Variable circulating hybrid electric propulsion system applied to unmanned aerial vehicle and propulsion method of variable circulating hybrid electric propulsion system

Abstract

The invention provides a variable circulation hybrid electric propulsion system applied to an unmanned aerial vehicle and a propulsion method of the variable circulation hybrid electric propulsion system, and belongs to the technical field of aircraft propulsion. The problems of insufficient power and endurance of the unmanned aerial vehicle are solved. The four liquid rocket engines are arranged around the unmanned aerial vehicle body through the vehicle arms; each rotor wing is correspondingly arranged above the liquid rocket engine; a motor and a pump are arranged in the liquid-propellant rocket engine, and the combustion chamber is located below a shell of the liquid-propellant rocket engine and connected with the spray pipe. A fuel cell in the unmanned aerial vehicle body is located at the upper end of the unmanned aerial vehicle body. An energy storage cell is embedded into the lower middle portion of the fuel cell. The energy management system is embedded into the middle-upper part of the fuel cell; and the oxygen tank is positioned at the lower end of the fuselage. The fuel cell is adopted to charge the energy storage cell, the energy storage cell drives the pump to stably convey fuel to the combustion chamber, the problem that a traditional liquid rocket engine depends on complex external energy when started for multiple times is effectively solved, and rapid and reliable repeated starting of the engine is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aircraft propulsion technology, and relates to a variable cycle hybrid engine, in particular to a variable cycle hybrid propulsion system applied to a UAV and a propulsion method thereof. BACKGROUND

[0002] In recent years, vertical take-off and landing UAVs and high-speed cruise aircraft technology have attracted widespread attention in the military, civil and commercial fields. The power system needs to meet the demand for large thrust during vertical take-off and landing / short take-off, and the demand for high efficiency and long endurance during cruising. However, the existing single type power system is difficult to maintain optimal performance in this wide flight envelope, and there are significant technical contradictions.

[0003] The current pure battery-electric rotor system drives the motor through the battery to drive the rotor to generate lift and thrust. Its advantages are simple structure, low noise and zero emission. However, due to the energy density of the current lithium battery, this system has the fatal defects of short endurance time and low payload, which cannot meet the long endurance task demand. At the same time, its power is limited, and it is difficult to achieve high-speed flight or stable maneuvering in adverse weather conditions such as strong wind. The traditional fuel engine has high energy density and can provide longer endurance and higher flight speed. However, it is a heat engine that generates power by burning, has an energy conversion efficiency ceiling, and has significant noise and infrared signal characteristics, which is not conducive to covert operations. More importantly, the traditional engine has very low efficiency and high fuel consumption in low-speed hovering and vertical take-off conditions, and cannot provide the required thrust-to-weight ratio in the vertical direction. It usually needs to be matched with a complex mechanical transmission structure (such as a tilting mechanism), which increases the system complexity, weight and failure rate. SUMMARY

[0004] Therefore, in order to solve the problem of insufficient power and endurance of the UAV and expand the flight envelope of the UAV, the present application provides a variable cycle hybrid propulsion system applied to a UAV and a propulsion method thereof. Four liquid rocket engines are arranged below the rotors, which can not only generate a large instantaneous thrust, but also realize vertical take-off and omnidirectional attitude control. In addition, in the cruising mode, the high energy density of the fuel cell drives the rotor to generate power, which can provide longer cruising time.

[0005] To achieve the above purpose, the present application adopts the following technical scheme: a variable cycle hybrid propulsion system applied to a UAV, comprising a liquid rocket engine system, four rotors, a UAV body and an arm; the four liquid rocket engines are arranged around the UAV body through the arm; each rotor is arranged above the liquid rocket engine; The liquid rocket engine comprises a liquid rocket engine shell, a motor, a pump, a combustion chamber and a nozzle, the motor and the pump are arranged in the liquid rocket engine shell, the combustion chamber is arranged below the liquid rocket engine shell and is connected with the nozzle. The unmanned aerial vehicle body comprises a fuel cell, an energy storage battery, an energy management system, a fuel tank and an oxygen tank, the fuel cell is located at the upper end of the unmanned aerial vehicle body, the energy storage battery is embedded in the lower part of the fuel cell, the energy management system is embedded in the upper part of the fuel cell, the fuel tank is located in the middle part of the body, and the oxygen tank is located at the lower end of the body.

