A high-altitude, high-power-to-weight ratio auxiliary power unit and aircraft

Abstract

The application belongs to the field of aviation technology, and discloses a high-altitude, high-power-weight-ratio auxiliary power device and an airplane. The device comprises an air inlet, a load compressor, a core compressor, a double-loop cavity combustion chamber and a counter-rotating turbine. The load compressor and the core compressor are arranged downstream of the air inlet. The load compressor provides bleed air for an environmental control subsystem and a starting subsystem of the airplane. The core compressor pressurizes the airflow of the air inlet and provides the double-loop cavity combustion chamber. The double-loop cavity combustion chamber provides power for the counter-rotating turbine. The counter-rotating turbine comprises front and rear turbine rotors. The front and rear turbine rotors rotate in opposite directions. The front turbine rotor is coaxial with the rotating shaft of the core compressor. The rear turbine rotor is coaxial with the rotating shaft of the load compressor. The device is compact, efficient, stable, and has a wide working speed range. The device is beneficial to improving the aerodynamic performance and the power-weight ratio of the auxiliary power device at high altitudes, and meets the needs of future airplane high-altitude flight.

Description

Technical Field

[0001] This invention belongs to the field of aviation technology and relates to an auxiliary power unit and an aircraft, specifically to an auxiliary power unit and an aircraft with high service ceiling and high power-to-weight ratio. Background Technology

[0002] Auxiliary power units are small, self-contained engines installed on aircraft that do not rely on any external energy source. They provide auxiliary energy such as electricity and compressed air for starting aircraft engines and ground maintenance, playing an important role in improving aircraft safety and autonomous support capabilities. There are more than a hundred types of products, with power ranging from tens of kilowatts to thousands of kilowatts, and they have become an indispensable key airborne equipment for modern military and civilian aircraft.

[0003] Internationally, major aviation powers such as the US, Russia, and France place great emphasis on auxiliary power units (APUs), establishing their own specialized research and development units. Domestically, while APU development has made some progress, basically meeting the needs of third- and fourth-generation aircraft and barely supporting the development of fifth-generation aircraft, high-altitude, high-power-to-weight-ratio APUs remain a gap. With the increasing flight envelope of future aircraft, traditional APU structural layouts will be insufficient, necessitating innovative development of APU layouts to improve aerodynamic performance and power-to-weight ratio at high altitudes, thus meeting the functional performance requirements of future aircraft.

[0004] The counter-rotating turbine technology was first proposed in the field of aero-engines. However, as research deepened, scholars discovered that with counter-rotating turbines, as the rotational speed decreases, the inlet airflow angle of the low-pressure turbine deviates from the high-efficiency region, easily causing a sharp drop in the engine's efficiency. Although, in principle, the low-pressure turbine utilizes the circumferential pre-swirl generated by the high-pressure turbine rotor outlet airflow to directly perform work, eliminating guide vanes and reducing component weight, the low efficiency at low reduced rotational speeds has prevented the widespread practical application of counter-rotating turbine technology in aero-engines. Compared to traditional aero-engines, auxiliary power units, as secondary power sources, typically operate within a narrow operating range of 90%–115% of their reduced rotational speed. Using counter-rotating turbines in this context is theoretically feasible and could further reduce the engine's weight, making it worthy of further exploration and research. Summary of the Invention

[0005] To address the issue that existing auxiliary power units have poor structural layout performance and cannot meet the functional performance requirements of future aircraft, this invention provides a high-ceiling, high-power-to-weight-ratio auxiliary power unit that maximizes the aerodynamic performance and power-to-weight ratio of the auxiliary power unit at high altitudes, thereby meeting the functional performance requirements of future aircraft.

[0006] The technical solution of the present invention is as follows:

[0007] A high-ceiling, high-power-to-weight-ratio auxiliary power unit includes an air intake, a load compressor, a core compressor, a dual-annular combustion chamber, and a counter-rotating turbine. The load compressor and the core compressor are located downstream of the air intake. The load compressor bleeds air to supply the aircraft's environmental control subsystem and starting subsystem. The core compressor pressurizes the airflow in the air intake and supplies it to the dual-annular combustion chamber, which in turn powers the counter-rotating turbine. The counter-rotating turbine includes a front turbine rotor and a rear turbine rotor, which rotate in opposite directions. The front turbine rotor is coaxial with the shaft of the core compressor, and the rear turbine rotor is coaxial with the shaft of the load compressor.

