Hybrid lift and thrust system for low altitude vertical take-off and landing aircraft and method of operation thereof

Abstract

This invention belongs to the field of aviation propulsion system technology and discloses a method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft. The system includes a low-pressure compressor, a starter / generator, a high-pressure compressor, a gas turbine, an adjustable thrust nozzle, a PEM fuel cell, an electric motor, and a lift propeller. The low-pressure compressor, starter / generator, high-pressure compressor, and gas turbine are coaxial. The compressed air from the low-pressure compressor is divided into two paths. One path of compressed air enters the high-pressure compressor for further pressurization and then enters the main combustion chamber, which is connected to the gas turbine at the rear end. The other path of compressed air from the low-pressure compressor enters the cathode inlet of the PEM fuel cell and the adjustable thrust nozzle. The PEM fuel cell supplies power to the electrical busbar, and the reaction end of the PEM fuel cell is connected to a mixer. The exhaust port of the gas turbine is connected to the mixer, which mixes the exhaust gas from the gas turbine and the exhaust gas from the PEM fuel cell before supplying it to the adjustable thrust nozzle at the rear end to provide thrust. The starter / generator is connected to the electrical busbar, which is connected to the electric motor, and the motor shaft drives the lift propeller. This invention can be used in manned and unmanned aircraft that employ rotor takeoff and landing and thrust cruise, reducing the number of shafts used, simplifying the system structure, reducing the demand for H2, and increasing system operating time.

Description

Technical Field

[0001] This invention belongs to the field of aviation power system technology, and relates to a hybrid lift and thrust system for low-altitude vertical take-off and landing aircraft, specifically a hybrid lift and thrust system for low-altitude vertical take-off and landing aircraft. Background Technology

[0002] With the advent of the low-altitude economy, the development of low-altitude manned / unmanned aerial vehicles (UAVs) has been rapid. Currently, most of these UAVs use a battery-powered technology, with an electric motor driving a lift propeller to provide lift. However, limited by the energy density of batteries, current battery-powered low-altitude UAVs cannot sustain long-term flight, hindering their development. This patent proposes a hybrid lift and thrust system combining a PEM fuel cell and a gas turbine to replace the current battery-powered system. The jet thrust of the gas turbine provides propulsion for the aircraft, while the electrical energy generated by the gas turbine and fuel cell drives an electric motor to drive a lift propeller, providing lift. This invention provides a new technical solution for long-endurance aircraft. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a hybrid lift and thrust system and its operation method for low-altitude vertical takeoff and landing aircraft. This system can simultaneously provide lift and thrust, is flexible in adjustment, and has a long endurance. This invention can provide multi-electric long-endurance hybrid power technology for low-altitude economic aircraft.

[0004] The technical solution of the present invention is as follows:

[0005] A hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft includes a low-pressure compressor, a generator / starter, a high-pressure compressor, a gas turbine, an adjustable thrust nozzle, a PEM fuel cell, an electric motor, and a lift propeller. The low-pressure compressor, generator / starter, high-pressure compressor, and gas turbine are coaxial. The air compressed by the low-pressure compressor is divided into two paths. One path of compressed air enters the high-pressure compressor for further pressurization before entering the main combustion chamber, which is connected to the gas turbine at the rear end. The other path of compressed air from the low-pressure compressor enters the cathode inlet of the PEM fuel cell and the adjustable thrust nozzle. The PEM fuel cell supplies power to an electrical busbar, and the reaction end of the PEM fuel cell is connected to a mixer. The exhaust port of the gas turbine is connected to the mixer, which mixes the exhaust gas from the gas turbine and the exhaust gas from the PEM fuel cell before supplying it to the adjustable thrust nozzle at the rear end to provide thrust. The generator / starter is connected to the electrical busbar, which is connected to the electric motor, and the motor shaft drives the lift propeller.

[0006] Furthermore, it also includes a secondary combustion chamber, which is located at the reaction end of the PEM fuel cell. The unreacted combustible gas and oxygen in the PEM fuel cell are further combusted in the secondary combustion chamber, and the further combusted gas then enters the mixer.

[0007] Furthermore, it also includes an H2 fuel tank and a fuel tank, with the fuel tank connected to the main combustion chamber and the H2 fuel tank connected to the anode inlet of the PEM fuel cell.

[0008] Furthermore, it also includes a system controller and a starter. The starter is powered by an electrical busbar and is connected to a generator. The system controller connects to and controls the starter, generator, PEM fuel cell, and thrust regulating valve. The thrust regulating valve is located on the branch of the low-pressure compressor that branches off to the adjustable thrust nozzle.

