WO2023246980A1

WO2023246980A1 - Propulsion system for an aircraft

Info

Publication number: WO2023246980A1
Application number: PCT/DE2023/100456
Authority: WO
Inventors: Hermann Klingels; Sascha Kaiser; Petra Kufner; Simon Schuldt
Original assignee: MTU Aero Engines AG
Priority date: 2022-06-22
Filing date: 2023-06-19
Publication date: 2023-12-28
Also published as: DE102022115585A1

Abstract

The invention relates to a propulsion system (1) for an aircraft, comprising a gas turbine (2) having a core flow channel (10), wherein a compressor (12), a combustion chamber (13), a first turbine, in particular a high-pressure turbine (14), for driving the compressor (12), and a second turbine, in particular a low-pressure turbine (15) are arranged in the core flow channel (10) in the flow direction, and comprising a water system (30) for providing water via recovery from an exhaust gas from the core flow channel (10).

Description

Propulsion system for an aircraft

The invention relates to a drive system for an aircraft. The propulsion system has a gas turbine with a core flow channel and an exhaust gas treatment system. A compressor, a combustion chamber, a first turbine for driving the compressor, and a second turbine for driving the fan are arranged in the core flow channel in the direction of flow.

In the past, many concepts for low-emission combustion were developed for stationary gas turbines and aircraft engines. Various measures are taken, all of which aim to avoid high peak temperatures and the associated formation of nitrogen oxides while at the same time keeping emissions of carbon monoxide and unburned hydrocarbons low. It is known that the medium water or water vapor can be used in turbomachines to increase performance and reduce emissions.

It also makes sense to use water vapor in aircraft engines to improve the environmental impact of air traffic. Steam offers new options for fuel preparation and thus a new concept for low-pollutant combustion in a turbomachine. For example, in a steam generator arranged downstream of an engine turbine, steam can be generated using exhaust gas energy and supplied in the area of the combustion chamber. After flowing through the steam generator, moist exhaust gas can flow through other components that serve to separate water from the exhaust gas. However, in the known methods for operating aircraft engines, steam generation concepts require large, heavy steam generators.

In addition, the classic concepts of aircraft engines are very mature and only promise incremental improvements in efficiency in the future. Thus, despite increasing complexity, changes to the gas turbine cycle become more attractive because they promise significant improvements in efficiency (SFC). Proceeding from this, it is an object of the invention to provide an improved propulsion system for an aircraft and an aircraft. It is also an object of the present invention to propose an improved method for operating a turbomachine for an aircraft, in which in particular the efficiency of the turbomachine is improved.

This task is solved by a drive system with the features of claim 1 and claim 19. The further task is solved using a method with the features of claim 20. Further advantageous refinements are the subject of the subclaims.

Description of the invention

To solve the problem, a drive system for an aircraft is proposed, comprising a gas turbine which has a core flow channel, wherein in the core flow channel in the direction of flow there is a compressor, a combustion chamber, a first turbine, in particular a high-pressure turbine, for driving the compressor, and a second turbine, in particular low-pressure turbines are arranged. Furthermore, the drive system includes a water system for providing water that is recovered from a working gas from the gas turbine or exhaust gas from the core flow channel.

The gas turbine has at least one core flow channel or a main flow channel if it is a bypass engine with a bypass channel. The water system is part of the exhaust gas treatment system, which in a preferred embodiment also has a steam system. The water system comprises at least one water separation device and a condenser with preferably at least one capacitor module, wherein the gas turbine preferably has an outer housing that delimits the bypass flow channel radially on the outside. The high-pressure turbine drives the compressor, in particular an entire high-pressure compressor, which preferably consists of the rear stages of the compressor that are axially separated from other stages via an intermediate compressor housing, preferably via a first shaft. The low-pressure turbine drives a fan of the drive system, particularly preferably via a gear that is arranged between a second shaft and the fan. In particular, it can be provided that the drive system also has a steam turbine that has a power, in particular via a Steam turbine gearbox on the second shaft, to the fan. The steam turbine can be arranged on a third shaft.

In the following, an axial direction of a gas turbine runs parallel to an engine axis, that is to say a shaft axis of a drive shaft of the gas turbine. A radial direction is perpendicular to the engine axis. The formulation, radial direction ⁴ , is not restricted to the geometric normal plane to the engine axis. Finally, the gas turbine has a circumferential direction that describes a direction around the engine axis.

In one embodiment, the water obtained in the water separation device is fed to the steam system. The water is evaporated in the steam system in a steam generator by exhaust heat and, in a preferred embodiment, drives a steam turbine, which feeds additional power into the overall system. In a further preferred embodiment, the steam is then fed to the core stream and passed into the combustion chamber with the compressed air, which increases the mass flow and specific power and brings about a reduction in the nitrogen oxide content in the exhaust gas. In one embodiment, the steam can be mixed with the working gas before being introduced into the combustion chamber and/or introduced directly into the combustion chamber. Furthermore, the steam can be used to cool components of the gas turbine.

A drive system for an aircraft, comprising a gas turbine with a main flow duct, a bypass duct, a water system and a steam system, the water system comprising at least one water separation device and a condenser, in particular with at least one capacitor module, the gas turbine having an outer housing that surrounds the bypass duct on the outside , in particular limited, is improved according to the invention in that the water system and the steam system are arranged in and/or in the radial direction within the outer housing and/or the inner housing. It can advantageously also be provided that the water system and the steam system together have a total weight and at least 80%, preferably at least 90%, in particular 95%, of the total weight in and / or in the radial direction within at least one housing around the core stream and / or are arranged around the outer housing of a secondary flow engine. The drive system according to the invention is preferably designed so that the total pressure ratio of the gas turbine is between 20 - 40, and preferably 22 - 35. A propulsion system operating in this range has significantly reduced consumption, particularly in cruise flight.

In a preferred embodiment of the drive system according to the invention, the compressor, in particular the high-pressure compressor, has a pressure ratio of 13 to 30, preferably 16 to 27. A compressor operated in this way provides the combustion chamber with an ideally compressed gas. This is particularly advantageous if the gas has previously been mixed with a vapor in a mixing chamber, which increases the mass throughput and thus the specific power. Particularly advantageously, an ideal overall pressure ratio can be achieved together with a fan of the gas turbine.

A further developed drive system according to the invention, the gas turbine of which has a first drive shaft which is driven by the first turbine, in particular high-pressure turbine, and drives a compressor and has a second drive shaft which is driven by the second turbine, in particular low-pressure turbine, and in particular via a gearbox, drives a fan, is particularly preferably further developed in that the compressor is the only compressor driven via a drive shaft of the gas turbine. As a result, the rotors of the compressor in the main flow channel can advantageously be driven without a low-pressure turbine or without the mechanical power component of a low-pressure turbine.

In a particularly preferred development of the drive system, the gas turbine is designed as a bypass engine and has a bypass flow ratio that is greater than 30, or the gas turbine is designed as an open rotor and has a bypass flow ratio that is greater than 50, preferably greater than 60 and more preferably greater than 70. Open rotor means that the rotor or rotors of the fan are arranged outside a housing or core housing surrounding a core flow channel and in particular are not surrounded by another outer housing. In an open-rotor gas turbine, a rotor tip of the fan represents an outermost point of the gas turbine. Furthermore, mounting points for attaching the gas turbine to a pylon or wing of the aircraft are arranged on the core housing. In an advantageous embodiment of the drive system, the gas turbine can be a gas turbine that can be operated with hydrogen. The exhaust gas treatment system, in particular the water system, preferably has a heat exchange device to support the recovery of water based on the cooling effect of the cryogenic hydrogen in particular. The temperature difference between the working gas and the hydrogen is advantageously used to support the recovery of water. The weight and installation space of the exhaust gas treatment system can thereby be reduced.

Water system

In a further aspect of the invention, the drive system can advantageously be developed in such a way that a housing, in particular an outer housing or inner housing, surrounds the core flow channel and/or a secondary flow channel radially on the outside, and that the water system is at least partially arranged in and/or on the housing . This creates a system that is very compact.

Furthermore, the water system of the drive system according to the invention can comprise at least one water separation device and a heat exchanger, in particular designed as a condenser, for cooling the exhaust gas by means of a cooling fluid which has a lower temperature and/or a high flow rate relative to the exhaust gas. In the present case, a high flow velocity is understood to mean a flow velocity that typically occurs as an inflow velocity in the aviation sector. A speed of >50m/s can usually be assumed. If a heat exchanger is arranged in the sheath flow of an engine, significantly higher flow velocities can occur, in the range of Mach 0.4 to Mach 0.5.

In addition, the drive system according to the invention can be developed in such a way that the heat exchanger, which is designed in particular as a capacitor, comprises at least one capacitor module, and/or the water separation device is arranged in the housing, and/or that the at least one capacitor module is arranged in the bypass flow channel and has exhaust gas channels, which is an exhaust gas from the Lead the main flow channel primarily radially outwards through the secondary flow channel, particularly into the housing.

Steam system

An extremely advantageous development of the drive system according to the invention provides that the drive system has a steam system for generating steam from the water provided from the water system, the steam being supplied to the working gas and/or being used to cool components. This makes it possible to advantageously increase the mass flow of the working gas, i.e. the fluid flowing through the core flow, or to cool components such as the compressor, the combustion chamber or the turbine and in particular their casings, which allows the corresponding components to be operated at even higher temperatures. In particular, compared to components cooled purely by air, higher convection and thus higher heat dissipation can be achieved.

The drive system according to the invention can advantageously be designed in such a way that a proportion of 5-40% by mass, preferably 15-35% by mass, of water in the working gas can be set during operation using the steam system. In this way, an optimum of a working gas mixture can be achieved that is at least close to an optimum set in terms of power loss and mass flow. This can be achieved, for example, via valves or injection nozzles leading into a mixing chamber.

Particularly preferably, the steam system can be designed so that a proportion of 10-30% by mass, preferably 15-25% by mass, of water in the working gas can be adjusted during cruise flight using the steam system.

Fluid guidance

In an advantageous development of the invention it is provided that the water separation device is arranged in the outer housing, in particular in the cowling and/or an outer region or inner region of the outer housing, and/or that the at least one capacitor module is arranged in the bypass flow channel and exhaust gas channels which has an exhaust gas from the main flow channel to the outside, in particular in at least in the radial direction of the gas turbine, through the bypass channel and into the outer housing. This design, in which the exhaust channels guide the exhaust gas, particularly preferably predominantly in the radial direction, at least partially through the bypass channel and into the outer housing, allows the exhaust gas to be cooled in a simple manner in order to then separate the water contained therein. In at least the radial direction means that the course of the exhaust gas flow or the exhaust gas channels runs essentially in the radial direction, but can also follow directions that deviate from the radial direction. The exhaust ducts can also extend only partially, in particular in at least a radial direction, at least in sections in a radial direction and/or partially parallel to a radial direction, through the bypass flow duct. The outer housing can be integrally formed or have several outer housing parts. An integral or one-piece design of the outer housing has the advantage that fewer leaks occur and the overall system therefore has a higher efficiency.

In particular, fastening means for mounting the gas turbine on a pylon or a wing of an aircraft can be provided on or in the outer housing. In addition, a compact and integrated design of the gas turbine including the water and steam system and thus the entire drive system can advantageously be achieved. It is advantageously no longer necessary to have to rely on components or the installation space of the wing or the pylon. Furthermore, this drive system saves weight compared to the drive systems known in the prior art. A further advantage over drive systems from the prior art is that the drive system as a whole can be mounted on a pylon of a wing without parts of the drive system having to be arranged in the pylon or the wing. In this way, maintenance can be limited to the drive system and maintenance costs can thus be profitably reduced. The main flow channel, which is also referred to as the core flow channel, is used to guide fluid through the gas turbine components, comprising a compressor, in particular a low-pressure and a high-pressure compressor, a combustion chamber and a turbine, in particular a high-pressure and a low-pressure turbine. The exhaust gas from the main flow channel has a high temperature due to combustion in the combustion chamber. The bypass duct, which can also be referred to as a bypass, serves to guide a large part of the total air flow conveyed by the fan and is mainly used to generate thrust. The air bypass flow in the bypass flow duct has a low temperature, which is in a temperature range slightly above the ambient temperature. In an advantageous embodiment, the capacitor module is designed as a plate heat exchanger. This configuration allows particularly efficient heat transfer and can be easily integrated into the bypass channel.

