Aircraft engine and method for operating an aircraft engine

Abstract

The invention relates to an aircraft engine (1; 11; 31) with a nacelle (2; 12; 32), with an electric ring motor and with a heat exchanger (6; 16; 36), wherein - a rotor of the ring motor is a propulsor (4; 14) or drives a propulsor (34), - the gondola (2; 12; 32) forms a circumferential boundary for a propulsor airflow which, when the aircraft engine (1; 11; 31) is operated, is accelerated by the propulsor (4; 14; 34) and flows through a gondola interior (3; 13; 33), - one coolant side of the heat exchanger is thermally coupled to a heat source inside and / or outside the aircraft engine, - the propulsor airflow (E; M) accelerated by the propulsor (4; 14; 34) during operation of the aircraft engine (1; 11; 31) flows through an annular space between a central area (3a; 13a; 42) and the surrounding boundary and / or flows outside the nacelle interior (3; 13; 33), while the heat exchanger (6; 16; 36) is cooled on one air side by a portion (H) of the propulsor airflow and / or by additional air (D) flowing into the nacelle interior (3; 13; 33) and - the heat exchanger (6; 16; 36) is arranged radially within a flow area of ​​air, which was accelerated by the propulsor (4; 14; 34) during the operation of the aircraft engine (1; 11; 31) and / or which additionally flows into the nacelle interior (3; 13; 33).

Description

[0001] The invention relates to an aircraft engine with a nacelle, an electric ring motor, optionally a fuel cell system for supplying the ring motor, and a heat exchanger. The invention also includes an arrangement comprising the aircraft engine and the fuel cell system, and an aircraft, in particular an airplane, with such an aircraft engine. The invention further relates to a method for operating such an aircraft engine, a method for operating the arrangement comprising the aircraft engine and the fuel cell system, and a method for operating an aircraft comprising the aircraft engine or the arrangement. Besides conventional airplanes, the aircraft engine according to the present invention can also be used to power other aircraft, for example, an airship.

[0002] Aircraft engines with electric motors powered by a fuel cell system have been proposed. The fuel cell system generates heat during operation, which is dissipated via a heat exchanger. However, aircraft engines also have other heat sources that can be advantageously cooled by means of a heat exchanger; that is, the heat from these sources is typically transferred to the heat exchanger via a circulating heat transfer medium and then dissipated into the surrounding air.These heat sources include the electromagnets of the electric motor that drives the propulsor of the aircraft engine, in this case the ring motor, the inverter that converts direct current from the fuel cell system into alternating current for the electric motor, and the electrical components, such as electrical lines, in particular high-voltage lines, buffer storage battery for pumps, in particular pumps for the heat transfer medium and / or for a compressor of the fuel cell system.

[0003] It is an object of the present invention to provide an aircraft engine and a method for operating an aircraft engine which enable an efficient way of cooling at least one heat source of the aircraft engine and / or of devices such as the fuel cell device, which are optionally arranged outside the aircraft engine.

[0004] It is proposed to generate the thrust produced by the aircraft engine for propulsion using an electric ring motor. One advantage of a ring motor, whose rotor acts as a propulsor to generate the thrust airflow, is that it achieves lower air turbulence at the blade tips compared to conventional propulsors. This results in reduced noise. Furthermore, it is proposed to thermally couple the fuel cell system intended to power the ring motor to a coolant side of a heat exchanger. Alternatively or additionally, at least one other heat source (for example, one of the previously mentioned heat sources) is coupled to the coolant side of the heat exchanger. As is customary, the coolant side of the heat exchanger is understood to be the side where heat is received from the heat source via the heat transfer medium or coolant.In the case of heat being transferred from the heat exchanger to air (as is the case here with an aircraft engine), the other side of the heat exchanger can be referred to as the air side. The term "side" here is not necessarily to be understood geometrically; that is, the coolant side is not necessarily opposite the air side, even though this is possible with some heat exchanger designs.