[0009] Furthermore, it also includes a DC / DC power conversion unit and an AC / DC power conversion unit. The starter / generator supplies power to the busbars through the AC / DC power conversion unit, and the PEM fuel cell supplies power to the busbars through the DC / DC power conversion unit.

[0010] Furthermore, it also includes a water cooling circuit, a heat exchanger, and a refrigerant cooling circuit. The water cooling circuit splits into two water circuits after passing through the cold end of the heat exchanger: one water circuit mixes with the compressed air entering the cathode of the PEM fuel cell to form humid air; the other water circuit exchanges heat for the entire PEM fuel cell before being injected into the main combustion chamber. The refrigerant cooling circuit exchanges heat for the system controller, starter, DC / DC power conversion unit, and AC / DC power conversion unit after passing through the hot end of the heat exchanger, before entering the hot end of the heat exchanger for circulation.

[0011] Furthermore, it also includes a secondary exhaust valve, which is connected and controlled by the system control system. The secondary exhaust valve is located at the rear end of the secondary combustion chamber, and the other end of the secondary exhaust valve is connected to the outside.

[0012] A method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft, using the aforementioned hybrid lift and thrust system for a low-altitude VTOL aircraft, includes the following method:

[0013] The operating mode is switched according to the aircraft status and system operating requirements. During takeoff, the aircraft needs to provide high power energy. By controlling the starter / generator to adjust the power extraction of the gas turbine engine, the thrust of the adjustable thrust nozzle is reduced to zero. The PEM fuel cell works at the same time, and the power distribution system distributes the electric motor power to drive the lift propeller to provide takeoff lift. After the aircraft enters the cruise phase, the energy extraction of the starter / generator is reduced, and the gas turbine exhaust gas provides thrust through the adjustable thrust nozzle.

[0014] Furthermore, by controlling the generator at different flight altitudes of the aircraft, the speed of the low-pressure compressor can be adjusted, thereby stabilizing the high-pressure airflow entering the cathode of the PEM fuel cell.

[0015] Furthermore, the starter / generator is controlled to operate at low speed for energy saving when the aircraft is on the ground; when the aircraft is at high altitude, the system controller controls the starter / generator to operate at high speed, while simultaneously opening the water cooling circuit to assist in water cooling and humidification, maintaining the operating environment temperature of the PEM fuel cell in both low and high altitude states.

[0016] Advantages of this invention:

[0017] 1. This invention provides a hybrid lift and thrust system for low-altitude vertical take-off and landing aircraft, which can be used in manned and unmanned aircraft employing rotor take-off and landing and thrust cruise.

[0018] 2. This invention reduces the number of shafts used. By mounting the low-pressure compressor, high-pressure compressor, gas turbine, and starter / generator on the same shaft, the traditional gear reduction transmission device is eliminated, greatly simplifying the system structure.

[0019] 3. The main combustion chamber of this invention can accept portable fuels such as kerosene, and is designed with a water spray structure, using water cooling to convert into steam, which avoids the performance degradation caused by the use of cooling air, and at the same time reduces pollutant emissions.

[0020] 4. This invention designs a fuel cell power generation unit consisting of an H2 fuel tank, a PEM fuel cell, and a secondary combustion chamber. The PEM fuel cell receives high-temperature compressed air from a low-pressure compressor. The high-temperature, high-pressure air from the compressor can purge the fuel cell during cold starts, helping the PEM fuel cell solve the problem of low-temperature start-up. At the same time, the high-temperature, high-pressure air at the compressor outlet is humidified and cooled by liquid water, simplifying the requirements for system accessories.

[0021] 5. This invention adopts a dual-fuel approach. The PEM fuel cell uses high-purity hydrogen supplied by the H2 tank, while the gas turbine unit uses portable fuel supplied by the fuel tank. On the one hand, this solves the problem of H2 being difficult to carry on aircraft to a certain extent, thus reducing the demand for H2. On the other hand, the fuel tank carries portable fuels such as kerosene, which increases the system's operating time. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the structure of a dual-fuel aircraft combined propulsion system according to the present invention;

[0024] Among them, 1-low-pressure compressor, 2-starter / generator, 3-high-pressure compressor, 4-main combustion chamber, 5-fuel tank, 6-gas turbine, 7-mixer, 8-adjustable thrust nozzle, 9-secondary combustion chamber, 10-PEM fuel cell, 11-H2 fuel tank, 12-pump, 13-heat exchanger, 14-battery, 15-electric motor, 16-lift propeller, 17-power distribution system, 18-electric busbar, 19-DC / DC power conversion unit, 20-AC / DC power conversion unit, 21-system controller, 22-starter. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Example 1:

