities of fuel or in large concentrations in a fuel mixture.

The inventors have found that by preferentially using fuel with relatively low nvPM emissions (e.g. compared to fossil kerosene) in the operating range with pilot injection only compared to the operating range with pilot and main injection, the nvPM emissions are still significant can be reduced without having to use a large amount of the low-nvPM fuel throughout the entire operating range of the combustion chamber.

Therefore, in the present example, the first fuel in the first fuel source 302 is associated with an nvPM production that is lower than that of the second fuel in the second fuel source 304 (e.g., when used under appropriate conditions). The fuel delivered to the pilot injectors during at least a portion of the pilot-only operating range is also associated with nvPM production that is less than that delivered to one or both of the pilot injectors and main injectors during at least a portion of the pilot-injected operating range. As explained below, the fuel for the pre- and Main injectors 313, 314 are provided exclusively from one of the two available fuel sources 302, 304 or as a mixture of fuel from the first and second fuel sources 302, 304.

In some examples, the fuel system may be configured so that the main injectors 314 may be powered by either the first fuel source 302 or the second fuel source 304, and also so that the pilot injectors 313 may be powered by either the first fuel source 302 or the second fuel source 304 can. Although some of the examples presented below do not include such a flexible fuel system, it is beneficial for safety reasons to ensure that each fuel tank can supply fuel to each injector of any engine.

In some of the examples described herein, a single injector 313, 314 is supplied with either only fuel from the first fuel source 302 or with fuel from the second fuel source 304, i.e. H. the fuel system switches between the two fuel sources.

In other examples, the fuel system also includes the necessary equipment to mix fuel from the two onboard fuel sources (e.g., high soot index and low soot index fuels), varying the mixing ratio according to various decision criteria to achieve a fuel composition produce the characteristics of which correspond to those of the fuel composition with a low soot index (mixing ratio 100:0) or those of the fuel composition with a high soot index (mixing ratio 0:100) or lie somewhere in between (mixing ratio x:100-x with 0 < x <100).

In various examples, switching between predetermined fuel compositions and/or a mixed fuel composition can be created for only the pilot injectors 313. In such examples, the main injectors 314 may be supplied with fuel from one of the fuel sources (e.g., the high nvPM fuel) at any time. However, to increase flexibility, in some examples it may be provided that the main injectors 314 may be switched to the fuel from the other source (e.g., the low nvPM fuel composition) and/or to a mixed fuel composition during certain abnormal operating times, e.g . B. in the event of a loss of fuel with a high nvPM value, e.g. B. due to a fuel leak.

In some examples, the fuel characteristic that distinguishes the fuel from the first fuel source 302 from the fuel from the second fuel source 304 may be the percentage of sustainable aviation fuel (SAF) contained in the respective fuel. The fuel delivered to the pilot injectors 313 during at least a portion of the pilot-only operating range would also have a different percentage of SAF than the fuel delivered to one or both of the pilot injectors 313 and the main injectors 314 during at least a portion of the pilot-injected operating range becomes.

Compared to fossil kerosene, SAF has significantly lower soot or more general nvPM emissions. Roughly speaking, when SAF is used as part of a fuel blend with fossil kerosene, the higher the percentage of SAF in the mixture (and therefore the lower the percentage of fossil kerosene), the greater the reduction in nvPM emissions, at least within certain areas of the SAF share. This effect will be in 7 illustrating the dependence of nvPM number emissions on fuel flow rate W _F for a standard fuel composition (solid line) and for three additional fuel compositions A, B and C (labeled) for a particular flight condition, e.g. B. is defined by altitude and forward speed. The standard fuel composition and fuel compositions A, B and C are each characterized by a progressively higher proportion of SAF and a correspondingly lower proportion of fossil kerosene. The default fuel composition could be 100% fossil kerosene or a blend consisting mainly of fossil kerosene and a small amount of SAF, as is standard at some airports.

In 7 is the factor for reducing nvPM number emissions compared to the standard fuel composition achieved by each fuel mixture, as constant with W _F during operation with pilot injection only and also constant with W _F during operation with pilot and Main injection shown, although the reduction factors in these two operating ranges are shown as different. It is clear that other dependencies of W _F can be observed in different implementations and are also considered in the present application.

8th shows such an alternative dependence on W _F , which is caused by an increase in the nvPM number reduction in operation with pilot injection only factor for each fuel mixture when W _F is reduced from the step point SP towards a lower fuel flow rate. Other variations are possible; in particular, the dependence of the nvPM number reduction factor on W _F does not have to be the same for every fuel mixture and/or does not have to be a monotonically increasing or monotonically decreasing function of W _F. Although the following examples in the present application are based on in 7 Based on the form shown, more general forms are of course also conceivable.

The inventors have found that when operating a gas turbine engine 10 in the pilot and main injection operating regime, soot emissions are inherently low and replacing the standard fuel composition (e.g. fossil kerosene) with SAF (or a high percentage SAF blend) or a other fuel with low soot formation only results in a small further reduction in soot emissions. On the other hand, if the engine 10 is operated at a flow rate that is below, but still close to, the stage point SP, soot emissions can be reduced by using a fuel composition containing a higher percentage of low soot fuel (e.g. SAF) and a lower percentage of fossil kerosene (or another heavily sooty fuel) can be significantly reduced compared to a standard fuel composition. By using fuel with different fuel characteristics in different operating ranges of the combustion chamber, the percentage of SAF in the fuel composition burned in the pilot-only operation can be increased (e.g., maximized), while the percentage of SAF in the fuel composition burned in the pilot and main injection operation can be increased Fuel composition is reduced (e.g. minimized). In this way, the nvPM reducing effect of the available SAF can have a greater effect than using a constant percentage SAF composition over the entire operating range of the combustor.

In various other examples, one or more other characteristics of the fuel may be varied alternatively or in addition to the SAF content. Changes in other characteristics between the fuels of the first and second fuel sources may additionally or alternatively be associated with different values of the nvPM number. For example, the first fuel source 302 may be characterized by a fuel having a lower level of certain components that cause soot or other nvPM emissions than the second fuel source 304. In some examples, the fuel of the first fuel source 302 may be characterized by a lower level of aromatic hydrocarbons, in particular by a lower naphthalene content compared to the second fuel source 304. A lower content of such soot-forming compounds can be associated with SAF compared to fossil kerosene. However, this does not always have to be the case. Some SAFs may be associated with higher soot production compared to others (e.g. if they have a greater proportion of synthetic aromatics added to them), or they may be associated with higher soot production compared to a fossil fuel such as fossil kerosene in which the aromatics were removed to obtain a predominantly paraffinic portion.

Various examples of supplying fuel to the pilot and main injectors 313, 314 from the first and second fuel sources 302, 304 (exclusively, at least under normal operating conditions) or a mixture thereof at various times during the operating ranges of the combustion chamber are described below.

Figures 9, 10 and 11

9 shows an example in which the fuel supply controller 306 is arranged to supply fuel from the first fuel source 302 to the pilot injectors 313 during operation in both the pilot and main injection only operating ranges and fuel from the second fuel source 304 to the pilot injectors 313 Main injection nozzles 314 during operation in the operating range with pilot and main injection. In this example, the fuel supply controller 306 includes a pilot controller 306a that is in fluid communication with the first fuel source 302 via the first fuel pump 308a. The fuel supply controller 306 further includes a separate main controller 306b, which is in fluid communication with the second fuel source 304 via the second fuel pump 308b. The pilot controller 306a is arranged to deliver fuel to the pilot distributor 309 and the pilot injectors 313. The main regulator 306b is arranged to deliver fuel to the main manifold 310 and the main injectors 314. The fuel supply regulator 306 therefore includes two separate flow paths through which fuel from each fuel source 302, 304 is supplied to the combustion chamber 16. The flow rate of fuel through the pilot controller 306a and the main controller 306b may be controlled independently using control signals that the fuel delivery controller 306 receives from the EEC 42. The pilot injectors 313 are therefore always supplied with fuel from the first fuel source 302 and the main injectors 314 are always supplied with fuel from the second fuel source 304. The fuel flow too the main injectors 314 can be essentially zero in the operating range with pilot injection only. This means that the composition of the fuel flowing through a single injector does not change throughout the flight and is fixed before flight (at least under normal operating conditions).

In the example of 9 the first fuel source 302 includes a fuel associated with low nvPM production, e.g. B. a fuel with a relatively high SAF content (e.g. a SAF-rich fuel). The second fuel source 304 includes a fuel associated with high nvPM production, e.g. B. a fuel with a relatively low SAF content (ie lower than the first fuel), e.g. B. a low-SAF fuel. The term “SAF-rich” may be used here to refer to a fuel that has a higher SAF content than a “SAF-poor” fuel. The term “SAF-rich” fuel may include fuel with a SAF content of 100%. The “low SAF” fuel may include a fuel with 0% SAF, e.g. B. fossil kerosene. In some examples, the high SAF fuel may contain up to 50% SAF and the low SAF fuel may contain essentially zero% SAF, e.g. B. it can be standard fossil kerosene fuel.

1. a) Die Höhe der für einen geplanten Flug verfügbaren oder zugewiesenen SAF;
2. b) den Gesamtbedarf an Kraftstoff für die Voreinspritzdüsen der Piloten für den gesamten Flug (berechnet nach Verfahren, die dem Fachmann bekannt sind); und
3. c) Etwaige Begrenzungen des höchstzulässigen SAF-Anteils, z. B. Zertifizierungsgrenzen oder z. B. technische Grenzen in Bezug auf das betreffende Luftfahrzeug und/oder die Voreinspritzdüsen selbst, oder die maximale prozentuale Mischung, in der SAF zum Zeitpunkt der Kraftstoffbefüllung verfügbar ist.

In the example of 9 The composition of the SAF-rich fuel can be determined by one or more of the following factors:

1. a) The level of SAF available or allocated for a planned flight;
2. b) the total fuel requirement for the pilots' pilot injectors for the entire flight (calculated according to methods known to those skilled in the art); and
3. c) Any limitations on the maximum permissible SAF share, e.g. B. Certification limits or e.g. B. technical limitations related to the aircraft in question and/or the pilot injectors themselves, or the maximum percentage mixture in which SAF is available at the time of fuel filling.

The desired SAF content in the composition of the SAF-rich fuel can be calculated as 100% times factor a) divided by factor b), subject to a maximum permissible value which is the minimum of the various possible limits specified in factor c). Adjustment may be required to account for the different volumetric energy densities of SAF and fossil kerosene using methods known to those skilled in the art.

In the present example, the low SAF fuel composition may have a standard SAF percentage of zero (or the lowest possible percentage given the standard fuel supply at the airport where the aircraft is fueled) but any SAF assigned to the proposed flight and not included in the SAF-rich fuel composition for the pilot injectors 313 is used as part of the low-SAF fuel composition for the main injectors 314. The resulting percentage of SAF in the low-SAF fuel composition is determined by any certification limits or technical limits related to the particular aircraft and/or main injectors or the maximum percentage of the mixture in which SAF is available at the time of fuel loading , capped.

The operation of the combustion chamber in 9 may not be possible on all flights because the size of the available fuel tanks for SAF-rich fuel composition and for SAF-poor fuel composition are not sufficient to accommodate the required fuel volume for one or both pilot injectors 313 and main injectors 314. This may be the case on long-haul flights where all fuel tanks must be completely filled before departure and where the respective fuel volume requirements for the various injectors may not exactly match the source volumes.

10 shows the dependence of the nvPM number on the flow rate of fuel W _F for the arrangement of the fuel regulator 9 (dashed line) compared to the corresponding dependence for a standard fuel composition such as fossil kerosene (solid line). In this illustration it is assumed that the SAF-rich fuel composition is fuel composition A 7 corresponds. As in 10 As can be seen, there is an advantageous reduction in the nvPM number in the operating range with pilot injection only, while in the operating range with pilot and main injection there is only a small or no change in the nvPM number. In this example, a limited amount of available SAF has therefore been more effectively targeted to a portion of the operating range (i.e. pilot injection only) where it can provide the greatest benefit in terms of nvPM reduction.

11 illustrates a method 4000 for operating a gas turbine engine using the staged combustor system of 9 can be carried out. The procedure 4000 includes controlling the fuel supply 4002 to the pilot and main injectors 313, 314 from the first fuel source 302 and the second fuel source 304. As described above, controlling the fuel supply generally includes supplying fuel to the pilot injectors 313 during at least a portion the pilot injection only operating region having different fuel characteristics than the fuel delivered to one or both of the pilot injectors 313 and main injectors 314 during at least a portion of the pilot and main injection operating region. In the example of 11 The control of the fuel supply 4002 includes the supply of fuel 4004 from the first fuel source 302 to the pilot injectors 313 during operation both in the operating range with pilot injection only and in the operating range with pilot and main injection and of fuel from the second fuel source 304 to the main injectors 314 during the operating range with pilot and main injection. All other features related to above 9 have been described can be included in the procedure of 11 included, even if they are not repeated here.

Figures 12, 13 and 14

In the in the 9 , 10 and 11 In the example shown, the advantageous reduction in the nvPM number (compared to the standard fuel composition) observed particularly during operation with only pilot injection (ie to the left of point SP) is made possible by the priority supply of SAF to the pilot injectors, resulting in a higher SAF proportion the fuel composition for these injectors is achieved. However, in pilot and main injector operation (where soot formation is minimal even when operating on fossil kerosene), a SAF-rich fuel composition is still supplied to the pilot injectors. Even more efficient use of the SAF-rich fuel can be achieved by further flexibility in the fuel supply to the combustion system.

12 shows an example in which the fuel supply controller 306 is arranged to switch the supply of fuel to the pilot injectors 313 between the first fuel source 302 and the second fuel source 304. In the example described, the switchover occurs at the limit of the operating range only with pilot injection (e.g. at stage point SP). In other examples, there may be multiple switching points, including at the limit and/or within the pilot injection-only operating range. More generally, the fuel supply controller 306 is arranged to switch the supply of fuel to the pilot injectors 313 between the first and second fuel sources 302, 304 at one or more operating points within or at a boundary of the pilot-only operating range.

As in 12 shown, the pilot control controller 306a includes two separate, independently controllable controllers, a first controller 315a, which is in fluid communication with the first fuel source 302, and a second controller 315b, which is in fluid communication with the second fuel source 304. The first and second controllers 315a, 315b of the pilot controller 306a are controllable by signals received from the EEC 42. Both the first and second controllers 315a, 315b are in fluid communication with the pilot distribution 309 so that they can control the delivery of fuel to the pilot injectors 313.

The fuel supply controller 306 is arranged to switch the supply of fuel to the pilot injectors 313 between fuel from the first fuel source 302 and fuel from the second fuel source 304 according to a mode signal indicative of a change in the operating range of the staged combustion system. The mode signal may be received by the EEC 42 from the combustion system 64 (or the combustion chamber 16) and a corresponding control signal may be sent to the controllers 315a, 315b so that the switching at the stage point between the operating region with pilot injection only and the operating region with pilot and Main injection can take place. The fuel supply controller 306 is thus configured to switch the pilot injectors 313 between the first fuel and the second fuel (or vice versa) each time the stage point SP is exceeded. The EEC may be configured to receive a signal from the combustion system 64 (or combustion chamber 16) indicating its mode of operation (pilot injection only or pilot and main injection). Alternatively, the EEC 42 may instruct the combustion system 64 to switch from one operating mode to the other. In this example, the mode signal may already be present in the EEC 42 and used to switch fuel delivery by the fuel delivery controller 306. Switching fuel delivery in accordance with a mode signal indicating a change in the operating mode of the combustion chamber 16 may ensure an acceptable level of synchronization between the operating mode of the combustion chamber and the fuel composition of the pilot injectors. This can help ensure rapid switching between fuel sources when the stage point is exceeded.

In the example described here, the pilot control controller 306a is arranged to switch between supplying fuel exclusively from the first fuel source 302 and exclusively from the second fuel source 304. The first and second fuel controllers 315a, 315b may therefore be arranged to switch between the following operating states: i) the first is completely closed (so that no fuel is supplied to the combustion chamber 16 from the corresponding source), and the second becomes Controlling the flow rate from the other fuel source used; and ii) the second is completely closed (so that no fuel is supplied to the combustion chamber 16 from the corresponding source), and the first is used to control the flow rate from the other fuel source. In other examples, any other suitable arrangement of the fuel pilot controller 306a may be provided to enable switching between fuel sources.

The in 12 Fuel supply controller 306 shown may be arranged to deliver fuel such that when the engine 10 is operated in pilot injection only mode, the pilot injectors 313 are supplied with a SAF-rich fuel composition and when the engine is operated in pilot and main injection mode both the pilot injectors 313 and the main injectors 314 are supplied with a low-SAF fuel composition.

1. a) die Höhe der für einen geplanten Flug verfügbaren oder zugewiesenen SAF;
2. b) den Gesamtbedarf an Kraftstoff für die Voreinspritzdüsen während des Betriebs nur mit Voreinspritzung für den gesamten Flug (berechnet nach Verfahren, die dem Fachmann bekannt sind); und
3. c) etwaige Begrenzungen des höchstzulässigen SAF-Anteils, z. B. Zertifizierungsgrenzen oder z. B. technische Grenzen in Bezug auf das betreffende Luftfahrzeug und/oder die Voreinspritzdüsen selbst, oder die maximale prozentuale Mischung, in der SAF zum Zeitpunkt der Kraftstoffbefüllung verfügbar ist.

In this example, the composition of the SAF-rich fuel is determined by the following factors:

1. (a) the level of SAF available or allocated for a planned flight;
2. b) the total fuel requirement for the pilot injectors during operation with pilot injection only for the entire flight (calculated according to methods known to those skilled in the art); and
3. c) any limitations on the maximum permissible SAF share, e.g. B. Certification limits or e.g. B. technical limitations related to the aircraft in question and/or the pilot injectors themselves, or the maximum percentage mixture in which SAF is available at the time of fuel filling.

The desired SAF content in the SAF-rich fuel composition is then simply 100% times factor a) divided by factor b), subject to a maximum allowable value that represents the minimum of the various potential limits determined in factor c). Adjustment may be required to account for the different volumetric energy densities of SAF and fossil kerosene using methods known to those skilled in the art.

The composition of the low SAF fuel can be determined according to the same procedure and with the same restrictions as that in the 9 , 10 and 11 Example described can be determined, if necessary additionally with the practical restrictions with regard to the pilot injectors 313.

13 shows the dependence of the nvPM number on the fuel flow rate W _F for the fuel supply controller 12 (dashed line) compared to the corresponding dependence for a standard fuel composition such as fossil kerosene (solid line). In this illustration it is assumed that the SAF-rich fuel composition is fuel composition B 7 and the low SAF fuel composition corresponds to the standard fuel composition.

As in 13 As can be seen, the fuel supply regulator 316 allows off 12 for a fixed amount of SAF assigned to a single flight, a higher percentage of SAF content of the SAF-rich fuel composition compared to the example 9 , as the use of the SAF-rich fuel composition is further limited to pilot injection operation only. As a result, SAF is deployed more effectively in an operating range where the beneficial reduction in nvPM is greater.

As in the example of 9 , 10 and 11 The capacity of the fuel tanks on some flights may require operation following the example of 12 prevent as it can be difficult to match the volumes of the different fuel tanks to the required volumes of the SAF-rich and SAF-poor fuel compositions.

14 illustrates a method of operating a gas turbine engine 10 using the staged combustor system of 12 can be carried out. The procedural steps that follow the process of 11 are common are marked accordingly. In this example, the fuel supply control 4002 includes switching 4006 the supply of fuel to the pilot injectors 313 between the first fuel source 302 and the second fuel source 304 at the stage point SP. Each of the above related 12 The features described can be incorporated into the process 14 included, even if they are not repeated here.