[0008] Furthermore, the load compressor includes inlet guide vanes and a load impeller, with the rear turbine rotor coaxial with the load impeller.

[0009] Furthermore, the core compressor includes a centrifugal impeller with splitter blades and a tubular diffuser. The centrifugal impeller pressurizes the airflow from the intake duct, and the tubular diffuser further decelerates and pressurizes the airflow. The front turbine rotor is coaxial with the centrifugal impeller.

[0010] Furthermore, the dual-annular combustion chamber drives the front turbine rotor.

[0011] Furthermore, the counter-rotating turbine also includes turbine inlet guide vanes, which control the airflow from the dual-annular combustion chamber to flow towards the front turbine rotor. The front turbine rotor depressurizes the airflow and then controls the airflow to pass through the rear turbine rotor, which depressurizes the airflow again before finally controlling the airflow to be discharged.

[0012] Furthermore, the dual-annular combustion chamber is divided into an outer annular chamber and an inner annular chamber; during the start-up and idle phases of the auxiliary power unit, fuel is supplied only to the outer annular chamber; under the design conditions, fuel is supplied to both annular chambers simultaneously, including ground maintenance conditions and maximum bleed air conditions.

[0013] Furthermore, the optimal operating conditions for the counter-rotating turbines are designed within the range of 90% to 115% of the equivalent speed, with the pressure ratio between the front turbine rotor and the rear turbine rotor being 1.6:1 to 1.1:1, and the overall pressure ratio of the counter-rotating turbines being 4:1 to 9:1.

[0014] Furthermore, the inlet guide vanes of the load compressor adopt a variable curvature design, with a constant inlet angle and an outlet angle adjusted by a combination of 1 to 3 motors; the outlet angle of the load compressor is 0 to 90°, and the number of inlet guide vanes of the load compressor is 20 to 60; and through holes of 6 to 15 mm are drilled on 3 to 6 blades at different circumferential positions to facilitate borehole inspection and maintenance.

[0015] Furthermore, the centrifugal impeller of the core compressor has 1 to 3 split blades; the casing of the centrifugal impeller is equipped with expansion holes, and the number of expansion holes is 10 to 40.

[0016] Furthermore, the generator consists of a stator assembly, a rotor assembly, and a cooling assembly to integrate the auxiliary power unit's power generation and starting functions. The generator's power output ranges from 0 to 1200 kW.

[0017] Furthermore, the electronic controller is used to control the dual-axis reverse operation of the auxiliary power unit, and it is equipped with a health management and fault diagnosis module to monitor the stable operating status of the auxiliary power unit under different working conditions in real time.

[0018] Furthermore, the air intake is made of resin-based composite material, the load compressor and the core compressor are made of titanium-aluminum alloy, the dual-annular combustion chamber is made of metal-based composite material, and the counter-rotating turbine is made of high-temperature alloy casting to achieve the requirements of lightweight and long service life.

[0019] Furthermore, the auxiliary power unit has a power rating of 100–1500 kW.

[0020] Furthermore, an aircraft includes any of the auxiliary power units described above.

[0021] The beneficial effects of this invention are as follows:

[0022] The high-ceiling, high-power-to-weight-ratio auxiliary power unit of the present invention has the advantages of being compact, efficient, and having a wide stable operating speed range. It is beneficial to improve the aerodynamic performance and power-to-weight ratio of the auxiliary power unit at high altitudes, and meet the high-altitude flight requirements of future aircraft. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this invention, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a traditional auxiliary power unit.

[0025] Figure 2 This is a schematic diagram of the auxiliary power device disclosed in this invention.

[0026] Figure 3 This is a schematic diagram of the counter-rotating turbine disclosed in this invention.