[0029] A hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft includes a low-pressure compressor 1, a starter / generator 2, a high-pressure compressor 3, a gas turbine 6, an adjustable thrust nozzle 8, a PEM fuel cell 10, an electric motor 15, and a lift propeller 16. The low-pressure compressor 1, starter / generator 2, high-pressure compressor 3, and gas turbine 6 are coaxial. The air compressed by the low-pressure compressor 1 is divided into two paths: one path enters the high-pressure compressor 3 for further pressurization before entering the main combustion chamber 4, with the rear end of the main combustion chamber 4 connected to the gas turbine 5; the low-pressure compressor 1... Another compressed air stream enters the cathode inlet of the PEM fuel cell 7 and the adjustable thrust nozzle 8 respectively; the PEM fuel cell 7 supplies power to the electric busbar, and the reaction end of the PEM fuel cell 7 is connected to the mixer 7; the exhaust port of the gas turbine 5 is connected to the mixer 7, and the mixer 7 mixes the exhaust gas of the gas turbine 5 and the exhaust gas of the PEM fuel cell 7, and then provides it to the adjustable thrust nozzle 8 at the rear end to provide thrust; the starter / generator 2 is connected to the electric busbar 18, the electric busbar 18 is connected to the electric motor 15, and the shaft of the electric motor 15 drives the lift propeller 16.

[0030] It also includes a secondary combustion chamber 9, which is located at the reaction end of the PEM fuel cell 7. The combustible gas and oxygen that are not fully reacted in the PEM fuel cell 7 are further burned in the secondary combustion chamber 9, and the further burned gas then enters the mixer 7.

[0031] It also includes H2 fuel tank 11 and fuel tank 5, with fuel tank 5 connected to the main combustion chamber 4 and H2 fuel tank 11 connected to the anode inlet of the PEM fuel cell 7.

[0032] It also includes a system controller 21 and a starter 22. The starter 22 is powered by the electric busbar 18 and is connected to the starter / generator 2. The system controller 21 connects to and controls the starter 22, the starter / generator 2, the PEM fuel cell 7 and the thrust regulating valve. The thrust regulating valve is located on the branch of the low-pressure compressor 1 that splits into the adjustable thrust nozzle 8.

[0033] It also includes a DC / DC power conversion unit 19 and an AC / DC power conversion unit 20. The starter / generator 2 supplies power to the busbar 18 through the AC / DC power conversion unit 20, and the PEM fuel cell 7 supplies power to the busbar 18 through the DC / DC power conversion unit 19.

[0034] It also includes a water cooling path, a heat exchanger 13, and a refrigerant cooling circuit. The water cooling path is divided into two water paths after passing through the cold end of the heat exchanger 13: one water path mixes with the compressed air entering the cathode of the PEM fuel cell 10 to form humid air; the other water path exchanges heat with the entire PEM fuel cell 10 and then is injected into the main combustion chamber 4. The refrigerant cooling circuit exchanges heat with the system controller 21, starter 22, DC / DC power conversion unit 19, and AC / DC power conversion unit 20 after passing through the hot end of the heat exchanger 13.

[0035] It also includes a secondary exhaust valve, which is connected and controlled by the system control system 21. The secondary exhaust valve is located at the rear end of the secondary combustion chamber 9, and the other end of the secondary exhaust valve is connected to the outside.

[0036] A method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft, using the aforementioned hybrid lift and thrust system for a low-altitude VTOL aircraft, includes the following method:

[0037] The operating mode is switched according to the aircraft status and system operating requirements. During takeoff, the aircraft needs to provide high power energy. By controlling the starter / generator 2 to adjust the power extraction of the gas turbine engine, the thrust of the adjustable thrust nozzle 8 is reduced to zero. The PEM fuel cell 7 works at the same time, the secondary exhaust valve is opened, and the power distribution system 17 distributes the electric motor 15 to drive the lift propeller 16 to provide takeoff lift. After the aircraft enters the cruise phase, the energy extraction of the starter / generator 2 is reduced and the secondary exhaust valve is closed. The exhaust gas of the gas turbine 6 provides thrust through the adjustable thrust nozzle 8.

[0038] The control of the generator 2 at different flight altitudes of the aircraft enables the speed regulation of the low-pressure compressor 1, thereby stabilizing the high-pressure air flow entering the cathode of the PEM fuel cell 7.