In a preferred development of the drive system, an exhaust gas flow direction of the at least one capacitor module and an air bypass flow direction of the bypass flow duct are arranged in a cross flow to one another. The cross-flow arrangement created in this way allows a particularly simple flow of the exhaust gas from the main flow channel into the outer housing of the gas turbine in order to be able to separate the water present there in liquid form while it flows in the condenser and crosses the air side stream flowing essentially in the axial direction.

The drive system is particularly preferably further developed in that the at least one capacitor module has a side surface that at least partially faces the air bypass flow direction. The condenser module has an angle of attack relative to the air flow, which promotes flow through the condenser and whereby pressure losses can be reduced.

Furthermore, in a preferred development of the drive system, it can be provided that the at least one capacitor module has cooling channels which direct an air bypass flow of the bypass channel from the side surface that at least partially faces the air bypass flow direction to a side surface of the at least one capacitor module that faces away from the air bypass flow direction. This advantageously increases the flow surface of the capacitor modules, which reduces the flow velocity through the at least one capacitor module, thereby further reducing pressure losses. In addition, there is a flow on and along the back of the capacitor modules, i.e. the side surface facing away from the flow direction of the bypass channel. instead, so that the heat transfer is advantageously further increased.

In an advantageous development of the drive system, capacitor modules are arranged in groups, so that the at least one capacitor module is used as a first capacitor module and additionally a second capacitor module as a pair of capacitor modules Air bypass flow direction of the bypass flow duct are arranged in pairs, the capacitor modules of a capacitor module pair having a smaller internal distance from one another in the circumferential direction of the gas turbine than an external distance in the circumferential direction of the gas turbine from other capacitor modules. In particular, it can be provided that the internal distance is smaller than the external distance, at least in the flow direction of the air bypass flow direction, in a first half of the capacitor module pair. This creates areas with a relatively hot side stream of air in the narrower spaces within the pairs of capacitor modules, which have an at least slightly increased specific enthalpy for generating thrust. In addition, the relatively cold spaces, i.e. the bypass channel areas, which are arranged between two pairs of capacitor modules, are intended to be able to drain away impurities in the air bypass flow. Alternatively, it can also be provided that the inner distance is larger than the outer distance, at least in the flow direction of the air bypass flow direction, in a first half of the capacitor pair.

In an advantageous development of the drive system, a first capacitor module and a second capacitor module are arranged in pairs as a pair of capacitor modules in the air bypass direction of the bypass channel, the first capacitor module having a first angle of attack relative to the flow direction in the bypass channel and the second capacitor module having a first angle of attack relative to the flow direction in the bypass channel has a second angle of attack that is different from the first angle of attack. In a further embodiment, the first angle of attack and the second angle of attack have a different sign relative to the flow direction in the bypass flow channel. Furthermore, it can be provided that the two angles of attack have the same absolute value.

Furthermore, it can advantageously be provided that the first capacitor module and the second capacitor module are connected to one another by an inlet panel arranged upstream, which divides an air bypass flow of the bypass flow duct and guides it along side surfaces of the first capacitor module and the second capacitor module facing the secondary air flow. The inlet cover can advantageously contribute to generating or maintaining a favorable air flow and directing foreign objects away from the capacitor modules. In an advantageous development, the first capacitor module and the second capacitor module are arranged in a V arrangement in the bypass channel. This advantageously creates nozzle-like areas for conducting the corresponding heated partial bypass flow between two capacitor modules, so that no additional partition walls have to be inserted into the bypass flow channel. In particular, at least one area with relatively undisturbed air flow in the bypass flow channel can be achieved between two pairs of capacitor modules.

In an advantageous embodiment of the drive system, the at least one water separation device, in particular a core outlet nozzle of the at least one water separation device or a swirl generator of the at least one water separation device, is arranged in the circumferential direction between two capacitor modules, in particular between two pairs of capacitor modules in a circumferential plane intersecting the outer housing. This allows the installation space in the cowling, i.e. in the outer housing, to be used advantageously better.

In a particular improvement of the exhaust gas treatment system, exhaust gas channels of at least one, in particular two, capacitor modules open into a water separation device, in particular into an inlet channel of the water separation device. Exhaust gas channels from three or more capacitor modules can also flow into a water separation device. In particular, these can be adjacent capacitor modules. This allows the use of the installation space in the outer housing to be further improved.

Furthermore, it can advantageously be provided that the at least one capacitor module is delimited by an outlet panel arranged downstream. With an outlet cover, the secondary air flow can be easily aligned in the desired direction of thrust with little loss.

As an advantageous embodiment of a gas turbine, which has a main drive shaft with a rotation axis, which is driven by a turbine and, in particular via a gearbox, drives a fan and / or a compressor, a steam turbine is arranged, in particular concentrically, to the main drive shaft and their mechanical performance a steam turbine gearbox feeds the main drive shaft. This makes it possible to create a very compact drive system that can use a heat flow from the exhaust gas to generate additional power. In particular, compared to an embodiment with an eccentrically arranged third shaft, the turbomachine part is further simplified and this results in lower power losses and improved utilization of installation space.

Heat exchanger

In a further aspect of the invention, a heat exchanger for a drive system according to the invention for cooling a hot fluid by means of a cooling fluid which has a lower temperature relative to the hot fluid and has a high flow rate is proposed, which comprises a high-temperature grid for guiding the hot fluid and a low-temperature grid for guiding the cooling fluid . According to the invention, it is provided that a diffuser region for delaying the inflowing fluid is arranged in at least one first low-temperature channel of the low-temperature grid through which the cooling fluid flows. Furthermore, it is provided according to the invention that the diffuser area and a first high-temperature channel of the high-temperature grid through which the hot fluid flows have at least one common wall for heat transfer. Due to the common wall, the diffuser area is already involved in the heat transfer, so that valuable installation space can be used thermally and the size of the heat exchanger can be reduced.

Further embodiments of the heat exchanger and details of the heat exchanger that can be used in a drive system according to the invention are described below.

According to one embodiment of the invention, the low-temperature channel can have a deflection area which is arranged upstream of the diffuser area and in which the cooling fluid is redirected but not yet delayed. In other words, the cooling fluid can first be deflected with a substantially constant or decreasing cross-sectional area before it enters the diffuser region, in which the cross-sectional area of the low-temperature channel increases. This allows the cold flow to change direction from the angle of attack to the main angle of inclination Low temperature channel before entering the diffuser area. The cooling fluid can preferably be accelerated in the deflection area, that is to say the cross-sectional area of the deflection area decreases in the direction of flow. In a preferred development, the diffuser area can have essentially flat side walls, since the deflection already occurs in the deflection area.

The heat exchanger can be designed as a condenser for separating liquids from a gas flowing through the condenser as the hot fluid. The hot fluid can in particular be an exhaust gas from a turbomachine such as a gas turbine or an aircraft engine. The hot fluid can also be a coolant of a fuel cell in order to preferably support the thermal management of a fuel cell and to be able to cool a fuel cell more efficiently. In particular, compressed air is preferably provided as the cooling fluid. The deceleration of the incoming cooling fluid represents a reduction in the flow velocity, so that a cooling fluid flowing in at high speed can advantageously be slowed down to a reduced speed in order to absorb as much heat as possible. The high-temperature grid is in particular composed of a plurality of high-temperature channels, which include at least the first high-temperature channel. Furthermore, the low-temperature grid is preferably formed by a plurality of low-temperature channels, which include at least the first low-temperature channel. Preferably, the high-temperature grid is arranged at least in sections in a cross-current and/or countercurrent configuration relative to the low-temperature grid. In a particularly preferred embodiment, the low-temperature channels and the high-temperature channels are arranged in a cross-flow configuration.

The diffuser area consists of one or more areas which have a flow-through cross-sectional area of the low-temperature grid in an inlet cross-section or a minimal cross-section, in particular a minimum inlet cross-section, of the diffuser area of the low-temperature channel, in particular the plurality of low-temperature channels, to a downstream cross-section that is larger than the inlet cross-section, in particular Expand the main cross section of the low temperature channel. This reduces the flow rate of the cooling fluid in each of these areas. The high-temperature grid and the low-temperature grid each represent a flow space for a fluid, wherein the two grids, the high-temperature grid and the low-temperature grid, can preferably consist together of an integral grid body with common walls of the two grids or a grid body comprising common walls of the two grids, can have. The high-temperature channels and the low-temperature channels are arranged in the grid body. The common walls preferably have at least the smallest distance between the two flow spaces transversely to a respective travel extent of the walls. It can also be provided that the walls have a constant wall thickness at least in sections.

The common wall can be defined in that its first wall side surface forms a part of the low-temperature grid and its second wall side surface facing away from the first wall side surface forms a part of the high-temperature grid. The first wall side surface extends into the diffuser area.

In a first embodiment, the heat exchanger is further developed such that the at least one common wall for forming the diffuser region in the first low-temperature channel has a convexly curved first diffuser section. This advantageously increases the heat flow. Preferably, the common wall downstream in the low-temperature grid has an adjoining straight main section to form a main region of the first low-temperature channel with a constant cross-section.

In a further preferred embodiment, a second common wall is arranged in the low-temperature channel opposite the first common wall, which adjoins a second high-temperature channel of the high-temperature grid in the diffuser area on the wall side facing away from the first low-temperature channel, it being provided that the second common Wall in the diffuser area has a flat or planar or concavely curved second diffuser section, a curvature of the convexly curved first diffuser section being smaller than a curvature of the second diffuser section. The diffuser area and thus the diffuser sections begin in particular at a narrowest cross-sectional area of the low-temperature channel, if possible directly behind an inlet of the low-temperature channel. Accordingly, in a preferred, further embodiment it can be provided that an inlet for redirecting the cooling fluid into the diffuser area is arranged in front of the diffuser area in the flow direction of the cooling fluid. The inlet serves to direct the fluid from the flow channel into the low-temperature channel. In this case, an entry surface facing away from the wind in the flow channel is advantageously elongated, while an opposite entry surface facing the wind is bent by approximately 180 °. The smallest cross-sectional area of the low-temperature channel is preferably located at the end of the bend of the entry surface facing the wind in the low-temperature channel. At the other end of the bend, the entry surface facing the wind merges into an entry surface of an adjacent low-temperature channel facing away from the wind. In the direction of flow in the low-pressure channel, the diffuser area ideally follows the inlet in order to delay the flow. As a result, the flow direction of the cooling fluid is advantageously aligned with the flow direction in the diffuser area and the air resistance is reduced.

In order to achieve the most ideal flow possible through the low-pressure channel, in a further embodiment an outlet area with an outlet nozzle for accelerating the cooling fluid is arranged in the heat exchanger downstream of the diffuser area.

