Aircraft propulsion system with propeller and cooling fan

Abstract

An aircraft propulsion system includes an engine, a propulsor drive shaft drivingly engaged with the engine, a propulsor for propelling the aircraft, and a fan driving cooling air along a flow path in thermal communication with the engine. The engine can be an internal combustion engine or other engine type having heat rejection requirements, and the fan can facilitate cooling of the engine. The propulsion system can have a propulsor configuration.

Description

Technical Field

[0001] This disclosure relates generally to aircraft engines, and more specifically to cooling aircraft engines during operation. Background Technology

[0002] Aircraft engines used in propulsion systems are often more difficult to cool than those used in traction systems. In traction systems, the downdraft from the propeller can be used to generate airflow to cool the engines of the aircraft's propulsion system. However, this effect is absent in propulsion systems. To overcome this problem, additional cooling equipment can be installed, but this increases the weight and size of the aircraft's propulsion system. Improvements are desired. Summary of the Invention

[0003] In one aspect, this disclosure describes an aircraft propulsion system comprising: an internal combustion engine that uses intermittent combustion during operation; a thruster drive shaft droguely engaged with the internal combustion engine; a thruster for propelling the aircraft, the thruster being droguely engaged with the thruster drive shaft; and a fan operatively configured to drive cooling air along a flow path in thermal communication with the internal combustion engine, the fan being droguely engaged with the thruster drive shaft.

[0004] In another aspect, this disclosure describes an aircraft propulsion system having a propulsion mechanism structure. The aircraft propulsion system includes: an engine; a propeller drive shaft dromedarily engaged with the engine; a propeller for propelling the aircraft, the propeller having propeller blades and dromedarily engaged with the propeller drive shaft and disposed behind the engine; a fan operably configured to drive cooling air along a flow path in thermal communication with the engine, the fan having fan blades and dromedarily engaged with the propeller drive shaft; and a heat exchanger configured to facilitate heat transfer between the fan-driven cooling air and a fluid carrying heat from the engine.

[0005] In another aspect, this disclosure describes a method for cooling an internal combustion engine in a propulsion system for an internal combustion aircraft. The method includes: operating the internal combustion engine using intermittent combustion to drive the propulsion unit via a propulsion drive shaft; driving a fan via the propulsion drive shaft, the fan driving cooling air along a flow path in thermal communication with the internal combustion engine; and facilitating heat transfer between the cooling air and the internal combustion engine.

[0006] Further details of these and other aspects of the subject matter of this application will become apparent from the detailed embodiments and accompanying drawings included below. Attached Figure Description

[0007] Now refer to the attached diagram, in which:

[0008] Figure 1 A schematic side view of an aircraft propulsion system with a propulsion structure and cooling fan as described herein is shown;

[0009] Figure 2 yes Figure 1 A perspective view of the rear section of the aircraft's propulsion system;

[0010] Figure 3 yes Figure 1 A frontal view of the rear section of the aircraft's propulsion system;

[0011] Figure 4 yes Figure 1 An enlarged axial cross-sectional view of the rear section of the aircraft's propulsion system;

[0012] Figure 5 yes Figure 1 A perspective view of the rear section of the aircraft's propulsion system, with components removed to show the fan shroud;

[0013] Figure 6 yes Figure 1 A perspective view of the rear section of the aircraft's propulsion system, with the fan shield removed;

[0014] Figure 7 A flowchart illustrating an exemplary method for cooling the propulsion mechanism of an internal combustion engine in an aircraft; and

[0015] Figure 8 A schematic side view of an aircraft propulsion system with a traction mechanism and cooling fan as described herein is shown. Detailed Implementation

[0016] The following disclosure describes an aircraft propulsion system and related methods for cooling the engine of such an aircraft propulsion system. In various embodiments, the systems and methods described herein utilize a fan driven and engaged with a propeller drive shaft driven by the engine to drive cooling air along a flow path in thermal communication with the engine (e.g., via convective heat transfer). In some embodiments, the systems and methods described herein can provide a relatively simple, compact, and lightweight cooling arrangement for aircraft propulsion systems with propulsion mechanism structures. However, aspects of the systems and methods described herein are also applicable to aircraft propulsion systems with traction mechanism structures.

[0017] In some embodiments, the systems and methods described herein can also facilitate cooling of the aircraft engines when the aircraft with the engines is stationary, or when the ambient air around the engines is moving relatively slowly and cannot provide significant cooling to the engines on its own, or when gliding at low speeds on the ground. The systems and methods described herein can also facilitate cooling of the aircraft engines during the takeoff and / or initial climb phases, during which the engines operate at or near maximum power output and the requirements for heat dissipation are relatively high.