Figures 15 and 16

The fuel supply regulator 12 may, in some examples, be configured to switch the delivery of fuel to the pilot injectors 313 between the first fuel source 302 and the second injector 304 at a threshold TP within the pilot-only operating range. Fuel from the second fuel source 304 may be supplied to the pilot injectors 313 at flow rates below the threshold, fuel from the first fuel source 302 is supplied to the pilot injectors 313 at flow rates between the threshold and the limit of the pilot only operating range (stage point), and fuel from the Second fuel source 304 can be supplied to pilot injectors 313 at flow rates above the limit. The main injectors 314 can be supplied with fuel from the second fuel source 304 at any time.

Similar to the previously described examples, the first fuel in the first fuel source 302 may be a low nvPM fuel, e.g. B. a SAF-rich fuel, while the second fuel in the second fuel source 304 may be a high nvPM fuel, e.g. B. a low-SAF fuel. When the combustion chamber 16 is operated in the pilot-only mode near the stage point SP (as determined by the position of the threshold), the pilot injectors 313 are supplied with the SAF-rich fuel composition. At all other times, the pilot injectors 313 are supplied with a low SAF fuel composition.

This example can enable even more efficient use of SAF and, compared to examples where the switchover only occurs at the stage point SP, in cases where the SAF proportion in the SAF-rich fuel composition of the second example is determined by the availability of SAF and is not limited by the engine's approval limits, is an additional advantage. The present example, in which two switchover points are provided, can also overcome difficulties with potential inconsistencies between individual fuel tank capacities and the required amounts of high-SAF and low-SAF fuel compositions.

1. a) eine erste Schwellenwert-Kraftstoffdurchflussrate, bei deren Überschreiten die Erzeugung von nvPM durch das Gasturbinentriebwerk 10 einen Schwellenwert der nvPM-Menge überschreitet, die von dem Gasturbinentriebwerk während des Betriebs erzeugt wird, bei dem die Voreinspritzdüsen 313 mit Kraftstoff der zweiten Kraftstoffzusammensetzung versorgt werden. Der Schwellenwert kann beispielsweise als Betrieb nur mit Voreinspritzung bei einer Durchflussrate definiert werden, die bei einer Standard-Kraftstoffzusammensetzung wie fossilem Kerosin zu Rußemissionen führen würde, die einen Schwellenwert überschreiten. Die von dem Gasturbinentriebwerk erzeugten Rußemissionen oder nvPM können entweder als Anzahl der pro Masseneinheit Kraftstoff emittierten Rußpartikel (d. h. als Emissionsindex) oder als Anzahl der pro Zeiteinheit emittierten Rußpartikel (d. h. auch unter Berücksichtigung der Durchflussrate des Kraftstoffs) oder als Anzahl der pro Flugstreckeneinheit emittierten Rußpartikel (d. h. auch unter Berücksichtigung der Geschwindigkeit des Luftfahrzeugs) definiert werden.
2. b) einen zweiten Schwellenwert, der als vordefinierte Schwellenwert-Kraftstoffdurchflussrate definiert ist, die geringer ist als die Kraftstoff-Durchflussrate am Stufenpunkt SP (wie für die aktuellen Flugbedingungen, z. B. die aktuelle Höhe, definiert). Der vordefinierte Schwellenwert kann entweder ein Prozentsatz der Kraftstoff-Durchflussrate am Stufenpunkt oder ein absoluter Wert des Durchflusses sein, der unter dem des Stufenpunktes liegt.

The position of the switching threshold TP can be set depending on one or more factors so that switching occurs “close” to the step point SP. The threshold can be, for example:

1. a) a first threshold fuel flow rate, exceeding which the production of nvPM by the gas turbine engine 10 exceeds a threshold amount of nvPM produced by the gas turbine engine during operation in which the pilot injectors 313 are supplied with fuel of the second fuel composition. For example, the threshold may be defined as operating with pilot injection only at a flow rate that would result in soot emissions exceeding a threshold for a standard fuel composition such as fossil kerosene. The soot emissions or nvPM produced by the gas turbine engine can be expressed either as the number of soot particles emitted per unit mass of fuel (i.e. as an emissions index), or as the number of soot particles emitted per unit of time (i.e. also taking into account the flow rate of the fuel), or as the number of soot particles emitted per unit of flight distance ( i.e. also taking into account the speed of the aircraft).
2. b) a second threshold defined as a predefined threshold fuel flow rate that is less than the fuel flow rate at the stage point SP (as defined for the current flight conditions, e.g. current altitude). The predefined threshold can be either a percentage of the fuel flow rate at the step point or an absolute value of the flow that is less than that of the step point.

The first threshold and/or the second threshold may be set with reference to the amount of SAF available for a proposed flight, assuming that as much of the available SAF as possible is incorporated into the SAF-rich fuel composition, and namely, taking into account the fuel volume required for a proposed flight for the pilot injectors when operating "close to point SP" according to a candidate value of the first threshold and / or the second threshold, the required fuel volume being determined according to methods known to those skilled in the art.

The second threshold may be determined with reference to the fuel tank volume available on board the aircraft 1 for the SAF-rich fuel composition, again taking into account the fuel volume requirement for a proposed flight for the pilot injectors operating "near point SP", the fuel volume requirement according to procedure is determined, which are known to the person skilled in the art. On some flights, especially long-haul flights, where the entire available fuel capacity must be used, the size of the available fuel tanks 53, 55 may limit the available options with respect to the second threshold to ensure that the capacity of the fuel tank for the SAF-rich fuel composition is fully utilized. This would impose corresponding restrictions on the SAF content in the SAF-rich fuel composition

1. a) Die Höhe der für einen geplanten Flug verfügbaren oder zugewiesenen SAF;
2. b) der Gesamtkraftstoffbedarf für die Voreinspritzdüsen bei Betrieb nur mit Voreinspritzung in der Nähe des Stufenpunktes für den gesamten Flug (berechnet nach Verfahren, die dem Fachmann bekannt sind, und unter Berücksichtigung der entsprechenden Kraftstofftankvolumina, wie oben beschrieben); und
3. c) Etwaige Begrenzungen des höchstzulässigen SAF-Anteils, z. B. Zertifizierungsgrenzen oder praktische Grenzen, die mit dem jeweiligen Luftfahrzeug und/oder den Voreinspritzdüsen selbst zusammenhängen, oder die maximale prozentuale Mischung, in der SAF zum Zeitpunkt der Kraftstoffbefüllung verfügbar ist.

In cases where the first threshold and/or the second threshold have not been established with reference to the amount of SAF available, the composition of the SAF-rich fuel may be determined by one or more of the following factors:

1. a) The level of SAF available or allocated for a planned flight;
2. b) the total fuel requirement for the pilot injectors when operating with pilot injection only near the stage point for the entire flight (calculated using methods known to those skilled in the art and taking into account the appropriate fuel tank volumes as described above); and
3. c) Any limitations on the maximum permissible SAF share, e.g. B. Certification limits or practical limits associated with the particular aircraft and/or the pilot injectors themselves, or the maximum percentage mixture in which SAF is available at the time of fuel filling.

The SAF content in the composition of the SAF-rich fuel is then simply 100% times factor a) divided by factor b), subject to a maximum allowable value which represents the minimum of the various potential limits determined in factor c). Adjustment may be required to account for the different volumetric energy densities of SAF and fossil kerosene using methods known to those skilled in the art.

The composition of the low-SAF fuel can be determined using the same procedure and under the same boundary conditions as, for example, in connection with 12 are described.

15 illustrates the dependence of the nvPM number on the fuel flow rate W _F (dashed line) for an example in which two switching points are provided, one at a threshold TP in the pilot-injection only operating range and a second TP2 at the step point SP, compared to the corresponding dependency for a standard fuel composition such as fossil kerosene (solid line). In this illustration, the SAF-rich fuel composition is assumed to be of fuel composition C 7 and the low SAF fuel composition corresponds to the standard fuel composition. The switching points TP, TP2 can be recognized by the rapid changes in the nvPM number at the corresponding fuel flow rate.

16 shows a method 4000 for operating a gas turbine engine 10 using the staged combustor system of 12 can be carried out in which two switching points TP, TP2 are provided. Procedural steps that correspond to the process of 14 are common are marked accordingly. In this example, the fueling control 4002 further includes a step of switching 4008 the supply of fuel to the pilot injectors between the first fuel source 302 and the second fuel source 304 at a threshold within the pilot-only operating range in addition to switching 4006 at the stage point. Each of the above related 15 The features described can be incorporated into the process 16 to get integrated.

Figures 17, 18 and 19

In the previously described examples, the fuel supplied to the pilot and main injectors 313, 314 is limited to the fuel characteristics of the two predefined fuels (the first and the second fuel) contained in the first and second fuel sources 302, 304. The inventors have discovered that further advantages can be achieved by supplying fuel containing a mixture of fuel from the first and second fuel sources 302, 304 to the combustion chamber 16 to provide greater flexibility in the fuel composition supplied to the injectors 313, 314 to reach.

17 shows an example in which the fuel supply controller 306 includes a fuel mixing device 318. The fuel mixing device 318 is arranged to receive a fuel supply from both the first and second fuel sources 302, 304 and to dispense fuel from the first fuel source 302, fuel from the second fuel source 304, or a mixture thereof (e.g., a Mixing ratio, which can vary from 100% of the first fuel and 0% of the second fuel to 0% of the first fuel and 100% of the second fuel and any ratio in between). The fuel mixer 318 is in fluid communication with the pilot distribution 309 and is arranged to deliver fuel to the pilot injectors 313. The fuel supply regulator 306 consists of a main regulator 306b, which connected to the second fuel source 304 and arranged to supply the main manifold 310 and the main injectors 314, similar to other examples. In other examples, the mixer may be arranged to supply both the main and pilot injectors 313, 314. By using the fuel mixer 318, a mixture of fuel can be supplied to the pilot injectors 313 with pilot injection only, at least during part of the operating range. For other portions of pilot-only operation and during pilot and main injector operation, the pilot injectors 313 may be supplied with fuel from only one of the fuel sources by the fuel mixing device 313. A mixture of fuel from both sources can also be provided during the entire operating range with pilot injection only and/or during the operating range with pilot and main injection.

Similar to the previously described examples, the first fuel in the first fuel source 302 may be a low nvPM fuel, such as. B. a SAF-rich fuel, while the second fuel in the second fuel source 304 may have a high nvPM emission, such as. B. a low-SAF fuel. If the combustion chamber 16 is operated with pilot injection only, a fuel mixture can be supplied to the pilot injectors 313, so that the fuel supplied is associated with a lower nvPM value than the fuel supplied to the main and/or pilot injectors 313, 314 during operation Pilot and main injection, where the nvPM value is inherently lower. This can enable even more efficient use of low nvPM fuel. The fuel supplied to the pilot injectors 313 during at least a portion of pilot-only operation may therefore contain more of the first fuel compared to the fuel supplied to the main injectors 314 during pilot and main injection operation. In the example of 17 The fuel supply controller 306 allows the fuels from the first and second sources 302, 304 to be mixed by the fuel mixer 318 in a desired mixing ratio and supplied to the pilot distribution 309. This is in contrast to the example of 12 , 13 and 14 , in which a fuel mixture formed by mixing a quantity of fuel from the first source 302 and a quantity of fuel from the second source 304 cannot be provided.

There are a number of advantages associated with providing blended fuel in this manner. For example, a hard limit or switching point (e.g. the threshold value TP described above) may be within the pilot injection only range, below which a low-SAF fuel composition is supplied to the pilot injectors 313 and above which a SAF-rich fuel composition is supplied to the pilot injectors 313 , be avoided. This can reduce the risk of a sudden increase in soot emissions when fuel flow is reduced, which could otherwise lead to unnecessarily high soot emissions, for example during the approach and/or final approach phase.

Adding fuel can also be advantageous because near the step point SP (i.e., at flow rates just below the step point), where the nvPM number is highest, a fuel mixture that reduces the nvPM value more can be used. In this way, overall nvPM emissions can be better controlled and fuels with low nvPM numbers can be used more effectively.

The percentage of SAF in the SAF-rich first fuel may be as high as possible, subject to any restrictions on the maximum allowable SAF content, e.g. B. Certification limit values or e.g. B. technical limitations associated with the particular aircraft and/or the pilot injectors themselves, or the maximum percentage mixture in which SAF is available at the time of fuel filling.

The percentage of SAF in the SAF-rich first fuel may also be limited by the required fill factor of the fuel tank(s) used for the SAF-rich fuel composition in conjunction with the amount of SAF intended for the planned flight. For example, on long-haul flights that require all fuel tanks 53, 55 to be completely filled, the volume of the SAF-rich fuel composition must not be less than the capacity of the smallest single fuel tank that could contain the first fuel source.

The composition of the low SAF fuel, i.e. H. of the second fuel, can be determined using the same procedure and under the same conditions as in the previously described examples.

In some examples, the fuel delivery controller 306 may be configured to provide a constant mixing ratio of fuel from the first fuel source 302 and fuel from the second fuel source 304. This allows the combustion chamber to be supplied with fuel that has different characteristics than those for the combustion chamber Supplying the aircraft 1 with available fuels. This can enable further flexibility and improved nvPM control. For example, the mixture ratio for a particular flight may be determined and fixed once the amount of fuel in the first and second fuel sources 302, 304 allocated to the flight is known.

In other examples, the fuel mixer 318 is arranged to supply a fuel mixture having a varying mixing ratio of fuel from the first fuel source 302 and fuel from the second fuel source 304 to the pilot injectors 313. The mixing ratio can be varied within the operating range with pilot injection only according to the fuel flow rate or according to the fuel flow rate divided by the fuel flow rate at the stage point SP. In some examples, the fuel mixture may be varied to reduce the proportion of fuel from the first fuel source 302 compared to that from the second fuel source 304 as the flow rate decreases within the pilot-only operating range. This allows the amount of low nvPM fuel (e.g. SAF) to be reduced as the flow rate decreases. In other examples, the dependence of the first fuel on the flow rate can also be reversed. Thus, in some cases, the percentage reduction in nvPM due to the use of SAF may be greater at low power settings (e.g., low fuel flow) than at higher power settings (e.g., high fuel flow).

1. a) Zuführen von Kraftstoff aus der zweiten Kraftstoffquelle 304, z. B. von Kraftstoff mit hohem nvPM-Wert, wie SAF-armen Kraftstoff, sowohl für die Vor- und Haupteinspritzdüsen 313 als auch für die Haupteinspritzdüsen 314 mit Durchflussraten oberhalb des Stufenpunktes;
2. b) Zuführen von Kraftstoff zu den Voreinspritzdüsen 313 aus der ersten Kraftstoffquelle 302, z. B. von Kraftstoff mit niedrigem nvPM-Wert, wie SAF-reichem Kraftstoff, bei und/oder unmittelbar unter der Durchflussrate des Kraftstoffs am Stufenpunkt SP; und
3. c) Zuführen von Kraftstoff zu den Voreinspritzdüsen 313 mit einer Mischung, die zunehmend weniger des ersten Kraftstoffs aus der ersten Kraftstoffquelle 302 und entsprechend mehr des zweiten Kraftstoffs aus der zweiten Kraftstoffquelle 304 enthält, wenn die Gesamtdurchflussrate des Kraftstoffs unter den Stufenpunkt gesenkt wird.

The fuel flow controller 306 of the example in 17 can be arranged so that it:

1. a) supplying fuel from the second fuel source 304, e.g. B. high nvPM fuel, such as low SAF fuel, for both the pilot and main injectors 313 and the main injectors 314 with flow rates above the step point;
2. b) supplying fuel to the pilot injectors 313 from the first fuel source 302, e.g. B. low nvPM fuel, such as SAF-rich fuel, at and/or immediately below the flow rate of the fuel at stage point SP; and
3. c) supplying fuel to the pilot injectors 313 with a mixture containing progressively less of the first fuel from the first fuel source 302 and correspondingly more of the second fuel from the second fuel source 304 as the total flow rate of the fuel is reduced below the stage point.

The ratio between the first fuel and the second fuel supplied to the pilot injectors 313 during pilot-only operation may be varied according to a fuel mixture schedule. The fuel mixing schedule may be determined by the EEC 42 and used to send control signals to the fuel delivery controller 306 to control the mixture ratio.

In some examples, the dependence of the proportion of fuel from the first fuel source 302 compared to that from the second fuel source 304 on the flow rate of the fuel may be determined according to a desired resulting nvPM value at a particular flow rate of the fuel. For example, the mixture ratio can be set so that the nvPM number for a particular fuel flow rate does not exceed a predetermined threshold. For a particular flight condition (e.g., altitude and forward speed), a lookup table can be used to determine the mixing ratio (e.g., SAF percentage) required to achieve a particular level of nvPM number at a particular W _F to reach. Knowing the characteristic values of the first and second fuels (i.e., the SAF percentage within each of the two given fuel compositions, SAF-rich and SAF-poor), the proportion of the SAF-rich fuel composition that must be delivered to the pilot injectors can be determined . The proportion of the low SAF fuel that is mixed with the high SAF fuel to produce an instantaneous fuel composition to be delivered to the pilot injectors 313 can then also be determined to ensure nvPM generation throughout operation only To keep pre-injection within a threshold value. The determination of the proportion of each fuel in the mixture may be made by the EEC 42 based on information from the lookup table, information about the fuel characteristics of the first and second fuel sources, and the current flow rate of the fuel. Once the EEC 42 has determined a mixture ratio, the blender 318 can be controlled accordingly by control signals sent from the EEC 42 to the fuel supply controller 306. In some examples, the EEC 42 may calculate the mixture ratio in real time in response to changes in current flight conditions or current atmospheric conditions.

In another example, the fuel blending schedule (taking into account the change in the nvPM number (or nvPM mass) reduction factor for a particular fuel composition relative to that for the standard composition or low SAF composition with W _F ) may be determined as follows that the total number (or mass) of nvPM emitted during an operating period of the gas turbine engine 10, e.g. B. a landing and take-off cycle (LTO), is minimized (or kept within a predefined threshold).

Before a flight, with the help of knowledge of the desired dependence of the nvPM number on W _F and the flight conditions, the characteristics of the first and second fuel and knowledge of the amount of fuel consumed at each value of W _F and each flight condition, the Total amount of first and second fuel required for the planned flight (see below). The aircraft can therefore be loaded with the appropriate amount of fuel before the flight.

18 shows an example of the dependence of the nvPM number on the flow rate of fuel W _F for the in 17 Example shown (dashed line) compared to the corresponding dependence for a standard fuel composition such as fossil kerosene (solid line). In this example, the first fuel is a SAF-rich fuel composition similar to fuel composition C 7 and the second fuel is a low SAF fuel composition similar to the standard fuel composition in 7 corresponds.

In the example of 18 the characteristic of the fuel supplied to the pilot injectors 313 during operation with pilot injection only is determined such that the nvPM number does not exceed a predetermined threshold value, which in the example shown corresponds to the nvPM number of the SAF-rich fuel composition at the stage point SP . In this example, there is an operating region with low values of W _F in which the pilot injectors 313 are supplied with the low SAF fuel composition. As W _F increases and the nvPM number increases, at some point a SAF-rich fuel composition must be blended to prevent the nvPM number from rising above the predetermined threshold. As W _F continues to increase, the proportion of SAF-rich fuel composition in the mixture continues to increase until it reaches 100% at the stage point SP. At even higher values of W _F , corresponding to operation with pilot and main injection, the pilot injectors 313 are again supplied with low-SAF fuel composition.