[0005] The heat exchanger can extend in a ring-shaped and / or non-ring-shaped configuration, comprising multiple segments around the rotational axis of the ring engine. Optionally, the ring or segments can be arranged symmetrically to the rotational axis. Alternatively or additionally, the heat exchanger can be integrated as a single unit within the nacelle. The same applies to the fuel cell system, which, however, can also be located outside the engine.

[0006] Furthermore, it is proposed to arrange the heat exchanger radially within a flow region of air accelerated by the propulsor during the operation of the aircraft engine, relative to the rotor's axis of rotation. In this radially inner region, no significant portion of the thrust airflow generated during the operation of the electric ring motor flows. Rather, the flow velocities in this inner region are considerably lower than in radially outer regions of the nacelle interior or, in some aircraft engine designs, than the flow velocities of the air accelerated by the propulsor outside the nacelle interior. In other words, the heat exchanger does not present a significant obstacle to the thrust airflow that would reduce the efficiency of the propulsion system.Air with a higher degree of turbulence and lower velocity is better suited for absorbing heat from the heat exchanger, thus achieving the same heat transfer capacity with a lower air mass flow rate. However, such air is not well suited as part of the thrust airflow. Furthermore, the air flowing in the inner area can optionally be designed with a swirl, which increases heat transfer efficiency due to the longer interaction time between the air and the heat exchanger, i.e., the time available for heat transfer from the heat exchanger to the air.

[0007] In a specific embodiment where the rotor of the ring motor is open in the region of its axis of rotation, i.e., there is no hub, air can flow through this open area into the nacelle interior without being accelerated, or only minimally accelerated, by the rotor. It is particularly advantageous if, as proposed, the heat exchanger is arranged radially within a flow region of air accelerated by the propulsor during the operation of the aircraft engine, and if the heat exchanger is cooled by the air flowing in through the open area. No drive power from the ring motor is required for this air, and its lower velocity compared to the air accelerated by the propulsor is beneficial for cooling the heat exchanger.A high degree of turbulence and / or a swirl of air can be achieved through a suitable design of the airflow.

[0008] In particular, the following is proposed: An aircraft engine with a nacelle, with an electric ring motor, optionally with a fuel cell device (inside and / or outside the nacelle) to supply the ring motor and with a heat exchanger, wherein - a rotor of the ring motor is a propulsor or drives a propulsor, - the nacelle forms a circumferential boundary for a propulsor airflow, which, when the aircraft engine is operating, is accelerated by the propulsor and flows through a nacelle interior, - one coolant side of the heat exchanger is thermally coupled to a heat source inside and / or outside the aircraft engine, - the propulsor airflow accelerated by the propulsor during the operation of the aircraft engine flows through an annular space between a central area and the surrounding boundary and / or flows outside the nacelle interior, while the heat exchanger on one air side is cooled by part of the propulsor airflow and / or by additional air flowing into the nacelle interior and - the heat exchanger is arranged radially within a flow area of ​​air, relative to a rotational axis of the rotor, which was accelerated by the propulsor during the operation of the aircraft engine and / or which additionally flows into the nacelle interior.

[0009] Furthermore, a corresponding method for operating an aircraft engine is proposed, comprising a nacelle, an electric ring motor, optionally a fuel cell device for supplying the ring motor and a heat exchanger, wherein - a rotor of the ring motor is a propulsor or drives a propulsor, - the nacelle forms a circumferential boundary for a propulsor airflow, which, when the aircraft engine is operating, is accelerated by the propulsor and flows through a nacelle interior, - heat is supplied to the heat exchanger on one coolant side from a heat source inside and / or outside the aircraft engine, - the propulsor airflow, accelerated by the propulsor during the operation of the aircraft engine, flows through an annular space between a central area and the surrounding boundary, while the heat exchanger on one air side is cooled by part of the propulsor airflow and / or by additional air flowing into the nacelle interior and - the heat exchanger is arranged radially within a flow area of ​​air, relative to a rotational axis of the rotor, which was accelerated by the propulsor during the operation of the aircraft engine and / or which additionally flows into the nacelle interior.

[0010] Preferably, the heat exchanger is located in the central area of ​​the nacelle interior of the aircraft engine. As mentioned, the airflow velocities are particularly favorable for heat transfer there, and the flow of air accelerated by the propulsor is least obstructed to generate thrust.