[0027] Among them, 1-intake duct, 2-inlet guide vane, 3-load impeller, 4-centrifugal impeller, 5-wedge diffuser, 6-annular combustion chamber, 7-two-stage turbine, 8-exhaust section, 9-gearbox, 10-variable camber adjustable blade, 11-tubular diffuser, 12-double annular combustion chamber, 13-counter-rotating turbine, 14-turbine inlet guide vane, 15-front turbine rotor, 16-rear turbine rotor. Detailed Implementation

[0028] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; they can refer to mechanical connections or point connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Example 1:

[0032] A high-ceiling, high-power-to-weight-ratio auxiliary power unit includes an air intake 1, a load compressor, a core compressor, a dual-annular combustion chamber, and a counter-rotating turbine 13. The load compressor and the core compressor are located downstream of the air intake 1. The load compressor bleeds air to supply the aircraft's environmental control subsystem and starting subsystem. The core compressor pressurizes the airflow in the air intake 1 and supplies it to the dual-annular combustion chamber 12. The dual-annular combustion chamber 12 provides power to the counter-rotating turbine 13. The counter-rotating turbine 13 includes a front turbine rotor 15 and a rear turbine rotor 16, which rotate in opposite directions. The front turbine rotor 15 is coaxial with the shaft of the core compressor, and the rear turbine rotor 16 is coaxial with the shaft of the load compressor.

[0033] The load compressor includes inlet guide vanes and load impeller 3, and the rear turbine rotor 16 is coaxial with the load impeller 3.

[0034] The core compressor includes a centrifugal impeller 4 with splitting blades and a tubular diffuser 11. The centrifugal impeller 4 pressurizes the airflow from the intake duct 1, and the tubular diffuser 11 further decelerates and pressurizes the airflow. The front turbine rotor 15 is coaxial with the centrifugal impeller 4.

[0035] The dual-annular combustion chamber 12 drives the front turbine rotor 15.

[0036] The counter-rotating turbine 13 also includes a turbine inlet guide vane 14, which controls the airflow from the dual-annular combustion chamber to flow to the front turbine rotor 15. The front turbine rotor depressurizes the airflow and then controls the airflow to pass through the rear turbine rotor 16. The rear turbine rotor depressurizes the airflow again and finally controls the airflow to be discharged.

[0037] The dual-annular combustion chamber 12 is divided into an outer annular chamber and an inner annular chamber; during the start-up and idle phases of the auxiliary power unit, fuel is supplied only to the outer annular chamber; under the design conditions, fuel is supplied to both annular chambers simultaneously, including ground maintenance conditions and maximum bleed air conditions.

[0038] The optimal operating conditions for the counter-rotating turbine 13 are designed within the range of 90% to 115% of the equivalent speed. The pressure ratio between the front turbine rotor 15 and the rear turbine rotor 16 is 1.6:1 to 1.1:1, and the overall pressure ratio of the counter-rotating turbine 13 is 4:1 to 9:1.

[0039] The inlet guide vanes of the load compressor adopt a variable curvature design, with a constant inlet angle and an outlet angle adjusted by a combination of 1 to 3 motors; the outlet angle of the load compressor is 0 to 90°, and the number of inlet guide vanes of the load compressor is 20 to 60; and through holes of 6 to 15 mm are drilled on 3 to 6 vanes at different circumferential positions to facilitate borehole inspection and maintenance.

[0040] The centrifugal impeller 4 of the core compressor has 1 to 3 split blades; the casing of the centrifugal impeller is provided with expansion holes, and the number of expansion holes is 10 to 40.

[0041] The generator consists of a stator assembly, a rotor assembly, and a cooling assembly to integrate the auxiliary power unit's power generation and starting functions. The generator's power output ranges from 0 to 1200 kW.

[0042] The electronic controller is used to control the dual-shaft reverse operation of the auxiliary power unit, and it is equipped with a health management and fault diagnosis module to monitor the stable operating status of the auxiliary power unit under different working conditions in real time.

[0043] The air intake duct 1 is made of resin-based composite material, the load compressor and the core compressor are made of titanium-aluminum alloy, the dual-annular combustion chamber 12 is made of metal-based composite material, and the counter-rotating turbine is cast from high-temperature alloy 13 to achieve the requirements of lightweight and long service life.

[0044] The power output of the auxiliary power unit is in the range of 100 to 1500 kW.

[0045] An aircraft comprising any of the auxiliary power units described above.

[0046] Example 2:

[0047] The present invention aims to provide an auxiliary power unit and an aircraft, which has the advantages of being compact, efficient, stable and wide operating speed range. It is beneficial to improve the aerodynamic performance and power-to-weight ratio of the auxiliary power unit at high altitudes, reduce the fuel consumption rate of the aircraft, and meet the high-altitude flight requirements of future aircraft.