Although 18 shows a limited dependence of the nvPM number on W _F , it becomes clear that by appropriately determining the dependence of the mixture ratio on W _F in the entire range of operation only with pilot injection, any desired dependence of the nvPM number on W _F can be achieved, subject to an upper limit corresponding to the dependence of the second fuel (i.e. the high nvPM fuel, e.g. low SAF composition) and a lower limit corresponding to the dependence of the first fuel, i.e. the high nvPM fuel value, such as B. the SAF-poor fuel composition) and a lower bound corresponding to the dependence on the first fuel (ie the low nvPM fuel, such as the SAF-rich fuel composition). The SAF-rich fuel composition corresponds to the fuel composition C 7 , the addressable area is indicated by the hatched area in 19 shown.

Within the addressable range, in principle, any single-valued function of the nvPM number compared to W _F can be achieved through suitable scheduling depending on W _F in operation with pilot injection only. 20 shows another example of how the nvPM number can depend on fuel flow rate.

By supplying a fuel mixture to the pilot injectors in pure pilot injection mode (or at least in one or more areas of pilot injection mode) in this way, the rate of change of the nvPM number with W _F can be significantly lower than with the standard fuel composition, e.g. B. fossil kerosene, and also lower than in other examples in which the fuel sources 302, 304 are switched. Therefore, operation could only be done with pre-injection, as in the example of 17 , W _F can be varied for reasons other than soot emissions without significantly changing soot emissions. In US2022042465 For example, the fuel flow rates of the individual engines are varied during the final approach in order to limit the bleed noise. If one assumes that the thrust requirement on final approach corresponds to an area in which only pre-injections take place, then the examples described here, in which the fuel is mixed by the fuel mixing device 318 according to the invention, can reduce the change in soot emissions that would otherwise be associated with such noise-related changes the fuel throughput would be significantly reduced.

The ones in the 13 and 15 Examples shown can be viewed as special cases of the blended fuel example, where the SAF-rich fuel composition is used not only at the stage point SP, but also in an area extending a short distance to the left of the stage point (i.e. at lower flow rates). In the example of 13 This area extends to the left side of the diagram. In the example of 15 there is a switching point at which the composition of the fuel within the operating range with pilot injection only switches sharply to the low-SAF fuel composition. It becomes clear that switching from one fuel type to another corresponds to changing the mixture ratio from 0:100 to 100:0 or vice versa.

21 illustrates a method 4000 for operating a gas turbine engine 10 using the system of 17 can be carried out. The steps that also occur in other previously described procedures are marked accordingly. In this example, the fuel supply regulation 4002 includes: mixing 4010 a supply of fuel from both the first and second fuel sources 302, 304 to form a mixed fuel consisting of fuel from the first fuel source 302, fuel from the second fuel source 304 or a mixture thereof; and supplying 4012 the mixed fuel to the pilot injectors 313. Any of the above in connection with 17 The features described can be incorporated into the process 21 included, even if they are not repeated here.

n vPM cost function

In the examples described above, control of the fuel characteristics delivered to the injectors is based on a desired form of dependence of the nvPM number on W _F , which is used to determine the fuel characteristics to be used at each value of W _F , thus achieving this desired form can be achieved. The fuel supply controller in these examples can therefore be controlled to minimize the engine's nvPM production. nvPM production may refer to the nvPM content of the engine exhaust, e.g. B. on the mass or number of nvPM particles generated.

To enable even better control of nvPM emissions, additional factors may be taken into account since the inventors have determined that one emitted soot particle is not as detrimental as another emitted soot particle. Therefore, in some examples, the amount of cost or damage caused by each soot particle emitted may be taken into account. For example, soot particles emitted at ground level can be expected to have a greater impact on human health than soot particles emitted at several thousand feet above the ground (indeed, soot emissions at an altitude of less regulated above 3000 feet above the runway, while soot emissions at higher altitudes are not regulated).

The fuel controller of one of the examples described herein may be configured to deliver fuel to the pilot injectors to control (e.g., optimize or reduce) the nvPM effects of the engine exhaust. The fuel delivery controller 306 may therefore be configured to deliver fuel to the pilot injectors to minimize a cost function that depends on one or more parameters of the nvPM effect. The nvPM impact parameters may relate to the cost or damage of nvPM emissions (e.g. soot) of a particular type or in a particular situation. In this way, the gas turbine engine 10 can be operated to reduce the nvPM emissions that would otherwise cause the most harm compared to those that have less impact on the environment and/or human health.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Position (z. B. Standort, z. B. Längen- und Breitengrad) der nvPM-Produktion. Die Kosten der nvPM-Emissionen können als Funktion der 3D-Position der Rußemissionen (z. B. Höhe, Längen- und Breitengrad) definiert werden, wobei die Nähe zu Bevölkerungszentren oder anderen wichtigen Orten berücksichtigt werden kann;
• iii) Wetter-/Atmosphärische Bedingungen am Ort der nvPM-Produktion. Die Kostenfunktion kann beispielsweise vorherrschende Winde, Wettermuster und atmosphärisches Verhalten wie Abbauprozesse berücksichtigen, um die künftige Lage der emittierten Rußpartikel im Verhältnis zu Bevölkerungszentren oder anderen wichtigen Orten zu bewerten;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion. So können beispielsweise die klimatischen Auswirkungen der Ablagerung von Ruß an bestimmten Orten berücksichtigt werden. Solche Orte können ansonsten hochalbedohaltige Oberflächen, z. B. Eis, umfassen;
• v) Masse/Größe der einzelnen erzeugten nvPM-Partikel. Die Kostenfunktion kann so definiert werden, dass die Verringerung der nvPM-Anzahl und/oder -Masse in einem oder mehreren spezifischen Partikelgrößenbereichen gegenüber der Verringerung der nvPM-Anzahl und/oder -Masse in einem oder mehreren weiteren Größenbereichen Vorrang hat. Die Kostenfunktion kann beispielsweise eine gewichtete Summe über die Anzahl (oder Masse) der Partikel in verschiedenen Größenbereichen umfassen, wobei die Gewichtung so definiert ist, dass sie den Gedanken widerspiegelt, dass einige Größenbereiche möglicherweise gesundheitsschädlicher sind oder zu einem nachteiligeren Umweltergebnis führen als andere (und daher innerhalb der Kostenfunktion eine größere Bedeutung haben), ohne jedoch die anderen Größenbereiche völlig zu ignorieren;
• vi) Potenzielle Kondensstreifenproduktion und/oder Kondensstreifenmerkmale. Beispielsweise könnte die Kostenfunktion die Wahrscheinlichkeit berücksichtigen, dass bestimmte nvPM-Emissionen die Bildung eines Kondensstreifens durch das Luftfahrzeug verursachen oder die Eigenschaften oder Merkmale eines vom Luftfahrzeug erzeugten Kondensstreifens beeinflussen. Dies kann insbesondere für Kondensstreifen gelten, die sich am oberen Ende der Sinkflugphase des Luftfahrzeugs bilden, wo der Betrieb der Brennkammer wahrscheinlich deutlich unter dem Stufenpunkt liegt und die Verwendung von Kraftstoff mit niedrigem nvPM-Wert eine größere Wirkung haben kann;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) Menge der erzeugten nvPM. Die Kostenfunktion kann die Menge der vom Triebwerk erzeugten nvPM-Emissionen berücksichtigen, z. B. in Form der Gesamtmasse und/oder der Anzahl der nvPM-Partikel in einer bestimmten Zeit, oder einen Emissionsindex für die Masse (oder Anzahl) der nvPM pro Masseneinheit des verbrauchten Kraftstoffs.

The one or more nvPM influencing parameters on which the cost function is based may include one or more of the following elements:

• i) height above ground at which nvPM production takes place;
• ii) Position (e.g. location, e.g. longitude and latitude) of nvPM production. The cost of nvPM emissions can be defined as a function of the 3D location of the black carbon emissions (e.g. altitude, longitude and latitude), taking into account proximity to population centers or other important locations;
• iii) Weather/atmospheric conditions at the location of nvPM production. For example, the cost function can take into account prevailing winds, weather patterns and atmospheric behavior such as degradation processes to assess the future location of emitted soot particles relative to population centers or other important locations;
• iv) Climate impacts associated with the location of nvPM production. This is how you can for example, the climatic effects of the deposition of soot in certain locations must be taken into account. Such places may otherwise contain high albedo surfaces, e.g. B. ice cream;
• v) Mass/size of each nvPM particle produced. The cost function may be defined such that reducing nvPM number and/or mass in one or more specific particle size ranges takes precedence over reducing nvPM number and/or mass in one or more additional size ranges. For example, the cost function may include a weighted sum over the number (or mass) of particles in different size ranges, with the weighting defined to reflect the idea that some size ranges may be more harmful to health or result in a more adverse environmental outcome than others (and therefore have greater importance within the cost function), but without completely ignoring the other size ranges;
• vi) Potential contrail production and/or contrail features. For example, the cost function could take into account the probability that certain nvPM emissions will cause the formation of a contrail by the aircraft or influence the properties or characteristics of a contrail produced by the aircraft. This may be particularly true for contrails that form at the top of the aircraft's descent phase, where combustion chamber operation is likely to be well below the stage point and the use of low nvPM fuel may have a greater effect;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) Amount of nvPM generated. The cost function can take into account the amount of nvPM emissions produced by the engine, e.g. B. in the form of the total mass and/or number of nvPM particles in a given time, or an emissions index for the mass (or number) of nvPM per unit mass of fuel consumed.

Any number of the above influencing parameters may be defined to determine a cost function to be minimized and to control the fuel delivery controller 306 to deliver fuel with the required characteristics to the combustion system 16. In some examples, the nvPM production cost function could be integrated into a broader cost function with other costs.

Control of the fueling controller 306 of each example described herein may be based on the cost function. For example, the on-board mixture of the first and second fuels (SAF-rich and SAF-poor) can be used to achieve a desired nvPM number in each operating condition when operating with pilot injection only. The fuel characteristics delivered to the pilot injectors 313 during pilot-only operation (and hence the corresponding mixing ratio between the amount of low-SAF and the amount of high-SAF fuel composition) may no longer be just a simple function of W _F (yes , it is not even a single-valued function of W _F ), but can vary depending on other parameters to minimize a total cost function.

Switching between operation with pilot injection only and operation with pilot and main injection during cruise flow

In known staged combustion systems, the stage point SP is usually selected so that cruise flight operation takes place in the operating range with pre-injection and main injection. Operation at low power settings, such as B. taxiing, descent and landing approach, often takes place in the area of only pre-injection.

The inventors have found that it is also advantageous to operate a staged combustion system in such a way that it only carries out pre-injections during at least part of the cruise flight and at the same time selectively feeds fuel from two different sources into the combustion chamber during the cruise flight.

In another example of the present application, this is in 5 illustrated staged combustion system 64 additionally or alternatively arranged so that it switches between the operating range with pilot injection only and the operating range with pilot and main injection at a stage point that is selected so that it corresponds to a stationary cruise operating range of the engine 10. The step point in this example is arranged to define a boundary between a first engine cruise operating range and a second engine cruise operating range. In other words, the step point is chosen to be at an engine power setting (or other engine operating parameter indicating the engine power setting) that is above the minimum engine power setting factory is where the engine works in stationary cruise flight. This defines a region of relatively low cruise engine power conditions in which the staged combustion system operates in pilot-injection-only operation, compared to operation with pilot and main injection at relatively higher cruise power settings. This shifts the stage point to a higher power setting, so that the combustion system can still work in pure pre-injection mode even at higher power levels than the minimum cruise power. The pilot injection only and pilot and main injection regions are therefore redefined so that the staged combustion system 64 switches between operating modes at a different W _F , ie the boundary between the regions is changed compared to prior art systems.

In this example, the fuel supply controller 306 is arranged to supply fuel to the pilot injectors 313 during at least part of, or preferably all of, the first cruise operating range, fuel that has different fuel characteristics than the fuel supplied to one or both of the pilot injectors 313 and the main injectors 314 is supplied during the second cruise operating range. More specifically, during the first cruise operating range, the fuel controller 306 supplies the pilot injectors with fuel from the available fuel sources that is different from the fuel supplied to the injectors during the second cruise operating range. This can be fuel that is supplied to both the pilot and main injectors as well as the pilot injectors in main and pilot operation.

The inventors have found that by adjusting the step point so that cruise flight with lower power is possible in pure pilot injection operation, certain engine emissions can be reduced and combustion efficiency can be improved. In conjunction with the selective use of fuels with different characteristics, the inventors have found that adverse emissions effects that would otherwise result from shifting the stage point can be mitigated. The combination of these factors therefore leads to an overall improvement in combustion efficiency and a reduction in emissions.

Pollutant emissions can be characterized by an emissions index (EI), which indicates the mass (or number) of a particular pollutant per unit mass of fuel consumed. The inventors have found that when operating only with pre-injection and at very low engine power, the mass emission index of carbon monoxide (CO) and unburned hydrocarbons (HC) can be relatively high.

Not only does this represent a release of pollutants into the atmosphere, but it also reduces fuel efficiency due to incomplete combustion of the fuel, i.e. not all of the fuel is completely burned. This may result in increased mission fuel consumption and/or reduced aircraft payload capacity. As engine power increases (still operating with pilot injection only), both EI(CO) and EI(HC) decrease and remain low thereafter. However, when transitioning to even higher engine power settings and operating with pilot and main injection, EI(CO) and EI(HC) increase again before decreasing again at even higher engine power settings. This is in 22 shown showing the dependence of EI(CO) and EI(HC) on the power setting of the engine, where the vertical dashed line represents the step point SP.

During the first portion of cruise flight, the engine operates at relatively low power settings, so CO and HC emissions would be relatively high if the stage point were chosen so that the combustion system operates in pilot and main injection mode. Because even if the step point were chosen so that the cruise flight takes place in pre-injection and main-injection mode, i.e. H. occurs above the step point SP, some parts of the cruise may be quite close to the step point (e.g. just above). This would have the disadvantage that HC and CO emissions may be high during this operation and, as a result, combustion efficiency may be adversely and significantly reduced (which may result in higher fuel consumption and/or reduced aircraft payload).

By setting the step point so that cruise flight with low power only takes place in pre-injection mode, this disadvantageous emission of CO and HC can be reduced or avoided. This will be in 23 illustrated, which shows how the setting of the step point SP 'impacts the determination of a first cruise range 320a and a second cruise range 320b. As in 23 As can be seen, the first cruise operating range 320a corresponds to the low power cruise flight, ie below the stage point SP', while the second cruise operating range 320b corresponds to the higher power cruise flight above the stage point SP'. Within the first cruise operating range 320a, the staged combustion system 64 is configured to operate with pilot injection only and thus provide low CO and HC emissions generated. By moving the step point to a higher power setting (e.g. from the thin to the thick dashed line in 23 , labeled SP and SP', respectively), CO and HC emissions remain low over a wider range of engine power settings (e.g. the thick solid line versus the thin dashed line in the dependence on EI(CO) and EI(HC) from the power setting).

The inventors have further determined that the emission index of nvPM increases rapidly with engine power for pure pilot injection, but is typically uniformly low for pilot and main injection. For nvPM, the emissions index can be described in terms of the mass of the nvPM or the number of nvPM particles (per unit mass of fuel). An example of the dependence of the nvPM on the engine power setting is in 24 shown.

As a result of effectively moving the step point to a higher power setting, the standard El(nvPM) is adversely increased. How out 24 As can be seen, operation in pure pilot injection mode at higher outputs would lead to increased nvPM production, since less engine power is produced when operating with only pilot and main injection, where nvPM production is low, and the nvPM increases quickly at higher outputs in pure pilot injection mode increases.

The inventors have determined that this otherwise detrimental increase in nvPM can be mitigated by the selective use of a fuel with a different fuel characteristic, at least during the cruise pilot-only portion of the operating range where a high nvPM would otherwise be produced. For example, the fuel supplied to the pilot injectors 313 during the first portion of the pilot and main injector cruising operating range of the engine 320a may be selected to be associated with lower nvPM production than the fuel supplied to either or both Pilot injectors and main injectors 313, 314 are supplied at least during part of the second part of the operating range with pilot and main injectors in cruise flight of the engine 320b. This can be achieved in that the fuel contained in the first fuel source 302 has a low nvPM generation compared to the second fuel source 304 (under corresponding combustion conditions).

The effect of selectively using fuel with a different fuel characteristic during the engine's first cruise range 320a is shown in 25 shown. The thick solid line in the EI(nvPM) dependence on power can be compared to the thick dotted line in the first cruise operating region 320a that results from using a lower nvPM fuel.

In some examples, the fuel characteristic that distinguishes the fuel from the first fuel source 302 from the fuel from the second fuel source 304 may be the percentage of sustainable aviation fuel (SAF) contained in the respective fuel, as described above. The fuel supplied to the pilot injectors 313 at least during a portion of the operating range with only pilot injection in cruise flight would also have a different SAF proportion than the fuel supplied to one or both of the pilot injectors 313 and the main injectors 314 at least during a portion of the operating range Pilot injection is supplied. As previously mentioned, SAF has a significantly lower nvPM compared to fossil kerosene and can therefore be used to mitigate the increase in nvPM that would otherwise result from additional operation with only pre-injection at cruise. Thus, the fuel supplied to the pilot injectors during the first cruise range 320a may have a higher SAF content than the fuel supplied to the injectors during the second cruise range 320b. In this way, a limited amount of SAF (or other low nvPM fuel) can be used selectively to reduce overall nvPM, CO and HC emissions.

However, this does not always have to be the case. In some examples, fossil kerosene may be treated to remove aromatic components, particularly naphthalenes, to produce a largely paraffinic fuel of fossil origin, which would be a low nvPM fuel. Other fuel characteristics may therefore be associated with low nvPM, such as: B. the percentage of aromatics or naphthalene.

The inventors have therefore found that through a combination of selective use of two fuel types and operation in pilot-injection-only mode during low power cruise flight, the beneficial reduction in CO and HC emissions is accompanied by a smaller detrimental increase in nvPM, than would be the case without the use of a SAF-rich fuel composition (or other low nvPM fuel) in the relevant range of engine power settings.

Selective cruise pre-injection-only operation and selective use of fuel compare favorably to other known methods for reducing total nvPM, HC and CO emissions. Alternative solutions include, for example, a "pilot and semi-main injection" operating region that lies between the pilot injection only region and the pilot and main injection region. If the power setting of the engine corresponds to the pilot and semi-main injection, not all of the main fuel is ignited, but only a part (e.g. half) of it, for example with an alternating on-off-on-off distribution around the Combustion chamber ring (other arrangements are also conceivable, e.g. igniting the main burners on one half of the ring and not on the other half). However, this leads to uneven combustion characteristics in the annular space of the combustion chamber and can also have a detrimental effect on the operation and service life of the turbine. Another approach is a staged pilot system in which the "pilot injection only" operating region is divided into subregions in which an increasingly larger number of pilot injectors are turned on at increasingly higher engine power settings within the overall "pilot injection only" region. Such a configuration has the disadvantage of adding weight and complexity, which can be avoided by the methods of the present application.

In one example, the first range of cruise operations corresponds to operating the aircraft in a later portion of a cruise segment of a flight, and the second range of operations corresponds to operating the aircraft in a relatively earlier portion of the cruise segment. For example, the cruise flight of an aircraft may be divided into one or more cruise segments during a flight cycle. These can correspond to stationary cruise operations at different altitudes. Towards the end of a cruise segment, the engine power setting required to maintain steady cruise flight at the specified Mach number and altitude decreases as the aircraft burns fuel and loses weight. Therefore, since less thrust is required in the later part of the cruise, the engine power setting is reduced. The combustion system of the present application can therefore be arranged to switch to pilot injection only operation at low engine power near the end of a cruise segment, rather than to pilot and main injection operation throughout the entire cruise segment (or segments if there are more than one). to stay. This helps reduce HC and CO production that might otherwise occur toward the end of the cruise segment.

