PROPULSION SYSTEM THERMAL MANAGEMENT

Abstract

A flying vehicle propulsion system including a propulsor, a drive system and a heat exchanger. The drive system is arranged to drive the propulsor and the heat exchanger is arranged to thermally regulate at least part of the drive system. The propulsor is arranged to move fluid, thereby producing a propulsor fluid flow having a main direction. The system is arranged such that in a first operation configuration, at least part of the propulsor fluid flow is incident on the heat exchanger, thereby thermally regulating the at least part of the drive system.

Claims

1. A flying vehicle propulsion system comprising a propulsor, a drive system and a heat exchanger, where the drive system is arranged to drive the propulsor and the heat exchanger is arranged to thermally regulate at least part of the drive system, the propulsor being arranged to move fluid, thereby producing a propulsor fluid flow having a main direction, and where the system is arranged such that in a first operation configuration, at least part of the propulsor fluid flow is incident on the heat exchanger, thereby thermally regulating the at least part of the drive system.

2. A flying vehicle propulsion system according to claim 1 where in a second operation configuration, the system is arranged such that a ram fluid flow produced by forward flight of the vehicle equipped with the system, is incident on the heat exchanger, thereby thermally regulating the at least part of the drive system.

3. A flying vehicle propulsion system according to claim 2 where the main direction of propulsor fluid flow is different from a main direction of the ram fluid flow.

4. A flying vehicle propulsion system according to claim 3 where the main direction of the propulsor fluid flow is substantially perpendicular to the main direction of the ram fluid flow.

5. A flying vehicle propulsion system according to claim 2 where the first operation configuration is a configuration in which the ram fluid flow is not present or has a velocity below a predetermined threshold.

6. A flying vehicle propulsion system according to claim 2 where the system comprises a housing in which the heat exchanger is provided.

7. A flying vehicle propulsion system according to claim 6 where the housing comprises a propulsor fluid flow inlet port in fluid communication with a first chamber of the housing on an inlet side of the heat exchanger, the propulsor fluid flow inlet port being arranged to receive propulsor fluid flow for ingestion into the first chamber and heat exchanger.

8. A flying vehicle propulsion system according to claim 7 where the propulsor fluid flow inlet port comprises a valve arranged to close the propulsor fluid flow inlet port when the valve is closed and open the propulsor fluid flow inlet port when the valve is open.

9. A flying vehicle propulsion system according to claim 8 where the system is configured such that the balance of forces on the valve is such that it opens and/or closes passively in dependence on the operation configuration of the system.

10. A flying vehicle propulsion system according to claim 7 where the housing comprises a ram fluid flow inlet port in fluid communication with the first chamber of the housing on the inlet side of the heat exchanger, the ram fluid flow inlet port being arranged to receive ram fluid flow for ingestion into the first chamber and heat exchanger.

11. A flying vehicle propulsion system according to claim 10 where the valve, propulsor fluid flow inlet port and ram fluid flow inlet port are arranged such that propulsor fluid flow provides a force tending to open the valve and ram fluid flow provides a force tending to close the valve.

12. A flying vehicle propulsion system according claim 7 where the housing comprises an exit port in fluid communication with a second chamber of the housing on a discharge side of the heat exchanger, the exit port being arranged to exhaust fluid that has passed from the first chamber, through the heat exchanger to the second chamber, out of the housing.

13. A flying vehicle propulsion system according to claim 12 where the exit port is provided on a side wall of the housing.

14. A flying vehicle propulsion system according to claim 6 where the heat exchanger is arranged obliquely within the housing.

15. A flying vehicle propulsion system according to claim 6 where at least part of the drive system is provided within the housing.

16. A flying vehicle propulsion system according to claim 1 where the system comprises a pylon arranged to mount the propulsor to a flying vehicle.

17. A flying vehicle propulsion system according to claim 1 where the drive system comprises a fuel cell which is at least partially thermally regulated by the heat exchanger.

18. (canceled)

19. (canceled)

20. A flying vehicle comprising the system of claim 1.

21. A flying vehicle according to claim 20 where the flying vehicle is arranged for vertical take-off and/or landing and/or short take-off and/or rolling vertical landing with the propulsor providing at least part of the vertical lift force required.

22. A flying vehicle according to claim 20 where the flying vehicle comprises one or more forward thrust system arranged to provide forward thrust for at least one of taxiing, conventional take-off, short take-off or forward flight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0050] FIG. 1 shows a perspective view of part of flying vehicle according to an embodiment of the invention; and

[0051] FIG. 2 shows a perspective view of a part of a flying vehicle propulsion system according to an embodiment of the invention.