[0011] As mentioned, the axis of rotation of the rotor of the electric ring motor is located in a central area of ​​the nacelle interior. In particular, the ring motor does not need to have a shaft in the area of ​​the axis of rotation (although this is possible within the scope of the invention), so that the central area of ​​the nacelle interior is available for other parts of the aircraft engine. The ring-shaped rotor of the ring motor can be rotatably mounted in its outer area, especially if the central area of ​​the nacelle interior is to be cooled by air for the heat exchanger. A shaft in the area of ​​the axis of rotation is therefore not required. Alternatively, the rotor can be rotatably mounted in the central area. In particular, the stator of the ring motor can be located on the nacelle wall, which forms the boundary of the nacelle interior.The rotor of the ring motor can either be designed as a propulsor itself or drive a propulsor, for example via a shaft and / or a gearbox. The propulsor is understood to be the rotating part of the aircraft engine that generates the majority of the thrust.

[0012] The propulsor thus generates the propulsor airflow, which is crucial for thrust. At least a portion of the propulsor airflow flows through the nacelle interior. However, it is also possible that a portion of the propulsor airflow flows around the outside of the nacelle, as will be explained in more detail in one of the accompanying figures. The propulsor airflow flowing through the nacelle interior reaches its highest velocities near the outer wall of the nacelle. Radially further inward, and especially in the central area of ​​the nacelle interior, the air velocities are much lower. As mentioned, this can be advantageously used for cooling the fuel cell system and / or another heat source by means of a heat exchanger.

[0013] As mentioned, the propulsor generates an airflow. Furthermore, it follows from the above description that the heat exchanger is subjected to an airflow to dissipate heat. Appropriate air ducts may be present in the aircraft engine for this purpose. At least one of the air ducts within the nacelle may be ring-shaped and / or divided into multiple ring segments, or alternatively, implemented as an air duct at another location.

[0014] This heat exchanger is thermally connected on its coolant side to the heat source, in particular the fuel cell unit, or to a plurality of heat sources, especially via a fluid circuit. Only in specific embodiments is the fluid (i.e., the heat transfer medium to the coolant side of the heat exchanger) a liquid. In the case of cooling a fuel cell unit, a fluid suitable for this unit must be selected. In principle, all possible heat exchanger designs are suitable. A preferred embodiment is one in which the cooling air also flows through the heat exchanger, i.e., air channels are located between material sections of the heat exchanger. This results in overall good heat transfer.For example, the heat exchanger is a plate-fin heat exchanger, in particular one in which the plates are permeated by the preferably liquid coolant of the coolant circuit of the heat exchanger.

[0015] In particular, the aircraft engine can include a fuel cell system for supplying the ring motor with electrical energy for its operation, or the aircraft engine can be part of an arrangement consisting of the aircraft engine and a fuel cell system located outside the aircraft engine for supplying the ring motor. It is also possible that only part of the fuel cell system is located outside the aircraft engine. In any case, it is preferred that the fuel cell system is thermally coupled to a coolant side of the heat exchanger via a coolant circuit in order to transfer heat from the fuel cell system to the heat exchanger.

[0016] For optimal thermal coupling between the fuel cell unit and the heat exchanger, and to save material and minimize obstruction of the propulsor airflow within the nacelle, it is advantageous for the fuel cell unit to also be located within the nacelle. The area behind the heat exchanger in the central region of the nacelle interior (viewed along the direction of the propulsor airflow) is well-suited. Depending on the size of the fuel cell unit, it can also be located, at least partially, outside the nacelle, for example, on an aircraft wing.

[0017] On its air side, the heat exchanger is cooled, as mentioned above, by part of the propulsor airflow and / or by additional air flowing into the gondola interior.