[0006] Furthermore, the fuel is guided from the fuel tank to the anode of the fuel cell through a pipeline, and is guided from the fuel tank to the combustion chamber through a pipeline, bypassing the combustion chamber, and is driven into the combustion chamber by the pump for combustion.

[0007] Furthermore, the oxygen is guided from the oxygen tank to the cathode of the fuel cell through a pipeline, and is guided from the oxygen tank to the combustion chamber through a pipeline, bypassing the combustion chamber, and is driven into the combustion chamber by the pump for combustion.

[0008] Furthermore, the tail gas of the fuel cell is discharged through the pipelines before and after the fuel cell, is wound into the pipelines of the fuel cell, is distributed to the four liquid rocket engines, and is discharged through the combustion chamber and the nozzle.

[0009] Furthermore, the heat carried by the tail gas of the fuel cell is transmitted to the fuel and oxygen input into the fuel cell through the pipelines.

[0010] Furthermore, the electric energy is generated by the fuel cell, is transmitted to the energy storage battery in one way, and is transmitted to the energy management system in another way, the energy management system distributes the electric energy to the motor to drive the pump and the rotor to operate.

[0011] The propulsion method of the variable cycle hybrid electric propulsion system applied to the unmanned aerial vehicle: In the cruising mode, the fuel is guided from the fuel tank to the cathode of the fuel cell through a pipeline, the oxygen is guided from the oxygen tank to the anode of the fuel cell through a pipeline, the fuel and the oxygen react in the fuel cell to generate electric energy, the electric energy is transmitted to the energy management system, a part of the electric energy is supplied to the energy storage battery, another part of the electric energy is distributed to the motor, the motor drives the rotor to generate power, and the tail gas of the fuel cell is guided through a pipeline to exchange heat with the fuel and the oxygen input into the fuel cell, so that the fuel and the oxygen input into the fuel cell reach the reaction temperature condition, and then are transmitted to the combustion chamber through the pipeline and are discharged through the nozzle.

[0012] The propulsion method of the variable cycle hybrid electric propulsion system applied to the unmanned aerial vehicle: The electric energy of the energy storage battery is provided to the energy management system in the boost mode, the energy management system distributes the electric energy to each motor to drive the pump to operate, the pump preheats the fuel in the fuel tank and the oxygen in the oxygen tank around the combustion chamber, cools the outer wall of the combustion chamber, and then enters the combustion chamber to burn to generate thrust through the nozzle pressure reduction and speed increase, and the fuel and oxygen entering the combustion chamber are controlled through the valve to realize the omnidirectional attitude control of the unmanned aerial vehicle. Compared with the prior art, the variable cycle hybrid electric propulsion system applied to the unmanned aerial vehicle and the propulsion method thereof have the following beneficial effects: (1) The four liquid rocket engines supported by the arms are arranged around the fuselage, which can generate extremely high instantaneous thrust, and the fuel and oxidant flow entering the combustion chamber are adjusted to realize dynamic control of the thrust, thereby stably completing vertical take-off and landing and omnidirectional attitude adjustment, and the control ability and adaptability of the unmanned aerial vehicle during the take-off and landing and maneuvering flight stages are significantly improved.

[0013] (2) The fuel cell is used to charge the energy storage battery, and the pump is driven by the energy storage battery to stably deliver the fuel to the combustion chamber. The energy circulation architecture effectively solves the problem that the conventional liquid rocket engine relies on complex external energy for multiple starts, and realizes rapid and reliable repeated start of the engine.

[0014] (3) In the cruising stage, the fuel cell is used to directly drive the rotor to operate. Benefiting from the much higher energy density of the fuel cell system than that of the conventional battery, the endurance time of the unmanned aerial vehicle in the cruising state is improved.