[0018] The described systems and methods can be used to cool various types of aircraft engines, including internal combustion engines or other types of engines with relatively high heat dissipation requirements. The described systems and methods can be used on various types of manned or unmanned aircraft (e.g., drones), such as corporate aircraft, private aircraft, fixed-wing aircraft, commercial aircraft, and passenger aircraft. In some embodiments, the systems and methods described herein can also facilitate favorable airflow conditions on the spinner mounted on the hub of the propulsion mechanism.

[0019] In the following text, the terms “connection” or “linked to” can include direct connection or linkage (where two elements are in contact with each other) and indirect connection or linkage (where at least one additional element is located between the two elements). The term “substantially” as used herein can be applied to modify any quantity representation, which may vary without altering its associated essential function.

[0020] Various aspects of the embodiments are described below with reference to the accompanying drawings.

[0021] Figure 1 A schematic axial cross-sectional view of an aircraft propulsion system 10 (hereinafter referred to as "system 10") with a propulsion mechanism structure is shown. System 10 may include an engine 12 having a propulsion drive shaft 14 with which a thruster 16 can be droopily engaged. Figure 1 The diagram shows the fore-and-aft orientation of system 10 in the propulsion structure on the aircraft. The thruster 16 can be located behind the engine 12. System 10 can be integrated into various aircraft and in various locations on such aircraft. For example, system 10 can be mounted on the fuselage or the wing of a fixed-wing aircraft.

[0022] Engine 12 may comprise any suitable type of aircraft engine with heat dissipation requirements. In some embodiments, engine 12 may comprise a gas turbine engine in a turboprop engine assembly. In some embodiments, engine 12 may comprise an internal combustion engine that uses intermittent combustion during operation and has relatively high heat dissipation requirements. Such an internal combustion engine may be, for example, a piston engine or (e.g., a Wankel) rotary engine. In some embodiments, engine 12 may be a compound cycle engine as described in U.S. Patent No. 10,107,195 (title: COMPOUUND CYCLE ENGINE), the entire contents of which are incorporated herein by reference. Engine 12 may be located within a cavity of housing 26, which may be, for example, the cabin or aft fuselage portion of an aircraft.

[0023] Depending on the type of engine used, engine 12 may drive propeller drive shaft 14 using continuous or intermittent combustion of a fuel-air mixture. In an example embodiment, air is received within housing 26 via inlet 24 and directed to engine 12. Exhaust gas generated by combustion within engine 12 may exit system 10 via exhaust outlet 28 or otherwise. Exhaust outlet 28 may include one or more exhaust stubs extending through housing 26.

[0024] Engine 12 may include or be connected to one or more heat exchangers 30 (e.g., radiators, referred to in the singular hereinafter) for dissipating heat generated by engine 12. Heat exchangers 30 may facilitate heat transfer between two or more fluids. For example, heat exchangers 30 may be in fluid communication with one or more fluids (e.g., coolant and / or lubricating oil) that circulate through engine 12 and carry heat away from engine 12. The fluid flow carrying heat from engine 12 to heat exchangers 30... Figure 1 The flow of the same fluid that returns to the engine 12 after having released heat via heat exchanger 30 is indicated by arrow C1. Figure 1 The arrow C2 indicates this. The heat exchanger 30 may be housed within the casing 26. The heat exchanger 30 may be a cross-flow heat exchanger. The heat exchanger 30 may be a liquid-air convection type heat exchanger, in which heat is transferred from the heat transfer fluid to the cooling airflow.

[0025] System 10 may include a thruster 16 driven into engagement with a thruster drive shaft 14. In an example embodiment, the thruster 16 is mechanically fixed to the thruster drive shaft 14 and rotates at the same speed as the thruster drive shaft 14. In other words, the thruster 16 may be driven by and mounted to rotate with the thruster drive shaft 14. The thruster 16 may be coaxially aligned with the thruster drive shaft 14. The axis AA may be the axis of rotation of the thruster 16 and the thruster drive shaft 14. A gearbox 44 may be operably disposed between the engine 12 and the thruster drive shaft 14. The gearbox 44 may be of a reduction type, such that the rotational speed of the thruster drive shaft 14 may be lower than the output rotational speed of the engine 12. The thruster 16 may include a plurality of thruster blades for generating thrust. The orientation (i.e., pitch) of the thruster blades may be controllably variable.