A further aspect of the invention is a heat exchanger arrangement with a heat exchanger, in particular for a drive system according to the invention, in particular with a heat exchanger described above, comprising a flow channel for the cooling fluid to flow to the heat exchanger. The heat exchanger is arranged in the flow channel for guiding the cooling fluid, and the low-temperature grid and the high-temperature grid form a first heat exchanger module of the heat exchanger. According to the invention, it is provided that a plurality of common walls together form a first inflow surface in the flow channel which delimits the first heat exchanger module and is spanned by the common walls, the inflow surface having an inflow angle between 0° and 45°, advantageously between 3° and 15°, to a main channel direction of the flow channel. Advantageously, a particularly uniform flow through the heat exchanger and the individual low-temperature channels can be achieved, which leads to a homogeneous flow in each of the low-temperature channels and thus advantageously a homogeneous heat flow from the hot fluid to the cooling fluid. The area of the flow channel in front of the heat exchanger can also be referred to as the inflow area, with the main channel direction in this inflow area and the inflow area forming the inflow angle. Preferably, the flow angle is constant along at least part of the extent of the flow surface. In a supplementary or alternative embodiment, the inflow surface can be curved or angled, in which case the inflow angle can then assume corresponding different values. The inflow surface results from a surface spanned by the heat exchanger, that is to say an enveloping surface, the surface adjoining the flow channel upstream and is an auxiliary construction for describing the boundaries of the heat exchanger. The inflow surface can be flat, curved and/or twisted, in particular in sections, depending on the arrangement of the common walls. Viewed in space, an inflow surface designed as a plane has line contact with every common wall. In a section through the heat exchanger, the contact is reduced to point contact with the common walls. If the inflow surface is curved, the contact expands accordingly.

In a particularly preferred embodiment of the flow channel, the cross section of the flow channel decreases in the flow direction in front of the inflow surface along the area occupied by the heat exchanger module. It can be advantageously provided that at a design point of the heat exchanger, which can be determined, for example, by a travel speed of the turbomachine surrounding the heat exchanger, the cooling fluid is sucked into the low-temperature grid in layers from a low-temperature channel to a next low-temperature channel. This is achieved in particular because the inlet cross section of a first, in particular each, low-temperature channel is aligned with the main channel direction or is transverse to it. Preferably, a second inlet of a second low-temperature channel adjacent to the first low-temperature channel can be arranged offset. As a result, hardly any spatial flows arise along the flow in the flow channel, so that the heat exchanger arrangement works particularly efficiently.

In a preferred development of the heat exchanger arrangement, a main area of the low-temperature channel with an extension axis borders the diffuser area downstream, in particular directly, the direction of the extension axis, in particular a direction of a traveling extension of the common Wall in the main area, to which the flow surface of the heat exchanger has a main inclination angle between 0° and 60°, preferably between 30° and 45°. The extension axis of the main area is preferably a straight line and can in particular run parallel to an extension direction of the side surfaces of at least one of the common walls in the main area, in particular in the direction of flow. The main region can preferably have a constant cross-sectional area normal to the extension axis along the extension axis. In the main area, a large part of the heat transfer takes place between the low-temperature grid and the high-temperature grid. Because the cross-sectional area is designed to be constant along the longitudinal extent, a uniform heat exchanger can be formed and advantageously contributes to the fact that the walls of the heat exchanger can be designed to be at least largely identical and thus cost-saving. This design has a positive synergistic effect, particularly in a heat exchanger arrangement comprising a heat exchanger with a grid matrix of low and high temperature grids, the low and high temperature channels of which are each designed uniformly at least along an extent of the heat exchanger. Furthermore, calculations have shown that the formation of main areas oblique to the inflow surface, in particular oblique to the main channel direction, can lead to high flow losses. This is advantageously avoided according to the invention by the delay in the diffuser.

In a further embodiment, the heat exchanger arrangement can be developed in such a way that a plurality of common walls together form a first outflow surface in the flow channel which delimits the first heat exchanger module and is spanned by the common walls, the first outflow surface having a first outflow angle between 0° and 45° , advantageously between 3 ° and 15 °, to a main channel direction in the flow channel. In an advantageous embodiment, the outflow angle of a heat exchanger module corresponds to the inflow angle of this heat exchanger module. However, it can also be provided that the outflow angle is different from the inflow angle. In an advantageous embodiment, the outflow direction corresponds to the inflow direction and thus the main channel direction. The cross section of the flow channel preferably increases in the flow direction behind the outflow surface along the area occupied by the heat exchanger module, in particular in the extent to which the cross section of the flow channel has decreased in the direction of flow in front of the inflow surface.

In addition, an embodiment of the heat exchanger arrangement can provide that the heat exchanger is formed from the first heat exchanger module and a further second heat exchanger module, that a further plurality of low-temperature channels form the second heat exchanger module and that a further plurality of common walls together delimit the second heat exchanger module and of form the second inflow surface spanned by the common walls in the flow channel, the second inflow surface forming a second inflow angle between 0° and -45°, advantageously between -3° and -15°, to a main channel direction of the flow channel.

In a preferred embodiment of the heat exchanger arrangement, the further plurality of common walls together form a second outflow surface in the flow channel which delimits the second heat exchanger module upstream, wherein the second outflow surface forms a second outflow angle between 0° and 45°, advantageously between 3° and 15° Main channel direction of the flow channel forms.

In a particularly preferred embodiment of the heat exchanger arrangement, it is provided that the first heat exchanger module and the second heat exchanger module are designed to be surface-symmetrical to a common surface lying between the first and second heat exchanger modules, which runs parallel to a main channel direction of the flow channel.

Furthermore, in a preferred embodiment, the heat exchanger arrangement can be developed in such a way that part of the flow channel forms a cold channel running past the heat exchanger. As a result, only a portion of the available cooling fluid can advantageously be used for cooling. In an engine in particular, the remaining air can be used immediately to generate thrust. Furthermore, it can be provided that the flow channel (3) is a secondary flow channel and the low-temperature grid (20) is in fluid communication with the secondary flow channel and/or the high-temperature grid (30) is in fluid communication with the main flow channel.

Single-stage high-pressure turbine In a further advantageous embodiment of the drive system for an aircraft, the drive system has a gas turbine, which in particular has a main flow channel, at least one compressor, a combustion chamber, a high-pressure turbine for driving the compressor, a low-pressure turbine and a secondary flow channel, a water system and a steam system, by means of which Steam is supplied to the combustion chamber. The drive system is improved according to the invention in that the high-pressure turbine is designed in one stage. Due to the steam supply in the combustion chamber, the energy content of the working gas is increased compared to conventional gas turbines and it has been shown that sufficient power can be implemented with a single high-pressure turbine stage to achieve the compression required in the compressor, in particular in the high-pressure compressor. In this way, axial installation space can be saved compared to classic two-stage high-pressure turbines. Another advantage is the higher temperature of the working gas downstream of the high-pressure turbine, which promotes the evaporation process in the steam system.

According to a preferred development of the invention, in addition to the cooled high-pressure turbine, at least the first stage of the low-pressure turbine can also be designed to be cooled or, like at least parts of the high-pressure turbine, can be made at least partially from a ceramic fiber composite material (CMC). Due to the single-stage high-pressure turbine, the temperature in the front area of the low-pressure turbine is higher than in classically designed gas turbines for aircraft engines, which means that cooling the first stage or the use of high-temperature-resistant materials can bring advantages in terms of service life or fatigue strength. According to a further preferred embodiment of the invention, the low-pressure turbine and/or high-pressure turbine can be cooled using steam from the steam system.

According to a preferred embodiment of the invention, the high-pressure turbine can be designed with an expansion ratio between 2.3 to 3.2, in particular 2.5 to 3.0. These areas have proven to be particularly advantageous in order to be able to provide the desired compressor performance through steam injection, taking into account the higher energy content in the working gas. According to a preferred embodiment, the steam content behind the combustion chamber can make up between 15% and 35% of the mass flow. These areas have proven to be particularly suitable for increasing the efficiency of the system.

According to a further embodiment of the invention (under cruise operating conditions with steam injection), a working gas flowing through the main flow channel of the gas turbine can have a temperature in the range from 1600 °K to 1900 °K, preferably from 1650 °K to 1750 °K, at the outlet of the combustion chamber. With a design in these areas, the formation of nitrogen oxides during combustion can be significantly reduced.

According to a further preferred embodiment, the high-pressure turbine can drive the high-pressure compressor via a high-pressure shaft and the low-pressure turbine can drive a fan via a low-pressure shaft, in particular via a gearbox. In an alternative embodiment, a low-pressure compressor is provided on the low-pressure turbine shaft.

Advantageously, the drive system can be designed for a thrust in the range of 19 to 23 kN or can be set up to generate a thrust in the range of 19 to 23 kN in cruise operation.

In an advantageous embodiment, the water system has at least one capacitor module, which is arranged in the bypass channel and can be designed as a plate heat exchanger. This configuration is particularly efficient.

Combustion chamber steam supply

A further improved propulsion system for an aircraft according to the invention has a gas turbine having a main flow duct, a fan, at least one compressor, a combustion chamber, a high pressure turbine for driving the compressor, a low pressure turbine for driving the fan and a bypass duct, a water recovery system for recovering water from an exhaust gas from the gas turbine and a steam system by means of which steam is supplied to the combustion chamber. According to the invention, the gas turbine is designed in such a way that during operation, in particular in cruising flight or cruise mode, a proportion of 15-30 mass% is achieved by means of the steam system. in particular 19-25 mass%, water is set in the working gas and the gas turbine has a bypass ratio of >30. Due to the high specific work in the core engine, steam injection makes it possible to achieve higher bypass flow ratios and thus better efficiencies than would be possible with conventional turbo aircraft engines.

According to a preferred development, the gas turbine can have a total pressure ratio (OPR) <32, in particular <30, preferably during operation, in particular in cruise flight or cruise mode. While the trend in conventional turbo aircraft engines is towards total pressure ratios >50, with the design according to the invention, a comparatively low compression is sufficient, which means that the axial length in the compressor and weight can be saved.

According to a preferred embodiment of the invention, the fan can be designed to achieve a compression ratio of 1.1 to 1.3, preferably 1.15 to 1.25, radially on the inside, i.e. on the main flow channel. With such an embodiment, the high-pressure compressor can advantageously achieve a compression ratio of 23 to 32, in particular 25 to 30, particularly preferably 26 to 28, during operation, in particular in cruise or cruise mode. Such a design makes it possible to design the gas turbine without an intermediate pressure compressor or booster module between the fan and high-pressure compressor, which saves additional space and weight.

According to a preferred embodiment, the steam content behind the combustion chamber can make up between 15% and 35% of the mass flow. These areas have proven to be particularly suitable for increasing the efficiency of the system.

According to one embodiment, the fan can have a fan diameter between 1.90m and 2.30m. The diameter can preferably be between 2.10 and 2.25m. The design with steam injection enables very high bypass flow ratios, even with comparatively small fan diameters, which are suitable for medium-sized aircraft.

According to a further embodiment of the invention (under cruise operating conditions with steam injection), a working gas flowing through the main flow channel of the gas turbine can have a temperature in the range of 1600 ° K to 1900 ° K at the outlet of the combustion chamber, preferably from 1650 °K to 1750 °K. With a design in these areas, the formation of nitrogen oxides during combustion can be significantly reduced.

Advantageously, the drive system can be designed for a thrust in the range of 19 to 23 kN.

Exhaust water injection

According to the invention, a drive system is further proposed, with an exhaust gas duct running through the water system and the steam system, through which an exhaust gas from the main flow duct or core flow duct of the gas turbine can flow, the steam system being a first cooling device, preferably designed as a steam generator, and the water system being preferably a first cooling device Condenser-shaped second cooling device for cooling an exhaust gas flow flowing through the exhaust gas duct, the condenser being arranged downstream of the steam generator in relation to a direction of the exhaust gas flow. Water system and steam system are part of the exhaust gas treatment system. A feed device is arranged between the steam generator and the condenser and is designed to introduce water into the exhaust gas flow to cool the exhaust gas flow. The exhaust gas flow can therefore be cooled in several sections or steps, in particular using different cooling processes or procedures, in order to improve the separation of water from the exhaust gas flow.

The steam system and the water system are part of an exhaust gas treatment system of the gas turbine and can be arranged downstream of the core flow channel of the drive system in the flow direction. Thus, an exhaust gas from the drive system, in particular from the turbine, can flow through the exhaust gas duct of the exhaust gas treatment system and be pre-cooled to a temperature below an original exhaust gas temperature by means of the steam generator serving as the first cooling device. The first cooling device is located upstream of the condenser serving as the second cooling device. It goes without saying that a reverse order of the first and second cooling devices is also possible. During operation, the exhaust gas can be pre-cooled with the steam generator, which can, for example, enable efficient operation of the downstream condenser. In particular, the exhaust gas flow is supplied with energy by means of the steam generator, in particular for generation of water vapor, which reduces the temperature of the exhaust gas flow.