DETAILED DESCRIPTION

[0052] Referring to FIGS. 1 and 2, a part of a flying vehicle (in this case an aircraft) is generally shown at 1. The flying vehicle 1 has a wing 3 provided on which are a flying vehicle propulsion system generally shown at 5 and a forward thrust system generally shown at 7.

[0053] The flying vehicle propulsion system 5 is arranged to provide vertical thrust for the flying vehicle 1, whereas the forward thrust system 7 is arranged to provide forward thrust for the flying vehicle 1.

[0054] The flying vehicle propulsion system 5 has a pylon 9 which is mounted to the wing 3 and projects forward therefrom. Mounted at a forward end 11 of the pylon 9, distal to its mount with the wing 3, is a propulsor (in this case a rotor 13). The rotor 13 is disposed above the pylon 9 with a plain of rotation substantially parallel to a top wall 15 of the pylon 9. The rotor 13 is thus disposed to face the top wall 15 of the pylon 9.

[0055] Also mounted to the pylon 9 is a drive system (in this case a fuel cell 17). The fuel cell 17 is mounted to an underside of the pylon 9. The fuel cell 17 is arranged to power rotation of the rotor 13.

[0056] Also mounted to the underside of the pylon 9 is a heat exchanger (in this case a radiator 19). The radiator 19 is mounted forward of the fuel cell 17 (nearer to the forward end 11 of the pylon 9, and in this case substantially at the forward end 11 of the pylon 9). The radiator 19 comprises part of a fluid circuit (not shown) in thermal communication with ambient fluid surrounding fins (not shown) of the radiator 19. The fins increase surface area and promote thermal communication between a heat-transfer fluid (provided in the fluid circuit in use) and the ambient fluid. As the heat-transfer fluid is pumped around the fluid circuit by a pump thereof, (not shown) it is also in thermal communication with a further heat exchanger, which is itself also in thermal communication with the fuel cell 17. As will be appreciated various options are possible with regard to the particular design of the further heat exchanger and its interface with the fuel cell 17 (it could be for instance that the further heat exchanger forms part or all of an outer casing of the fuel cell 17 and/or that the further heat exchanger forms one or more plates within a stack of plates of the fuel cell 17).

[0057] Also mounted to the underside of the pylon 9 is a fuel tank 21. The fuel tank 21 is mounted aft of the fuel cell 17 (nearer to the mount of the pylon 9 with the wing 3). The fuel tank 21 is arranged in use to contain fuel for the fuel cell (e.g. hydrogen in the case of a hydrogen fuel cell) for delivery to the fuel cell 17 as required.

[0058] The radiator 19 and fuel cell 17 are provided within a housing 23. A top wall 25 of the housing 23 is provided by the pylon 9. The remainder of the housing 23, including a front wall 27, side walls 29 and bottom wall 31 are provided by a shroud 31 suspended below the pylon 9. The housing 23 is substantially rectangular in cross-section with a forward portion 33 which tapers down towards the front wall 27. The housing 23 provides a fluid tight container with the exception of various ports discussed further below. The radiator 19 is planer in form and arranged obliquely within the housing 23. The radiator 19 meets the housing 23 around its entire perimeter, creating a seal at the interface. A first side of the radiator 19 is located proximate an interface between the front 27 and bottom 31 walls. Second and third walls of the radiator 19 are respectively located against opposite side walls 29. A fourth wall of the radiator 19 is located against the top wall 25.

[0059] The housing 23 has three propulsor fluid flow inlet ports 35 on the top wall 25 of the housing 23. The propulsor fluid flow inlet ports 35 face the rotor 13 which is disposed above the top wall 25. The propulsor fluid flow inlet ports 35 are positions forward of the interface between the fourth wall of the radiator 19 and the top wall 25 (that is nearer to the forward end 11). The propulsor fluid flow inlet ports 35 allow fluid communication between the inside and outside of the housing 23 and in particular provide fluid communication with a first chamber 37 inside of the housing 23 on an inlet side of the radiator 19. Also providing fluid communication between outside the housing 23 and the first chamber 37 is a ram fluid flow inlet port 39 on the front wall 27 of the housing 23.