[0026] The fairing 18 can be mounted to rotate with the thruster 16 and can include channels that allow the corresponding thruster blades of the thruster 16 to pass through the fairing 18. The fairing 18 may include a rear distal end 20. The fairing 18 may be a streamlined fairing mounted on the hub of the thruster 16.

[0027] Fan 22 may be operatively configured to drive cooling air along a flow path in thermal communication with engine 12. Fan 22 may be part of the propulsion assembly of system 10. The flow path of cooling air may extend from inlet 24 to cooling air outlet 27 within housing 26. Fan 22 may also be driven into engagement with propulsion drive shaft 14. System 10 is shown as a propulsion system with fan 22, propulsion 16, and shroud 18 positioned behind (i.e., downstream) engine 12. Fan 22 may drive cooling air from outside housing 26 through inlet 24 into the interior of housing 26, and may also drive cooling air out of the interior of housing 26 via cooling air outlet 27. Heat exchanger 30 may be positioned within the flow path of cooling air to facilitate heat transfer between the fluid carrying heat from engine 12 and the cooling air. Cooling air upstream of heat exchanger 30 is designated F. The cooling air inside housing 26 and downstream of heat exchanger 30 is labeled F', and the cooling air exiting housing 26 via cooling air outlet 27 is labeled F''. Since fan 22 is positioned downstream of heat exchanger 30 relative to the flow path, fan 22 can drive cooling air through heat exchanger 30 by suction. Figure 1 As shown, some ambient air received via inlet 24 can be directed to engine 12 to maintain the intermittent or continuous combustion process occurring within engine 12. Some ambient air received via inlet 24 can be directed to heat exchanger 30 to facilitate heat removal from engine 12.

[0028] Fan 22 can be driven by thruster drive shaft 14 and can be mounted coaxially with thruster 16 and thruster drive shaft 14. Fan 22 can be mounted to rotate together with thruster 16. In other words, fan 22 can be mounted to rotate at the same speed and in the same direction as thruster 16. Fan 22 may include a bladed disk in which multiple (e.g., a circular array) fan blades are assembled together with or integrally formed with the rotor disk, such that the fan blades and rotor disk have an integral construction.

[0029] Figure 2 This is a perspective view of the rear portion of system 10, showing the cooling air outlet 27 associated with the thruster 16, the fairing 18, and the exhaust outlet 28. With respect to axis AA, the cooling air outlet 27 may be located radially inside the exhaust outlet 28.

[0030] Figure 3 This is a front view of the rear portion of system 10, see reference. Figure 2 and Figure 3 The cooling air outlet 27 may be generally annular and coaxial with axis AA and propeller drive shaft 14. The cooling air outlet 27 may extend substantially entirely around propeller drive shaft 14. Fan 22 may be mounted inside cooling air outlet 27 and axially spaced from the blades of propeller 16. Fan 22 may be positioned in front of (i.e., upstream of) the blades of propeller 16; for example, fan 22 may be positioned in front of shroud 18, and the blades of propeller 16 may be axially positioned between fan 22 and the distal end 20 of shroud 18.

[0031] Cooling air outlet 27 may be located radially outside the shroud 18. For example, an annular cooling air outlet 27 may surround the shroud 18, such that the air outlet 27 exits from the cooling air outlet 18 (see...). Figure 2 The cooling air (F'') can be discharged in a direction substantially tangential to the outer surface of the shroud 18. In some embodiments, depending on applicable flow conditions, the cooling air discharged from the cooling air outlet 27 can promote favorable flow conditions around the shroud 18 by re-exciting the boundary layer and potentially reducing drag. In some embodiments, fixed or variable-orientation guide vanes can be disposed in the flow path of the cooling air upstream of the fan 22 (e.g., immediately upstream) to achieve desired flow conditions for the cooling air leaving the cooling air outlet 27. Such guide vanes can be mounted on the outer shroud 36 and / or the inner shroud that at least partially defines the cooling air outlet 27. The fan 22 can be a ducted fan passing through the outer shroud 36.