Typically, this temperature is in a range in which water present in the exhaust gas flow is, in particular, exclusively in gaseous form.

In the condenser, the exhaust gas flow is further cooled, for example with air from a side stream of the drive system, in particular until the exhaust gas flow reaches a dew point temperature and water can be separated in a liquid state. The dew point temperature is the condensation point of the water in the exhaust gas flow or the temperature that must be fallen below at a predetermined pressure and a predetermined air or exhaust gas flow humidity so that water vapor can separate as liquid water. The liquid water portion can be separated from the exhaust gas flow in a water separation device and, for example, returned to an exhaust gas treatment process of the exhaust gas treatment system and/or fed to an operating process of the aircraft engine.

In order to further cool the exhaust gas flow before it reaches the second cooling device, which is preferably designed as a condenser, in particular liquid water or water in a liquid state is introduced into the exhaust gas flow by means of the feed device. For this purpose, the feed device is designed in particular to deliver the water into the exhaust gas flow or the exhaust gas duct, in particular to inject or inject it. This additional cooling makes it possible to condense the water portion of the exhaust gas flow before further cooling using the second cooling device, which is preferably designed as a condenser. In particular, the condensation can be improved by providing condensation nuclei in the exhaust gas flow using the water supplied in order to promote a condensation process in the exhaust gas flow. Overall, for example, a higher thermal efficiency can be achieved by using the exhaust gas energy and the formation of contrails can be minimized.

The aspect of the invention is based, among other things, on the consideration that the water present in the exhaust gas flow or the water vapor present in the exhaust gas flow must be cooled below the dew point or the dew point temperature in order to come into a liquid state. At the dew point, relative humidity increases to 100% and saturation is achieved. With further cooling below the dew point the saturation vapor pressure decreases faster than the water partial pressure, which leads to supersaturation and water droplets are formed on condensation nuclei. The lower the exhaust gas temperature, the less water that can be present in vapor form in the exhaust gas.

The aspect of the invention is now based on the idea of introducing water, in particular liquid water, into a region of the exhaust gas flow in which water present therein is in gaseous form in order to cool the exhaust gas flow in order to support condensation of the water vapor present therein and thus water recovery to improve the exhaust gas flow. At the same time, liquid components can be provided in the exhaust gas flow in order to improve a condensation process in the exhaust gas flow. The supplied liquid components or water droplets can act as condensation nuclei to which further liquid water resulting from the water vapor in the exhaust gas flow attaches or can attach. This means that larger drops can be formed at the end of the condensation process, which can be more easily separated from the exhaust gas flow in a water separation device, for example.

In one embodiment, the water to be introduced to cool the exhaust gas flow and into it has a lower temperature than the exhaust gas flow at the point of introduction. Here, water in a liquid state can be supplied to the exhaust gas flow in order to achieve cooling of the exhaust gas flow. Since water in its liquid state has a lower temperature under the same pressure than in its gaseous state, the exhaust gas flow can be cooled by supplying liquid water. Depending on the temperature difference between the exhaust gas flow temperature and the temperature of the water to be supplied or supplied, a degree of cooling of the exhaust gas flow can be specified. As a result, a temperature of the exhaust gas flow can be reduced as required, for example to make adjustments to changed environmental conditions.

In one embodiment, the feed device is set up to introduce the water into the exhaust gas flow in atomized form. Here, the supply device can be set up to inject, inject and/or atomize the water into the exhaust gas flow and for this purpose in particular have an injection, nozzle and/or atomization device, with a degree of atomization or a droplet size of the water to be supplied being adjustable by means of the supply device can. This can result in a high degree of atomization of the water or a small droplet size of the water promotes the cooling of the exhaust gas flow, since a large number of water droplets and thus their surface area available for heat exchange can be increased. In addition, supplying the smallest possible drops of water with the same supply quantity can increase the number of potential condensation nuclei for the accumulation of further water from the exhaust gas flow. Furthermore, the atomized water can be distributed evenly in the exhaust gas flow in order to enable a cooling effect over the entire cross section of the exhaust gas flow.

In one embodiment, the feed device is set up to introduce the water essentially homogeneously into the exhaust gas flow. Homogeneous means in particular a uniform distribution of the water over a cross section, in particular a cross section at the point of introduction or a cross section of the exhaust gas flow spaced downstream from this point. This includes process-related deviations from a completely homogeneous mixing of exhaust gas flow and supplied water. Here, the feed device can be set up to introduce the water, in particular uniformly all around, under a predetermined pressure and/or over a predetermined distance into the exhaust gas flow in order to enable mixing of water and exhaust gas flow and thereby improve a temperature transition.

In one embodiment, the water is provided to the feed device by means of a water separation device of the exhaust gas treatment system. The water separation device can be arranged downstream of the second cooling device, which is preferably designed as a condenser, or can form part of the second cooling device, which is preferably designed as a capacitor. This means that the water to be supplied or supplied can be kept in a circuit or the cooling process, whereby an additional water supply for the exhaust gas treatment system in particular can be eliminated or at least made smaller. The water separation device is in particular designed to be able to separate the additional amount of water that is intended for cooling the exhaust gas flow. Alternatively or additionally, it can also be provided that the water is provided from a water reservoir.

In one embodiment, the feed device is set up to introduce water into the exhaust gas flow in such a way that the exhaust gas flow reaches a dew point temperature Exhaust gas flow is cooled before it reaches the second cooling device. As a result, a condensation process of the water portion of the exhaust gas flow can begin before the second cooling device is reached. After the condensation of the water in the exhaust gas flow begins, heat transfer, for example to channel walls of the second cooling device, can take place more effectively than is possible in a purely gaseous state. Due to the resulting liquid content in the exhaust gas flow, heat transfer in the exhaust gas flow can be improved, in particular in relation to a heat exchange surface of the second cooling device, whereby the second cooling device can in particular be designed to be more compact and have a reduced weight.

In one embodiment, the first cooling device has a steam generator which is assigned to the exhaust gas duct and/or the second cooling device has a heat exchanger which is set up for cooling with air and is preferably designed as a condenser. Here, the steam generator can extract energy from the exhaust gas stream to produce water vapor, which can reduce the temperature of the exhaust gas stream. Typically, the exhaust gas flow temperature achieved in this way is above the dew point temperature. The heat exchanger of the second cooling device can be designed as a capacitor (condenser heat exchanger) and use air as a cooling fluid, which is conveyed, for example, by means of a fan or a fan of the drive system. This heat exchanger can essentially have two areas, with the essentially gaseous exhaust gas flow being cooled down to its dew point temperature in a first area arranged upstream. In a second region downstream of the first region, the exhaust gas flow is further cooled, so that liquid water components are present in the exhaust gas flow, which can be separated from the exhaust gas flow. Since, for example, the temperature of the air used for cooling can depend on a flight altitude and/or weather conditions, the additional cooling made possible by the supply device can support operational water recovery.

According to a further aspect, a method for operating a drive system described herein having an exhaust gas treatment device is proposed, wherein the exhaust gas duct is flowed through with exhaust gas, the exhaust gas flow is pre-cooled by means of the first cooling device, the pre-cooled exhaust gas flow by means of the feed device by supplying water, in particular liquid water, into the Exhaust gas flow is further cooled, and the pre-cooled exhaust gas flow is condensed by means of the second cooling device.

Here, the exhaust gas treatment device can have a control device that is set up to control the first and second cooling devices and the feed device. In particular, a cooling capacity of the first cooling device, the second cooling device and/or the supply device can be changed by means of the control device. The control device can specify a respective operating state or a respective cooling capacity, for example depending on an ambient temperature, an exhaust gas flow temperature and/or taking into account further operating parameters, for example of the drive system or an aircraft engine.

In one embodiment of the method, the water condensed by the second cooling device is collected. The condensed water can be collected, for example, by means of a water separation device arranged in particular in, on or downstream of the second cooling device and in particular at least partially provided to the feed device.

In one embodiment of the method, a volume flow and/or a mass flow of the water to be introduced can be specified depending on at least one property of the exhaust gas flow. A corresponding property of the exhaust gas flow can be, for example, a current temperature, a speed, a pressure, a composition and/or a specific gravity. In addition, at least one operating parameter of the aircraft engine or an environment can also be taken into account when determining the volume flow to be supplied. This allows, for example, cooling of the exhaust gas flow and in particular water recovery from the exhaust gas flow to be carried out efficiently under varying conditions.

In one embodiment of the method, a degree of atomization of the water to be introduced can be varied or adjusted depending on at least one property of the exhaust gas flow. In this way, for example, a temperature of the exhaust gas flow can be kept constant before entering the second cooling device in order to enable smooth operation of the exhaust gas flow and thus continuous water recovery from the exhaust gas flow under varying conditions. The invention also relates to an aircraft with a propulsion system according to the invention described above.

Operation of the gas turbine

To solve the problem, a method for operating a gas turbine for an aircraft engine with a compressor, combustion chamber, turbine and a heat exchanger downstream of the turbine, in particular designed as a steam generator, through which a gas flow flows in one flow direction is also proposed, the heat exchanger being made of water by means of a Energy of the gas flow generates a steam, which is fed to the gas flow for burning with fuel in the combustion chamber or the combustion chamber. The heat exchanger may be part of the exhaust gas treatment system, wherein the exhaust gas treatment system may consist of a steam system and/or a water system. The gas flow has a temperature between 700 and 980 K and preferably between 800 and 980 K when exiting the turbine, in particular when exiting a low-pressure turbine, in order to provide the energy to generate the steam.

This increases the gas flow temperature at a turbine outlet, particularly compared to known gas turbines, whereby a larger temperature difference between the gas flow and the water to be evaporated in the heat exchanger can be achieved. This heat exchanger can therefore be dimensioned smaller and lighter, whereby a weight reduction of the heat exchanger and thus of the gas turbine can be achieved. Overall, this can improve the efficiency of the gas turbine. A temperature of the gas flow when exiting a low-pressure turbine in the range of 980 K represents a particularly hottest temperature during a hot-day takeoff.

According to a further aspect, a gas turbine for an aircraft engine is proposed with a compressor, combustion chamber, turbine through which a gas flow flows in a flow direction and a heat exchanger downstream of the turbine, the heat exchanger being set up to generate steam from water using energy from the gas flow, which can be supplied with fuel to the gas flow for burning in the combustion chamber. The gas turbine is set up to carry out a method according to one or more of the aspects described herein. Such a gas turbine for an aircraft engine has a compressor, a combustion chamber and a turbine. During operation of the gas turbine, air is compressed in the compressor, mixed with a fuel before or in the combustion chamber and ignited to drive the turbine. Accordingly, the gas turbine can have a fuel preparation system for preparing the fuel before it is burned in the combustion chamber, which in particular uses the steam generated in the heat exchanger. The proposed gas turbine also has another heat exchanger arranged downstream of the turbine. In the other heat exchanger, steam is generated from water, which is extracted in particular from the gas flow or the exhaust gas of the gas turbine and fed to the heat exchanger, using the energy of the gas flow. In the context of the present disclosure, the gas flow after exiting the turbine is also referred to in particular as exhaust gas or exhaust gas flow.

An aircraft drive can have such an axial gas turbine, which in particular has an exhaust gas treatment system, which is preferably arranged downstream of the turbine of the turbomachine. The exhaust gas treatment system can have a heat exchanger, a cooling device and a water separation device, which are arranged on an exhaust gas duct of the exhaust gas treatment system in the flow direction of the gas flow. The gas flow after the turbine or an exhaust gas from the aircraft engine or the turbine can flow through the exhaust duct of the exhaust gas treatment system and be cooled by means of the heat exchanger to a temperature below the temperature when exiting the turbine or an original exhaust gas temperature. Here, energy is removed from the gas flow of the heat exchanger to generate water vapor, which reduces the temperature of the gas flow.