[0018] In one embodiment, the heat exchanger is located downstream of a hub along the direction of the propulsor airflow. A portion of the propulsor airflow enters the central area of ​​the nacelle interior behind the hub, cooling the heat exchanger. The hub allows the propulsor airflow used for thrust to be further accelerated, or the mass flow rate of the air to be increased. A small portion of the propulsor airflow can then be diverted to cool the heat exchanger. Particularly when the hub rotates together with the propulsor, it can be mounted on a pivot bearing in the region of the rotor's axis of rotation.

[0019] In another design, the central area of ​​the nacelle interior is open at one air inlet side, allowing additional air to flow into the central area alongside the propulsor airflow during operation of the aircraft engine, thus cooling the heat exchanger. This ensures that the inlet cross-section of the nacelle interior is well utilized for incoming air.

[0020] In one design of the propulsor, it does not merely accelerate air flowing through the nacelle interior, but at least partially, and preferably predominantly, the air flows past the outside of the nacelle. This allows for the use of a significantly larger propulsor (in the radial direction) compared to the size of the nacelle, resulting in greater thrust, for example, to power larger aircraft. In this case, the rotor of the ring motor is not the main propulsor, as will be explained in more detail with reference to an accompanying figure. For example, the rotor is coupled to the main propulsor via a shaft and / or a gearbox and drives it. Particularly in this design, the heat exchanger and / or the fuel cell assembly can be located within the nacelle interior, but not in the central area of ​​the nacelle interior around the rotor's axis of rotation.Overall, this design provides more space in the gondola interior in a radial direction, allowing the heat exchanger and fuel cell system to be arranged one behind the other or next to each other in a radial direction.

[0021] Exemplary embodiments of the invention will now be described with reference to the accompanying drawing. The individual figures in the drawing schematically illustrate: Fig. 1 a first embodiment of an aircraft engine with a ring motor without a hub, Fig. 2 a second embodiment of an aircraft engine with a ring motor having a hub, and Fig. 3 a third embodiment of an aircraft engine with a propulsor driven by a rotor of a ring engine.

[0022] Fig. Figure 1 shows a longitudinal section through a first embodiment of an aircraft engine 1. The dashed horizontal line at the bottom in the Fig. Figure 1 symbolizes the axis of rotation of a propulsor 4 of the aircraft engine 1. Only parts and areas above the axis of rotation are shown. In particular, of the parts located in the central area 3a around the axis of rotation, only the areas above the axis of rotation are shown.

[0023] The components of the aircraft engine 1 can be designed to be rotationally symmetrical about the axis of rotation or (as in the case of the propulsor 4) can be transformed into identical shapes by imaginary or actual rotations about the axis of rotation. For example, if the propulsor 4 is rotated about the axis of rotation by the angle of rotation between the individual blades or by an integer multiple thereof, then its shape and position are indistinguishable from those before the rotation. It is also possible that such rotational congruence is only approximately achieved.

[0024] The aircraft engine 1 has a nacelle 2, which has an interior 3 containing various parts of the aircraft engine 1, which will be discussed in more detail later. The nacelle 2 is in Fig. Only the upper section of the wall is visible. The wall of the gondola 2 completely surrounds the interior space 3. The axis of rotation of the propulsor 4 lies in the central area 3a of the interior space 3. However, the interior space 3 is not necessarily rotationally symmetric, even though it can be considered approximately rotationally symmetric.

[0025] The longitudinal section shows only one of the multiple propulsor blades of the propulsor 4. The propulsor 4 is configured as the rotor of a ring motor. In other embodiments of the invention, the rotor of a ring motor can be configured not as a propulsor but instead drive a propulsor, for example, coupled via a shaft. At the radially outer end (perpendicular to the axis of rotation of the propulsor 4), which is Fig. Figure 1 schematically indicates a rotatably mounted rotor section 9. The rotary bearing is designated by reference numeral 91. In this section 9, the propulsor blade is magnetically designed, preferably with a permanent magnet, to interact with the stator 10. The term "blade" is also commonly used. In a known manner, the magnetic field generated by the stator 10, rotating about the axis of rotation, causes the rotational movement of the propulsor 4 or drives the propulsor 4. A dashed line indicates the area in which the magnetic pairs (rotor-stator) are arranged to generate the drive of the ring motor by magnetic forces.