[0032] Figure 4This is an enlarged axial cross-sectional view of the rear portion of system 10. Fan 22 can be driven into engagement with thruster drive shaft 14 in any suitable manner. For example, fairing rear plate 34 can interconnect fairing 18 and thruster drive shaft 14. For example, fairing rear plate 34 can be fastened to fairing 18 and also to flange 32 of thruster drive shaft 14. Fan 22 can be fastened to fairing rear plate 34 at fastened position 35. For example, the same bolts can be used to fasten fairing 18 and fan 22 to fairing rear plate 34. Fairing adapter 40 can interconnect fairing 18 with fairing rear plate 34. Thruster 16 can also be fastened to flange 32 of thruster drive shaft 14 at fastened position 37. For example, the same bolts can be used to fasten both fairing rear plate 34 and thruster 16 to flange 32 of thruster drive shaft 14. In some embodiments, the fan 22 and the rear panel 34 may be integrally formed to have a single structure, rather than separate components. This integral structure may also optionally include a fairing adapter 40.

[0033] The shroud 36 can be fastened to the housing of the gearbox 44 at a fastening position 42. Alternatively, the shroud 36 can be mounted to another fixed component of the system 10, such that the shroud 36 can be fixed relative to the rotating fan 22. A (e.g., compressible) seal 38 can be installed between the outer surface of the shroud 36 and the housing 26. The seal 38 prevents leakage of ambient air from inside the housing 26 to facilitate the intake of cooling air driven by the fan 22 into the flow path via the inlet 24 and through the heat exchanger 30. The seal 38 can extend circumferentially around the shroud 36.

[0034] Figure 5 This is a perspective view of the rear portion of system 10, with components removed to show the shroud 36 and its attachment to the gearbox 44 at the fastened position 42. The shroud 36 may be connected to the inner ring 48 via one or more radial struts 46 that act as spokes and structurally interconnect the shroud 36 with the inner ring 48. The inner ring 48 may include fastener holes for securing the inner ring 48 to the gearbox 44 at the fastened position 42. The struts 46 may extend radially across a generally annular cooling air outlet 27.

[0035] Figure 6 This is a perspective view of the rear portion of system 10, in which the fan shroud 36 is removed to show the fastening position 42 provided on the housing of gearbox 44 for mounting the shroud 36 to gearbox 44.

[0036] Figure 7This is a flowchart of an exemplary method 700 for cooling a (e.g., internal combustion) aircraft engine that drives a propulsion system (e.g., in a propulsion structure). Method 700 can be performed using the system 10 described herein or utilizing other aircraft propulsion systems. It should be understood that aspects of method 700 can be combined with other aspects or steps described herein.

[0037] refer to Figure 1 Method 700 may include: operating (e.g., internal combustion) engine 12 (e.g., using intermittent combustion) to drive propeller 16 via propeller drive shaft 14 (block 702); driving fan 22 via propeller drive shaft 14, wherein fan 22 drives cooling air along a flow path in thermal communication with engine 12 (block 704); and facilitating heat transfer between cooling air and engine 12 (block 706).

[0038] In some embodiments of method 700, the thruster 16, fan 22, and thruster drive shaft 14 may rotate at the same rotational speed. Facilitating heat transfer between the cooling air and the engine 12 may include facilitating heat transfer between the cooling air and another different fluid (e.g., a liquid) that carries heat away from the engine 12.

[0039] Figure 8 A partial schematic side view of an aircraft propulsion system 100 having the traction mechanism and fan 22 described herein is shown. The aspects described above with respect to system 10 also apply to system 100. System 100 may have elements previously described above with respect to system 10. The same elements have been identified using the same reference numerals. In the traction mechanism, the fan 22, thruster 16, and fairing 18 may be positioned in front of (i.e., upstream of) the engine 12. Furthermore, instead of being positioned within a cooling air outlet, the aforementioned cooling air outlet 27 may serve as a cooling air inlet, and the fan 22 may drive the cooling air by pushing it along a flow path and passing it through the heat exchanger 30.

[0040] During operation of system 100, fan 22 draws in ambient air F through a cooling air inlet defined by shroud 36 and drives the cooling air along one or more flow paths F' inside housing 26, which may include heat exchanger 30. The cooling air can then be discharged from outlet 50 and / or other outlets(s).

[0041] The embodiments described in this document provide non-limiting examples of possible implementations of the technology. Upon reading this disclosure, those skilled in the art will recognize that changes can be made to the embodiments described herein without departing from the scope of the technology. In view of this disclosure, those skilled in the art can make further modifications that will be within the scope of the technology.

