GB2419180A - A combustion device including upstream secondary fuel delivery - Google Patents

A combustion device including upstream secondary fuel delivery Download PDF

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Publication number
GB2419180A
GB2419180A GB0422865A GB0422865A GB2419180A GB 2419180 A GB2419180 A GB 2419180A GB 0422865 A GB0422865 A GB 0422865A GB 0422865 A GB0422865 A GB 0422865A GB 2419180 A GB2419180 A GB 2419180A
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GB
United Kingdom
Prior art keywords
fuel
fuel delivery
delivery means
duct
combustion device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0422865A
Other versions
GB2419180B (en
GB0422865D0 (en
Inventor
David Steele
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rolls Royce PLC
Original Assignee
Rolls Royce PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolls Royce PLC filed Critical Rolls Royce PLC
Priority to GB0422865A priority Critical patent/GB2419180B/en
Publication of GB0422865D0 publication Critical patent/GB0422865D0/en
Priority to US11/248,189 priority patent/US7603862B2/en
Publication of GB2419180A publication Critical patent/GB2419180A/en
Application granted granted Critical
Publication of GB2419180B publication Critical patent/GB2419180B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/34—Feeding into different combustion zones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/22—Fuel supply systems
    • F02C7/228—Dividing fuel between various burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/26—Control of fuel supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/26—Control of fuel supply
    • F02C9/28—Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K3/00—Plants including a gas turbine driving a compressor or a ducted fan
    • F02K3/08—Plants including a gas turbine driving a compressor or a ducted fan with supplementary heating of the working fluid; Control thereof
    • F02K3/10—Plants including a gas turbine driving a compressor or a ducted fan with supplementary heating of the working fluid; Control thereof by after-burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K3/00—Plants including a gas turbine driving a compressor or a ducted fan
    • F02K3/08—Plants including a gas turbine driving a compressor or a ducted fan with supplementary heating of the working fluid; Control thereof
    • F02K3/105—Heating the by-pass flow
    • F02K3/11—Heating the by-pass flow by means of burners or combustion chambers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/002—Regulating fuel supply using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/16—Systems for controlling combustion using noise-sensitive detectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2237/00—Controlling
    • F23N2237/02—Controlling two or more burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/00013—Reducing thermo-acoustic vibrations by active means

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)

Abstract

A combustion device has a duct 2 in which a gas flow is established in operation, a primary fuel inlet 12, and a secondary fuel inlet 20, the fuel inlets delivering fuel to the duct. The secondary fuel inlet is provided upstream of the primary fuel inlet, with respect to the gas flow direction. A control device including a valve 18 controls the primary fuel delivery in response to pressure fluctuations within the duct. The valve diverts fuel from the primary fuel inlet to the secondary fuel inlet. The control device may include a pressure transducer 24 and a controller 22, and the control means may operate to reduce the flow of fuel to the primary fuel inlet under conditions of peak pressure in the duct. The secondary inlet may be positioned such that the delivered fuel reaches the duct during low pressure troughs in the duct fluctuating pressure. The combustion device may be a gas turbine afterburner, and the distance 'X' between the primary and secondary fuel inlets may be between 0.5 and 1m. The control device may reduce combustion-induced instabilities.