The cooling device downstream of the heat exchanger in the flow direction can be designed as a condenser (condenser heat exchanger) or have one and use ambient air as a cooling fluid, which is conveyed, for example, by means of a blower or a fan of the aircraft engine. Such a condenser heat exchanger can essentially have two areas, with cooling of the essentially gaseous exhaust gas flow taking place in a first area arranged upstream. In a second area downstream of the first area, the exhaust gas flow continues cooled so that liquid water components are present in the exhaust gas flow, which can be separated from the exhaust gas flow. The liquid water portion can be separated from the gas flow in the water separation device, provided to the heat exchanger for steam generation and thus returned to an operating process of the gas turbine. Overall, for example, a higher thermal efficiency can be achieved by using the exhaust gas energy and the formation of contrails caused by the exhaust gas flow can be reduced.

In the proposed method, at least part of the steam generated in the heat exchanger can be directed, in particular via a steam line or steam supply, into a mixing chamber of a fuel preparation system - depending on the design of the fuel preparation. Fuel can be introduced into such a mixing chamber and thus fed to the steam also introduced into it, whereby the fuel can evaporate. A mixture can thus be formed from the steam and the fuel, which can ultimately be fed to the combustion chamber of the gas turbine for combustion. In other embodiments of fuel preparation, the steam can also be supplied to the gas flow before and/or in the combustion chamber.

The invention is based, among other things, on the idea of increasing a temperature difference between the gas flow used in the heat exchanger and provided by the turbine and the water to be evaporated in order to improve steam generation or superheating of steam by means of the heat exchanger and in particular to make it more efficient.

This can be achieved, for example, by a reduced expansion of the gas flow or the working fluid in the turbine and thus a reduced work extraction or energy absorption and thus an energy content or a temperature of the gas flow or the exhaust gas when exiting the turbine or is increased at a downstream turbine outlet. As a result, the energy that can be provided in the heat exchanger or evaporator can be increased, which can result in a weight saving on the heat exchanger, especially in comparison to known gas turbines. In one embodiment of the method, the gas flow has a temperature between 1600 and 1750 K, in particular 1650 K to 1750 K, when exiting the combustion chamber. Because water is supplied to the combustion chamber in addition to fuel and air, the combustion chamber outlet temperature is lower than known gas turbines due to the additional energy required to evaporate the water. Accordingly, a gas turbine that is set up to carry out the method proposed here can be designed with a particularly significantly lower expansion ratio than a classic gas turbine.

In one embodiment, the gas flow has a temperature between 400 and 480 K when it exits the heat exchanger. The difference between the outlet temperature at the turbine and the outlet temperature at the heat exchanger can be used as energy to generate steam by means of the heat exchanger, thereby promoting the generation of steam, in particular superheated steam. This means that superheated steam can be generated from the exhaust gas energy in the heat exchanger, which has a high energy density.

In one embodiment, the heat exchanger heats the steam to a temperature between 600 and 900 K, in particular to 700 K to 740 K. At this temperature, superheated steam has a high energy density, so that undesirable condensation of the evaporated water, for example in the area of the fuel processing system to burn the fuel contained in the mixture in the combustion chamber can be avoided.

In one embodiment of the method, the overall pressure ratio (OPR) of the gas turbine is 20 to 40, in particular from 22 to 35. The overall pressure ratio of the gas turbine or the overall compression ratio between the fan and the combustion chamber is in particular the ratio of a dynamic pressure of the working fluid at a downstream outlet side of the compressor of the engine or an upstream inlet side of the combustion chamber to a dynamic pressure of the working fluid at an upstream inlet side of the fan or a ratio of a total pressure of the working fluid at an inlet to the combustion chamber to a total pressure of the working fluid at an inlet of the fan. The total pressure is in particular the pressure that arises in a flowing medium or the working fluid at a measuring point at which the Flow velocity is reduced isentropically or loss-free until it almost comes to a standstill.

A total pressure ratio of the gas turbine of 20 to 40 and in particular of 22 to 35 makes it possible within the framework of the proposed method to achieve an optimal compromise between a high turbine outlet temperature and thus a high heat potential for the evaporator, a small number of stages, in particular of the low-pressure compressor, the simplest possible materials, and high cycle efficiency .

In one embodiment, water and/or steam is provided to the heat exchanger by a water separation device downstream of the heat exchanger. The water separation device can be arranged downstream of the cooling device or form part of it. The separated water can be provided to the steam generator or the heat exchanger, for example by means of a feed device, whereby the water can optionally be fed via a water treatment system into a water reservoir, where it is stored in particular for further use. In this way, the water to be supplied or supplied to the heat exchanger can be kept in a circuit, which means that an additional water supply for the combustion process can be eliminated.

In one embodiment, the turbine of the gas turbine is set up to provide the gas flow at a temperature between 700 and 980 K at the turbine outlet. The turbine outlet is the downstream exit side at which the gas flow leaves the turbine or the low-pressure turbine of the turbine. In particular, the turbine is designed in such a way that it has a significantly reduced expansion ratio, in particular by more than 20%, compared to turbines of classic turbo aircraft engines.

In one embodiment, the gas turbine has an exhaust gas treatment system downstream of the turbine in the flow direction, which comprises the heat exchanger, a cooling device and a water separation device. The exhaust gas treatment system can have an exhaust gas duct through which the exhaust gas of the aircraft engine can flow and on which the heat exchanger, the cooling device and the water separation device are arranged in order to be flowed through by the gas flow. This allows water to be separated from the gas flow or Exhaust gas flow and thus a provision of water to be evaporated for the heat exchanger are made possible.

Further features, advantages and possible applications of the invention result from the following description in connection with the figures. In general, features of the various exemplary aspects and/or embodiments described herein may be combined with one another unless clearly excluded in the context of the disclosure.

In the following portion of the description, reference is made to the figures shown to illustrate specific aspects and embodiments of the present invention. It is to be understood that other aspects may be used and structural or logical changes to the illustrated embodiments are possible without departing from the scope of the present invention. The following description of the figures is therefore not to be understood as limiting. It shows

Fig. 1 shows an embodiment of a first drive system according to the invention with a gas turbine in a meridian section

Fig. 2 shows the exemplary embodiment of the drive system according to the invention in a circumferential view

Fig. 3 is a schematic representation of a second exemplary drive system according to the invention

Fig. 4 is a schematic representation of a flow chart of a method according to the invention for operating a turbomachine for the drive system according to Fig. 3

5 shows a schematic representation of a third exemplary drive system according to the invention; and

6 shows a schematic representation of a flowchart of an exemplary method according to the invention for operating an exhaust gas treatment system.

Fig. 7 shows an exemplary embodiment of a heat exchanger arrangement according to the principle of the prior art

8a shows a first exemplary embodiment of a heat exchanger arrangement for a drive system according to the invention in a sectional view of a circumferential plane of the gas turbine Fig. 8b shows the first exemplary embodiment of the heat exchanger arrangement in a meridian section of the gas turbine

Fig. 9 shows an exemplary embodiment of a heat exchanger according to the invention in a detailed view A from Fig. 8a

10 shows a second exemplary embodiment of a heat exchanger arrangement according to the invention in a sectional view of a circumferential plane of a turbomachine

11 shows a third exemplary embodiment of a heat exchanger arrangement according to the invention in a sectional view of a circumferential plane of a turbomachine

Fig. 12 is a schematic representation of an embodiment of a gas turbine according to the invention

An exemplary embodiment of a drive system according to the invention is described below with reference to FIGS. 1 and 2. In Fig. 1, the drive system 1 is shown in a meridian section, that is, in a plane spanned by the radial direction R of the gas turbine and the axial direction Ax of the gas turbine. In Fig. 2, the drive system is shown along the laterally shown sections AA and BB using a rolled-up representation of circumferential planes, that is, it is shown in a plane spanned by the axial direction Ax and circumferential direction U.

The drive system 1 includes a gas turbine 2 and is connected to a wing 4 of an aircraft via a pylon 3. The gas turbine 2 has an inlet 7, which is arranged at the front in an outer housing 5, the so-called cowling, in the axial direction Ax of the gas turbine 2. The gas turbine has an inner housing 6, which can also be referred to as a core housing. A fan 8 is arranged behind the inlet 7 and is driven by a drive shaft 9 of the gas turbine 2 mounted in the inner housing 6, sucks in air and promotes the total air flow into a main flow duct 10 and a secondary flow duct 20 of the gas turbine 2. The fan 8 is coupled to the drive shaft 9 with a gear 11 also arranged in the inner housing 6. The outer housing 5 surrounds the bypass channel 20 on the outside and delimits it at least in sections, while the inner housing 6 forms an inner channel wall for the bypass channel 20 and thus delimits it on the inside. In the exemplary embodiment shown, the fan 8 is designed with a diameter of 2.2m. The specific work in the steam turbine, which is increased by approx. 19-21% by mass through steam injection, makes it possible to achieve a high bypass flow ratio of approx. 34 even with a relatively small fan diameter, which enables very good efficiencies with engine diameters that are also suitable for medium-sized aircraft , for example in the narrowbody area.

In the present exemplary embodiment, the exhaust gas from the main flow channel 10 is not ejected directly, but is after-treated in a water system 30 and a steam system 40. The water system 30 and the steam system 40 are arranged in the gas turbine 2. Components of the water system 30 are arranged in the bypass channel 20 and partly in the inner housing 6 and the outer housing 5 of the gas turbine 2. The water system 30 recovers water from the exhaust gas of the main stream and feeds the steam system 40 with water. The steam system 40 evaporates the water and supplies hot steam to the main stream in order to increase its mass flow and thus the specific power of the gas turbine. The flows of exhaust gas, water and steam are shown purely schematically in Fig. 1.

The main flow channel 10 has a compressor 12 in the direction of flow, a mixing chamber 48 downstream of the compressor 12 for mixing the compressed air and a hot steam, an adjoining combustion chamber 13 which supplies fuel to the air-steam mixture and burns it to form an exhaust gas High-pressure turbine 14 and a low-pressure turbine 15, which expand the exhaust gas and provide mechanical power for the drive, and finally pass it on into a turbine outlet housing 16. It can be provided that the high-pressure turbine 14 drives a high-pressure compressor via a second shaft of the gas turbine 2.

The bypass flow channel 20 has a capacitor 21 designed as a plate heat exchanger downstream, which comprises a plurality of inlet panels 22, capacitor modules 23 connected to the inlet panels 22, and outlet panels 27 which terminate the capacitor modules 23 downstream. The capacitor modules 23 are arranged in the so-called C channels of the gas turbine and inclined outwards in the direction of flow. The capacitor modules 23 extend in the radial direction R from the Inner housing 6 to the outer housing 5. It is possible that the capacitor 21 only extends in a partial area between the outer housing 5 and the inner housing 6 or only forms a cross flow to the bypass flow channel in a partial area. A large part of the air volume conveyed by the fan 8 is supplied as a bypass air flow to the bypass flow channel 20 and partially flows through the condenser 21 there before the air bypass flow leaves the gas turbine 2 to generate thrust. The air side stream is partially heated in the condenser 21, which works as a heat exchanger, and cools the exhaust gas flowing through the condenser 21.

A steam generator 41 of the steam system 40 is arranged downstream of the turbine outlet housing 16, through which the hot exhaust gas from the low-pressure turbine 15 flows outwards in the radial direction R. The exhaust gas then flows further in the radial direction to the condenser 21 of the water system 30 and through this through exhaust gas channels 26, which also run in the radial direction. The exhaust gas is further cooled in the condenser 21. During the cooling of the exhaust gas, water from the exhaust gas at least partially condenses, with the exhaust gas-water mixture continuing to flow radially outward into a water separation device 31. There it is first guided forward in the axial direction Ax of the gas turbine 2 in an inlet channel 32, deflected by approximately 180 ° in a manifold 33 and fed to a swirl generator 34 in an outlet channel 35, which centrifuges the exhaust gas. As a result, the water in the exhaust gas-water mixture is eliminated and can be passed into the further water system 30 in liquid form. The dehumidified and cooled exhaust gas is released and expanded via a core outlet nozzle 36 and also serves to generate thrust. The components of the water system 30 are shown in FIG. 2. Only arrows are shown in FIG. 1, which are intended to schematically illustrate the direction of the exhaust gas.