In another example, the first cruise operating range 320a corresponds to stationary subsonic cruise operation of the engine and the second cruise operating range 320b corresponds to stationary supersonic cruise operation of the engine. In this example, the gas turbine engine 10 is designed to be operable in both subsonic and supersonic cruise flight of the aircraft in which it is installed. The step point can be set so that operation with pilot injection only in cruise flight corresponds to subsonic operation with relatively low engine power, while operation with pilot and main injection corresponds to supersonic operation with higher engine power.

For a supersonic aircraft, supersonic cruise over oceans is probably possible, but over land cruise may be limited to subsonic for noise control reasons. In such an example, supersonic cruise flight may correspond to a high engine power setting that is well above the step point. However, subsonic cruise flight in this example may correspond to a much lower engine power setting, close to a standard or state-of-the-art staging point, resulting in low combustion efficiency and high CO and HC emissions during subsonic cruise flight leads. An aircraft traveling at supersonic speed may consume a significant portion of its fuel in subsonic cruise flight, so combustion efficiency is of great importance in this operating condition. Operating with pilot injection only during subsonic cruise flight can reduce CO and HC emissions while allowing fuel with other characteristics to be supplied to minimize increases in nvPM production. Stationary supersonic cruise flight can occur before stationary subsonic cruise flight or vice versa. In some examples, the stationary subsonic cruise operation may be a subsonic cruise operation over land, while the stationary supersonic cruise operation may be a supersonic cruise operation over water (e.g., over the sea).

To supply the pilot injectors 313 with fuel during the first cruise that is different from the fuel supplied to the combustion chamber during the second cruise, the fuel supply controller 306 is arranged to selectively supply fuel from the first and second fuel sources 302, 304, as described above (e.g. fuel only from the first force fuel source 302, fuel only from the second fuel source 304 or a mixture thereof). In one example, the fuel supply controller 306 may include a fuel mixer 318, as shown in 17 shown. Similar to what was described above, the fuel mixer is arranged to receive fuel from both the first and second fuel sources 302, 304 and output a fuel consisting of fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof . This mixed fuel is supplied to the pilot injectors 313 while the main injectors 314 are supplied with fuel from a single fuel source (second fuel source 304 in the example above). In other examples, the mixer may be configured to supply both the pilot and main injectors with an appropriate fuel mixture. In still other examples, the fuel delivery controller 306 of any of the examples described herein may be used to deliver fuel in the first and second cruise operating ranges (e.g., using separate controllers for the first and second fuel sources or a pilot controller located between the fuel sources).

As above in connection with the in 17 As discussed in the example shown, the dependence of the proportion of fuel from the first fuel source 302 compared to that from the second fuel source 304 on the flow rate of the fuel may be determined according to a desired resulting nvPM value at a particular flow rate of the fuel. For example, the proportion of fuel delivered from the first fuel source 304 compared to that from the second fuel source 304 may be determined according to a desired resulting nvPM value at a particular flow rate within the first cruise range of the engine. The amount of fuel delivered by each fuel source may be determined such that the nvPM does not exceed a predetermined threshold or such that nvPM generation is minimized over a period of operation of the gas turbine engine as described above. In any of the examples described herein, this may be accomplished by appropriate control of the mixer 318 or one of the other fuel delivery controllers 306 described herein.

1. a) der Menge des Kraftstoffs mit dem ersten Kraftstoffmerkmal und die Menge des Kraftstoffs mit dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung stehen. Dies kann z. B. durch eine Schätzung oder Messung der Kraftstoffmenge in den Kraftstofftanks 53, 55, die die erste und zweite Kraftstoffquelle bilden, erfolgen;
2. b) der Menge des gesamten Kraftstoffbedarfs für die Einspritzdüsen 313 während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem Kraftstoff von der ersten Kraftstoffquelle 302 bereitgestellt wird; und/oder
3. c) einem Grenzparameter für die Kraftstoffzusammensetzung (z. B. eine Zertifizierungsgrenze, die für die Betankung verfügbare Kraftstoffzusammensetzung oder Grenzwerte für Luftfahrzeuge/Triebwerke).

In some examples, the proportion of fuel delivered by the first fuel source 302 compared to the fuel delivered by the second fuel source 304 during the first cruise operating range may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the amount of fuel with the second fuel characteristic available for a planned flight. This can e.g. B. by estimating or measuring the amount of fuel in the fuel tanks 53, 55 which form the first and second fuel sources;
2. b) the amount of total fuel demand for the injectors 313 during operation with pilot injection only for the entire flight in an operating range in which fuel is provided by the first fuel source 302; and or
3. (c) a fuel composition limit parameter (e.g. a certification limit, fuel composition available for refueling, or aircraft/engine limits).

26 illustrates a method 4014 for operating a gas turbine engine according to the example above, in which fuel with a different fuel characteristic is supplied to the pilot injectors during the first cruise region of the engine. The method 4014 includes the control 4016 of the fuel supply to the pilot injectors and/or the main injectors 313, 314 from the first fuel source 302, which contains a first fuel with a first fuel characteristic, and the second fuel source 304, which contains a second fuel with a second fuel characteristic includes, as described above, using the fuel supply controller 306 of any example herein (ie, fuel only from the first fuel source 302, fuel only from the second fuel source 304, or a mixture thereof). The second fuel feature is different from the first, as described above.

The method further includes switching 4018 between the pilot injection only operating region and the pilot and main injection operating region at a stage point during stationary cruise operation of the engine to define a first pilot injection operating region 320a and a second main injection operating region 320b. The method further includes delivering fuel 4020 to the pilot and main injectors 313 during at least a portion of the first operating range 320a of the engine in cruise flight, which has different fuel characteristics than the fuel delivered to one or both of the pilot and main injectors 313, 314 is delivered during the second operating region 320b of the engine in cruise flight. Each of the features described above in connection with the examples where in the first and second cruise ranges of the engine different fuel is supplied may be included in procedure 4014, although not repeated here.

Varying step ratio in stationary cruise flight near the step point

In another example of the present application, the in 5 shown staged combustion system 64 additionally or alternatively arranged so that it works in an operating range between the operating range with pilot injection only and the operating range with pilot and main injection. In the present examples, the transition area is provided during stationary cruise operation of the engine. In the operating range with pilot and main injectors, fuel is delivered to both the pilot injectors and the main injectors 313, 314 in a transitional step ratio. As defined elsewhere herein, the step ratio defines the relative fuel flow rates associated with the pilot injectors 313 compared to the main injectors 314. In the operating range with pilot injection only, the step ratio is by definition 100:0. In the pilot and main injection operating range, the combustion chamber is configured to operate with a pilot and main injection ratio that can be 20:80 or 30:40, etc. In the pilot and main injection operating region, the combustion chamber is configured to operate with a transitional stage ratio that is different from the stage ratio in the pilot and main injection operating region (and also different from the stage ratio in the pilot injection only operating region, since fuel is during of the transitional operating range is delivered to both the main and pilot injectors). More specifically, the proportion of the fuel flow rate attributable to the pilot injectors compared to the main injectors is greater in the transition operating region than in the pilot and main injection operating region. In other words, a smooth or medium transition is created in which a greater proportion of the fuel is delivered to the pilot injectors than if a direct switch were made between a state in which all fuel is delivered to the pilot injectors in pilot only mode and one State with the step ratio of operation with pilot and main injection, in which a smaller proportion of the fuel is supplied to the pilot injectors. In other words, instead of moving the sharp step point to a higher power setting (as described elsewhere herein), the inventors have found that a transition region can be included that is characterized by a slower transition (relative to the engine power setting) from only includes pre-injection step ratio (100:0) to the selected pre- and main injection ratio (e.g. 20:80).

The inventors have found that by configuring the staged combustion system 64 to operate in a transition region (ie, a transition region of operation) between pilot injection only operation and pilot and main injection operation, the CO and HC emissions in this region the power settings of the engine can be reduced. This will be in 27 illustrating the dependence of the CO and HC emission index (EI) for a staged combustor (such as those described here) on the engine power setting. The transition area is marked 322 and lies in an engine performance range between operation with pilot injection only and operation with pilot and main injection. At engine performance within the transition range, high HC and CO emissions would arise if the combustion chamber 16 were operated with the pilot and main injection ratio, as the dashed line in the HC and CO curve in 27 shows. Operating at the transition step ratio (which in this case gradually decreases as engine power increases) reduces the CO and HC emission index, as shown by the thick solid line in the HC and CO curve in the transition region.

In this example, the fuel supply controller 306 is arranged to deliver fuel to one or both of the pilot and main injectors 313 and 314 during the operating transition region that has a different fuel characteristic than the fuel supplied to one or both of the pilot and main injectors 313 , 314 is supplied at least during part of the operating range with pilot and main injection. The inventors have further discovered that the standard El(nvPM) within the transition region 322 is disadvantageously increased for fuel with the same characteristics. This is in 28 which shows the dependence of the emission index nvPM on the engine performance for a staged combustion chamber. The thin dotted line in 28 represents the nvPM emissions when the transition region 322 is not provided. The thick solid line shows the impact of introducing transition region 322 on nvPM emissions. In the present example, the inventors have determined that EI (nvPM) in the transition region 322 can be mitigated by using fuel with a different fuel characteristic (e.g., SAF-rich fuel), such as the thick dotted line in the nvPM curve within of the transition area shows. Thus, the nvPM disadvantage (which is required to achieve lower CO/HC emissions nen in the transition region 322) by using a SAF-rich fuel composition within the transition region 322 compared to the use of a standard fuel composition within the transition region 322.

Therefore, in some examples, the fuel delivered to at least the pilot injectors 313 by the fuel supply controller 306 during the operating transition region 322 may be selected to be associated with an nvPM production that is less than that of the fuel that is at least is delivered to one or both during part of the operating range with pilot and main injectors 313, 314. This can be achieved by the fuel contained in the first fuel source 302 having a low nvPM production compared to the fuel contained in the second fuel source (under appropriate combustion conditions). In some examples, the fuel delivered to both the pilot and main injectors 313, 314 by the fuel supply controller 306 during the operating transition region 322 is low nvPM fuel. In some other examples, only the fuel delivered to the pilot injectors 313 during the operating region 322 is selected to be associated with a low nvPM value (i.e., the fuel delivered to the main injectors remains the same). This allows the available amount of fuel to be better utilized with low nvPM, as delivering fuel to the main injectors (i.e. the lean part of the fuel system) can have less impact on reducing nvPM.

In some examples, the fuel characteristic that distinguishes the fuel from the first fuel source 302 from the fuel from the second fuel source 304 may be the percentage of sustainable aviation fuel (SAF) contained in the respective fuel, as described above. The fuel supplied to the pilot injectors 313 during the transition region 322 would also have a different SAF proportion than the fuel supplied to one or both of the pilot injectors 313 and main injectors 314 during at least a portion of the pilot and main injection operating region. As previously mentioned, SAF has a significantly lower nvPM compared to fossil fuel kerosene and can therefore be used to mitigate the increase in nvPM that would otherwise result from additional cruise operations. The fuel that is supplied to the pilot injectors in the transition region can have a higher proportion of SAF than the fuel that is supplied to the main injectors in the operating region with pilot and main injection. In this way, a limited amount of SAF (or other low nvPM fuel) can be used selectively to reduce overall nvPM, CO and HC emissions.

However, this does not always have to be the case. In some examples, fossil kerosene may be treated to remove aromatic components, particularly naphthalenes, to produce a largely paraffinic fuel of fossil origin, which would be a low nvPM fuel. Other fuel characteristics may therefore be associated with low nvPM, such as: B. the percentage of aromatic components or the naphthalene content. The first and second fuels can therefore differ in fuel characteristics other than SAF content and still achieve the desired effect on nvPM emissions.

During the transition region of operation 322, the transition step ratio may vary with the changing power setting of the engine. In one example, the transition stage ratio varies continuously with the change in engine power within the transition region 322. This may allow for a smooth transition between the stage ratio in the pilot injection only operating region and the pilot and main injection operating region. The continuous variation may be such that the proportion of the total fuel flow to the injectors (i.e., the total flow to the pilot and main injectors) that is attributable to the fuel flow to the pilot injectors 313 decreases as engine power increases during the operating region 322. The proportion of fuel that flows to the main injectors 314, on the other hand, increases with increasing engine power in the transition area 322.

In other examples, the transition step ratio may have a constant intermediate value that is different from the ratio between pilot and main injection. The transition stage ratio can be between the ratio of pilot injection only and the ratio of pilot and main injection. This results in a more gradual transition from pure pilot injection to pilot and main injection. For example, the transition stage ratio can be 70:30, which is between 100:0 in the area of pure pre-injection and a pre- and main injection ratio of, for example, 20:80 or 30:70.

In other examples, the transition step ratio varies between a series of constant intermediate values, each different from the ratio between pilot and main injection. In addition, each of the intermediate ratios can lie between the ratio of pure pilot injection and that of pilot and main injection. For example, the transition step ratio may be a range of values of 80:20, 60:40 and 40:60. In this example, the ratio between pilot and main injection can be 20:80. The intermediate stage ratios can therefore decrease in the direction of the pilot and main injection ratio (ie an increasingly smaller proportion of the total fuel is supplied to the pilot injectors and an increasingly larger proportion of the total fuel is supplied to the main injectors). However, this is just an example and any other number and value of inter-transition step ratios can be used.

In some examples, the transition step ratio may exhibit a continuous variation with engine performance in one portion of the transition region and may have one or more constant values in another portion of the transition region. The above examples can therefore be combined. In other examples, the step ratio may have a continuous variation over the entire transition range of operation or one or more constant values over the entire transition range of operation.

In order to supply the pilot injectors 313 during the transitional operating region 322 with fuel that is different from the fuel supplied to the combustion chamber 16 during the pilot and main injection operating region, the fuel supply controller 306 is arranged to selectively supply fuel from the first and second fuel sources 302, 304 as described above (e.g. only from the first fuel source 302, only from the second fuel source 304 or a mixture thereof). In one example, the fuel supply controller 306 may include a fuel mixer 318, as shown in 17 shown. Similar to what was described above, the fuel mixer is arranged to be fueled by both the first and second fuel sources 302, 304 and to output fuel from the first fuel source, fuel from the second fuel source, or a mixture thereof. This mixed fuel is supplied to the pilot injectors 313, with the fuel from a single fuel source (in the example above, the second fuel source 304) being supplied to the main injectors 314. In other examples, the mixer may be configured to supply both the pilot and main injectors with an appropriate fuel mixture. In still other examples, the fuel delivery controller 306 of any of the examples described herein may be used to deliver fuel in the pilot only, transient, and pilot and main regions (e.g., using separate regulators for the first and second fuel sources or a pilot controller that switches between the fuel sources).

As above in connection with the in 17 As discussed in the example shown, the dependence of the proportion of fuel from the first fuel source 302 compared to that from the second fuel source 304 on the flow rate of the fuel may be determined according to a desired resulting level of nvPM at a particular flow rate of the fuel. For example, the proportion of fuel delivered from the first fuel source 302 compared to the fuel delivered from the second fuel source 304 may be set according to a desired resulting level of nvPM at a particular flow rate within the transition region 322. The amount of fuel supplied from each source may be determined such that the nvPM does not exceed a predetermined threshold or such that nvPM generation is minimized over a period of operation of the gas turbine engine as described above. In any of the examples described herein, this may be accomplished by appropriate control of the mixer 318 or one of the other fuel delivery controllers 306 described herein.

1. a) der Menge des Kraftstoffs mit dem ersten Kraftstoffmerkmal und die Menge des Kraftstoffs mit dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung stehen. Dies kann z. B. durch eine Schätzung oder Messung der Kraftstoffmenge in den Kraftstofftanks 53, 55, die die erste und zweite Kraftstoffquelle bilden, erfolgen;
2. b) der Menge des gesamten Kraftstoffbedarfs für die Einspritzdüsen 313 während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem Kraftstoff von der ersten Kraftstoffquelle 302 bereitgestellt wird; und/oder
3. c) einen Grenzparameter für die Kraftstoffzusammensetzung (z. B. eine Zertifizierungsgrenze, die für die Betankung verfügbare Kraftstoffzusammensetzung oder Grenzwerte für Luftfahrzeuge/Triebwerke).

In some examples, the proportion of fuel delivered by the first fuel source 302 compared to the fuel delivered by the second fuel source 304 during the transition operating region 322 may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the amount of fuel with the second fuel characteristic available for a planned flight. This can e.g. B. by estimating or measuring the amount of fuel in the fuel tanks 53, 55 which form the first and second fuel sources;
2. b) the amount of total fuel demand for the injectors 313 during operation with pilot injection only for the entire flight in an operating range in which fuel is provided by the first fuel source 302; and or
3. (c) a fuel composition limit parameter (e.g. a certification limit, fuel composition available for refueling or aircraft/engine limits).

29 illustrates a method 4022 for operating a gas turbine engine according to the above example, in which fuel with a different characteristic is supplied to the pilot injectors during the transition region 322 compared to the operating region with pilot and main injection. The method 4022 includes the control 4024 of the fuel supply to the pilot and/or main injectors 313, 314 from the first fuel source 302, which contains a first fuel with a first fuel characteristic, and the second fuel source 304, which contains a second fuel with a second fuel characteristic includes, as described above, using the fuel delivery controller 306 of any example herein (eg, such that the fuel delivered is fuel only from the first fuel source, fuel only from the second fuel source, or a mixture thereof). The second fuel feature is different from the first, as described above.

The method further includes operating 4026 the staged combustion system in a transition operating region 322 between pilot injection only operation and pilot and main injection operation in which fuel is delivered to both the pilot and main injectors at a transitional staging ratio which is different from the pre- and main injection stage ratio. Controlling 4024 the fuel supply to the pilot and/or main injectors includes supplying 4028 fuel to one or both of the pilot and main injectors during the operating range 322 with a fuel characteristic that is different from the fuel supplied to one or both of the pilot injectors. and main injectors during at least part of the operating range with pilot and main injection. Any of the features described above in connection with the examples in which different fuel is delivered in the operating region 322 may be included in the method 4022, although they are not repeated here.

Staged combustion chamber control during acceleration

The engine is accelerated by intentionally increasing the flow rate of fuel to a value greater than that required to maintain steady-state operation. The inventors have found that this “overfeeding” results in an initial increase in the fuel-to-air ratio in the combustion chamber and can result in increased production of nvPM (soot or smoke), particularly at engine power settings consistent with operation only with pilot injection.

To reduce the generation of excessive amounts of nvPM during acceleration, it is known to enter an "acceleration" operating mode of a gas turbine engine in which the step point is at a lower engine power setting. The transition to operation with pilot and main injection takes place at a lower engine power setting than in stationary operation. This helps reduce the total amount of nvPM generated during acceleration.

The inventors have found that switching to such a known acceleration mode can, however, have a number of disadvantages. For example, there may be an increase in HC and CO emissions. In some known solutions, maintaining acceptable CO and HC levels results in higher _NOx emissions because the leanest flames, which produce the least _NOx in that range, produce too much CO and HC, and vice versa, design changes that aimed at reducing CO and HC, lead to higher NO _x emissions across the entire performance curve. For example, a known solution could be to physically modify and enrich the entire main injector to reduce CO and HC emissions, which would then result in higher NOx emissions at all powers.

In another example of the present application, the in 5 staged combustion system 64 shown is additionally or alternatively set up to operate in an acceleration mode. In acceleration mode, the fuel supply controller 306 is arranged to deliver fuel to the fuel injectors (ie, the pilot and/or main injectors 313, 314) that has different fuel characteristics than the fuel supplied to the fuel injectors (ie, the pilot and/or main injectors 313, 314). Main injectors 313, 314) is supplied during at least part of the stationary operating mode.