Description

A COMBUSTION DEVICE
This invention relates to a combustion device and is particularly, although not exclusively, concerned with a combustion device in the form of an afterburner of a gas turbine engine.
Combustion-induced instabilities arise in afterburners and other combustion devices.
These tend to have a cyclic form, and create pressure fluctuations in the gas flow through the combustion device. The combustion-induced instabilities can create acoustic pressure fluctuations which may couple with the combustion-induced instabilities so causing them to grow larger, with potentially damaging effects on the structure of the combustion device.
In order to control such combustion-induced instabilities, GB 2239961 discloses a combustion device in the form of an afterburner comprising a duct in which a gas flow is established in operation, primary fuel delivery means being provided for delivering fuel to the duct, and control means being provided for controlling the primary fuel delivery means, the control means comprising a valve which is operable in response to pressure fluctuations in the duct to divert fuel from the primary fuel delivery means.
It is usual for the fuel to an afterburner of a gas turbine engine to be delivered from a pump through a metering arrangement. The metering arrangement can control the fuel flow rate to meet operating requirements, such as a required power output, but it cannot respond rapidly enough to adjust the fuel flow in response to pressure fluctuations.
Such pressure fluctuations may typically have a frequency up to 120 Hz.
Consequently, control systems of the kind described in GB 2239961 have tended to use spill valves as the valve operable in response to the pressure fluctuations. A spill valve extracts a proportion of the fuel flowing between the measuring arrangement and the primary fuel delivery means leaving only the remainder to pass into the combustion device to be ignited. However, the management of the extracted fuel causes problems. 2
The extracted fuel may simply be dumped, but, if this is unacceptable, retrieval and storage measures are required, in the form of pumps, catch tanks and associated pipework In many circumstances, the extracted fuel cannot be returned to the main fuel supply, since there is a risk that it will be contaminated, for example by hydraulic fluid picked up from the main fuel supply pump and metering arrangement.
According to the present Invention, secondary fuel delivery means is provided upstream of the primary fuel delivery means with respect to the gas flow direction, the secondary fuel delivery means, in operation, receiving fuel diverted by the valve from the primary fuel delivery means.
The control means preferably comprises a pressure transducer exposed to the pressure within the duct. The control means may act to reduce the supply of fuel to the primary fuel delivery means during periods of increasing pressure, as detected by the pressure transducer. Additional control of combustion-induced instability can be achieved if the diverted fuel delivered by the secondary fuel delivery means reaches the axial position of the primary fuel delivery means during periods of reduced pressure in the duct. By way of example, the secondary fuel delivery means may be situated a distance upstream of the primary fuel delivery means which is in the range 0.5 to 1 m or more preferably in the range 0. 6 to 0.8 m Thus, combustion-induced stability can be controlled by reducing the heat input at pressure peaks by reducing the supply of fuel through the primary fuel delivery means, and by increasing heat input at pressure troughs by increasing the supply of fuel through the secondary fuel delivery means.
In a preferred embodiment In accordance with the present invention, the combustion device is an afterburner of a gas turbine engine having a bypass duct, and the secondary fuel delivery means is disposed in the bypass duct.
For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a schematic view of a gas turbine engine having an afterburner; and Figure 2 Is a diagrammatic view, on an enlarged scale, of part of the afterburner of the engine of Figure 1.
The engine shown in Figure 1 comprises an engine casing 2, the downstream end of which defines a duct serving as an afterburner 4. The casing 2 encloses a fan 6 and a core engine 8 (comprising a compressor stage, combustion chambers and a turbine stage). A bypass duct 10 is provided between the casing 2 and the core engine 8. In operation, a flow of air, generated by the fan 6, passes through the bypass duct 10.
The afterburner 4 is situated downstream of the core engine 8, and receives combustion products from the core engine 8 and air from the bypass duct 10. The afterburner 4 comprises primary fuel delivery means 12 and a flame holder structure 14. The primary fuel delivery means 12 may comprise an array of fuel spray bars, which may or may not be separately fuelled, and the flame holder structure 14 may comprise annular or radial elements having a profile which diverges in the downstream direction, with respect to the direction of gas flow through the engine.