[0015] (4) The high-temperature exhaust gas generated by the fuel cell is used to preheat the fuel and oxygen input into the fuel cell to reach the optimal reaction temperature, the closed-loop optimization of the internal thermal management of the system is realized, and the circulation efficiency and energy utilization rate of the whole power system are further improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The illustrative embodiments of the application and their description serve to explain the application. They do not, however, limit the application, which is defined merely by the appended claims. In the drawings: Fig. 1 It is a structural schematic view of the variable cycle hybrid electric propulsion system applied to the unmanned aerial vehicle. Fig. 2 It is an appearance structure view of the unmanned aerial vehicle fuselage. In the figure: 1-liquid rocket engine system; 11-liquid rocket engine shell; 12-motor; 13-pump; 14-combustion chamber; 15-nozzle; 2-rotor; 3-UAV body; 31-fuel cell; 311-anode of fuel cell; 312-cathode of fuel cell; 313-fuel cell shell; 32-energy storage battery; 33-energy management system; 34-fuel tank; 341-fuel tank shell; 35-oxygen tank; 351-oxygen tank shell; 4-arm; 5-valve; 6-pipeline; 61-pipeline shell. DETAILED DESCRIPTION

[0017] The application will be further described below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are intended to be illustrative only and not limiting of the application. In addition, it should be understood that the drawings are not necessarily to scale and that the specific embodiments described herein are merely exemplary and not limiting of the application. The terms used herein are for the purpose of describing specific embodiments and are not intended to limit the application.

[0018] Reference Figs. 1-2 In this embodiment, a variable cycle hybrid propulsion system applied to a UAV includes four liquid rocket engines 1, four rotors 2, a UAV body 3, and arms 4. The four liquid rocket engines 1 are arranged around the UAV body 3 through the arms 4. Each rotor 2 is arranged above the liquid rocket engine 1. The liquid rocket engine 1 includes a liquid rocket engine shell 11, a motor 12, a pump 13, a combustion chamber 14, and a nozzle 15. The motor 12 and the pump 13 are arranged in the liquid rocket engine shell 11. The combustion chamber 14 is arranged below the liquid rocket engine shell 11 and connected to the nozzle 15. The fuel cell 31 is arranged at the upper end of the UAV body 3. The pipelines 6 are distributed around the fuel cell shell 313. The energy storage battery 32 is embedded in the lower part of the fuel cell 31. The energy management system (EMS) 33 is embedded in the upper part of the fuel cell 31. The fuel tank 34 is arranged in the middle of the UAV body and placed in the fuel tank shell 341. The oxygen tank 35 is arranged at the lower end of the UAV body and placed in the oxygen tank shell 351. The pipeline shell 61 is arranged on both sides of the UAV body 3.

[0019] Fuel from the fuel tank 34 enters the anode 311 of the fuel cell through the pipeline 6. Another route of fuel from the fuel tank 34 flows through the valve 5, bypasses the combustion chamber 14, and is driven into the combustion chamber 14 by the pump 13 for combustion.

[0020] The oxygen from the oxygen tank 35 enters the cathode 312 of the fuel cell through the pipeline 6, and the other part of the oxygen from the oxygen tank 35 enters the combustion chamber 14 through the pipeline 6, bypasses the combustion chamber 14, and is driven by the pump 13 to enter the combustion chamber 14 for combustion; the tail gas of the fuel cell 31 is discharged through the pipeline 6 before and after the fuel cell 31, and is wound into the pipeline of the fuel cell 31 and is distributed to the four liquid rocket engines 1 and is discharged through the combustion chamber 14 and the nozzle 15.

[0021] The heat carried by the tail gas of the fuel cell 31 is transmitted to the fuel and oxygen input into the fuel cell 31 through the pipeline 6.

[0022] The electric energy generated by the fuel cell 31 is transmitted to the energy storage battery 32 and the energy management system 33, and the energy management system 33 distributes the electric energy to the motor 12 to drive the pump 13 and the rotor 2 to operate.

[0023] The electric energy generated by the fuel cell 31 is input into the pump 13 and the energy storage battery 32.

[0024] The energy storage battery 32 is embedded in the fuel cell 31 and obtains electric energy from the fuel cell 31 for repeated starting of the liquid rocket engine 1.