[0060] Each of the propulsor fluid flow inlet ports 35 has a valve 41 arranged to close the respective propulsor fluid flow inlet port 35 when the valve 41 is closed and open the propulsor fluid flow inlet port 35 when the valve 41 is open. Each valve 41 takes the form of a door hinged along its side nearest to the forward end 11, with the door opening into the housing 23. Each valve is sprung loaded so as to be biased closed.

[0061] Also providing fluid communication between outside the housing 23 and the inside of the housing 23 are fore 43 and aft 45 exit ports, one in each pair being provided on a respective one of the side walls 29. The exit ports 43, 45 provide fluid communication between outside of the housing 23 and a second chamber 47 inside of the housing 23 on a discharge side of the radiator 19. The radiator 19 provides a separating wall between the first 37 and second 45 chambers, though fluid can pass between the chambers 37, 47 through the radiator 19 as heat exchange occurs. The second chamber 47 also contains the fuel cell 17 positioned further from the forward end 11 than the fore exit ports 43 and nearer to the forward end 11 than the aft exit ports 45.

[0062] As can be seen in FIG. 1, the flying vehicle 1 has an additional pylon and rotor arrangement generally shown at 49. A rotor 51 of the additional pylon and rotor arrangement 49 is arranged to provide vertical thrust for the flying vehicle 1 in a similar manner to the rotor 13 of the flying vehicle propulsion system 5, but in this embodiment is powered by the fuel cell 17 of the flying vehicle propulsion system 5. A pylon 53 of the additional pylon and rotor arrangement 49 is mounted to and extends rearwards from the wing 3 in a substantially symmetric fashion with the pylon 9.

[0063] As will be appreciated, in other embodiments, the additional pylon and rotor arrangement may have its own fuel cell 17 and radiator 19 and be commensurate with and optionally independent of the flying vehicle propulsion system 5.

[0064] The forward thrust system 7 is arranged to provide forward thrust for the flying vehicle 1. The forward thrust system 7 is mounted to the wing 3 proximate its wingtip, The forward thrust system 7 comprises a rotor 55 which is powered by the fuel cell 17. In other embodiments however the rotor 55 may be provided with its own and/or a different drive system.

[0065] In use, the fuel cell 17 is arranged to drive the rotors 13, 51 and 53 and the radiator 19 is arranged to thermally regulate the fuel cell 17.

[0066] When the aircraft 1 is operated in a manner whereby it is travelling in a forward direction, a ram fluid flow having a main direction opposite to the direction of forward motion will be generated. When the rotor 13 is operating, a propulsor fluid flow having a main direction perpendicular to the plane of rotation of the rotor 13 and towards the pylon 9 is generated. The main directions of the ram fluid flow and the propulsor fluid flow are therefore different, and indeed are perpendicular. Consequently, if sufficiently ingested, each respective fluid flow has the potential to compensate for the loss of the other in providing thermal regulation for the fuel cell 17 as aircraft 1 operation changes.

[0067] As will be appreciated the aircraft 1 can be operated so as to have varying forward velocities as powered at least in part by the forward thrust system 7. Ram fluid flow will be ingested into the first chamber 37 via the ram fluid flow inlet port 39 on the front wall 27 of the housing 23 and impinge on the radiator 19. This is because the front wall 27 of the housing 23 faces into the main direction of the ram fluid flow. Where the aircraft 1 is operated in a manner such that the ram fluid flow has at least a velocity predetermined to be sufficient for thermally regulating the fuel cell 17, the force of that ram fluid flow in combination with the biasing of the valves 41 is greater than any force produced by the propulsor fluid flow, and thus the valves 41 are closed. In this manner, ram fluid flow tends not to escape from the housing 23 through the propulsor fluid flow inlet ports 35. Consequently, ram fluid flow entering the housing 23 tends to pass through the radiator 19 from the first chamber 37 to the second chamber 47. In doing so it provides thermal regulation to the heat-transfer fluid running through the radiator 19, and thereby, via the circuit and heat exchanger, to the fuel cell 17. After entering the second chamber 47, the ram fluid flow exits the housing via the fore 43 and aft 45 exit ports. Ram fluid flow exiting via the aft 45 exit ports also passes directly over the fuel cell 17 and thereby provides an additional degree of thermal regulation. As the ram fluid flow exits the fore 43 and aft 45 exit ports, it passes into ram fluid flow passing around the housing 23. Consequently ram fluid flow is encouraged to flow through the housing 23 by the Venturi effect and entrainment.