The water collected in the water separation device 31 is conveyed to a water reservoir 38 via water pipes 37. From there, the water, now referred to as feed water, is supplied to the steam generator 41 of the steam system 40 by means of a feed device preferably designed as a water pump 39. The water pump 39 is preferably controllable and can supply feed water to the steam generator according to the required steam output. In the present exemplary embodiment, the water reservoir 38 and the water pump 39 are located in the inner housing 6 of the gas turbine. In particular, the water pump 39 can also be in one Core flow 10 encasing inner housing 6, in particular in an inner housing closure 6 'which closes the inner housing 6 and is arranged in the axial direction Ax behind the turbine outlet housing 16. The inner housing closure 6' also creates a flow deflection chamber for the hot exhaust gas emerging from the turbine 14, 15. A central exit of the exhaust gas stream G from the main flow channel into an environment is no longer advantageous, but the highly heated exhaust gas can be post-treated. The arrangement of the water pump in the inner housing closure 6 'has the advantage that a weight distribution of the water pump is very balanced by an extension of the axis of rotation or the drive shaft 9 of the gas turbine 2. At the same time, the center of gravity of the gas turbine is shifted further back under the wing, which has a positive effect on the load distribution of a wing and the flight characteristics.

The steam generator 41 is preferably designed as a so-called tube bundle heat exchanger in a cross-countercurrent arrangement to the exhaust gas with several passages. It is preferably accommodated rotationally symmetrically and concentrically to the engine axis within the inner housing of the gas turbine, that is, the core engine cowling. The steam generator 41 includes a preheater 42 for heating the feed water, an evaporator 43 for converting the feed water into steam, and a superheater 44 for superheating the steam. The arrangement within the steam generator is only shown schematically in FIG. Other configurations with more or fewer elements of the steam generator 41 are also possible. The preheater 42, the evaporator 43 and the superheater 44 can be designed as pipes that cross one another in a spiral shape. The particularly superheated steam is fed through a steam line 45 to a steam turbine 46 and drives it. The steam expanded in the steam turbine 46 is then passed into the mixing chamber 48 for use in the combustion chamber 13. It can be provided that part of the steam is passed directly into the combustion chamber or is diverted for cooling purposes. The steam turbine 46 is coupled to the drive shaft 9 of the gas turbine through a steam turbine gearbox 47. In use, the transmission ratio of the steam turbine transmission 47 is in the range 1:5 to 1:10, since the steam turbine 46 achieves significantly higher speeds than the low-pressure turbine 15 and thus the drive shaft 9. The mechanical power thus obtained in the steam turbine 46 is supplied to the drive shaft 9 and the exhaust gas heat is made available again to the cycle of the gas turbine 2. The arrangement of the capacitor 21 is described below with reference to FIG. 2. In Fig. 2, sectional planes along the lines AA and BB are drawn into the gas turbine shown in the meridian section on the left side, the associated schematically illustrated circumferential planes of which are shown unrolled.

In section AA, a capacitor 21 is shown to the side of the pylon 3, which is arranged in the C channel and consists of several capacitor modules 23, 23 '. The capacitor modules 23, 23' are arranged in pairs as capacitor module pairs 25 and these capacitor module pairs 25 are connected to one another in an upstream area of the bypass channel 20 by an inlet cover 22. Each of the capacitor modules 23, 23 'is delimited in the direction of flow by an outlet cover 27, 27'. The capacitor module pairs 25 therefore consist of a first capacitor module 23 and a second capacitor module 23 '. The two capacitor modules 23, 23 'have an angle of attack a, a' relative to the bypass flow direction in the bypass flow channel, in particular an axial direction Ax of the gas turbine. The first capacitor module 23 has a first angle of attack a, which corresponds in magnitude, that is to say an absolute value, to a second angle of attack a 'of the second capacitor module 23 ', but has a different sign. This results in a V arrangement for the capacitor module pairs 25. An internal distance i in the circumferential direction U is provided between the first capacitor module 23 and the second capacitor module 23 'of a capacitor module pair 25, which in the present exemplary embodiment extends everywhere along the axial extent of the capacitor The external distance a in the circumferential direction U between two pairs of capacitor modules 25 is smaller.

The air conveyed by the fan 8 is divided by the inlet cover(s) 22 and then flows along the outer side surfaces 24a of the capacitor modules 23, 23 'facing the air bypass flow direction. Part of this air flows through cooling channels 24c between the plates of the capacitor modules 23, 23' onto the side surfaces 24b of the capacitor modules 23, 23' facing away from the air bypass flow direction.

The part of the air bypass flow that does not flow through the capacitor modules 23, but essentially flows straight past the capacitor modules 23, leaves the gas turbine 2 to generate thrust between two adjacent outlet covers 27, 27 'of two adjacent capacitor module pairs 25. These adjacent outlet covers 27 of two adjacent capacitor module pairs 25 form a cold bypass nozzle 28.

The air that flows through the capacitor modules 23 is guided into an interior of the capacitor module pairs 25, heated and blown out between two outlet covers 27, 27 'of a capacitor module pair 25. In this way, the two adjacent outlet covers 27, 27' of a pair of capacitor modules 25 form a hot bypass nozzle 29.

This arrangement also has the advantage that foreign bodies that may be present in the bypass flow at high speed are guided along the condenser side surfaces into the cold bypass nozzle 28. This means that possible damage and contamination can be avoided or at least reduced.

As the air flows through the capacitor modules, exhaust heat is transferred to the air, causing its temperature to rise. The exhaust gas cools until the water it contains is at least partially condensed and is in liquid form. As described above, the exhaust gas is passed through exhaust channels 26 inside the condenser 21. The exhaust channels 26 are located in each of the capacitor modules 23, 23 '. The exhaust gas is guided radially outwards through the exhaust channels 26 into the inlet channels 32 of the water separation devices 31, which are arranged in the outer housing 5, which is also referred to as a cowling or nacelle. The water separation devices 31 are connecting channels between the capacitor modules 23, 23 ' and the core outlet nozzles 36. In the embodiment shown, the exhaust gas streams are combined from the two capacitor modules 23, 23 ' of a capacitor module pair 24. After exiting the capacitor modules 23, 23 ', the exhaust gas first flows forward in an inlet channel 32 of the water separation device 31 in the direction of the engine inlet and then, after a 180 ° turn in a manifold 33 in the outlet channel 35 in the direction of the core engine nozzle 36. In one

Water separation device 31 can be accommodated in addition to the above-mentioned swirl generator 34, other elements that serve to separate water. Fig. 3 shows a turbomachine 2 according to the invention designed as a gas turbine for an aircraft, which is set up to carry out a method described herein, in a schematic representation.

The turbomachine designed as a gas turbine 2 is designed, for example, as a turbofan engine and has a compressor 12, a combustion chamber 13 and a turbine 14, 15 with a low-pressure turbine 15, through which a gas flow G can flow in a flow direction or during operation of the gas turbine 2 be flowed through by the gas flow G. The gas flow G has a temperature Ti between 700 and 980 K when exiting the turbine 14, 15 or when exiting the low-pressure turbine 15 in order to provide energy for generating the steam by means of a steam generator 41.

Downstream of the turbine 14, 15 in the flow direction, the gas turbine 2 has the steam generator 41, which is set up to generate steam from water using energy from the gas flow G. This steam can be supplied via a steam line 45, in particular with a fuel, into the gas flow for combustion in the combustion chamber 13. The steam supply, in particular in the form of a steam line 45, can have a mixing chamber 48 of a fuel processing device, into which fuel can be introduced and thus supplied to the steam flowing through it, whereby the fuel can evaporate. The steam and fuel can thus be supplied to the combustion chamber 13 of the gas turbine 2 in the form of a mixture. In other embodiments, the steam and/or the fuel can also be supplied directly to the gas flow G before and/or in the combustion chamber 13. After combustion in the combustion chamber 13 or upon exiting the combustion chamber 13, the gas flow G in particular has a temperature T4 between 1650 and 1750 K, in particular approximately 1700 K.

Based on a flow direction of the gas flow G illustrated by the arrow, the gas flow G first passes through the compressor 12, the combustion chamber 13 and the turbine 14, 15 with the low-pressure turbine 15. After the turbine 14, 15, the gas flow G can also be used as an exhaust gas flow from the gas turbine 2 be referred to. This (exhaust) gas flow G flows from the turbine 14, 15 into an exhaust gas duct 17, on which the steam generator 41, a condenser 21 and a water separation device 31 are arranged downstream. The Steam generator 41 can have a preheater 42, an evaporator 43 and a superheater 44 according to the exemplary embodiment in FIG and to heat it to 740 K, in particular to about 720 K.

Here, energy is removed from the gas flow G to evaporate the water and this has a temperature T2 between 400 and 480 K when it emerges from the steam generator or downstream of the steam generator 41. The condenser 21 is arranged downstream of the steam generator 41 in relation to the flow direction of the gas flow G and can be provided for cooling with ambient air in order to enable the separation of water vapor and/or water present in the gas flow G.

In the present exemplary embodiment, a water separation device 31 is arranged downstream of the condenser 21, which can be designed as a droplet separator. For example, the gas flow G in the water separation device 31 can be set in rotation, as a result of which water drops can be guided radially outwards by centrifugal force and the water can be collected. The remaining gas flow G can leave the exhaust duct 17 via an outlet 28, 29 designed as a cold bypass nozzle 28 or a hot bypass nozzle 29 and, in particular, can be released into the environment.

The separated water can, for example, be fed into a water reservoir 38 via an optional water treatment system 38 ', where it can be available for further use. By means of a supply device 39, the water can be provided to the steam generator 41 in order to generate water vapor, which can be supplied to the gas flow G in the area of the combustion chamber 13.

4 shows a schematic representation of an exemplary embodiment of a method 500 for operating the exemplary gas turbine 2 from FIG is flowed through by a gas flow G. Here, the gas flow G has a temperature Ti between 700 and 980 K when exiting the turbine 14, 15 or when exiting the low-pressure turbine 15 in order to provide energy for generating steam by means of the steam generator 41. In a further step b, the gas flow G is generated by the steam generator 41 from water provided there, in particular from the gas flow G or the exhaust gas flow after the steam generator 41, using the energy of the gas flow G steam, whereby the gas flow G cools down. Here, the gas flow G has a temperature T2 between 400 and 480 K when it exits the steam generator 41 or downstream of the steam generator 41.

In a further step c, the pre-cooled gas flow G is condensed using the condenser 21. The water condensed in the condenser 21 is collected in a further step d, in particular by means of the water separation device 31. In a further step e, the collected water is provided in particular by means of a feed device 39 to the steam generator 41 for generating steam, with steam being generated in step b by means of the steam generator 41 or evaporator 43. Here, the steam generator 41 heats the steam to a temperature T3 between 600 and 900 K, preferably between 650 K and 750 K, in particular to approximately 720 K.

In a further step f, at least part of the steam generated in the steam generator 41 can be passed via a steam supply or steam line 45, for example, into a mixing chamber 48 of a fuel processing system, where a steam/fuel mixture can be generated, which is finally in a step g Gas flow G, in particular in the combustion chamber 13 of the gas turbine 2, is supplied for combustion.

The gas flow G can have a temperature T4 between 1650 and 1750 K, in particular approximately 1700 K, when exiting the combustion chamber 13.