[0048] Please see Figure 1 Traditional auxiliary power units consist of an intake duct 1, an adjustable inlet blade 2, a load impeller 3, a centrifugal impeller 4, a wedge diffuser 5, an annular combustion chamber 6, a two-stage turbine 7, an exhaust section 8, and a gearbox 9. These auxiliary power units are long in axial length and heavy in weight.

[0049] Please see Figure 2 and Figure 3 The auxiliary power unit disclosed in this invention comprises an intake duct 1, variable camber adjustable blades 10, a load impeller 3, a centrifugal impeller 4, a tubular diffuser 11, a double annular combustion chamber 12, a counter-rotating turbine 13, and an exhaust section 8; the counter-rotating turbine 13 includes a turbine inlet guide vane 14, a front turbine rotor 15, and a rear turbine rotor 16, with the front turbine rotor 15 and the rear turbine rotor 16 rotating in opposite directions;

[0050] The starter generator is mounted on gearbox 9; the stator assembly of the starter generator is wound around the periphery of the rotor assembly; the rotor assembly is connected to the gearbox via a splined shaft; the cooling assembly is located around the stator assembly and is mainly cooled by lubricating oil; when the auxiliary power unit starts, the starter generator is driven by an external power source, which drives the centrifugal impeller and the front turbine rotor to rotate coaxially; when the auxiliary power unit reaches the preset speed, the starter generator starts generating electricity to provide power to the rest of the equipment on the aircraft; it realizes the integrated design of the starter and generator, effectively reducing the weight of the auxiliary power unit;

[0051] The above layout enables the auxiliary power unit to operate stably at altitudes of 0-18km, with minimal aerodynamic performance degradation under high-altitude low Reynolds number conditions, strong high-altitude ignition capability, and improved fuel consumption rate and output shaft power characteristics of the auxiliary power unit.

[0052] The core compressor consists of a centrifugal impeller with splitter blades and a compact tubular diffuser. The centrifugal impeller pressurizes the airflow from the intake duct, and the tubular diffuser then decelerates and pressurizes the airflow.

[0053] The dual-annular combustion chamber ignites and burns the airflow from the core compressor;

[0054] The counter-rotating turbine consists of a turbine inlet guide vane, a front turbine rotor, and a rear turbine rotor. The front turbine rotor and the rear turbine rotor rotate in opposite directions. The turbine inlet guide vane controls the airflow from the dual-annular combustion chamber to flow to the front turbine rotor. The front turbine rotor depressurizes the airflow and then controls the airflow to pass through the rear turbine rotor. The rear turbine rotor depressurizes the airflow again and finally controls the airflow to flow to the exhaust section.

[0055] The accessories include gearboxes, starter generators, electronic controllers, electric fuel regulators, etc.

[0056] Preferably, the inlet guide vanes of the load compressor adopt a variable camber design, with a constant inlet angle and an outlet angle adjusted by a combination of 1 to 3 motors. The variable angle is 60°, and the number of blades is 35. Furthermore, 8mm through holes are drilled on 3 to 6 blades at different circumferential positions to facilitate borehole inspection and maintenance.

[0057] Preferably, the centrifugal impeller of the core compressor has 1 split blade; the casing of the centrifugal impeller is provided with expansion holes, and the number of expansion holes is 22.

[0058] Preferably, the dual-annular combustion chamber is divided into an outer annular chamber and an inner annular chamber. During the start-up and idle phases of the auxiliary power unit, fuel is supplied only to the outer annular chamber. At this time, the fuel-air ratio in the outer annular chamber is high, the airflow velocity is low, and the combustion duration is long, which helps to reduce pollutant emissions. It also makes the auxiliary power unit start quickly, easy to ignite at high altitude, and less prone to flameout. Under the design conditions, fuel is supplied to both annular chambers simultaneously. At this time, the fuel-air ratio is low, the airflow velocity is high, the combustion duration is short, and the pollutant emissions are low. At the same time, an electric fuel regulator is used to adjust the fuel pattern under different operating conditions to improve the high-altitude ignition capability.

[0059] Preferably, the counter-rotating turbine is designed to ensure good performance within the equivalent speed range of 90% to 115%, with the pressure drop ratio of the front and rear rotors being 1.5 and the total pressure drop ratio being 4.5.