[0039] Example 2:

[0040] A hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft and its operation method are disclosed. The system includes a low-pressure compressor 1, a generator / starter 2, a high-pressure compressor 3, a gas turbine 6, an adjustable thrust nozzle 8, a PEM fuel cell 10, an electric motor 15, and a lift propeller 16. The low-pressure compressor 1, generator / starter 2, high-pressure compressor 3, and gas turbine 6 are coaxial. The compressed air from the low-pressure compressor 1 is divided into two paths. One path of compressed air enters the high-pressure compressor 3 and then the main combustion chamber 4, with the rear end of the main combustion chamber 4 connected to the gas turbine 5. The other path of compressed air enters the PEM fuel cell 7 and the adjustable thrust nozzle 8. The PEM fuel cell 7 supplies power to the electrical busbar, and the reaction end of the PEM fuel cell 7 is connected to a mixer 7. The mixer 7 is driven by both the main combustion chamber 4 and the PEM fuel cell 7. The exhaust passage of the gas turbine 5 passes through the adjustable thrust nozzle 8 to provide thrust.

[0041] It also includes a secondary combustion chamber 6, which is located between the PEM fuel cell 7 and the gas turbine 5. The unreacted fuel and air in the PEM fuel cell 7 are burned in the secondary combustion chamber 6.

[0042] It also includes H2 fuel tank 8 and fuel tank 3, with fuel tank 3 connected to the main combustion chamber 4 and H2 fuel tank 8 connected to the PEM fuel cell 7.

[0043] It also includes a system controller 21 and a starter 22, which is powered by an electrical busbar and is connected to a starter / generator 2; the system controller 21 connects to and controls the starter 22, the starter / generator 2, the power distribution system 17 and the PEM fuel cell 7.

[0044] It also includes a DC / DC power conversion unit 19 and an AC / DC power conversion unit 20. The starter / generator 2 supplies power to the busbar 18 through the AC / DC power conversion unit 20, and the PEM fuel cell 7 supplies power to the busbar 18 through the DC / DC power conversion unit 19.

[0045] The battery 14 and the power distribution system 17 distribute the power supply from the power bus bar 18 and control the charging / discharging process of the battery and the power supply of the motor 15.

[0046] It also includes a heat exchanger 13 and a pump 12. The water cooling circuit cools the heat exchanger 13 and the PEM fuel cell 7. The DC / DC power conversion unit 19, AC / DC power conversion unit 20, system controller 21, and starter 22 are cooled by a refrigerant medium. The refrigerant is driven by the pump 12 and connected to the cold end of the heat exchanger 13.

[0047] The main combustion chamber 4 is water-cooled, and the water spray cooling combustion can effectively reduce pollutant emissions.

[0048] A method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft includes the following steps:

[0049] The system controller 21 switches operating modes according to the aircraft status and system operating requirements. During takeoff, high-power energy is required. By controlling the starter / generator 2, the power extraction from the gas turbine engine is adjusted, reducing the thrust of the adjustable thrust nozzle 8 to zero. The PEM fuel cell 7 operates simultaneously, the secondary exhaust valve opens, and the power distribution system 17 distributes electricity to the electric motor 15 to drive the lift propeller 16 to provide takeoff lift. During the cruise phase, the system controller 21 controls the reduction of energy extraction from the starter / generator 2 and closes the secondary exhaust valve. The exhaust gas from the gas turbine 6 provides thrust through the adjustable thrust nozzle 8.

[0050] The system controller 21 regulates the speed of the air compressor 1 by controlling the starter / generator 2, thereby regulating the high-pressure air entering the cathode of the PEM fuel cell 7 and stabilizing the working conditions of the fuel cell.

[0051] The system controller 21 controls the starter / generator 2. When the aircraft is on the ground, the starter / generator 2 is controlled to operate at a low speed for energy saving, i.e., below 60% of the rated speed. When the aircraft is at high altitude, the system controller 21 controls the starter / generator 2 to operate at a high speed, i.e. above 90% of the rated speed. At the same time, the water cooling circuit is turned on to assist in water cooling and humidification, so as to maintain the working environment temperature of the PEM fuel cell 7 at low and high altitudes.