[0026] Two arrows, A and B, in the area of ​​stator 10 indicate that stator 10 is cooled by an airflow during flight. Since stator 10 is located on the shell of nacelle 2, and thus as far away as possible from the axis of rotation, the surface area used for cooling is large.

[0027] In the interior space 3, behind the propulsor 4, another blade or vane, namely a guide vane 5, is shown outside the central region 3a of the interior space 3. This guide vane 5 belongs to a ring with a plurality of fixed guide vanes, which are attached, in particular, to the inner edge of the wall of the nacelle 2 and additionally to a sleeve 8 of the central region 3a of the interior space 3 around the axis of rotation. In a manner familiar to those skilled in the art, this ring of guide vanes serves to direct the airflow and, in particular, to smooth the flow of the air accelerated by the propulsor 4. In the exemplary embodiment, the sleeve 8 begins around the central region 3a of the interior space 3 immediately behind the radially inner end of the blades of the propulsor 4. However, the central region 3a of the interior space 3 is not bounded by the sleeve 8 in the axial direction.Rather, air flows from the front into the central area 3a of the interior 3 of the gondola 2, which is not accelerated or only slightly accelerated by the propulsor 4. The jacket 8 also serves to separate the airflow accelerated by the propulsor 4 from the central area 3a of the interior 3. Since the jacket 8 is preferably, as in the exemplary embodiment of the . Fig. As shown in Figure 1, the nacelle's profile partially diverges from the axis of rotation in the direction of airflow. Depending on the design of the nacelle's shroud 2, the cross-section for the air accelerated by the propulsor 4 also narrows, leading to a further increase in air velocity. This aerodynamic design is part of the aircraft engine's design for the intended purpose.

[0028] As mentioned, air flows through the interior 3 during flight, as indicated by two further arrows C and D. Outside the central area 3a of the axis of rotation, this air (arrow C) is accelerated or compressed by the propulsor 4, thus propelling the aircraft. As arrow E indicates, this thrust airflow flows outside the area containing the heat exchanger 6 and the fuel cell assembly 7. The area-specific airflow is therefore greater outside the central area 3a, which contains the axis of rotation, than within the central area 3a around the axis of rotation. Arrow D indicates an airflow within the central area 3a of the axis of rotation. This airflow is not accelerated by the propulsor 4, or at most only slightly accelerated at its edges. It corresponds to the airflow resulting from the airspeed, encountering resistances that will now be discussed.

[0029] In the central region 3a of the interior 3 around and at the axis of rotation, a heat exchanger 6 is located in the exemplary embodiment, beginning in the axial region of the propulsor 4. The air flowing into the central region 3a of the interior 3 around the axis of rotation impinges on the heat exchanger 6 and cools it during flight operation. Depending on the design of the heat exchanger, the airflow is directed at and / or through its outer surfaces. In the specific embodiment described here, a fuel cell assembly 7 is located downstream of the heat exchanger 6 in the direction of airflow. This assembly supplies the ring motor with electrical energy. Alternatively, at least part of the fuel cell assembly 7 can be arranged externally on the nacelle (in the area of ​​the nacelle wall) and / or outside the nacelle, for example, on the wings of the aircraft.However, arranging the fuel cell unit 7 directly axially behind the heat exchanger 6 has the advantage that the heat transfer of waste heat generated during the operation of the fuel cell unit 7 to the heat exchanger only needs to occur over a short distance. Two arrows F indicate that a heat transfer medium (for example, a liquid or a gas) circulates between the heat exchanger 6 and the fuel cell unit 7 to transport the waste heat from the fuel cell unit 7 to the heat exchanger 6. The heat is transferred to the air via the flow of air to and / or through the heat exchanger 6.