The engine acceleration mode is a mode in which the fuel delivery controller 306 is arranged to deliver fuel to the injectors 313, 314 at a rate greater than that sufficient to maintain steady-state operation of the engine. This causes an acceleration of the engine, ie an increase in the angular velocity of one or more engine shafts. In the steady state The injectors are not supplied with excessive fuel so that the engine does not accelerate.

The inventors have determined that increased nvPM emissions when operating the engine in acceleration mode can be avoided or reduced by using a fuel with different fuel characteristics than steady-state operation. This allows the step point during acceleration mode to remain the same or similar to that of steady-state operation mode, thereby avoiding or reducing/limiting adverse increases in HC or CO emissions.

Therefore, in some examples, the fuel delivered to the fuel injectors (e.g., one or both of the pilot and main injectors 313, 314) during acceleration operation may be selected to be associated with lower nvPM production than that of the fuel delivered to the fuel injectors (e.g., one or both of the pilot and main injectors 313, 314) during at least a portion of steady-state operation. This can be achieved by the fuel contained in the first fuel source 302 having a low nvPM production compared to the fuel contained in the second fuel source 304 (under appropriate combustion conditions). Fuel with lower nvPM generation may be delivered to at least the pilot injectors 313 during acceleration mode operation as this will have the greatest impact on nvPM generation. Preferably, fuel with lower nvPM production may be delivered to only the pilot injectors during acceleration mode to better utilize a limited supply of this fuel.

In some examples, the fuel characteristic that distinguishes the fuel from the first fuel source 302 from the fuel from the second fuel source 304 may be the percentage of sustainable aviation fuel (SAF) contained in the respective fuel, as described above. The fuel delivered to the injectors during acceleration operation would similarly have a different percentage of SAF than the fuel delivered to one or both of the pilot injectors 313 and the main injectors 314 during at least a portion of steady-state operation. As previously mentioned, SAF has a significantly lower nvPM compared to fossil kerosene and can therefore be used to mitigate the increase in nvPM that would otherwise result from overfilling the combustion chamber during acceleration mode. For example, the fuel delivered to the injectors 313, 314 during acceleration mode may have a greater proportion of SAF than the fuel delivered to the injectors in steady state mode. In this way, a limited amount of SAF (or other low nvPM fuel) can be used selectively to reduce overall nvPM, CO and HC emissions.

However, as discussed in connection with other examples, this may not always be the case. In some examples, fossil kerosene may be treated to remove aromatic components, particularly naphthalenes, to produce a largely paraffinic fuel of fossil origin, which would be a low nvPM fuel. Other fuel characteristics may therefore be associated with low nvPM, such as: B. the percentage of aromatic components or the naphthalene content. The first and second fuels can therefore differ in fuel characteristics other than SAF content and still achieve the desired effect on nvPM emissions.

In some examples, the fuel delivery controller 306 is configured to deliver fuel with different fuel characteristics during acceleration operation following a pilot injection only operation. Therefore, in some examples, the fuel characteristics are changed only for engine accelerations that assume a power setting that is below the steady state step point. Since the power setting is below the steady state stage point, the combustion chamber is operated in pure pilot injection mode and acceleration can result in an increase in nvPM emissions without changing the fuel characteristics according to the methods of the present application. However, in other examples, acceleration may occur from any steady state operating mode, regardless of whether it is pilot and main injection operation or pilot injection only.

The staged combustion system 64 may be configured to switch between the operating range with pilot injection only and the operating range with pilot and main injection in acceleration mode at the same or higher engine power compared to the stationary mode. In other words, the staged combustion system 64 is controlled (e.g., by the EEC) using a stage point that is at the same or a higher engine power setting in acceleration mode than in stationary mode. This means that the step point will not change to a lower power setting during acceleration mode Engine is reduced, thereby avoiding or reducing an increase in HC or CO emissions or the need to enrich all main injectors for all engine outputs. In some examples, the step point may be the same in both acceleration and continuous operation. The step point used in acceleration mode may be referred to as the “acceleration step point,” while the step point used in steady-state operation may be referred to as the “cruise step point.” In this example, the acceleration step point is at a power setting greater than or equal to the cruise step point.

In other examples, the staged combustion system may be configured to switch between the pilot injection only operating region and the pilot and main injection operating region in acceleration mode at a lower engine power than in steady state mode. The staged combustion system 64 in this example is controlled (e.g., by the EEC) using a stage point that is at a lower engine power setting in acceleration mode than in stationary mode. In this example, the acceleration step point is greater than a standard acceleration step point at which the combustion system would be controlled if fuel of a different characteristic cannot be supplied to the combustion chamber. The acceleration step point is therefore reduced (relative to the cruise step point) by an amount that is less than the reduction to the standard acceleration step point that would be found in known systems.

The fuel supply controller 306 may, in some examples, be arranged to deliver fuel with different fuel characteristics to the pilot injectors 313 during pilot-only operation in the acceleration mode than to the main injectors 314 during pilot and main injection operation in the stationary engine operating mode. In this example, fuel with a different fuel characteristic (e.g., SAF rich fuel) is supplied to the pilot injectors 313 when operating in pure pilot mode during engine acceleration. Fuel with a high nvPM (e.g., low SAF fuel) is then delivered to the main injectors 314 during steady-state pilot and main injection operation, where nvPM emissions are inherently lower. In this way, a limited amount of fuel in the first fuel source (e.g. SAF-rich fuel) can be used more effectively by selectively using it only in the pilot injection during engine acceleration. In this example, the fuel with a different fuel characteristic is supplied to the pilot injectors 313 only during part of the acceleration operation. Once the step point is reached in acceleration mode, fuel can be supplied again in the same way as in stationary operation (e.g. low SAF fuel can be used again). In other examples, the SAF-rich fuel (or a fuel with a different characteristic) may be used at all engine powers within the acceleration mode (e.g., during pilot and main injection and pilot injection only operations).

In one example, the fuel delivery controller 306 is arranged to deliver fuel with a fuel characteristic determined based on a fuel-to-air ratio in the combustion chamber 16 during the pilot injection only operating range in the acceleration mode. In this example, as the air-fuel ratio decreases, the proportion of fuel delivered to the pilot injectors may also be reduced and is associated with low nvPM production. As the fuel-air ratio decreases (e.g. because as the engine speed increases, the air mass flow in the combustion chamber also increases), the amount of fuel with low nvPM generation (e.g. a SAF-rich fuel) can also be reduced. be reduced. In this way, the low nvPM fuel can be used during a portion of the acceleration operation where its benefits are greater, making better use of a limited availability of this fuel. In other examples, the fuel characteristics may be determined based on another suitable control parameter that is related to nvPM formation in the combustion chamber and is not the air-fuel ratio.

In other examples, the fuel supply controller 306 is arranged to switch the fuel supply to the injectors (one or both of the pilot and main injectors 313, 314) to a fuel characteristic with a different composition at the beginning of a period of operation in the acceleration mode. In this example, the fuel composition can therefore be changed to a different composition at the beginning of an acceleration phase (e.g. to an SAF-rich fuel). In some examples, the fuel controller 306 may continue to deliver the same fuel throughout the acceleration mode. In other examples, the fuel supply controller 306 is configured to supply fuel again with the same fuel characteristics after a transition to pilot and main injection operation painting as in stationary mode delivers. The fuel composition is therefore switched back to the standard fuel characteristics of steady-state operation as soon as the step point has been exceeded. This can also help limit the use of low nvPM emissions fuel to part of the acceleration mode, making more effective use of a limited supply of this fuel.

In order to supply fuel to the pilot injectors and/or the main injectors 313, 314 during the acceleration mode of the combustion system that is different from the fuel supplied to the combustion chamber during steady-state operation, the fuel supply controller 306 is arranged to selectively supply fuel to the first and second fuel sources 302, 304 as described above. In one example, the fuel supply controller 306 may include a fuel mixer 318, as shown in 17 shown. Similar to what was described above, the fuel mixing device is arranged to receive a fuel supply from both the first and second fuel sources 302, 304 and to output fuel from the first fuel source 302, fuel from the second fuel source 304, or a mixture thereof. This mixed fuel is supplied to the pilot injectors 313, with the fuel from a single fuel source (in the example above, the second fuel source 304) being supplied to the main injectors 314. In other examples, the mixer may be configured to supply both the main and pilot injectors 313, 314 with an appropriate fuel mixture. In still other examples, the fuel delivery controller 306 of any of the examples described herein may be used to deliver fuel (to one or both of the pilot and main injectors) that is different from the fuel delivered at least during at least a portion of the acceleration mode a portion of the steady-state operating mode (e.g., using separate controllers for the first and second fuel sources or a pilot controller arranged to switch between the fuel sources).

As above in connection with the in 17 As discussed in the example shown, the dependence of the proportion of fuel from the first fuel source 302 compared to that from the second fuel source 304 on the flow rate of the fuel may be determined according to a desired resulting nvPM value at a particular flow rate of the fuel. For example, the proportion of fuel delivered from the first fuel source 302 compared to that from the second fuel source 304 at a particular flow rate of fuel during acceleration mode may be set according to a desired resulting nvPM value. The amount of fuel delivered from each source may be determined so that the nvPM does not exceed a predetermined threshold or to minimize nvPM generation over a period of operation of the gas turbine engine as described above. In any of the examples described herein, this may be accomplished by appropriate control of the mixer 318 or one of the other fuel delivery controllers 306 described herein.

1. a) der Menge des Kraftstoffs mit dem ersten Kraftstoffmerkmal und die Menge des Kraftstoffs mit dem zweiten Kraftstoffmerkmal, die für einen geplanten Flug zur Verfügung stehen. Dies kann z. B. durch eine Schätzung oder Messung der Kraftstoffmenge in den Kraftstofftanks 53, 55 erfolgen, die die erste und zweite Kraftstoffquelle 302, 304 bilden;
2. b) der Menge des gesamten Kraftstoffbedarfs für die Voreinspritzdüsen 313 während des Betriebs nur mit Voreinspritzung für den gesamten Flug in einem Betriebsbereich, in dem Kraftstoff von der ersten Kraftstoffquelle 302 bereitgestellt wird; und/oder
3. c) einem Grenzparameter für die Kraftstoffzusammensetzung (z. B. eine Zertifizierungsgrenze, die für die Betankung verfügbare Kraftstoffzusammensetzung oder Grenzwerte für Luftfahrzeuge/Triebwerke).

In some examples, the proportion of fuel delivered by the first fuel source 302 compared to the fuel delivered by the second fuel source 304 during acceleration mode of the combustion system may be determined at least in part according to one or more of the following criteria:

1. (a) the amount of fuel with the first fuel characteristic and the amount of fuel with the second fuel characteristic available for a planned flight. This can e.g. B. by estimating or measuring the amount of fuel in the fuel tanks 53, 55 which form the first and second fuel sources 302, 304;
2. b) the amount of total fuel demand for the pilot injectors 313 during operation with pilot injection only for the entire flight in an operating range in which fuel is provided by the first fuel source 302; and or
3. (c) a fuel composition limit parameter (e.g. a certification limit, fuel composition available for refueling, or aircraft/engine limits).

30 illustrates a method 4030 for operating a gas turbine engine according to the example above, in which fuel with different fuel characteristics is delivered to the fuel injectors (e.g., one or both of the pilot and main injectors 313, 314) during at least a portion of the acceleration mode compared to at least one Part of stationary mode is delivered. The method 4030 includes regulating 4032 the supply of fuel to the pilot and main injectors 313, 314 from the first fuel source 302, which contains a first fuel with a first fuel characteristic, and from the second fuel source 304, which contains a second fuel with a second fuel characteristic , as described above using the fuel delivery controller 306 of any example herein. The second fuel characteristic is different than the first, as described above.

The method further includes operating 4034 the staged combustion system 64 in an acceleration mode that causes the engine to accelerate from a steady-state operating mode. The method 4030 further includes delivering 4036 fuel to the fuel injectors (eg, one or both of the pilot and main injectors 313, 314) during at least a portion of operation in the acceleration mode that has a different fuel characteristic than the fuel delivered to the fuel injectors ( e.g., one or both of the pilot and main injectors 313, 314) is delivered during at least a portion of the stationary operating mode of the engine.

Each of the features described above in connection with the examples, in which a different fuel is supplied in acceleration mode than in stationary cruise, can be included in method 4030 of the 30 included, even if they are not repeated here.

Determination of the stage point based on fuel characteristics

In other examples of the present application, the stage point at which the staged combustion system 64 operates may be determined based on a determination of the characteristics of the fuel supplied to it. The inventors have discovered that the stage point can be based on the characteristics of the fuel to advantageously utilize the particular fuel supplied to the engine 10.

In some examples this can be in 4 The aircraft shown may be set up to have only a single fuel source. In such an example, the fuel tanks 53, 55 may be fluidly coupled to form a single fuel source onboard the aircraft. The aircraft can therefore carry fuel with the same fuel characteristics instead of fuels with different characteristics.

31 shows an example of a staged combustion system 64, the features of which are those of 5 correspond, but is supplied with fuel from a single source on board the aircraft 1. In this example, the fuel is supplied by the fuel supply controller 306 via a fuel pump 308 from a single fuel source, e.g. B. the in 4 fuel tanks 53, 55 shown. Features that match the example in 5 match, are marked accordingly and will therefore not be described again.

In the in 31 In the example shown, the gas turbine engine 10 further includes a fuel characteristic determination module 330. The fuel characteristic determination module 330 is configured to determine one or more fuel characteristics of the fuel supplied to the fuel supply controller 306. In the example described, the fuel characteristic determination module 330 communicates with a sensor device 332 configured to take a measurement on the fuel flowing to the fuel delivery controller 306 to determine fuel characteristics. The sensor device 332 may take a number of different forms and may operate in accordance with any of the fuel characteristic determination examples disclosed herein. In other examples, the fuel characteristic determination module 330 may receive signals from a sensor device located elsewhere onboard the aircraft and configured to perform a fuel characteristic measurement. In still other examples, the fuel characteristic determination module 330 may obtain fuel characteristics from sources other than a sensor device as described elsewhere herein, e.g. B. the fuel characteristics may be received via a data communications channel or through user input.

The EEC 42 (which may be more generally referred to as a “controller”) communicates with the fuel characteristics determination module 330 so that it can receive the fuel characteristics of the fuel supplied to the fuel delivery controller 306. In the present example, the fuel characteristic determination module 330 is shown separately from the EEC, but in other examples they may be combined. The controller 42 is configured to determine the stage point at which the staged combustion system is switched between its pilot injection only operation and pilot and main injection operation. The stage point is determined based on one or more fuel characteristics. Once the stage point is determined in this manner, it is used by the controller 42 to control the operation of the staged combustion system 64, e.g. B. to control the operation of the fuel supply controller so that an appropriate fuel flow is supplied to the pilot distributor 309 or the pilot distributor 309 and the main distributor 310 for operation in the pilot injection only or in the pilot and main injection mode.

The inventors have found that the staged combustion system 64 can be advantageously controlled depending on the characteristics of the fuel supplied. In particular The stage point can be chosen so that the properties of the fuel supplied to the engine are used advantageously.

In one example, the stage point is determined based on one or more fuel characteristics that indicate that the fuel is associated with a low nvPM production level (e.g., low compared to fossil kerosene under appropriate combustion conditions). In this way, the step point can be adjusted to correspond to an engine operating condition that would otherwise result in high nvPM production. For example, as in the 23 and 25 Illustrated, determining that a low nvPM fuel is being supplied to the combustion chamber, the stage point can be adjusted to reduce CO and HC production without causing an adverse increase in nvPM production that would otherwise occur would occur when using a fuel with relatively high nvPM emissions.

In some examples, the fuel characteristic upon which the determination of the stage point is based may be the percentage of sustainable aviation fuel (SAF) in the particular fuel. As previously mentioned, SAF has a significantly lower nvPM compared to fossil kerosene and can therefore be used to mitigate stage point changes that would otherwise increase nvPM production.

In some examples, fossil kerosene may be treated to remove aromatic components, particularly naphthalenes, to produce a largely paraffinic fuel of fossil origin, which would be a low nvPM fuel. Other fuel characteristics may therefore be associated with low nvPM, such as: B. the percentage of aromatics or naphthalene content. In other examples, the fuel characteristics used to determine the step point may include the aromatic hydrocarbon content of the fuel and/or the naphthalene content of the fuel. These fuel characteristics can also provide an indication of the amount of nvPM produced by the fuel and allow the stage point to be determined accordingly.

The controller 42 may be configured to determine the stage point such that the stage point associated with a low nvPM generation fuel corresponds to a higher power setting of the engine than the stage point associated with one or more fuel characteristics thereon suggest that the fuel is associated with relatively higher nvPM generation. In other words, the step point can be raised to a higher engine power for a fuel with low nvPM production than for a fuel with higher nvPM production. The engine power at which the step point occurs can therefore be increased as the nvPM production of the fuel decreases. As already in connection with the 23 and 25 discussed, this step point increase may help reduce CO and HC production without causing a significant increase in nvPM. The low nvPM fuel may be a fuel that produces lower nvPM emissions compared to fossil kerosene under appropriate combustion conditions. The low-nvPM fuel can be a SAF-rich fuel that has at least some SAF content, preferably a SAF content of more than 10%, or even better of 50% or more.

In some examples, the stage point determined based on the fuel characteristics may be a cruise stage point used to control the combustion system 64 during stationary cruise operation of the engine. The controller 42 may be configured to determine the step point to correspond to an engine power setting that results in a transition between pilot injection only operation and pilot and main injection operation during steady state cruise flight. The stage point determined by the controller 42 based on the fuel characteristics may therefore form a boundary between a first engine cruise operating range and a second engine cruise operating range. The step point may be chosen to define these two cruise operating points when it is determined that a relatively low nvPM fuel is being used (e.g., a high SAF and/or low aromatics fuel). /or naphthalene content). This may allow operation with pilot injection only during cruise to take advantage of low HO and CO production while avoiding the increase in nvPM that would otherwise occur if the engine was fed a high nvPM fuel (see 27 and 28 and the associated description above).

The first cruise operating range may correspond to operating the aircraft in a later portion of a cruise segment of a flight, and the second operating range may correspond to operating the aircraft in a relatively earlier portion of the cruise segment. As already mentioned, this can be similar to staged burning The control system 64 allows switching to pilot injection-only operation during a later portion of a cruise segment (e.g., a constant altitude cruise segment). In another example, the first cruise operating range may correspond to stationary subsonic cruise operation of the engine and the second cruise operating range may correspond to stationary supersonic cruise operation of the engine. In both examples, the step point is chosen so that operation only takes place with pre-injection at low engine power in cruise flight, e.g. B. in a later part of a cruise segment or during subsonic cruise flight. Stationary supersonic cruise operations may occur before stationary subsonic cruise operations or vice versa. In some examples, stationary subsonic cruise may be subsonic cruise over land, while stationary supersonic cruise may be supersonic cruise over water.

In another example, the stage point determined according to the fuel characteristics may be an engine acceleration stage point according to which the staged combustion system is controlled during an acceleration state of the engine. In such an example, the controller may be configured to select the engine acceleration step point to match the point used in cruise flight. This may occur particularly if it is determined that a fuel with a low nvPM value is being used (e.g. a fuel with a high SAF content and/or a low aromatics and/or naphthalene content). As already mentioned, in this way acceleration can occur (at least partially) while continuing operation only in pilot injection, although the flow rate of fuel for acceleration has been increased. This can help avoid an increase in HC and CO production that would otherwise occur due to an increase in step point during engine acceleration.

In some examples, the controller 42 may be configured to determine the cruise and acceleration stage points or both, and may be configured to determine stage points for both supersonic/subsonic operation and earlier/later portions of a Cruise segment determined.