Fuel is delivered to the spray bars 12 from a pump and metering arrangement indicated generally at 16. A spill valve 18 is branched off the direct line between the pump and metering arrangement 16 and the spray bars 12, and is connected so that, when open, it diverts a proportion of the flow from the pump and metering arrangement 16 to secondary fuel delivery means 20. The secondary fuel delivery means 20 may comprise a single fuel injector, or a plurality of fuel injectors distributed around the engine. As shown in Figure 1, the secondary fuel delivery means 20 is positioned to deliver fuel into the bypass duct 10. - 4
The spill valve 18 is controlled by a controller 22 which receives pressure signals from a transducer 24 exposed to the pressure within the afterburner 4.
In operation of the afterburner 4, fuel is supplied to the spray bars 12 from the pump and metering arrangement 16. Although the flow rate of the fuel delivered by the pump and metering arrangement 16 can be varied to meet the power requirements of the engine, such variation occurs relatively slowly and, for the purposes of the present description, it can be assumed that the output of the pump and metering arrangement 16 is constant.
The fuel is atomised as it emerges from the spray bars 12, and is mixed with the combustion gases from the core engine 8 and the air from the bypass duct 10. The flame holders 14 establish a desired flow pattern within the afterburner 4, and the mixture of fuel, air and combustion gases is ignited to form a flame in a combustion zone 26 downstream of the flame holders 14. The release of heat in the combustion process creates acoustic pressure waves which can become coupled with combustion- induced instabilities so providing a feedback response which can result in pressure fluctuations of sufficient size to cause structural damage to the components of the afterburner 4 or other engine or airframe components.
As disclosed in GB 2239961, active control of such acoustically coupled combustion instabilities can be achieved by an intermittent reduction in the flow of fuel to the spray bars 12, synchronized with the pressure fluctuations and having a suitable phase relationship. This is achieved by means of the spill valve 18 which is opened to divert fuel from the spray bars 12 in accordance with a signal from the controller 22, which contains a control algorithm to define the correct phase relationship. The controller 22 receives signals from the transducer 24, representing the instantaneous pressure in the afterburner 4 at the location of the transducer 24, which is positioned at or close to the combustion zone 26.
Thus, the spill valve 18 serves to reduce the flow rate of fuel to the spray bars 12 so as to reduce the energy released by combustion at pressure peaks during the pressure fluctuation cycle. This serves to damp the acoustic pressure fluctuations.
In accordance with the present invention, the fuel diverted by the spill valve 18 is supplied to the secondary fuel delivery means in the form of the injector or injectors 20.
As shown in Figure 1, the injector 20 is positioned within the bypass duct 10 but alternative positions are possible. For example, in Figure 2, the injector 20 is shown just downstream of the fan 6 and adjacent to the core engine 8.
Because of the intermittent or pulsed opening of the spill valve 18 controlled by the controller 22, the fuel delivered by the injector 20 will also be pulsed and will be discharged into the bypass duct 10 in "packets" at substantially the same time as the reduction in the flow rate of fuel discharged from the spray bars 12. Because the "packet" of fuel delivered by the injector 20 is discharged upstream of the spray bars 12, that "packet" will reach the combustion zone 26 some time after the corresponding reduced flow of fuel from the spray bars 12. By appropriate selection of the distance X between the injector 20 and the spray bars 12, it is possible for the "packet" of fuel delivered by the injector 20 to reach the combustion zone 26 at a time when the pressure In the combustion zone 26 is at or approaching its lowest value in the cycle of pressure fluctuation. Thus, the fuel delivered by the injector 20 serves to increase the heat released at the troughs in the pressure fluctuation cycle, so as to provide additional damping of the acoustic pressure fluctuations.
The distance X will vary from engine to engine, depending on the gas flow rate through the engine, and in particular through the bypass duct 10, and on the frequency of the pressure fluctuations created in the afterburner 4. For a typical engine, it has been established that an appropriate distance X is approximately 0.7 m, although it will be appreciated that, for different engines, the distance may vary, for example within the range 0.5 to 1 m, or 0.6 to 0.8 m. - 6
It will be appreciated that the present invention provides a mean for damping pressure fluctuations within the afterburner 4 by decreasing the fuel flow through the spray bars 12, and so, decreasing the release heat when the pressure is highest, and by increasing the release of heat, by means of the fuel delivered by the injector 20, when the pressure is lowest. Furthermore, the problem of dealing with the fuel diverted by the spill valve 18 from the spray bars 12 is overcome by supplying that fuel to the injector 20.
Although the present invention has been described in the context of the afterburner 4 of a gas turbine engine, it may be applied also in other combustion devices where acoustically coupled combustion-induced instabilities may arise.