[0030] As already mentioned, the air in the central area 3a of the interior 3 of the nacelle 2 flows more slowly than the air that is accelerated by the propulsor 4 to generate the thrust airflow (arrow E). This slower-flowing air is sufficient, however, to cool the heat exchanger 6 and also, to a certain extent, to directly cool the fuel cell assembly 7 located downstream in this embodiment. Optionally, the air flowing into the central area 3a of the interior 3 can be given a swirl, i.e., the air rotates around the axis of rotation or an axis parallel to it as it moves axially backward. Such a swirl can be created, for example, by suitable [components / materials / etc.] Fig. The air deflectors (not shown) are reached or imprinted by the propulsor. The swirl has the advantage of increasing heat transfer from the heat exchanger to the air. The aforementioned jacket 8 separates the heat exchanger 6 and the fuel cell assembly 7 from the strong airflow outside the central area 3a. Furthermore, the jacket 8 ensures the efficiency of the thrust effect of the air accelerated by the propulsor 4. Heat can also be transferred through the jacket 8 from the cooling air of the heat exchanger 6 to the air accelerated by the propulsor 4. The air used for thrust therefore contributes to the cooling effect.

[0031] According to the first embodiment, the heat exchanger is cooled by air flowing into the nacelle interior in addition to the air accelerated by the propulsor 4, which generates the thrust of the aircraft engine.

[0032] Fig. Figure 2 shows a second embodiment of an aircraft engine 11 according to the invention. Again, there is a nacelle 12 whose wall completely surrounds an interior space 13. As in the first embodiment of the Fig. 1 The stator 20 of the ring motor is integrated into the wall. In contrast to the first embodiment, however, the propulsor 14 is radially rotatably mounted on a bearing 21 on the inside. In this specific embodiment, the blades of the propulsor 14 extend radially outwards from a conical hub area 22. As in the first embodiment, the magnetic area 19 is located radially outwards on the blades. As in Fig. 1 is indicated by two arrows A, B, that the stator 20 is cooled by the air flowing past the outside of the gondola 12.

[0033] This design also accelerates the air flowing into the interior 13 of the gondola 12 around the axis of rotation in the central area 13a by the propulsor 14. The total amount of incoming air is indicated by arrow G. Downstream of the propulsor 14, in the direction of airflow, there is a ring with a plurality of guide vanes 15 to smooth the flow of the accelerated air. The guide vanes 15 can connect the inner wall of the gondola 12, for example, to the stationary part of the rotary bearing 21. Specifically, in Fig. In the second embodiment shown, a section 23, which widens conically towards the rear in the axial direction, is mechanically connected to the guide vanes 15. At a small distance from the conical hub section 22, this section continues the conical shape of the hub section 22 to the rear. At the rear end of this section 23, there is an air inlet opening 24 into the central section 13a of the interior 13 around the axis of rotation. During flight, a portion of the air accelerated by the propulsor 14 flows through this air inlet opening 24 into the central section 13a of the interior 13 (arrow H). In the second embodiment, the central section (13a) of the interior therefore extends completely behind the propulsor 14 in the axial direction. As in the first embodiment, it is separated from the radially outer section of the interior 13, through which the thrust-generating air flows, by a sleeve 18 (arrow E).More precisely, the air flowing through the air inlet opening 24 also contributes a small portion to the thrust, since it has been accelerated by the propulsor 14. However, in the central area (13a) around the axis of rotation, this air encounters the heat exchanger 16 and (in this specific embodiment) also the fuel cell assembly 17 arranged axially behind it, thus slowing down the airflow. For further details, please refer to the description of the first embodiment.

[0034] According to the second embodiment, the heat exchanger is cooled by air that is accelerated by the propulsor 14. However, the introduction of this air into the central area (13a) around the axis of rotation causes the airflow to decelerate.

[0035] Furthermore, essentially the part of the air accelerated by the propulsor 14 that has the lowest velocity flows into the central region (13a), because it is generated by the radial section of the propulsor 14 which is located furthest inwards radially.

[0036] Combinations of the first and second embodiments are also possible. The device(s) in the central area of ​​the gondola interior can therefore be cooled by air that has not been accelerated by the propulsor, as well as by air that has been accelerated by the propulsor. For example, in the Fig. In the first embodiment shown in Figure 1, a portion of the air accelerated by the propulsor 4 is directed into the central area (13a) of the interior 3 to cool the heat exchanger 6 and / or the fuel cell device 7.