32 illustrates a method 4038 for operating a gas turbine engine for an aircraft. The procedure can be carried out using the device 31 be performed. The method 4038 includes determining 4040 one or more fuel characteristics of a fuel supplied to the combustion system; determining 4042 a stage point that defines the point at which the combustion system is switched between pilot injection only operation and pilot and main injection operation based on the determined one or more fuel characteristics; and the staged combustion system controller 4044 according to the determined stage point.

The one or more fuel characteristics may indicate that the fuel has low nvPM production compared to fossil kerosene as described above. Fuel characteristics include one or more of the following: (i) a percentage of sustainable aviation fuel in the fuel; (ii) an aromatic hydrocarbon content in the fuel; and/or (iii) a naphthalene content in the fuel. Other fuel characteristics may also be used.

The stage point determination 4042 may include the stage point determination 4046 such that the stage point associated with one or more fuel characteristics that indicate that the fuel is associated with low nvPM production, a higher engine power setting corresponds to the step point associated with one or more fuel characteristics that indicate that the fuel is associated with relatively higher nvPM production.

The one according to the procedure of 32 The determined 4042 stage point may be a cruise stage point and may be used during a later part of a cruise segment of a light or during subsonic cruise operations of a supersonic capable aircraft, as described in the various examples above.

Any of the features described above in connection with the examples where the stage point is determined based on one or more fuel features can be included in method 4038 of the 32 be included.

In the examples above, the stage point is determined based on the nvPM production characteristics of the fuel. However, this is just an example and other fuel characteristics may also be considered to determine an appropriate stage point to take advantage of the characteristics of the fuel delivered to the combustion chamber.

Determination of step ratio based on fuel characteristics

In other examples this is in 31 The control unit 42 shown is additionally or alternatively arranged so that it determines a step ratio corresponding to one or more fuel characteristics. As explained elsewhere, the controller 42 is configured to control the fuel supply controller 306 (and thus the staged combustion system 64) according to a stage ratio. The step ratio defines the ratio of the fuel flow of the pilot injector 313 to the fuel flow of the main injector 314. The inventors have discovered that the step ratio can be selected to take advantage of certain fuel characteristics of the fuel supplied to the fuel delivery regulator by Ratio is intelligently chosen based on fuel characteristics.

For example, the step ratio may be determined based on one or more fuel characteristics that indicate that the fuel is associated with low nvPM production (e.g., low compared to fossil kerosene under appropriate combustion conditions). In this way, the stage ratio can be adjusted to reduce CO and HC production in a way that would otherwise result in high nvPM production, as described in various examples above.

In some examples, the fuel characteristics on which the step ratio determination is based may be the percentage of sustainable aviation fuel (SAF) in the particular fuel. As previously mentioned, SAF has a significantly lower nvPM compared to fossil kerosene and can therefore be used to mitigate stage ratio changes that would otherwise increase nvPM production.

In some examples, fossil kerosene may be treated to remove aromatic components, particularly naphthalenes, to produce a largely paraffinic fuel of fossil origin, which would be a low nvPM fuel. Other fuel characteristics may therefore be associated with low nvPM, such as: B. the percentage of aromatics or naphthalene. In other examples, the fuel characteristics used to determine the step ratio may include the aromatic hydrocarbon content of the fuel and/or the naphthalene content of the fuel. These fuel characteristics can also provide an indication of the amount of nvPM produced by the fuel and allow the step ratio to be determined accordingly.

The controller 42 may be configured to determine a transition staging ratio that enables the staged combustion system 64 to operate in a transition region between the pilot injection only operating region and the pilot and main injection operating region, as described above in connection with 27 and 28 explained. The transition step ratio may be determined depending on one or more fuel characteristics that indicate that the fuel supplied to the fuel delivery controller 306 has a low nvPM production level (e.g., corresponding to SAF content, aromatics content, or naphthalene content; low nvPM production is relatively lower than fossil kerosene fuel). The transition staging ratio may be different from a pre-injection and main-injection staging ratio according to which the controller 42 controls the staged combustion system during operation with pre-injection and main injection. The pre-injection and main injection stage ratio can be a standard ratio and can be determined according to known methods.

As already in connection with the 27 and 28 As discussed, configuring the staged combustion system 64 to operate in the transition region between pilot injection only operation and pilot and main injection operation may reduce the amount of CO and HC emissions in this range of engine power settings. By determining that the combustion chamber is being supplied with a fuel that has low nvPM production, the controller can determine that the transition staging ratio can be used to reduce CO and HC emissions without an excessive increase in nvPM -causing production.

Any of the transition stage ratio characteristics discussed above may be incorporated into the examples currently described in which the transition stage ratio is selected depending on one or more fuel characteristics. For example, the transition stage ratio can vary during the transition phase with a changed power setting of the engine. In one example, the transition step ratio varies continuously with changing engine performance within the transition operating range. This can provide a smooth transition between the step ratio in the operating range with pilot injection only and in the operating range with pilot and main injection make possible. The continuous variation may be such that the proportion of the total fuel flow to the injectors (ie, the total flow to the pilot and main injectors) that is attributable to the fuel flow to the pilot injectors 313 decreases as engine power increases in the transition operating region. On the other hand, the proportion of the fuel flow to the injectors, which is accounted for by the fuel flow to the main injectors 314, increases with increasing engine power in the transition region.

In other examples, the transition step ratio has a constant intermediate value that is different from the ratio between pilot and main injection. The transition stage ratio can be between the ratio with pilot injection only and the pilot and main injection ratio. This results in a more gradual transition from pure pilot injection to pilot and main injection. For example, the transition stage ratio can be 70:30, which lies between 100:0 in the pure pre-injection range and a pre- and main injection ratio of 20:80 or 30:70.

In other examples, the transition staging ratio varies between a series of constant intermediate values, each different from the pilot and main injection staging ratio. In addition, each of the intermediate ratios can lie between the ratio of pure pilot injection and that of pilot and main injection. For example, the transition step ratio may vary between a range of values of 80:20, 60:40 and 40:60. In this example, the ratio between pilot and main injection can be 20:80. The interstage ratios may therefore decrease in the direction of the pilot and main injection ratio (i.e., an increasingly smaller proportion of the total fuel is supplied to the pilot injectors 313 and an increasingly larger proportion of the total fuel is supplied to the main injectors 314). However, this is just an example and any other number and value of inter-transition step ratios can be used.

In some examples, the transition step ratio may exhibit a continuous variation with engine performance in one portion of the transition region and may have one or more constant values in another portion of the transition region. The above examples can therefore be combined. In other examples, the step ratio may have a continuous variation with engine performance throughout the transition region, or may have one or more constant values with engine performance throughout the transition region.

33 illustrates an example of a method 4050 for operating a gas turbine engine. The method 4050 includes: determining 4052 one or more fuel characteristics of a fuel supplied to the staged combustion system 64; determining 4054 a step ratio that defines the ratio of pilot injector fuel flow to main injector fuel flow; and controlling 4056 the staged combustion system 64 according to the determined stage ratio. The procedure 4050 can be done with the in 31 The device shown can be carried out (in addition or as an alternative to the method 4038, in which a step point is determined).

The one or more fuel characteristics may indicate that the fuel has low nvPM production compared to fossil kerosene as described above. Fuel characteristics include one or more of the following: (i) a percentage of sustainable aviation fuel in the fuel; (ii) an aromatic hydrocarbon content in the fuel; and/or (iii) a naphthalene content in the fuel. Other fuel characteristics may also be used.

The controller 4056 of the staged combustion system 64 may include the controller 4058 of the staged combustion system 64 during the pilot and main injection operating region according to a pilot and main injection stage ratio, as described above. The step ratio determination 4054 may include the transition step ratio determination 4060. The controller 4056 of the staged combustion system 64 may then include the controller 4062 thereof such that it operates in a transitional operating region between a pilot injection only operating region and a pilot and main injection operating region, as described above. The transition step ratio can be determined according to one of the examples mentioned above.

Each of the features described above in connection with the examples in which the step ratio is determined depending on one or more fuel features can be incorporated into the method 4050 of the 33 be included.

In the examples above, the step ratio is determined based on the nvPM production characteristics of the fuel. However, this is just an example and other fuel characteristics may also be considered to arrive at a suitable AbStu The starting point must be determined so that the properties of the fuel supplied to the combustion chamber can be used.

Abnormal operating conditions

The control of the fuel supply according to one of the examples described here is suitable for operation under normal operating conditions of the gas turbine engine 10 or the aircraft 1. During abnormal operating conditions, the supply of fuel to the combustion chamber 16 (e.g. to control the nvPM) described herein may be disabled. The control of the fuel supply described here is therefore applicable at least during part of the operation of the associated gas turbine engine, e.g. B. when fuel availability does not prevent it, either due to tank capacity limits or unexpected abnormal operating conditions.

For example, in the event of abnormal operation, such as after an engine failure, the need to transfer fuel from one wing tank to another wing tank (to maintain an acceptable lateral center of gravity of the aircraft) may override the fuel delivery control in accordance with the present application. particularly in cases requiring fuel transfer from the first fuel source 302 to the second fuel source 304 or vice versa. However, if the two wing fuel tanks are both part of the same fuel source (i.e. both are part of the first fuel source 302 or both are part of the second fuel source 304) and either directly or via one or more additional fuel tanks that are also part of the same fuel source (the first or . second fuel source) are fluidly connected to each other, the fuel control described here can continue to function despite such abnormal conditions.

If the fuel supply controller 306 is configured to switch between the sources or mix fuel from the first and second fuel sources 302, 304, the switching or mixing may be disabled if one of the fuel sources due to a leak or other unexpected reasons (e.g. incorrect fuel loading) is exhausted. In some or all examples, particularly the one in 9 shown, a fuel bypass may be provided in which fuel may be distributed between the first and second fuel sources in the event of an abnormal operating condition. In the example of the 9 For example, a fuel bypass may be provided upstream of the fuel supply regulator 306 or between the fuel tanks of the first and second fuel sources 302, 304, which establishes an emergency connection between the first and second fuel sources. The pilot controller 306a and the main controller 306b can therefore be supplied with fuel from the first or second fuel sources 302, 304 if one of the fuel sources fails during operation.

The fuel supply control may also be disabled during part of the flight if sufficient primary and secondary fuel cannot be accommodated in the aircraft's fuel tanks. In some operations, the total fuel requirement for a planned flight may dictate the minimum level to which each fuel tank must be filled, and this may override certain other means of controlling fuel delivery in the various examples described herein.

Calculation of fuel allocation

The present application further provides a method for determining fuel allocation for an aircraft. The method enables determination of a fuel allocation according to which fuel is loaded into the aircraft 1 to execute a proposed flight or mission. The aircraft to which the procedure is applied may be in 4 10, which includes a first fuel source 302, which may include a first fuel with a first fuel characteristic, and a second fuel source 304, which may include a second fuel with a second fuel characteristic, the second fuel characteristic being different from the first. As already mentioned, the aircraft 1 includes one or more gas turbine engines 10 that are operated with fuel from the first and second fuel sources 302, 304. The gas turbine engines 10 each include a fuel supply controller 306 arranged to supply fuel from any fuel source or a mixture thereof, and a staged combustion system 64, as shown in FIG 5 shown or as described elsewhere herein.

A method 4070 for determining fuel allocation is in 34 shown. The method 4070 includes obtaining 4072 a proposed mission description with a list of operating points for the gas turbine engine(s) 10 of the aircraft 1 during an operational mission. The list of operating points contains information about the operation of the gas turbine engines 10 of the aircraft 1 expected for a certain planned operating period for which fuel is to be loaded into the aircraft. The list of operating points can contain a variety of information that determines the expected nvPM impact of the gas turbine friction mechanism can be determined during each part of the operational mission for the fuels used with different characteristics. The operating points of the mission description may include one or more of the following: one or more conditions under which the gas turbine engines 10 are intended to operate (e.g., the site and/or environmental conditions expected for the specific mission), one or more values for the fuel flow rate corresponding to an operating point and an operating duration at a corresponding operating point. The operating points may therefore indicate that the mission includes, for example, a period in which the engines are operated in a cruise flight under certain environmental conditions and in which a certain fuel flow rate is required. Any other appropriate information may be specified in the list of operating points so that nvPM production can be determined for the various parts of the flight given fuel characteristics. The mission description may include details of the operation of the aircraft on the ground to accomplish the operational mission.

The method 4070 further includes determining 4074 nvPM influence parameters for the gas turbine engines 10 based on the mission description received. The influencing parameters are associated with each of the operating points of the proposed mission and may define an amount of nvPM produced by the gas turbine engines 10 for various respective fuel compositions comprising the first fuel, the second fuel, or a mixture thereof at each operating condition of the mission description.

The amount of nvPM produced by the engine can be determined using a lookup table of the nvPM number as a function of W _F for all operating conditions (e.g., considering different positions of the stage point at different operating points of the mission) and for different fuel characteristics. The variation with fuel characteristics can be parameterized by the percent SAF content in some examples. The lookup table used to determine nvPM production can be selected from a number of lookup tables corresponding to different SAF types (HEFA, ATJ, etc.). If nvPM production is similar for different fuels, the same lookup table can be used for each.

• i) Höhe über dem Boden, in der die nvPM-Produktion stattfindet;
• ii) Position (z. B. Standort, z. B. Längen- und Breitengrad) der nvPM-Produktion;
• iii) Wetter-/Atmosphärenbedingungen am Ort der nvPM-Produktion;
• iv) Klimaauswirkungen in Verbindung mit dem Standort der nvPM-Produktion;
• v) Masse/Größe der einzelnen erzeugten nvPM-Partikel;
• vi) mögliche Kondensstreifenproduktion und/oder Kondensstreifenmerkmale;
• vii) Auswirkungen der Produktion von nvPM auf die lokale Luftqualität (LAQ); und/oder
• viii) Menge des produzierten nvPM (z. B. Masse/Anzahl)

The influencing parameters may be the nvPM influencing parameters described elsewhere, which may relate to the costs or damage of nvPM emissions (e.g. soot) of a specific type or in a specific situation (in addition or alternatively for easy indication of the amount of nvPM produced). The nvPM impact parameters may therefore include one or more of the following:

• i) height above ground at which nvPM production takes place;
• ii) position (e.g. location, e.g. longitude and latitude) of nvPM production;
• iii) weather/atmospheric conditions at the site of nvPM production;
• iv) climate impacts associated with the location of nvPM production;
• v) mass/size of each nvPM particle produced;
• vi) possible contrail production and/or contrail features;
• vii) Impact of nvPM production on local air quality (LAQ); and or
• viii) Amount of nvPM produced (e.g. mass/number)

The method 4070 further includes calculating 4076 an optimized set of one or more fuel characteristics for each operating point of the proposed mission defined in the mission description based on the nvPM influence parameters. In this step, the method calculates the fuel characteristics for each part of the proposed mission that yield an optimal set of nvPM influence parameters. Calculating the optimized set of one or more fuel characteristics includes minimizing a cost function depending on the one or more nvPM influencing parameters. In some examples, the cost function may only consider the amount of nvPM generated during each part of the mission, so it can be minimized. In other examples, more complex cost functions, as described elsewhere, may be defined to take into account other factors related to the impact of nvPM production (e.g. using the other influencing parameters defined above).

• i) eine Kraftstoffmenge (z. B. Volumen oder Masse), die jeweils der ersten und der zweiten Kraftstoffquelle zugeordnet ist. Dies kann es ermöglichen, die erforderliche Kraftstoffmenge während eines Betankungsvorgangs zu laden, bei dem das Luftfahrzeug an eine Kraftstoffquelle wie z. B. einen Tankwagen oder eine Kraftstoffversorgungsleitung angeschlossen ist;
• ii) das erste Kraftstoffmerkmal und/oder die zweiten Kraftstoffmerkmale; und/oder
• iii) ein Kraftstoff-Mischungsverhältnis (z. B. ein Verhältnis zwischen einem Standard- und einem Nicht-Standard-Kraftstoff).

Once the optimized set of fuel characteristics has been calculated, method 4070 includes determining 4078 a fuel allocation based on the optimized set of one or more fuel characteristics. Fuel allocation determines how fuel is allocated for the mission and how the aircraft is to be loaded with fuel to meet the requirements of the optimized fuel characteristics over the duration of the mission to complete. Fuel allocation may include one or more of the following:

• i) an amount of fuel (e.g. volume or mass) associated with the first and second fuel sources, respectively. This may allow the required amount of fuel to be loaded during a refueling operation in which the aircraft is connected to a fuel source such as a fuel source. B. a tanker truck or a fuel supply line is connected;
• ii) the first fuel feature and/or the second fuel features; and or
• iii) a fuel mixture ratio (e.g. a ratio between a standard and a non-standard fuel).

By specifying the quantity and characteristics of the fuel, the desired fuel can be loaded from the various types of fuel available. In some examples, the fuel may be blended from various available fuels before loading, e.g. B. from a standard and a non-standard fuel, as described later.

• i) einen Misch-Ablaufplan, nach dem Kraftstoff aus der ersten Kraftstoffquelle 302 und der zweiten Kraftstoffquelle 304 durch den Kraftstofflieferungsregler 306 gemischt wird (z. B. unter Verwendung des oben beschriebenen Kraftstoffmischers 318);
• ii) einen Umschalt-Ablaufplan, nach dem der Kraftstofflieferungsregler 306 so konfiguriert ist, dass er zwischen der Lieferung von Kraftstoff aus der ersten Kraftstoffquelle 302 und der zweiten Kraftstoffquelle 304 umschaltet;
• iii) ein bordseitiges Kraftstoffmischungsverhältnis, nach dem der Kraftstoff-Zufuhrregler 306 so konfiguriert ist, dass er Kraftstoff aus den Quellen an Bord des Luftfahrzeugs mischt;
• iv) eine Zuordnung von Kraftstofftanks 53, 55, die im Luftfahrzeug vorgesehen sind, um die erste Kraftstoffquelle 302 und die zweite Kraftstoffquelle 304 zu bilden. Dadurch kann die Zuordnung der Kraftstofftanks so konfiguriert werden, dass die für den Flug erforderliche Menge an Kraftstoff jedes Typs an Bord des Luftfahrzeugs gelagert werden kann; und/oder
• ii) die Einstellung eines Absperrventils für die Kraftstofftanks 53, 55, die die erste Kraftstoffquelle 302 und die zweite Kraftstoffquelle 304 bilden. Auf diese Weise kann die Konfiguration der Kraftstofftanks festgelegt werden, indem bestimmt wird, welche Tanks an Bord des Luftfahrzeugs isoliert sind oder miteinander in Fluidverbindung stehen.

The method 4070 may further include determining one or more fuel consumption parameters corresponding to the fuel allocation, the fuel consumption parameters defining how the fuel is to be used during the mission defined by the mission description. The fuel consumption parameters may define how the optimized fuel characteristics required for each part of the mission should be delivered to the combustion chamber 16 of the respective engine. The fuel consumption parameters can be combined into a “mission fuel consumption,” which defines how the fuel is used during the duration of the mission. The fuel consumption parameters may be provided to the aircraft 1 so that the gas turbine engine 10 (e.g., the fuel supply controller 306) can be controlled accordingly or the fuel tanks 53, 55 can be configured accordingly. The one or more fuel consumption parameters may include one or more of the following values:

• i) a mixing schedule in which fuel from the first fuel source 302 and the second fuel source 304 is mixed by the fuel delivery controller 306 (e.g., using the fuel mixer 318 described above);
• ii) a switching flowchart in which the fuel delivery controller 306 is configured to switch between delivering fuel from the first fuel source 302 and the second fuel source 304;
• iii) an onboard fuel mixing ratio according to which the fuel supply controller 306 is configured to mix fuel from sources onboard the aircraft;
• iv) an allocation of fuel tanks 53, 55 provided in the aircraft to form the first fuel source 302 and the second fuel source 304. This allows the allocation of fuel tanks to be configured so that the amount of fuel of each type required for the flight can be stored on board the aircraft; and or
• ii) the adjustment of a shut-off valve for the fuel tanks 53, 55 which form the first fuel source 302 and the second fuel source 304. In this way, the configuration of the fuel tanks can be determined by determining which tanks are isolated or in fluid communication with one another onboard the aircraft.