[0060] Preferably, the generator is composed of a stator assembly, a rotor assembly, and a cooling assembly to integrate the auxiliary power device's power generation and starting functions, and the generator has a power output of 200kW.

[0061] Preferably, the electronic controller is used to control the dual-axis reverse operation of the auxiliary power unit, and has a health management and fault diagnosis module for real-time monitoring of the stable operating status of the auxiliary power unit under different working conditions;

[0062] Preferably, the air intake is formed from resin-based composite material, the load compressor and the core compressor are formed from titanium-aluminum alloy; the dual-annular combustion chamber is formed from metal-based composite material; the counter-rotating turbine is cast from high-temperature alloy, and the exhaust section is formed from ceramic-based composite material; in order to achieve the requirements of lightweight and long service life.

[0063] Preferably, the auxiliary power unit has a power rating of 500kW.

[0064] Preferably, an aircraft includes any of the auxiliary power units described above.

[0065] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-ceiling-limit, high-power-to-weight-ratio auxiliary power device, characterized in that, It includes an air intake (1), a load compressor, a core compressor, a dual-annular combustion chamber, and a counter-rotating turbine (13). The load compressor and the core compressor are located downstream of the air intake (1). The load compressor bleeds air to supply the aircraft's environmental control subsystem and starting subsystem. The core compressor pressurizes the airflow in the air intake (1) and supplies it to the dual-annular combustion chamber (12). The dual-annular combustion chamber (12) provides power to the counter-rotating turbine (13). The counter-rotating turbine (13) includes a front turbine rotor (15) and a rear turbine rotor (16). The front turbine rotor (15) and the rear turbine rotor (16) rotate in opposite directions. The front turbine rotor (15) is coaxial with the shaft of the core compressor, and the rear turbine rotor (16) is coaxial with the shaft of the load compressor.

2. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The load compressor includes inlet guide vanes and a load impeller (3), and the rear turbine rotor (16) is coaxial with the load impeller (3).

3. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The core compressor includes a centrifugal impeller (4) with split blades and a tubular diffuser (11). The centrifugal impeller (4) pressurizes the airflow from the intake (1), and the tubular diffuser (11) further decelerates and pressurizes the airflow. The front turbine rotor (15) is coaxial with the centrifugal impeller (4).

4. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 3, characterized in that, The centrifugal impeller (4) of the core compressor has 1 to 3 split blades; the casing of the centrifugal impeller is provided with expansion holes, and the number of expansion holes is 10 to 40.

5. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The dual-annular combustion chamber (12) drives the front turbine rotor (15).

6. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The counter-rotating turbine (13) also includes turbine inlet guide vanes (14), which control the airflow from the dual-annular combustion chamber to flow to the front turbine rotor (15). The front turbine rotor depressurizes the airflow and then controls the airflow to pass through the rear turbine rotor (16). The rear turbine rotor depressurizes the airflow again and finally controls the airflow to be discharged.

7. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The dual-ring combustion chamber (12) is divided into an outer ring chamber and an inner ring chamber; during the start-up and idle phases of the auxiliary power unit, only the outer ring chamber is supplied with fuel; under the design conditions, both ring chambers are supplied with fuel simultaneously, including the ground maintenance condition and the maximum bleed air condition.

8. The high-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The optimal operating conditions of the counter-rotating turbine (13) are designed within the range of 90% to 115% of the equivalent speed. The ratio of the pressure drop ratio between the front turbine rotor (15) and the rear turbine rotor (16) is 1.6:1 to 1.1:1, and the overall pressure drop ratio of the counter-rotating turbine (13) is 4:1 to 9:

1.

9. A high-ceiling-ceiling, high-power-to-weight-ratio auxiliary power device according to claim 1, characterized in that, The inlet guide vanes of the load compressor adopt a variable curvature design, with a constant inlet angle and an outlet angle adjusted by a combination of 1 to 3 motors; the outlet angle of the load compressor is 0 to 90°, and the number of inlet guide vanes of the load compressor is 20 to 60; and through holes of 6 to 15 mm are drilled on 3 to 6 vanes at different circumferential positions to facilitate borehole inspection and maintenance.

10. An aircraft, characterized in that, Use a high-ceiling, high-power-to-weight-ratio auxiliary power device as described in any one of claims 1-9.

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