[0037] Fig. Figure 3 shows a third embodiment in which the propulsor 34 accelerates air (arrow I) flowing through the nacelle interior 33, but with respect to the thrust effect primarily accelerates air flowing past the outside of the nacelle 32 (arrow M). In particular, the majority of the air accelerated by the propulsor 34 flows past the outside of the nacelle 32.

[0038] Another difference from the first and second embodiments is that the propulsor 34 is not the rotor 44 driven directly by the stator 40 of the ring motor, but is driven by the rotor 44 via a gearbox 45. The gearbox 45 allows the rotational speed of the propulsor 34 to be adjusted for thrust.

[0039] Similar to the second embodiment according to Fig.2. The rotational movement of the rotor 44 is supported by a rotary bearing 41 in the region of the axis of rotation. The rotor 44 is driven by the stator 40 via the magnetic area 39 located radially outside the rotor 44. A ring of guide vanes 35 is located behind the rotor 44 in the direction of airflow. In the axial region in front of the inlet opening of the nacelle interior 33 and the guide vanes 35, a sleeve 43 extends, which delimits the central area 42 around the axis of rotation. This sleeve 43 not only serves to guide the airflow into the annular area within the nacelle interior 33, which extends around the central area 42 of the nacelle interior 33, but also serves to protect the gearbox 45.Air accelerated by the propulsor 34 enters the nacelle interior 33 and, after passing the ring of guide vanes 35, reaches an axial position where an air inlet opening 54 is located in a central area 42 around the axis of rotation. Air (arrow J), which has been accelerated by the propulsor 34 and flowed into the nacelle interior 33, enters the central area of ​​the nacelle interior 33 through this air inlet opening 54. In the specific embodiment described here, the heat exchanger 36 is not located there, but rather at least part of the fuel cell assembly 37.

[0040] The heat exchanger 36, on the other hand, is located radially further outwards, approximately in the same axial section as the fuel cell assembly 37. Two arrows L again indicate that a heat transfer medium circulates between the fuel cell assembly 37 and the heat exchanger 36 to remove heat from the fuel cell assembly 37. An arrow K shows that air flows through the heat exchanger 36.

[0041] The central area 42 around the axis of rotation is delimited in the axial section of the heat exchanger 36 and the fuel cell assembly 37 by a jacket 38, as in the other two embodiments described with reference to the figures. In this case, this serves to separate the still relatively strong flow in the outer area of ​​the nacelle interior 33, which cools the heat exchanger 36, from the airflow in the central area 42. In a modification of the third embodiment, the heat exchanger can be arranged in the central area 42 of the nacelle interior 33 around the axis of rotation. The fuel cell assembly can then optionally also be arranged in the central area 42, as in the embodiments described above, or on the nacelle wall or outside the nacelle.