The inventors have found that by calculating fuel allocation in this manner, fuel can be loaded onto the aircraft in such a way that the required amount of fuel with the required characteristics is on board the aircraft to carry out the planned operation while at the same time reducing the effects of the to reduce nvPM. This may allow better utilization of the properties of the available fuel to reduce NvPM than loading with a specific amount of the available fuel types. It may also ensure that sufficient fuel is available to perform the combustion chamber control methods described herein, in which fuel with different characteristics is intelligently delivered to the staged combustion system 64 under different operating conditions.

The first fuel characteristic may be associated with nvPM production that is lower than that of the second fuel characteristic (under appropriate combustion conditions). More specifically, the first fuel characteristic and the second fuel characteristic may be a percentage of SAF present in the respective fuel. As explained elsewhere, the SAF content can influence the level of nvPM production. The first and second fuels may differ in other fuel characteristics, including those defined herein. They can differ, for example, in their aromatics (or naphthalene) content.

In some examples, the aircraft may be loaded with various fuels available at the location where it is fueled. The type and amount of fuel available may vary from location to location. The present method can therefore make it possible to load an optimized amount of fuel of the available types into the aircraft, taking into account the characteristics of the available fuel and the available quantity. In some examples, the available fuel may be a “standard fuel” and a “non-standard fuel.” The standard fuel may be a widely available fuel consisting primarily of fossil kerosene (e.g. Jet A or JetA-1). Standard fuel may contain a small amount of SAF. The standard fuel therefore corresponds to a fuel that has the second fuel characteristics described elsewhere herein. It can be assumed that it is available in quantities for which there is no upper limit. The non-standard fuel may be a less widely available fuel and contains a relatively higher proportion of SAF compared to the standard fuel. The non-standard fuel may contain 50% or more SAF. It may contain other SAF levels significantly higher than standard fuel (the remainder is fossil kerosene) and may consist of 100% SAF.

• i) den erreichbaren Bereich von Kraftstoffzusammensetzungen, die vom Kraftstoff-Zufuhrregler 306 des Triebwerks 10 des Luftfahrzeugs 1, für das der Kraftstoff geladen wird, bereitgestellt werden können. Beispielsweise kann der Kraftstoff-Zufuhrregler 306 so eingerichtet sein, dass er eine Mischung aus Kraftstoff aus der ersten und der zweiten Kraftstoffquelle 302, 304 liefert, zwischen Kraftstoff aus der ersten und der zweiten Kraftstoffquelle umschaltet oder während des gesamten Einsatzes ausschließlich Kraftstoff aus der ersten Kraftstoffquelle 302 oder Kraftstoff aus der zweiten Kraftstoffquelle 304 an die Haupteinspritzdüsen 314 oder die Voreinspritzdüsen 313 liefert. Die Art des Reglers kann daher die Eigenschaften des Kraftstoffs, der der Brennkammer zugeführt werden kann, einschränken und kann daher vorteilhaft bei der Berechnung der Kraftstoffmerkmale berücksichtigt werden;
• ii) eine Gesamtmenge an nicht standardmäßigem Kraftstoff, die der Mission zugewiesen wird. Bei der Optimierung der erforderlichen Kraftstoffmerkmale kann die Menge des am Ort der Betankung verfügbaren nicht normgerechten Kraftstoffs berücksichtigt werden. Da der Vorrat an nicht normgerechtem Kraftstoff begrenzt sein kann, kann er bei der Optimierung des erforderlichen Kraftstoffs für jeden verfügbaren Typ berücksichtigt werden;
• iii) der Gesamtbedarf an Kraftstoff für die Mission. Beispielsweise kann auch die Gesamtmenge des für die Durchführung der Mission erforderlichen Kraftstoffs (einschließlich einer eventuellen Reservemenge) berücksichtigt werden;
• iv) das Fassungsvermögen der Kraftstofftanks des Luftfahrzeugs. Dadurch kann die Menge jedes Kraftstoffs, die in den Tanks des Luftfahrzeugs gespeichert werden kann, berücksichtigt werden. Einige Luftfahrzeuge können beispielsweise über eine feste Konfiguration von Kraftstofftanks verfügen, die eine vordefinierte Menge jedes verfügbaren Kraftstoffs aufnehmen können; und/oder
• v) Beschränkungen bei der Zuordnung der Kraftstofftanks des Luftfahrzeugs zu der ersten oder zweiten Kraftstoffquelle. Wie bereits erwähnt, können einige Luftfahrzeuge über eine konfigurierbare Anzahl von Kraftstofftanks verfügen, die für Flexibilität bei der Menge des Kraftstoffs jedes Typs sorgen, der an Bord des Luftfahrzeugs gelagert werden kann.

The optimized set of one or more fuel characteristics for each flight condition may be further determined based on one or more of the following criteria:

• i) the achievable range of fuel compositions that can be provided by the fuel supply controller 306 of the engine 10 of the aircraft 1 for which the fuel is being loaded. For example, the fuel supply controller 306 may be configured to deliver a mixture of fuel from the first and second fuel sources 302, 304, to switch between fuel from the first and second fuel sources, or to exclusively provide fuel from the first fuel source throughout the operation 302 or fuel from the second fuel source 304 to the main injectors 314 or the pilot injectors 313. The type of regulator can therefore limit the characteristics of the fuel that can be supplied to the combustion chamber and can therefore be advantageously taken into account when calculating the fuel characteristics;
• ii) a total amount of non-standard fuel allocated to the mission. When optimizing the required fuel characteristics, the amount of non-standard fuel available at the refueling location can be taken into account. Since the supply of non-standard fuel may be limited, it can be taken into account when optimizing the required fuel for each available type;
• iii) the total fuel requirement for the mission. For example, the total amount of fuel required to complete the mission (including any reserve amount) may also be taken into account;
• (iv) the capacity of the aircraft's fuel tanks. This allows the amount of each fuel that can be stored in the aircraft's tanks to be taken into account. For example, some aircraft may have a fixed configuration of fuel tanks that can hold a predefined amount of each available fuel; and or
• v) Restrictions on assigning the aircraft's fuel tanks to the first or second fuel source. As previously mentioned, some aircraft may have a configurable number of fuel tanks, providing flexibility in the amount of each type of fuel that can be stored on board the aircraft.

The method 4070 may be part of a method 4080 for loading fuel into an aircraft 1. Such a procedure is in 35 shown. Method 4080 may include determining 4082 a fuel allocation according to method 4070 described above. Once the fuel allocation is determined, the method 4080 includes loading 4084 fuel into the aircraft according to the fuel allocation. This may include loading fuel by connecting the aircraft 1 to a fuel supply according to a known method (e.g. as in 4 and may further include configuring fuel tanks as needed, selecting between fuels with different characteristics, and loading the required mass or volume of each fuel. The step of loading 4084 the fuel may also include storing any required control parameters in a control system of the engine in question (e.g., the EEC 42) or the aircraft. The control parameters can include, for example, the fuel consumption parameters described above.

Method 4070 is a computer-implemented method. In some examples, the method 4070 may be performed by a computing device on board the aircraft 1, e.g. B. from an aircraft control system (e.g. B. the EEC 42 or another control system of the engine or aircraft). Method 4070 may be performed by any suitable computing device, either on board the aircraft 1, separate from the aircraft 1 as part of a fuel loading system, or as a separate system.

36 illustrates a system 5000 for determining fuel allocation. The system 5000 can perform the method 4070 described above. Any feature disclosed above in connection with method 4070 may also apply to system 5000. The system 5000 includes a mission description acquisition module 5002 configured to obtain a proposed mission description that includes a list of operating points for the gas turbine engines 10 during the mission. The mission description may be obtained from any suitable source, including an external source with which the system 5000 communicates or a local storage configured to store a variety of different flight definitions.

The system 5000 further includes an influencing parameter determination module 5004 configured to determine nvPM influencing parameters for the gas turbine engines. As discussed above, the influencing parameters are associated with each operating point of the proposed mission using fuel compositions that include fuel from the first fuel source 302, fuel from the second fuel source 304, or a mixture thereof. The influencing parameters can be determined by accessing a lookup table as described above. The lookup table may be obtained by the system 5000 from an external source (e.g., to match a particular fuel available to the aircraft) or retrieved from local storage.

The system 5000 further includes a module 5006 for calculating fuel characteristics. The fuel characteristics calculation module is configured to calculate an optimized set of one or more fuel characteristics for each operating point of the proposed mission defined in the mission description based on the nvPM influence parameters. This can be done by optimizing a cost function, as described elsewhere.

The system 5000 further includes a module 5008 for determining fuel allocation. This is configured to receive the calculated fuel characteristics for each part of the mission and determine a fuel allocation based on this.

As previously mentioned, the first fuel feature may be associated with nvPM production that is lower than that of the second fuel feature. For example, the first fuel characteristic and the second fuel characteristic may be a percentage of SAF in the respective fuel. Other fuel characteristics may also be used, as described above in connection with the method of 34 described.

Each of the operating points of the mission description received from the mission description acquisition module 5002 may include one or more of the following: one or more operating conditions under which the gas turbine engines are to be operated, one or more fuel flow rate values corresponding to each operating point, and a time period of the Operating at an appropriate operating point.

The nvPM influence parameters determined by the influence parameter determination module 5004 may each define an amount of nvPM generated by the gas turbine engines for various fuel characteristics, which include the first fuel, the second fuel, or a mixture thereof at each operating condition of the mission description. The influence parameter acquisition module can either obtain the influence parameters from an external source or store them in local storage as described above.

The fuel allocation determined by the fuel allocation determination module 5008 may be as described above and may be determined according to any of the factors discussed above in connection with in 34 have been discussed in the example shown and will therefore not be repeated here. The system 5000 may further include a fuel consumption parameter determination module 5010 configured to determine one or more fuel consumption parameters as described above.

The fuel characteristic calculation module 5006 may be configured to calculate the optimized set of one or more fuel characteristics by minimizing a cost function depending on one or more nvPM influencing parameters. The one or more nvPM influence parameters used by the fuel characteristic calculation module 5006 may be any of the parameters described herein.

Fleet-wide allocation of fuel

In the examples above, the amount of fuel to be allocated to a particular mission is calculated using fuel with different characteristics. The inventors have further discovered that the available fuel can be intelligently divided across a series of missions to make even more advantageous use of the different types of fuel available.

The present examples relate to determining a fuel allocation for a plurality of missions (i.e., the amount of fuel allocated to each mission) performed by a plurality of aircraft supplied with fuel from a fuel source containing an amount of a standard fuel and an amount of a non-standard fuel. The fuel source may include fuel storage containers or tanks from which aircraft are refueled, the fuel storage containers keeping the standard fuel and non-standard fuel separate, e.g. B. the in 4 refueling source 60 shown and described above. The quantity of each of the fuels is stored at a refueling location at which the aircraft used to carry out the missions are refueled. A limited supply of fuel is therefore distributed from this fuel source across the multitude of missions. These may, for example, be missions that all depart from the same airport or from the same terminal at an airport and that all have access to the same fuel source. Fuel allocation can be determined for a variety of missions over a predefined time window. The time window may represent the period of time in which the fuel available at the fuel source is to be used, e.g. B. it may be the time between deliveries of fuel to be stored in the fuel source and made available to the aircraft. In other examples, the time period may correspond to one or more series of operations or a specific period of time such as one or more days or one or more weeks. The multitude of operations is referred to as a “fleet” to which fuel must be allocated and for which fleet-wide optimization should be carried out.

The fuel available at the refueling location may include a fixed amount of standard fuel and a fixed amount of non-standard fuel, as described above. The standard fuel may be fossil kerosene (or another low-SAF fuel), while the non-standard fuel may be a high-SAF fuel, e.g. B. with a SAF content of 50% or more or 100% SAF (the SAF-rich fuel can be any fuel that has a higher proportion of SAF compared to the low-SAF fuel). More generally, the non-standard fuel may be associated with lower nvPM production than the standard fuel (e.g. when used under appropriate conditions). The standard and non-standard fuel can have a variety of characteristics as described above.

1. a) Mischen aller verfügbaren nicht standardmäßigen Kraftstoffe mit einer geeigneten Menge standardmäßigen Kraftstoffs, um eine einzige Kraftstoffzusammensetzung zu erhalten, die von allen zu betankenden Luftfahrzeugen verwendet wird. Dies ist im Großen und Ganzen das, was im Stand der Technik derzeit geschieht.
2. b) Der gesamte verfügbare Nicht-Standard-Kraftstoff wird mit einer angemessenen Menge Standard-Kraftstoff gemischt, um den Kraftstoffbedarf für Missionen zu decken, bei denen Triebwerke mit fetter Verbrennung zum Einsatz kommen. Die Missionen mit Triebwerken mit magerer Verbrennung würden die Standardkraftstoffzusammensetzung erhalten oder zugewiesen bekommen, da das Magerverbrennungssystem zumindest für einen Teil ihres Betriebs die Rußemissionen sehr stark reduziert.
3. c) Wie b), wobei jedoch der verfügbare, nicht voreingestellte Kraftstoff nicht nur auf die Missionen mit fetter Verbrennung, sondern auch auf die Untergruppe der Missionen mit magerer Verbrennung aufgeteilt wird, die einen „großen“ Anteil ihres Kraftstoffs im Modus „nur Voreinspritzung“ verbrauchen (d. h. Kurzstreckenflüge oder Flüge, bei denen der Zielflughafen einen hohen Anteil an Rollvorgängen erfordert). Der Begriff „groß“ kann unter Bezugnahme auf einen vorgegebenen Schwellenwert definiert werden.
4. d) Wie c), wobei jedoch diejenigen Missionen mit magerer Verbrennung, die eine Zuteilung von Nicht-Standardkraftstoff erhalten, diesen ausschließlich in ihren Voreinspritzdüsen verwenden und den Standardkraftstoff in ihren Haupteinspritzdüsen einsetzen. Für die Missionen, die eine Zuteilung von nicht standardmäßigem Kraftstoff erhalten, entspricht diese Option dem in 9 dargestellten Beispiel.

When both standard fuel and non-standard fuel are provided at a refueling station, there are a number of ways in which these fuels can be used:

1. a) Mixing all available non-standard fuels with an appropriate amount of standard fuel to obtain a single fuel composition used by all aircraft to be refueled. This is largely what is currently happening in the state of the art.
2. b) All available non-standard fuel is blended with an appropriate amount of standard fuel to meet fuel requirements for missions using rich combustion engines. The lean-burn engine missions would receive or be assigned the standard fuel composition because the lean-burn system greatly reduces soot emissions for at least part of their operations.
3. c) Same as b), except that the available non-preset fuel is divided not only among the rich-burning missions, but also among the subset of lean-burning missions that consume a "large" portion of their fuel in "pre-injection only" mode. (i.e. short-haul flights or flights where the destination airport requires a high proportion of taxiing). The term “large” can be defined with reference to a given threshold.
4. d) Same as c), except that those lean burn missions that receive an allocation of non-standard fuel use it exclusively in their pilot injectors and use the standard fuel in their main injectors. For those missions that receive an allocation of non-standard fuel, this option corresponds to that in 9 example shown.

The inventors have found that the fuel available at the refueling point is still... This can be leveraged by determining optimized “fleet-wide” fuel allocation for the variety of missions that need to be performed using the fuel stored at the fuel source.

37 illustrates a method 4090 for determining optimized fleet-wide fuel allocation for the variety of missions presented above. The method includes determining 4092 an initial proposed fuel allocation for each of the multiple missions. The proposed initial fuel allocation may define an amount of non-standard fuel and an amount of standard fuel to be allocated for each mission, and optionally a mix ratio at which the standard and non-standard fuel are mixed prior to loading one Aircraft can be mixed. The proposed fuel allocation may have a corresponding fuel consumption (e.g., a "mission fuel consumption", which is composed of a fuel consumption parameter for each flight condition of the mission, as described above), which determines how the allocation will be allocated during the duration of the mission is to use. For aircraft with the appropriate capabilities, this may also include fuel composition and proposed switchover points and/or deployment schedules. The fuel utilization parameters may include a mixing ratio between the standard and non-standard fuel according to which the fuel should be mixed and loaded into the aircraft to accomplish a corresponding mission.

The initial proposed fuel allocation for each mission may be set to divide available fuel between aircraft so that each of the missions can be completed. The initially proposed fuel allocation may serve as a starting point for further optimization and therefore may not necessarily correspond to the optimal allocation for each of the missions. The initial allocation of fuel can e.g. B. using one of the above-mentioned methods a) to d).

Each of the numerous missions is assigned a corresponding NvPM influence parameter per mission. The per-mission impact parameter may be determined based on the fuel allocation for the particular mission and the fuel consumption, which determines how that fuel is to be used during the particular mission. The NvPM impact parameter per mission can be determined by combining an NvPM impact parameter for each operating point of the gas turbine engine(s) 10 of the respective aircraft 1 during the mission (e.g. as defined in a mission description). The NvPM impact parameters for each mission can be calculated as described below or using the procedures described above in the context of fuel allocation optimization for an individual mission.

Once an initial proposed fuel allocation for each of the missions has been obtained, the method 4090 includes performing 4094 a fleet-wide optimization in which the proposed fuel allocation for each of the plurality of missions is determined such that a combination of the nvPM impacts per mission is within the constraints the total amount of standard and non-standard fuel to be allocated to the variety of missions. In some examples, the amount of standard fuel may be considered unrestricted, with only the amount of non-standard fuel being limited.

The fuel allocation for each mission can be determined by modifying the originally proposed fuel allocation using an optimization procedure so that the total (e.g. sum) of the nvPM impacts for all missions is minimized. This can be done by using an appropriate optimization process (e.g. iterative optimization) that converges to a set of fuel allocations per mission that results in the lowest fleet-wide nvPM impact. Fleet-wide optimization results in setting optimized fuel consumption for each mission that uses available fuel as effectively as possible to minimize nvPM impacts for all missions rather than for each individual mission.

Method 4090 further includes determining 4096 fleet-wide fuel allocation for the majority of missions based on fleet-wide optimization. Fleet-wide fuel allocation may include fuel allocation for each of the multiple aircraft within the fleet. The allocation may correspond to that defined in the examples above for determining fuel allocation for a single aircraft/mission. The fleet-wide fuel allocation may specify the amount (either mass or volume) of standard fuel, non-standard fuel, or a mixture thereof that must be loaded onto the aircraft for each mission in order to have fuel available to meet the optimized fuel consumption requirements for that mission. The fleet-wide fuel allocation may also include fuel consumption for each aircraft in order to determine how the fuel loaded into the aircraft in question is to be used.

As previously mentioned, the non-standard fuel may be associated with lower nvPM production than the standard fuel. More specifically, the non-standard fuel may be formed from a mixture of a first fuel having a first fuel characteristic and a second fuel having another fuel characteristic different from the first. The first and second fuel characteristics may be a percentage of SAF in the respective fuel. The non-standard fuel may therefore be a mixture of a first fuel consisting of 100% SAF and a second fuel consisting of 100% fossil kerosene. The non-standard fuel may therefore be a SAF-rich fuel (e.g. with an SAF content in the non-standard fuel of 50% or more), while the standard fuel is a relatively low-SAF fuel. In other examples, the non-standard fuel may be a blend of fuels that differ by other fuel characteristics defined herein, e.g. B. by the aromatic content.