Claims (8)

1 A combustion device comprising a duct (2) in which a gas flow is established in operation, primary fuel delivery means (12) being provided for delivering fuel to the duct, and control means (18, 22, 24) being provided for controlling the primary fuel delivery means (12), the control means comprising a valve (18) which is operable in response to pressure fluctuations in the duct to divert fuel from the primary fuel delivery means (12), characterized in that secondary fuel delivery means (20) is provided upstream of the primary fuel delivery means (12) with respect to the gas flow direction, the secondary fuel delivery means (20), in operation, receiving fuel diverted by the valve (18) from the primary fuel delivery means (12).
2 A combustion device as claimed in claim 1, characterized in that the control means comprises a pressure transducer (24) responsive to the pressure in the duct (2).
3 A combustion device as claimed in claim 1 or 2, characterized in that the control means operates to reduce the flow of fuel to the primary fuel delivery means (12) in synchronism with peaks in the fluctuating pressure in the duct (2).
4 A combustion device as claimed in claim 3, characterized in that the secondary fuel delivery means (20) is positioned so that fuel diverted from the primary fuel delivery means (12) and discharged from the secondary fuel delivery means (20) reaches the axial position of the primary fuel delivery means (12) during troughs in the fluctuating pressure in the duct (2).
A combustion device as claimed in any one of the preceding claims, characterized in that the distance (X) between the primary fuel delivery means (12) and the secondary fuel delivery means (20) is not less than 0.
5 m and not more than 1 m - 8
6 A combustion device as claimed In claim 5, characterized in that the distance (X) is not less 0.6 m and not more than 0.8 m.
7 A combustion device as claimed in any one of the preceding claims, which comprises an afterburner for a gas turbine engine.
8 A combustion device as claimed in claim 7, characterized in that the secondary fuel delivery means (20) is disposed to deliver fuel to a bypass duct (10) of the gas turbine engine.
GB0422865A 2004-10-14 2004-10-14 A combustion device Expired - Fee Related GB2419180B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0422865A GB2419180B (en) 2004-10-14 2004-10-14 A combustion device
US11/248,189 US7603862B2 (en) 2004-10-14 2005-10-13 Combustion device

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GB0422865A GB2419180B (en) 2004-10-14 2004-10-14 A combustion device

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GB0422865D0 GB0422865D0 (en) 2004-11-17
GB2419180A true GB2419180A (en) 2006-04-19
GB2419180B GB2419180B (en) 2007-03-14

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Cited By (1)

* Cited by examiner, † Cited by third party
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US7841184B2 (en) 2007-04-19 2010-11-30 Pratt & Whitney Canada Corp. Start flow measurement

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WO2008070780A1 (en) 2006-12-07 2008-06-12 Novartis Ag Antagonist antibodies against ephb3
US9140214B2 (en) 2012-02-28 2015-09-22 United Technologies Corporation Method of using an afterburner to reduce high velocity jet engine noise
US9470151B2 (en) 2012-12-21 2016-10-18 United Technologies Corporation Alignment system and methodology to account for variation in a gas turbine engine
US11506125B2 (en) 2018-08-01 2022-11-22 General Electric Company Fluid manifold assembly for gas turbine engine
US20230349555A1 (en) * 2022-04-29 2023-11-02 General Electric Company Propulsion system for jet noise reduction

Citations (1)

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Publication number Priority date Publication date Assignee Title
US5428951A (en) * 1993-08-16 1995-07-04 Wilson; Kenneth Method and apparatus for active control of combustion devices

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US4312185A (en) * 1980-02-19 1982-01-26 General Electric Company Low profile fuel injection system
DE4040745A1 (en) 1990-01-02 1991-07-04 Gen Electric ACTIVE CONTROL OF COMBUSTION-BASED INSTABILITIES
GB2407152A (en) * 2003-10-14 2005-04-20 Alstom Apparatus and method for testing combustion

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5428951A (en) * 1993-08-16 1995-07-04 Wilson; Kenneth Method and apparatus for active control of combustion devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7841184B2 (en) 2007-04-19 2010-11-30 Pratt & Whitney Canada Corp. Start flow measurement

Also Published As

Publication number Publication date
US20060080962A1 (en) 2006-04-20
US7603862B2 (en) 2009-10-20
GB2419180B (en) 2007-03-14
GB0422865D0 (en) 2004-11-17

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20131014