[0052] 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 hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft, characterized in that, The system includes a low-pressure compressor (1), a starter / generator (2), a high-pressure compressor (3), a gas turbine (6), an adjustable thrust nozzle (8), a PEM fuel cell (10), an electric motor (15), and a lift propeller (16). The low-pressure compressor (1), starter / generator (2), high-pressure compressor (3), and gas turbine (6) are coaxial. The air compressed by the low-pressure compressor (1) is divided into two paths. One path of compressed air enters the high-pressure compressor (3) for further pressurization and then enters the main combustion chamber (4). The rear end of the main combustion chamber (4) is connected to the gas turbine (6). The other path of compressed air from the low-pressure compressor (1) enters the PEM fuel cell. The cathode inlet and adjustable thrust nozzle (8) of the fuel cell (10); the PEM fuel cell (10) supplies power to the busbar (18), and the reaction end of the PEM fuel cell (10) is connected to the mixer (7); the exhaust port of the gas turbine (6) is connected to the mixer (7), and the mixer (7) mixes the exhaust gas of the gas turbine (6) and the exhaust gas of the PEM fuel cell (10) and provides it to the adjustable thrust nozzle (8) at the rear end to provide thrust; the starter / generator (2) is connected to the busbar (18), the busbar (18) is connected to the motor (15), and the shaft of the motor (15) drives the lift propeller (16).

2. The hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a secondary combustion chamber (9), which is located at the reaction end of the PEM fuel cell (10). The combustible gas and oxygen that are not fully reacted in the PEM fuel cell (10) are further burned in the secondary combustion chamber (9), and the further burned gas enters the mixer (7).

3. The hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes an H2 fuel tank (11) and a fuel tank (5), with the fuel tank (5) connected to the main combustion chamber (4) and the H2 fuel tank (11) connected to the anode inlet of the PEM fuel cell (10).

4. The hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a system controller (21) and a starter (22), the starter (22) being powered by an electric busbar (18) and connected to a generator (2); the system controller (21) is connected to and controls the starter (22), the generator (2), the PEM fuel cell (10) and the thrust regulating valve, the thrust regulating valve being located on the branch of the low-pressure compressor (1) that branches off to the adjustable thrust nozzle (8).

5. A hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a DC / DC power conversion unit (19) and an AC / DC power conversion unit (20). The generator (2) supplies power to the busbar (18) through the AC / DC power conversion unit (20), and the PEM fuel cell (10) supplies power to the busbar (18) through the DC / DC power conversion unit (19).

6. A hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 5, characterized in that, It also includes a water cooling path, a heat exchanger, and a refrigerant cooling circuit. The water cooling path is divided into two water paths after passing through the cold end of the heat exchanger (13): one water path mixes with the compressed air entering the cathode of the PEM fuel cell (10) to form humid air; the other water path exchanges heat with the entire PEM fuel cell (10) and then injects it into the main combustion chamber (4); the refrigerant cooling circuit exchanges heat with the system controller (21), starter (22), DC / DC power conversion unit (19), and AC / DC power conversion unit (20) after passing through the hot end of the heat exchanger (13).

7. A hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a secondary exhaust valve, which is connected and controlled by the system controller (21). The secondary exhaust valve is located at the rear end of the secondary combustion chamber (9), and the other end of the secondary exhaust valve is connected to the outside.

8. A method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing (VTOL) aircraft, comprising using a hybrid lift and thrust system for a low-altitude VTOL aircraft as described in any one of claims 1-7, characterized in that, Including the following methods: The operating mode is switched according to the aircraft status and system working requirements. During the takeoff process, the aircraft needs to provide high power energy. By controlling the starter / generator (2), the power extraction of the gas turbine engine is adjusted, and the thrust of the adjustable thrust nozzle (8) is reduced to zero. The PEM fuel cell (10) works at the same time, the secondary exhaust valve is vented, and the power distribution system (17) distributes the electric motor (15) to drive the lift propeller (16) to provide takeoff lift. After the aircraft enters the cruise phase, the energy extraction of the starter / generator (2) is reduced and the secondary exhaust valve is closed. The exhaust gas of the gas turbine (6) provides thrust through the adjustable thrust nozzle (8).

9. The operating method of a hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 8, characterized in that, Controlling the generator (2) at different flight altitudes of the aircraft enables the speed regulation of the low-pressure compressor (1), thereby stabilizing the high-pressure airflow entering the cathode of the PEM fuel cell (10).

10. The method for operating a hybrid lift and thrust system for a low-altitude vertical takeoff and landing aircraft according to claim 9, characterized in that, The starter / generator (2) is controlled. When the aircraft is on the ground, the starter / generator (2) is controlled to work at a low speed to save energy. When the aircraft is at high altitude, the system controller (21) controls the starter / generator (2) to work at a high speed and opens the water cooling circuit to assist in cooling and humidifying with water, so as to maintain the working environment temperature of the PEM fuel cell (10) in both low and high altitude states.

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