Claims

1. An aircraft propulsion system, comprising: An intermittent combustion internal combustion engine is used during operation; A propeller drive shaft that is driven and engaged with the internal combustion engine; A thruster for propelling an aircraft, the thruster being droopily engaged with a thruster drive shaft; A fan, operably configured to drive cooling air along a flow path in thermal communication with the internal combustion engine, the fan being drivably engaged with the propeller drive shaft; An outer shroud, the outer shroud at least partially defining an annular cooling air outlet of the flow path, the fan being disposed within the outer shroud; as well as A gearbox, operably disposed between the internal combustion engine and the propeller drive shaft, wherein the outer casing is fastened to the gearbox housing via one or more struts extending radially across the annular cooling air outlet. The fan is a ducted type. The fan and the thruster are coaxial and configured to rotate together with the thruster drive shaft. The thruster is positioned behind the internal combustion engine to define the propulsion structure of the aircraft propulsion system. The fan is located behind the internal combustion engine.

2. The aircraft propulsion system of claim 1, further comprising a heat exchanger configured to facilitate heat transfer between the cooling air and a fluid carrying heat from the internal combustion engine.

3. The aircraft propulsion system according to claim 1, wherein, The fan is axially spaced from the blades of the thruster relative to the thruster drive shaft.

4. The aircraft propulsion system according to claim 1, wherein: The annular cooling air outlet is separate from the exhaust outlet of the internal combustion engine.

5. The aircraft propulsion system according to claim 4, wherein, The annular cooling air outlet is located radially inside the exhaust outlet relative to the propeller drive shaft.

6. The aircraft propulsion system according to claim 4, wherein, The annular cooling air outlet is substantially coaxial with the propeller drive shaft.

7. The aircraft propulsion system according to claim 1, wherein: The fan, the thruster drive shaft, and the thruster are coaxial; The fan is positioned in front of the blades of the thruster; as well as The annular cooling air outlet is separate from the exhaust outlet of the internal combustion engine.

8. The aircraft propulsion system of claim 7, comprising a fairing mounted on the hub of the thruster and a fairing rear plate interconnecting the fairing with the thruster drive shaft, the fan being fastened to the fairing rear plate.

9. An aircraft propulsion system having a propulsion mechanism structure, the aircraft propulsion system comprising: engine; A propeller drive shaft that is driven to engage with the engine; A propulsion device for propelling an aircraft, the propulsion device having propulsion blades and being drivably engaged with the propulsion drive shaft and disposed behind the engine; A fan, operably configured to drive cooling air along a flow path in thermal communication with the engine, the fan having fan blades and being operatively engaged with the propeller drive shaft; A heat exchanger configured to facilitate heat transfer between the cooling air driven by the fan and a fluid carrying heat from the engine. An outer shroud, the outer shroud at least partially defining an annular cooling air outlet of the flow path, the fan being disposed within the outer shroud; as well as A gearbox, operably disposed between the engine and the propeller drive shaft, wherein the outer shroud is secured to the gearbox housing via one or more struts extending radially across the annular cooling air outlet. The fan is a ducted type. The fan and the thruster are coaxial and configured to rotate together with the thruster drive shaft. The fan is located at the rear of the engine.

10. The aircraft propulsion system of claim 9, wherein the fan is axially spaced from the propulsion blades relative to the propulsion drive shaft.

11. The aircraft propulsion system according to claim 9, wherein: The annular cooling air outlet is separate from the engine's exhaust outlet.

12. The aircraft propulsion system according to claim 9, wherein: The fan, the thruster drive shaft, and the thruster are coaxial; and The fan is axially spaced from the thruster blades relative to the thruster drive shaft.

13. The aircraft propulsion system of claim 9, wherein the engine is an intermittent combustion internal combustion engine used during operation.

14. A method for cooling the propulsion unit of an internal combustion aircraft engine in a propulsion mechanism structure, the method comprising: The internal combustion engine is operated using intermittent combustion to drive the propeller via the propeller drive shaft; The fan is driven via the propeller drive shaft, and the fan drives cooling air along a flow path that is in thermal communication with the internal combustion engine; An outer shield is provided, the outer shield at least partially defining an annular cooling air outlet of the flow path, and the fan is disposed within the outer shield; A gearbox is provided, the gearbox being operatively disposed between the engine and the propeller drive shaft, the outer shroud being fastened to the housing of the gearbox via one or more struts extending radially across the annular cooling air outlet; as well as Promotes heat transfer between the cooling air and the internal combustion engine. The fan is a ducted type. The fan and the thruster are coaxial and configured to rotate together with the thruster drive shaft. The fan is located behind the internal combustion engine.

15. The method according to claim 14, wherein, Facilitating heat transfer between the cooling air and the internal combustion engine includes facilitating heat transfer between the cooling air and a fluid carrying heat from the internal combustion engine.

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