Performing 4094 fleet-wide optimization may include performing fleet-wide multi-parameter optimization to minimize the fleet-wide nvPM impact, i.e. H. the sum of the nvPM impact per mission from the plurality of missions within the limitations of the standard and/or non-standard fuel available for the plurality of missions. The optimization may include: i) performing 4097a an outer loop optimization in which the fuel allocation of one or more of the missions is varied to reduce the sum of the per-mission nvPM impact parameters of the multiple missions; and ii) performing 4097b an inner loop optimization in which a fuel consumption for each of the missions is obtained according to the constraints of the varied fuel allocation to determine a new proposed fuel consumption for each of the plurality of missions. Determining fuel consumption may include determining an optimized fuel consumption for the specific mission based on the varied fuel allocation to determine a new minimized per-mission nvPM impact parameter for that particular mission. This mission-specific optimization can be performed as described below or using one of the other techniques described herein. Fleet-wide optimization allows different distributions of SAF between the different missions to be tried out (i.e., the outer loop optimization), and for each proposed distribution, each mission then considers how it can best use its own proposed allocation (i.e., the in-loop optimization). the inner loop).

Fleet-wide optimization may begin by changing the original proposed fuel allocation obtained in step 4092. The fleet-wide optimization steps 4097a, 4097b may be repeated until the process converges to an optimized solution of the proposed fuel consumption for each of the multiple missions that corresponds to the minimum value of the sum of the nvPM influence parameters per mission. In each iteration of the outer loop optimization 4097a, fuel consumption may be varied by varying a suggested amount of non-standard fuel assigned to the corresponding mission. For example, an amount of non-standard fuel assigned to a mission can be moved to another mission so that the overall non-standard fuel can be allocated more optimally.

In some examples, the optimization in the inner loop 4097b may be to determine the fuel consumption of a particular mission using the result of a previous per-mission optimization for that mission. This can reduce the calculation time. Performing the optimization in the inner loop may consist of obtaining a prepared fuel consumption solution for this mission (e.g. SAF percentages within the SAF-poor and SAF-rich fuel compositions for this mission and the proposed switchover points and/or or the mixing schedule to be used on this mission) to minimize the overall nvPM for this mission. The prepared solution may be obtained from an approximate model, a lookup table, or an “answer function” from which an appropriate prepared solution can be determined for a particular proposed fuel allocation. In some examples, the prepared solution may also be determined based on other factors such as the proposed route for the particular operation and expected weather conditions.

• i) einem Prozentsatz eines ersten Kraftstoffs mit einem ersten Kraftstoffmerkmal innerhalb des Standardkraftstoffs, der den geringstmöglichen Prozentsatz an Kraftstoff mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann;
• ii) einem prozentualen Anteil des ersten Kraftstoffs mit dem ersten Kraftstoffmerkmal innerhalb des Nicht-Standardkraftstoffs, der den höchstmöglichen Prozentsatz des Kraftstoffs mit dem ersten Kraftstoffmerkmal definiert, der für die Verbrennung verwendet werden kann; und/oder
• iii) die Menge an nicht standardmäßigem Kraftstoff, die für die Vielzahl der Einsätze zur Verfügung steht.

In some examples, fleet-wide optimization may be based at least in part on one or more of the following factors:

• i) a percentage of a first fuel with a first fuel characteristic within the standard fuel that defines the lowest possible percentage of fuel with the first fuel characteristic that can be used for combustion;
• ii) a percentage of the first fuel with the first fuel characteristic within the non-standard fuel, which defines the highest possible percentage of the fuel with the first fuel characteristic that can be used for combustion; and or
• iii) the amount of non-standard fuel available for the variety of missions.

If the first fuel characteristic is the percentage SAF content of the fuel, then factors i) and ii) above can be used to determine the lowest and highest possible SAF content of a fuel consisting of the standard and non-standard -Fuel can be formed. For example, if the non-standard fuel contains 80% SAF and the standard fuel contains 10% SAF, the highest possible SAF content of a mixture of the two fuels is 80% and the lowest is 10%.

As previously mentioned, fuel consumption for each of the multiple missions is determined by determining an optimized fuel consumption for the particular mission, which determines how the allocated fuel will be used during the mission. The optimized fuel consumption may include one or more fuel consumption parameters that are used to control the combustion system of the respective aircraft or to mix and load the fuel into the aircraft. The utilization parameters may include, for example, the SAF percentages within the SAF-low and SAF-rich fuel compositions for that mission and the proposed switchover points and/or blending schedules. The usage parameters may be chosen to minimize a per-use nvPM impact parameter for the particular use within the limits of the fuel allocated to that use by the fuel allocation.

• i) Bestimmung 4098a eines Typs und/oder der Betriebsfähigkeiten einer Verbrennungsanlage, die von dem jeweiligen Luftfahrzeug, das für die Mission eingesetzt wird, verwendet wird;
• ii) Bestimmung 4098b des Gesamtbedarfs an Kraftstoff für die jeweilige Mission;
• iii) Bestimmung 4098c einer Kraftstoffmenge, die für jeden Typ von Einspritzdüsen in der Brennkammer für den jeweiligen Einsatz erforderlich ist;
• iv) Bestimmen 4098d der Abhängigkeit der nvPM-Emissionen für jeden Betriebspunkt des Triebwerks unter Verwendung von Kraftstoff mit den Merkmalen des Standardkraftstoffs, eines Nicht-Standardkraftstoffs oder einer Mischung davon; und
• v) Bestimmung eines optimierten Kraftstoffverbrauchs, der die gesamten nvPM-Emissionen für die Mission minimiert, 4098e.

The optimized fuel consumption for each mission (e.g. determined as part of the inner-loop optimization) can be determined by performing an optimization per mission (4098) according to 38 be determined. Per-mission optimization can be performed for each individual mission by:

• i) Determination 4098a of a type and/or operational capabilities of an incinerator used by the particular aircraft used for the mission;
• ii) Determination 4098b of the total fuel requirements for the particular mission;
• iii) determining 4098c an amount of fuel required for each type of injector in the combustion chamber for the particular application;
• iv) determining 4098d the dependence of the nvPM emissions for each operating point of the engine using fuel with the characteristics of the standard fuel, a non-standard fuel or a mixture thereof; and
• v) Determine an optimized fuel consumption that minimizes total nvPM emissions for the mission, 4098e.

In step i), the type and capabilities of the combustion system of the aircraft carrying out the respective mission are determined. It can be determined whether the aircraft has a staged lean combustion chamber or a rich combustion chamber. It can also be determined which combustion chamber control modes are available. So can e.g. For example, it may be determined whether the operating options include switching fuel between different sources supplied to the pilot injectors or providing a mixed fuel to the pilot injectors and/or the main injectors, as described in various examples herein. If the combustion chamber is a lean combustion chamber, determining the amount of fuel required for each type of injector includes determining the amount of fuel required for the pilot injectors during pilot-only operation. Additionally or alternatively, the amount of fuel required for the pilot injection nozzles during operation with pilot and main injection can be determined. Determining the amount of fuel required for each type of burner may, in some examples, include determining the amount of fuel required for the pilot injectors operating within a threshold range of operation at flow rates below that of the stage point. This may be the case in examples where SAF-rich fuel is supplied to the pilot injectors in pilot-injection-only mode near the stage point, as in connection with above 15 described. In step iv), the nvPM emission is determined for each operating point of the engine depending on the properties of the fuel burned. The engine operating points may be defined as in an operational description as described elsewhere herein. In step v), the optimized fuel consumption is determined based on the dependence of the nvPM emissions to determine the optimal fuel consumption (e.g. type or mixture of fuel used) for each engine operating condition in order to achieve the overall nvPM to minimize emissions. In some examples, the nvPM cost function may be minimized for each engine operating condition, as defined elsewhere herein.

The information determined in each of steps i) to iv) of the per-use optimization can be obtained or calculated using any suitable technique known to those skilled in the art. This may include, for example, access to stored information about the aircraft in question and descriptions of each of the numerous missions they are scheduled to fly.

The optimization per shipment can be carried out using one of the examples mentioned here, e.g. B. after in connection with 34 described.

Method 4090 is a computer-implemented method. Method 4090 may be implemented by any suitable computer, either onboard an aircraft, separate from the aircraft as part of a fuel loading system, or as a dedicated system configured to manage fuel allocation.

The method 4090 may be part of a method 4100 for loading fuel into the multiple aircraft for which the fuel allocation has been determined. Such a procedure is in 39 shown. Method 4100 may include determining fuel allocation 4102 for the plurality of missions using method 4090 described above. Once the fuel allocation is determined, the method 4100 includes loading 4104 fuel into the aircraft according to the fuel allocation. This may include loading fuel by connecting the aircraft to a fuel supply according to a known method. Fuel loading may also involve providing the aircraft with fuel consumption information calculated for each mission for storage in an on-board control system (such as EEC 42) so that the aircraft can be controlled accordingly. This may include fuel consumption information to enable configuration of fuel tanks as needed, selection between fuels with different fuel characteristics at specific operating points, and/or fuel blend scheduling. The consumption information may also include a ratio in which the standard and non-standard fuel must be mixed before being loaded onto the aircraft (e.g. for aircraft where onboard fuel mixing or selection is not possible ). The step of loading the fuel may also include storing all necessary control parameters in a control system of the relevant engine (e.g., the EEC 42).

40 shows a fleet-wide fuel allocation determination system 5100 for determining fuel allocation for a variety of missions. The system 5100 can perform the method 4090 described above. Any feature disclosed above in connection with method 4090 may therefore also apply to system 5100 40 apply.

The system 5100 for determining fleet-wide fuel allocation generally includes a module 5102 for determining the initial proposed fuel allocation, a module 5104 for fleet-wide optimization, and a module 5106 for determining fleet-wide fuel allocation. These modules may perform any of the steps defined above with respect to method 4090 for determining fleet-wide fuel allocation.

The initial proposed fuel allocation module 5102 is configured to determine a first proposed fuel allocation for each of the plurality of missions. As described above, this can form the starting point for fleet-wide optimization. The fleet-wide optimization module 5104 is configured to perform a fleet-wide optimization in which the proposed fuel allocation for each of the multiple missions is changed by a sum within the constraints of the total available standard and/or non-standard fuel from the fuel source to minimize the nvPM influence parameters per mission across all of the multiple missions. Each of the multiple missions may be assigned an NvPM influence parameter per mission, which is determined according to the proposed fuel consumption as described above.

The fleet-wide fuel allocation determination module 5106 is configured to determine the fleet-wide fuel allocation for the variety of missions based on the fleet-wide optimization.

As already mentioned, the non-standard fuel is associated with lower nvPM production than the standard fuel. The non-standard fuel is formed from a mixture of a first fuel having a first fuel characteristic and a second fuel having a second fuel characteristic different from the first. In particular, the first and second fuel characteristics may be a percentage of SAF in the respective fuel and wherein the non-standard fuel is a high SAF fuel and the standard fuel is a low SAF fuel.

• i) Durchführung einer Optimierung in einer äußeren Schleife, bei der die Kraftstoffzuteilung für eine oder mehrere der Missionen variiert wird, um die Summe der pro Mission geltenden nvPM-Einflussparameter der mehreren Missionen zu verringern; und
• ii) Durchführung einer Optimierung in einer inneren Schleife, bei der der Kraftstoffverbrauch für jede der Missionen gemäß den Beschränkungen der variierten Kraftstoffzuteilung ermittelt wird, um einen neuen vorgeschlagenen Kraftstoffverbrauch für jede der Vielzahl von Missionen zu bestimmen

The fleet-wide optimization module may be configured to perform the fleet-wide optimization described above. The fleet-wide optimization module 5104 is therefore configured to perform the following steps:

• i) performing an outer loop optimization in which the fuel allocation for one or more of the missions is varied to reduce the sum of the per-mission nvPM influence parameters of the multiple missions; and
• ii) performing an inner loop optimization in which fuel consumption for each of the missions is determined according to the constraints of the varied fuel allocation to determine a new proposed fuel consumption for each of the plurality of missions

The fleet-wide optimization module 5104 may be configured to repeat steps i) and ii) until an optimized fuel consumption is determined for each of the plurality of missions that corresponds to a minimized sum of the nvPM influencing parameters per mission. The fleet-wide optimization module 5104 may be configured to perform inner-loop optimization by obtaining a prepared fuel consumption solution for a given mission. This can be done using information already available to the system 5100, such as: B. the information stored in local or remote storage.

The fleet-wide optimization module 5104 may be configured to determine fuel consumption for each of the multiple missions by determining an optimized fuel consumption for the respective mission, which determines how to use the fuel for a respective mission, in order to achieve an NvPM -Minimize influence parameters per mission for this mission.

The fleet-wide optimization module 5104 may be configured to determine the optimized fuel consumption for each mission by performing per-mission optimization as described above. To perform the optimization per mission, the fleet-wide optimization module can use the in 38 Follow the steps shown or the steps described in the examples above. The details of the optimization per shipment will therefore not be repeated here. Other optimization techniques can also be used, such as: B. all described here.

All functions described above in connection with the examples of the method 4090 for determining fleet-wide fuel allocation can be performed by the modules of the system 5100. These functions are therefore not described again here.

The computer modules, systems, and computer-implemented methods described herein may be implemented in software executed by a processor, in hardware, or in a combination of both. In some embodiments, the modules, systems, and method steps described herein may be implemented by one or more computing devices. Such a computing device 6000 is in 41 shown, which includes one or more processors 6002, input/output interfaces 6004 and a memory 6006. The memory may include a computer or machine readable memory that forms a computer or machine readable medium. Those skilled in the art will understand that the memory may be provided by a variety of components, including volatile memory, hard disk, non-volatile memory, etc. The input/output interfaces may enable information such as a proposed mission description to be received from an external source and output the calculated fuel allocation or consumption parameters to another device (e.g., to a fuel charging system so that the fuel charging system can be appropriately controlled), or they may be output to a user.

Memory can store a set of computer-readable instructions, data structures, program modules, or other data. Computer-readable media may not include temporary computer-readable media (transitory media), such as: B. a modulated data signal and a carrier wave.

Those skilled in the art will understand that the computing modules and systems described herein need not be physically separate as individual components and may be located in a single location or distributed across multiple networked components. In some embodiments, the functionality of the modules/systems described herein may be distributed differently between the modules/systems, or other modules/systems may be provided to perform any of the functions described herein.

In one aspect of the present application, a machine/computer readable medium or computer program product is provided that contains instructions that, when read by read by a machine or computer, causing the performance of any of the computer-implemented methods described or claimed herein or parts thereof.

The machine-readable medium can be any of the following: a CD-ROM, a DVD ROM/RAM (including -R/-RW or +R/+RW), a hard drive, a memory (including a USB drive, an SD card, a compact flash card, or the like), a transmitted signal (including an Internet download, an FTP file transfer, or the like), a line, etc. The machine-readable medium may be a non-transferable computer-readable medium.

It is to be understood that the invention is not limited to the embodiments described above and various changes and improvements may be made without departing from the concepts described herein. Except where the features are mutually exclusive, each of the features may be used separately or in combination with other features, and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2022042465 [0357]

Claims (15)

Gas turbine engine (10) for an aircraft (1), which has: a staged combustion system (64) with pilot injection nozzles (313) and main injection nozzles (314) for fuel, the staged combustion system (64) being operable in an operating range with pilot injection only and an operating range with pilot and main injection; and a fuel supply regulator (306) arranged to control the supply of fuel (F) to the pilot and main injectors (313, 314); a fuel characteristic determination module (330) configured to determine one or more fuel characteristics of the fuel (F) supplied to the staged combustion system (64); and a controller (42) configured to determine a stage point that defines the point at which the staged combustion system (64) is switched between pilot injection only operation and pilot and main injection operation, the stage point is determined based on the determined one or more fuel characteristics, and the controller (42) is configured to control the staged combustion system (64) according to the determined stage point. Gas turbine engine (10). Claim 1 , where the one or more fuel characteristics indicate that the fuel is associated with a lower nvPM production level compared to fossil kerosene. Gas turbine engine (10). Claim 1 or Claim 2 , wherein the one or more fuel characteristics include one or more of the following characteristics: (i) a percentage of sustainable aviation fuel in the fuel (F); (ii) an aromatic hydrocarbon content in the fuel (F); and/or (iii) a naphthalene content of the fuel (F). A gas turbine engine (10) according to any one of the preceding claims, wherein the controller (42) is configured to determine the stage point such that a stage point associated with one or more fuel characteristics indicating that the fuel has a low nvPM -production corresponds to a higher power setting of the engine compared to a step point associated with one or more fuel characteristics that indicate that the fuel is associated with a relatively higher nvPM production. A gas turbine engine (10) according to any one of the preceding claims, wherein the particular stage point is a cruise stage point and the controller (42) is configured to control the combustion system (64) using the particular stage point during a cruise operating condition of the engine (10 ) controls. Gas turbine engine (10). Claim 5 , wherein the controller (42) is configured to determine the stage point such that the staged combustion system (64) is set up to switch between the operating range with pilot injection only and the operating range with pilot and main injection at a stage point, which corresponds to a stationary cruise operating mode of the engine, wherein the step point defines a boundary between a first cruise operating range and a second cruise operating range of the engine. Gas turbine engine (10). Claim 6 , wherein the first cruise operating range corresponds to the operation of the aircraft (1) in a later part of a cruise segment of a flight and the second operating range corresponds to the operation of the aircraft (1) in a relatively earlier part of the cruise segment. Gas turbine engine (10). Claim 6 , wherein the first cruise operating range corresponds to the stationary subsonic cruise operation of the engine (10) and the second cruise operating range corresponds to the stationary supersonic cruise operation of the engine (10). Gas turbine engine (10) according to one of the Claims 1 until 4 , wherein the determined stage point is an engine acceleration stage point and the controller (42) is configured to control the staged combustion system (64) using the determined stage point during an acceleration operating state of the engine, the engine acceleration stage point being determined such that it is the same as a cruise stage point in response to the one or more fuel characteristics. Method (4038) for operating a gas turbine engine (10) for an aircraft (1), the gas turbine engine (10) comprising a staged combustion system (64) with pilot injectors and main injectors (313, 314), the staged combustion system (64) in one Operating range can only be operated with pre-injection and an operating range with pre-injection and main injection, the method (4038) comprising: determining (4040) one or more fuel characteristics of a fuel (F) corresponding to the staged combustion system (64) is supplied; determining (4042) a stage point that defines the point at which the staged combustion system (64) is switched between pilot injection only operation and pilot and main injection operation based on the determined one or more fuel characteristics; and control (4044) of the staged combustion system (64) according to the determined stage point. Procedure (4038). Claim 10 , where the one or more fuel characteristics indicate that the fuel is associated with a lower nvPM production level compared to fossil kerosene. Procedure (4038). Claim 10 or Claim 11 , wherein the one or more fuel characteristics include one or more of the following characteristics: (i) a percentage of sustainable aviation fuel in the fuel (F); (ii) an aromatic hydrocarbon content in the fuel (F); and/or (iii) a naphthalene content of the fuel (F). Method (4038) according to one of the Claims 10 until 12 , wherein determining (4042) the step point includes determining (4046) the step point such that a step point associated with one or more fuel characteristics indicating that the fuel is associated with low nvPM production is a higher power setting of the engine corresponds compared to a stage point associated with one or more fuel characteristics that indicate that the fuel is associated with relatively higher nvPM production. Method (4038) according to one of the Claims 10 until 13 , wherein the particular stage point is a cruise stage point and the combustion system (64) is controlled (4044) using the particular stage point during a cruise operating state of the engine (10). Aircraft (1) with one or more gas turbine engines (10) according to one of Claims 1 until 9 .

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