[0068] Thus, when forward velocity is sufficient, the fuel cell 17 is thermally regulated without the requirement for alternative thermal regulation equipment. Where thermal regulation is provided by ram fluid flow in this manner, the flying vehicle propulsion system is considered to be operating in a second operation configuration. Operation in this configuration may for instance arise during at least one of conventional take-off or forward flight operation of the aircraft 1.

[0069] When travelling in the forward direction, the housing 23 also provides a degree of aerodynamic shielding from the ram fluid flow to the fuel tank 21.

[0070] As will be appreciated, the aircraft 1 can be operated with the rotor 13 running in order to produce a vertical thrust. In such cases, the rotor 13 produces a propulsor fluid flow with the downstream wash directed towards the pylon 9 and housing 23. Where the valves 41 are open, part of the propulsor fluid flow will be ingested into the first chamber 37 via the propulsor fluid flow inlet ports 35 on the top wall 25 of the housing 23 and impinge on the radiator 19. This is because the top wall 25 of the housing 23 faces into the main direction of the propulsor fluid flow. Where the aircraft 1 is operated in a manner such that the propulsor fluid flow has a velocity sufficient to overcome the biasing force on the valves 41 and the force created by any ram fluid flow, the valves 41 will open. Thereafter, propulsor fluid flow entering the housing 23 tends to pass through the radiator 19 from the first chamber 37 to the second chamber 47. In doing so, it provides thermal regulation to the heat-transfer fluid running through the radiator 19, and thereby, via the circuit and heat exchanger, to the fuel cell 17. After entering the second chamber 47, the tapering of the forward portion 33 tends to turn the propulsor fluid flow towards the fore 43 and aft 45 exit ports, through which it exits the housing 23. Propulsor fluid flow exiting via the aft 45 exit ports also passes directly over the fuel cell 17 and thereby provides an additional degree of thermal regulation. As the propulsor fluid flow exits the fore 43 and aft 45 exit ports, it passes into propulsor fluid flow passing around the housing 23. Consequently propulsor fluid flow is encouraged to flow through the housing 23 by the Venturi effect and entrainment.

[0071] Thus, when forward velocity is insufficient and the rotor 13 is running, the loss in thermal regulation that would otherwise have been provided by the ram fluid flow may be compensated for by the propulsor fluid flow. In this way the fuel cell 17 may continue to be thermally regulated without the requirement for alternative thermal regulation equipment. Where thermal regulation is provided by propulsor fluid flow in this manner, the flying vehicle propulsion system is considered to be operating in a first operation configuration. Operation in this configuration may for instance arise during at least one of static, taxiing, vertical take-off, short take-off, vertical flight, vertical landing or rolling vertical landing operation of the aircraft 1. The rotor 13 may be deactivated in forward motion such as cruise flight and/or fast taxiing/conventional take-off.

[0072] The fuel cell 17, thermally regulated as described above, additionally provides power for operation of the rotors 51 and 55 as desired/required.

[0073] In alternative embodiments where the rotor 51 is independently powered, the additional pylon and rotor arrangement 49 may be adjusted as appropriate by comparison with the description of the flying vehicle propulsion system 5 in order to allow ingestion of the relevant fluid flows. For instance, ingestion of the ram fluid flow may be facilitated by a ram fluid flow inlet port comprising a scooped portion of the housing.

[0074] As will be appreciated the fluid forming the ram fluid flow and/or propulsor fluid flow may be air or other liquids and/or gases encountered in the ambient environment and/or exhausted by flying vehicle propulsion system 5 and/or exhausted by other aircraft 1 systems.

[0075] As will be appreciated, the embodiment of FIGS. 1 and 2 has a rotor 12 that has a fixed mounting orientation with respect to the flying vehicle 1. Nonetheless, in other embodiments, the rotor may be a tilt-rotor, allowing for instance approximately 90 degree angular adjustment to give substantially different (e.g. substantially perpendicular) propulsor fluid flows in different flight modes. In this case, when the flying vehicle propulsion system is in the second configuration, it may be that it ingests one, other or a combination of both ram fluid flow and propulsor fluid flow into the ram fluid flow inlet port, and any such fluid so ingested may be incident on the heat exchanger and may provide thermal regulation.

[0076] Alternatively, the flying vehicle propulsion system may be arranged such that even where the propulsor is a tilt rotor, ingestion of propulsor fluid flow into the ram fluid flow inlet port is substantially avoided regardless of flight mode. This might for instance be achieved with one or more scoops allowing positioning of the ram fluid flow inlet port in a manner so as to limit or prevent the ingestion of propulsor fluid flow.

[0077] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0078] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0079] The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.