Claims

[1] Aircraft engine (1; 11; 31) with a nacelle (2; 12; 32), with an electric ring motor and with a heat exchanger (6; 16; 36), wherein - a rotor of the ring motor is a propulsor (4; 14) or drives a propulsor (34), - the gondola (2; 12; 32) forms a circumferential boundary for a propulsor airflow which, when the aircraft engine (1; 11; 31) is operated, is accelerated by the propulsor (4; 14; 34) and flows through a gondola interior (3; 13; 33), - one coolant side of the heat exchanger is thermally coupled to a heat source inside and / or outside the aircraft engine, - the propulsor airflow (E; M) accelerated by the propulsor (4; 14; 34) during operation of the aircraft engine (1; 11; 31) flows through an annular space between a central area (3a; 13a; 42) and the surrounding boundary and / or flows outside the nacelle interior (3; 13; 33), while the heat exchanger (6; 16; 36) is cooled on one air side by a portion (H) of the propulsor airflow and / or by additional air (D) flowing into the nacelle interior (3; 13; 33) and - the heat exchanger (6; 16; 36) is arranged radially within a flow area of ​​air, which was accelerated by the propulsor (4; 14; 34) during the operation of the aircraft engine (1; 11; 31) and / or which additionally flows into the nacelle interior (3; 13; 33). [2] Aircraft engine according to claim 1, wherein the heat exchanger (6; 16) is arranged in the central area (3a; 13a) of the nacelle interior (3; 13), the central area (3a; 13a) extending around a rotation axis of the rotor. [3] Aircraft engine according to claim 2, wherein a fuel cell device (7; 17) is arranged as a heat source along the flow direction of the propulsor airflow behind the heat exchanger (6; 16) in the central area (3a; 13a) of the nacelle interior (3; 13). [4] Aircraft engine according to claim 2 or 3, wherein the heat exchanger (16) is located along the flow direction of the propulsor airflow behind a hub (22) and wherein a part of the propulsor airflow behind the hub (22) flows into the central area (13a) of the nacelle interior (13) and cools the heat exchanger (16). [5] Aircraft engine according to claim 2 or 3, wherein the central area (3a) of the nacelle interior (3) is open on an air inlet side and, during operation of the aircraft engine (1), additional air flows into the central area (3a) in addition to the propulsor airflow and cools the heat exchanger (6). [6] Aircraft engine according to claim 1, wherein the propulsor (34) accelerates air during operation of the aircraft engine (31), which flows partly outside the nacelle (31). [7] Aircraft engine according to any one of claims 1 to 6, wherein the aircraft engine comprises a fuel cell arrangement (7; 17; 37) for supplying the ring engine with electrical energy for its operation or the aircraft engine is part of an arrangement comprising the aircraft engine and a fuel cell arrangement located outside the aircraft engine for supplying the ring engine, and wherein the fuel cell arrangement is thermally coupled to a coolant side of the heat exchanger via a coolant circuit in order to transfer heat from the fuel cell arrangement to the heat exchanger. [8] Aircraft with an aircraft engine according to any one of claims 1 to 7. [9] Method for operating an aircraft engine (1; 11; 31) comprising a nacelle (2; 12; 32), an electric ring motor and a heat exchanger (6; 16; 36), wherein - a rotor of the ring motor is a propulsor (4; 14) or drives a propulsor (34), - the gondola (2; 12; 32) forms a circumferential boundary for a propulsor airflow which, when the aircraft engine (1; 11; 31) is operated, is accelerated by the propulsor (4; 14; 34) and flows through a gondola interior (3; 13; 33), - the heat exchanger (6; 16; 36) on one coolant side receives heat from a heat source inside and / or outside the aircraft engine, - the propulsor airflow (E; M) accelerated by the propulsor (4; 14; 34) during operation of the aircraft engine (1; 11; 31) flows through an annular space between a central area (3a; 13a; 42) and the surrounding boundary, while the heat exchanger (6; 16; 36) is cooled on one air side by a part (H) of the propulsor airflow and / or by additional air (D) flowing into the nacelle interior (3; 13; 33) and - the heat exchanger (6; 16; 36) is arranged radially within a flow area of ​​air, which was accelerated by the propulsor (4; 14; 34) during the operation of the aircraft engine (1; 11; 31) and / or which additionally flows into the nacelle interior (3; 13; 33). [10] Method according to claim 9, wherein the heat exchanger (6; 16) is arranged in a central area (3a; 13a) of the gondola interior (3; 13), the central area (3a; 13a) extending around a rotation axis of the rotor. [11] Method according to claim 10, wherein a fuel cell device (7; 17) is arranged as a heat source along the flow direction of the propulsor airflow behind the heat exchanger (6; 16) in the central area (3a; 13a) of the gondola interior (3; 13). [12] Method according to claim 10 or 11, wherein the heat exchanger (16) is located along the flow direction of the propulsor airflow behind a hub and wherein a part of the propulsor airflow behind the hub flows into the central area (13a) of the gondola interior (13) and cools the heat exchanger (16). [13] Method according to any one of claims 9 to 11, wherein the central area (3a) of the gondola interior (3) is open at an air inlet side and additional air flows into the central area (3a) in addition to the propulsor airflow and cools the heat exchanger (6). [14] Method according to claim 8, wherein the propulsor (34) accelerates air during the operation of the aircraft engine (31), which flows partly outside the nacelle (32).

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