Fig. 5 shows an exhaust gas treatment system 18 according to the invention, which is arranged downstream of a main flow channel 10, which is only indicated schematically in this exemplary embodiment. The main flow channel 10 is arranged, for example, in a drive system 1 designed as a turbofan engine and has a compressor 12, a combustion chamber 13 and a turbine 14, 15. During operation, an exhaust gas flow G flows from the turbine 14, 15 into an exhaust gas duct 17 of the exhaust gas treatment system 18, which consists of a water system 30 and a steam system 40. Upstream of the main flow duct 10 is usually one not shown in this exemplary embodiment Fan 8 arranged, which feeds both the main flow channel 10 and a secondary flow channel 20.

Based on a flow direction of the exhaust gas flow G, the exhaust gas flow G first passes through a steam generator 41, which has a preheater 42, an evaporator 43 and a superheater 44. The steam generator 41 is a first cooling device for the exhaust gas flow G. Downstream of the steam generator 41, a feed device 39a is arranged on the exhaust gas duct 17, which is set up to introduce water W into the exhaust gas flow G in order to cool the exhaust gas flow G.

For this purpose, the feed device 39a has an injection device 39b and is set up to introduce the water W in an atomized and homogeneous manner into the exhaust gas flow G in order to achieve a uniform distribution of the supplied water W in the exhaust gas flow G and thus to promote heat transfer between the water W and the exhaust gas flow G . The water W at the point of introduction or in the area of the exhaust gas duct 17 on which the feed device 39a is arranged has a lower temperature than the exhaust gas flow G. The feed device supplies the water W to the exhaust gas flow G in such a way that the exhaust gas flow G is cooled towards a dew point temperature of the exhaust gas flow G before it reaches a heat exchanger designed as a condenser 21. The condenser 21 is a second cooling device for the exhaust gas flow G.

The condenser 21 is set up for cooling with ambient air and is arranged downstream of the feed device 39a in relation to the flow direction of the exhaust gas flow. Ambient air can flow through the condenser 21 in order to cool the exhaust gas flow in such a way that at least partial separation of the water W present in the exhaust gas flow G is made possible.

A water separation device 31, which can be designed as a droplet separator, is arranged downstream of the condenser 21. For example, the exhaust gas flow G can be set into rotation, as a result of which water drops are guided radially outwards under centrifugal force and the water W can be collected. The remaining exhaust gas flow G can leave the exhaust gas duct 17 via an outlet 28, 29, which is preferably designed as a cold bypass nozzle 28 and/or a hot bypass nozzle 29, and in particular to the environment. The separated water W can, for example, be fed into a water reservoir 38 via an optionally available water treatment system 38 ', where it can be available for further use and, for example, can be fed to the feed device 39a. In addition, the water W can be provided for the steam generator 41, and in particular the evaporator 43, in order to generate water vapor, which can be supplied to the gas turbine 2 in the area of the combustion chamber 13.

6 shows a schematic representation of an exemplary embodiment of a method 600 for operating the exemplary drive system 1 from FIG. 5, wherein in a step h the exhaust gas duct 17 is flowed through with exhaust gas from the main flow duct 10. In a second step i, the exhaust gas flow G is pre-cooled by means of the steam generator 41.

In a third step j, the pre-cooled exhaust gas flow G is further cooled by means of the feed device 39a by supplying, in particular, liquid water W into the exhaust gas flow G. Here, in particular by means of a control device of the exhaust gas treatment system 18, a volume flow and/or a degree of atomization of the water W to be introduced can be specified or varied depending on at least one property of the exhaust gas flow G. In a fourth step k, the pre-cooled exhaust gas flow G is condensed by means of the second cooling device 13. The water W condensed in the second cooling device 13 can be collected in an optional fifth step 1, in particular by means of the water separation device 31. As a result, a condensation process of the water W present in the exhaust gas flow G can be improved, since the exhaust gas flow G can be cooled before the condenser 21 and condensation nuclei in the form of water drops introduced by means of the feed device 39a can also be present in the exhaust gas flow G.

7 shows a heat exchanger arrangement 21' from the prior art in a sectional view, which shows a heat exchanger 21 with a low-temperature grid 20 and a high-temperature grid 30. The heat exchanger 21 is arranged in a flow channel 20, which is designed in particular as a bypass flow channel, between an inlet surface 20a and an outlet surface 20b of the flow channel 20. The heat exchanger has low-temperature channels in the low-temperature grid 200, which are formed essentially parallel to the main channel direction, which leads to a very large inflow area. The high-temperature channels run into the cutting plane. The large inflow surface, which is perpendicular to the direction of flow, also causes large air resistance, in particular pressure and shape resistance. The disadvantage is that such configurations are often too large to be effectively arranged in a real engine.

The descriptions of the exemplary embodiments according to the invention now follow. For the sake of simplicity, the same reference numbers are used in the description of the following exemplary embodiments according to the invention as in the description of the prior art, since they are the same component names.

8a shows a sectional view of a heat exchanger arrangement 21 'according to the invention with a flow channel 20 designed as a bypass channel 20 of a gas turbine 2 and a heat exchanger 21 designed in particular as a condenser 21 in the flow channel 20. The flow channel 20 is arranged in a gas turbine 2. A cooling fluid flows through the flow channel 20, the cooling fluid flowing into the flow channel 20 through an inlet surface 20a, flowing through the heat exchanger 21 and, after a further flow through the rear flow channel 20, exiting the flow channel 20 again at an outlet surface 20b. A main channel direction S is marked by an arrow. It may be that the direction of flow in a wake of the heat exchanger 21 differs from the area in front of the heat exchanger. In this case, to determine the respective main channel direction S in the leading or trailing channel direction S', the sections of the channels in front of and behind the heat exchanger must be considered, up to the corresponding inlet surface 20a or outlet surface 20b. Viewed spatially, the flow channel 20 has a circle, ellipse or rectangular shape curved around an engine axis or axial direction Ax in the circumferential direction U, with the flow channel being laterally delimited by channel sides. The arrangement of the flow channel 20 with the heat exchanger 21 can be repeated in the circumferential direction U, as shown for example in FIG. 2, in which case some common sides can then also be removed or omitted, so that a heat exchanger arrangement 21 'with several heat exchangers 21 results . For example Such a heat exchanger arrangement 21 'can extend around a core of an engine in the circumferential direction U.

The heat exchanger 21 is formed from an inlet panel 22, a grid matrix consisting of a low-temperature grid 200 and a high-temperature grid 300 and an outlet panel 27. The grid matrix is also referred to below as a heat exchanger module 23. The low and high temperature grids 200, 300, described in more detail in FIG. The low-temperature channels 201 largely run in the direction of the drawn extension axis E, while the high-temperature channels 301 run in a direction into the plane of the drawing.

8b shows a side view of the heat exchanger arrangement 1 from FIG. 8a, in which the direction V of the high-temperature channels 301 is shown schematically with larger arrows. The outlet cover 27 directs the flow of the cooling fluid in a wake downstream of the heat exchanger module 23.

The heat exchanger 21 generally has an inflow surface 24a, which is arranged inclined at an angle a.i to the main channel direction S. A more precise definition of the inflow area is described with reference to FIG. 9. Furthermore, the heat exchanger 21 has an outflow surface 24b which is inclined at an angle 012 to the further main channel direction S'. The inclination advantageously results in a large inflow area. Within the heat exchanger 21, the low-temperature channels 201 in turn have a main angle of inclination β to the inflow surface 24a, which is different from the angle a.i. This minimizes the entire redirection of the cooling air as it flows through the heat exchanger, so that pressure losses are reduced.

The fluid flowing through the flow channel 20 is neither decelerated nor accelerated in the area of the inlet fairing, since - as can be seen together from FIGS. 8a and 8b - the cross-sectional area normal to an axial direction Ax remains the same in this area. Although the flow channel 20 narrows in an axial direction Ax in FIG. 2a, since the inlet cover 22 already projects into the flow channel 20, however the flow channel 20 expands in a radial direction R, as can be seen from FIG. to create a jet flow.

In Fig. 8b, the first exemplary embodiment of the heat exchanger arrangement 21 'from Fig. 8a is shown in a side sectional view, in particular in a meridian section. The already mentioned flow direction E of the high-temperature grid 300 is shown. In a rear area of the heat exchanger, transverse ribs 207 are indicated in the low-temperature grid 200 and the high-temperature grid 300, which represent a measure to provide an enlarged surface for heat exchange.

In Fig. 9, the detailed view A shown in Fig. 8a is shown enlarged, whereby the actual courses of the grid matrix of the heat exchanger 21 can be seen. The heat exchanger 21 includes the low-temperature grid 200, which consists of a plurality of low-temperature channels 201, and the high-temperature grid 300, which consists of a plurality of high-temperature channels 301. The low-temperature channels 201 each have an inlet 202, which serves to introduce and first redirect the flow of the cooling fluid from the flow channel 20. In the present exemplary embodiment, the inlet 202 ends at a downstream narrow point, which serves as an inlet cross section 203 into a downstream diffuser region 204 of the low-temperature channel 201. The size of a cross-sectional area in the diffuser region 204 increases steadily along the longitudinal extent of the diffuser region 204 up to a maximum cross-sectional area 205 in the present exemplary embodiment. Adjacent to the diffuser region 204 downstream is a main region 206, the cross section of which is constant along its longitudinal extent. Thus, the maximum cross-sectional area is a constant cross-sectional area 205 in the main area 204. Downstream of the main area 206, a nozzle area 208 borders, the cross-sectional area of which reduces from the size of the constant cross-sectional area 205 to an outlet cross-sectional area 209, so that the flow of the cooling fluid is accelerated. The speed of the flow of the cooling fluid increases along the flow through the low-temperature channel 201 due to the heat flow from the high-temperature channel 301, through which a hot fluid flows which has a higher temperature than the cooling fluid. This further accelerates the flow in the low-temperature channel 201.

A low-temperature channel 201 and a first high-temperature channel 301 each have a first common wall 400. A high-temperature channel 301 is surrounded by a common wall, while a low-temperature channel 201 shares a common first wall 400 with a first adjacent high-temperature channel 301 and a further second common wall 400 with a second adjacent high-temperature channel 301.

The course of the first and second wall 400 in the sectional plane shown in FIG. 9 is initially described below with reference to the first wall 400: Starting at the inflow surface 24a, the wall 400 has an inlet section 402 facing away from the wind in the inlet area 202. At the inlet section 402 facing away from the wind, the common wall 400 in the diffuser region 204 has a convex diffuser section 402. Following the diffuser section 404, a first planar main section 406 is arranged in the main area 206. Its traveling distance is used to determine the main angle of inclination ß. The parallelism of the traveling extent in the main section 406 and the main extent E of the main region 206 of the low-temperature channel 201 is shown in FIG. 9 by parallel symbols. Adjoining the main section 406 of the common wall is a concave exit section 408 which extends to the outflow surface 24b. Opposite the first common wall section, a further common wall section is arranged in the low-temperature channel 201, which has the following course: Starting at the inflow surface 24a, the second common wall 400 has a wind-facing inlet section 403 in the inlet area 202, the wind-facing inlet section 403 being rounded and can extend to the point of the smallest cross-section. A concave diffuser section 405 in the diffuser section 204 adjoins the wind-facing inlet section 403. The curvature of the convex diffuser section 404 of the first common wall 400 is greater than the curvature of the concave diffuser section 405 of the second common wall 400, so that the diffuser region 204 expands and thus has a constantly increasing cross-sectional area along its longitudinal extent, whereby the flow is advantageous is delayed. A second planar main section 407 adjoins the concave diffuser section 405 Main area 206, which runs parallel to the extent of the first main section 406 in the sectional view. The second main section 407 is adjoined by a convex outlet section 409 in the outlet region 208, which extends to the outflow surface 24b. In the exemplary embodiment, a high-temperature channel 301 is surrounded by a single common wall 400 designed as a sheet metal, with the concave outlet section 408 and the convex outlet section 409 of the single common wall 400 abutting against one another and being welded or soldered and thus completely enclosing the high-temperature channel 301.

Fig. 10 shows a second exemplary embodiment of a heat exchanger arrangement 21 ', wherein the circumferential extent of the flow channel 20, here corresponding to the circumferential extent of the inlet surface 20a, is larger than in the first exemplary embodiment, while the size of the heat exchanger 21 is identical to the size in the first exemplary embodiment . As a result, the flow is divided, with part of the flow flowing into the heat exchanger 21 and a part being passed past the heat exchanger 21 as a cold stream. Accordingly, there is a hot flow channel 29 behind the outflow surface of the heat exchanger and a cold flow channel 28 next to the heat exchanger, the outlet surfaces of which contribute accordingly to a total mass flow.

11 shows a third exemplary embodiment of a heat exchanger arrangement 21 ', which in the exemplary embodiment represents a reflection of the heat exchanger arrangement 21 'on a mirror surface M, which is spanned by a radial direction R and an axial direction Ax. This results in a V arrangement of the heat exchanger arrangement 21', with the heat exchanger arrangement 21' having a first heat exchanger module 23 and a second heat exchanger module 23'. The two heat exchanger modules 23, 23 'are connected at the front in the direction of flow by a common inlet panel 22, but each has its own outlet panel 27. However, the inflow and outflow angles of the inflow and outflow surfaces 24a, 24b can vary depending on the installation situation. It can thus be provided that a first inflow angle ai of a first inflow surface 24a is smaller or larger than an inflow angle 012 of a second inflow surface 24a'. The same applies to the first outflow angle ai' of the first outflow surface 24b and the first outflow angle oU of the second outflow surface 24b'. The hot flow channel 29 originates at the two flow surfaces 24b and 24b' of the two heat exchanger modules 23, 23' and runs between them. The heated cooling gas expands between the outlet panels 27. The cold flow channel 7 is a channel section that is guided past the heat exchanger 21 on both sides.

The heat exchanger arrangement 1 described in FIGS. 10 and 11 can also be arranged in a repeating pattern, so that in particular a heat exchanger arrangement 21 'results with several alternating hot flow channels 29 and cold flow channels 28, as for example in FIG. 2 on the first Embodiment according to the invention is shown.

An embodiment of the gas turbine according to the invention is shown schematically in FIG. The high-pressure turbine shaft 9 is driven by the high-pressure turbine 14, via which the working gas from the combustion chamber 13 expands. The high pressure turbine shaft

9 drives the single multistage compressor of this embodiment. Because only the fan is driven via a gearbox by the low-pressure turbine shaft 9 ', which is driven by the low-pressure turbine 15. The steam turbine 46 also feeds its power into the low-pressure turbine via a steam turbine gearbox 47.

Reference symbol list

1 drive system

2 gas turbine / turbomachine

3 pylon

4 wings

5 outer casing of the gas turbine

6 inner casing of the gas turbine

6' inner casing termination

7 enema

8 fan

9 high pressure turbine shaft

9' low pressure turbine shaft

10 core flow channel or main flow channel

11 gears

12 compressors

13 combustion chamber

14 high pressure turbine

15 low pressure turbine

16 turbine outlet housing

17 exhaust duct

18 Exhaust gas treatment system

20 bypass channel (bypass)

21 capacitor

22 Entrance fairing

23 (first) capacitor module (of a pair of capacitor modules)

23 ' second capacitor module of a pair of capacitor modules

24a side surface of a capacitor module facing the air bypass flow direction, first

Flow surface

24a' second inflow surface

24b Side surface of a capacitor module facing away from the air bypass flow direction, first

From flow surface 24b 'second outflow surface

24c cooling channels

25 capacitor module pair

26 exhaust duct

27 Exit panel of the (first) capacitor module

27' exit panel of the second capacitor module

28 cold bypass nozzle

29 hot bypass nozzle

30 water system

31 Was serab sche deinstitution

32 inlet channel of the water separation device

33 manifolds

34 twist generators

35 outlet channel of the water separation device

36 core outlet nozzle

37 water pipe

38 water reservoir

38' water purification system

39 water pump

39a feed device

39b injection device

40 steam system

41 steam generators

42 preheaters

43 evaporators

44 superheaters

45 steam pipe

46 steam turbine

47 steam turbine gearboxes

48 mixing chamber

200 low temperature grids 201 low temperature channel

202 enema

203 entry cross section

204 diffuser area

205 constant cross-sectional area

206 Main area of a low temperature channel

207 transverse ribs

208 nozzle area

209 exit cross section

300 high temperature grids

301 high temperature channel

400 common wall for heat transfer

402 inlet section facing away from the wind

403 windward inlet section

404 common wall convex diffuser section

405 common wall concave diffuser section

406 straight main section of common wall

408 concave nozzle section of the common wall

409 concave nozzle section of the common wall

Ax axial direction

R radial direction

U circumferential direction

S channel main direction

S' channel from flow direction

E extension axis

M mirror surface

G (exhaust) gas flow

W water

100 turbomachine ai first approach angle a.2 second approach angle ai' first outflow angle oi2 ' second outflow angle ß main inclination angle

Ti temperature of the gas flow as it exits the (low-pressure) turbine

T2 Temperature of the gas flow exiting the steam generator

T3 Temperature of the steam leaving the steam generator T4 Temperature of the gas flow leaving the combustion chamber

500 method for operating a gas turbine a-g method steps 600 method for operating a gas turbine h-1 method steps

Claims

Patent claims

1. Drive system (1) for an aircraft, with a gas turbine (2) which has a core flow channel (10), wherein in the core flow channel (10) in the direction of flow a compressor (12), a combustion chamber (13), a first turbine, in particular high-pressure turbine (14), for driving the compressor (12), and a second turbine, in particular low-pressure turbine (15), are arranged, and a water system (30) for providing water by recovering an exhaust gas from the core flow channel (10).

2. Drive system according to claim 1, characterized in that the total pressure ratio of the gas turbine is between 20 to 40, and preferably 22 to 35.

3. Drive system according to one of the preceding claims, characterized in that the compressor (12), in particular high-pressure compressor, has a pressure ratio of 13 to 30, preferably 16 to 27.

4. Drive system according to one of the preceding claims, wherein the gas turbine (2) has a first drive shaft (9), which is driven by the first turbine (14), in particular a high-pressure turbine, and drives the compressor (12) and a second drive shaft (9 '), which is driven by the second turbine (15), in particular low-pressure turbine, and in particular drives a fan (8) via a gearbox (11), characterized in that the compressor (12) is the only one via one of the drive shafts Gas turbine (9, 9 ') driven compressor (12) of the gas turbine (2).

5. Drive system according to one of the preceding claims, characterized in that the first turbine (14) of the gas turbine is designed in one stage.

6. Drive system according to one of the preceding claims, characterized in that the expansion ratio of the first turbine (14) of the gas turbine is 2.3 to 3.2, in particular 2.5 to 3.0.

7. Drive system according to one of the preceding claims, characterized in that the gas turbine is designed as a bypass engine and has a bypass ratio that is greater than 30, or is designed as an open rotor and has a bypass ratio that is greater than 50, in particular greater than 60 and particularly preferably greater than 70.

8. Drive system according to one of the preceding claims, characterized in that the gas turbine is a gas turbine that can be operated with hydrogen and / or an exhaust gas treatment system, in particular the water system and / or a steam system, a heat exchange device to support the recovery of water based on the Has cooling effect of the cryogenic hydrogen in particular.

9. Drive system according to one of the preceding claims, characterized in that a housing (5, 6), in particular outer housing or inner housing, surrounds the core flow channel (10) and / or a secondary flow channel (20) radially on the outside, and that the water system (30) is arranged at least partially in and/or on the housing (5).

10. Drive system according to one of the preceding claims, characterized in that the water system (30) has at least one water separation device (31) and a heat exchanger (21), in particular designed as a condenser, for cooling the exhaust gas by means of a lower temperature relative to the exhaust gas and/or cooling fluid having a high flow velocity.

11. Drive system according to claim 10, characterized in that the heat exchanger (21) comprises at least one capacitor module (23), and / or the water separation device (31) is arranged in the housing (5), and / or that the at least one capacitor module ( 23) arranged in the secondary flow channel (20). is and has exhaust channels (26) which direct an exhaust gas from the main flow channel (10) predominantly radially outwards through the secondary flow channel (20), in particular into the housing (5, 6).

12. Drive system according to one of claims 10 or 11, wherein the water system (20) has a heat exchanger (21), in particular designed as a condenser (21), with a high-temperature grid (300) for guiding a hot fluid, in particular an exhaust gas from the gas turbine (2). , and with a low-temperature grid (200) for guiding a cooling fluid, in particular an air flow from a bypass channel (20), characterized in that in at least one first low-temperature channel (201) of the low-temperature grid (200) through which the cooling fluid flows, a diffuser region (204 ) is arranged to delay the cooling fluid, and that the diffuser area (204) and a first high-temperature channel (301) of the high-temperature grid (300) through which the hot fluid flows have at least one common wall (400) for heat transfer.

13. Drive system according to one of the preceding claims, wherein the drive system has a steam system (40) for generating steam from the water provided from the water system (30), the steam being supplied to the working gas and / or being used to cool components.

14. Drive system according to claim 13, characterized in that a proportion of 5-40% by mass, preferably 15-35% by mass, of water in the working gas can be set during operation by means of the steam system (40).

15. Drive system according to one of claims 13 to 14, characterized in that in cruise flight by means of the steam system (40) a proportion of 10-30 mass%, preferably 15-25 mass%, of water in the working gas can be set.

16. Drive system according to one of the preceding claims, wherein the water system (30) and / or the steam system (40) at least partially, preferably predominantly in and / or in the radial direction (R) within the housing (5, 6), in particular the outer housing (5) are arranged. Drive system (1) according to one of the preceding claims 13 to 16, with an exhaust gas duct (17) running through the water system (30) and the steam system (40), through which an exhaust gas from the main flow duct (10) of the gas turbine (2) can flow, wherein the steam system (40) has a steam generator (41) and the water system (30) has a condenser (21) for cooling an exhaust gas flow (G) flowing through the exhaust gas duct (17), the condenser (21) being related to a direction of the exhaust gas flow ( G) is arranged downstream of the steam generator (41), characterized in that a feed device (39a) is arranged between the steam generator (41) and the condenser (21), which is designed to supply water (39b) for cooling the exhaust gas flow (G). ) into the exhaust gas flow (G). Drive system according to one of claims 13 to 17, characterized in that a steam turbine (46) which can be operated by means of the steam from the steam system (40) is provided, which is arranged in particular concentrically to a drive shaft (9, 9 ') and its mechanical power, in particular via a steam turbine gearbox (47) to the drive shaft (9). Aircraft, in particular fixed-wing aircraft, with at least one drive system (1) according to one of the preceding claims. Method (500) for operating a drive system (1), in particular according to one of claims 1 to 18, for an aircraft with a compressor (12) through which a gas flow (G) flows in a main flow channel (10) of a gas turbine (2), a combustion chamber ( 13), turbine (14, 15) and a steam generator (41) downstream of the turbine (14, 15), the steam generator (41) generating steam from water using energy from the gas flow (G), which corresponds to the gas flow (G ) is supplied to the combustion chamber (13) for burning with fuel, characterized in that the gas flow (G) when exiting the turbine (14, 15), in particular when exiting a low-pressure turbine (15), has a temperature (Ti) between 700 and 980 K, in particular between 800 and 980 K, to provide the energy to generate the steam.

21. The method according to claim 20, wherein the gas flow (G) has a temperature (T4) between 1600K and 175K, in particular between 1650 and 1750K, when exiting the combustion chamber (13). 22. The method according to claim 20 or 21, wherein the gas flow (G) has a temperature (T2) between 400 and 480 K when emerging from the steam generator (41).

23. Method (500) according to one of claims 20 to 22, wherein the steam generator (41) heats the steam to a temperature (T3) between 600 and 900 K, in particular between 700K and 740K.