[0025] The four liquid rocket engines 1 are arranged around the fuselage 3 through the arm 4 and can generate a large instantaneous thrust, and the fuel and oxygen entering the combustion chamber 14 are controlled through the valve 5, so that the vertical take-off and landing and the omnidirectional attitude control can be realized.

[0026] The fuel in the fuel tank 34 and the oxygen in the oxygen tank 35 are wound around the combustion chamber 14 for heat exchange, so that the fuel and the oxygen are preheated and the outer wall of the combustion chamber 14 is cooled at the same time.

[0027] The unmanned aerial vehicle fuselage 3 is self-provided with fuel and oxidant and does not need to draw oxygen from the surrounding atmosphere, so that the adaptability is high. The specific operation process and working principle of the high-compact heat management type fuel cell jet engine multi-mode split hybrid propulsion system are as follows: In the cruising mode, the fuel from the fuel tank 34 enters the cathode 312 of the fuel cell through the pipeline 6, the oxygen from the oxygen tank 35 enters the anode 311 of the fuel cell through the pipeline, the fuel and the oxygen react in the fuel cell 31 to generate electric energy, which is transmitted to the energy management system 33, part of the electric energy is supplied to the energy storage battery 32, and the other part of the electric energy is distributed to the motor 12, the motor 12 drives the rotor 2 to generate power; at the same time, the tail gas of the fuel cell 31 exchanges heat with the fuel and the oxygen input into the fuel cell 31 through the pipeline 6, so that the fuel and the oxygen input into the fuel cell 31 reach the reaction temperature condition, and then are transmitted to the combustion chamber 14 through the pipeline 6 and are discharged through the nozzle 15.

[0028] In the boost mode, the electric energy of the energy storage battery 32 is provided to the energy management system 33, the energy management system 33 distributes the electric energy to each motor 12, drives the pump 13 to operate, the pump 13 preheats the fuel in the fuel tank 34 and the oxygen in the oxygen tank 35 around the combustion chamber 14, cools the outer wall of the combustion chamber 14, and then enters the combustion chamber 14 to burn, and generates thrust through the nozzle 15. At the same time, the amount of fuel and oxygen entering the combustion chamber 14 is controlled through the valve 5, so that the omnidirectional attitude control of the unmanned aerial vehicle can be realized.

[0029] In the description of the present application, it should be noted that the positional relationship of the terms up, down and the like is based on the positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] The above disclosed embodiments of the present application are only used to help explain the present application. The embodiments do not describe all the details, nor limit the application to the specific embodiments described. According to the content of the present application, many modifications and changes can be made. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application.

Claims

1. A variable-cycle hybrid propulsion system for use in unmanned aerial vehicles (UAVs), characterized in that: It includes a liquid rocket engine (1), four rotors (2), a drone fuselage (3) and an arm (4); the four liquid rocket engines (1) are mounted around the drone fuselage (3) via the arm (4); each rotor (2) is mounted above the liquid rocket engine (1); The liquid rocket engine (1) includes a liquid rocket engine casing (11), a motor (12), a pump (13), a combustion chamber (14), and a nozzle (15). The motor (12) and the pump (13) are installed inside the liquid rocket engine casing (11). The combustion chamber (14) is located below the liquid rocket engine casing (11) and is connected to the nozzle (15). The drone fuselage (3) includes a fuel cell (31), an energy storage battery (32), an energy management system (33), a fuel tank (34), and an oxygen tank (35). The fuel cell (31) is located at the upper part of the drone fuselage (3), the energy storage battery (32) is embedded in the lower part of the fuel cell (31), the energy management system (33) is embedded in the upper part of the fuel cell (31), the fuel tank (34) is located in the middle of the fuselage, and the oxygen tank (35) is located at the lower end of the fuselage.

2. The variable cycle hybrid propulsion system for unmanned aerial vehicles according to claim 1, characterized in that: Fuel enters the anode (311) of the fuel cell via pipeline (6) from the fuel tank (34), and flows through valve (5) from the fuel tank (34) via pipeline (6), bypassing the combustion chamber (14), and is driven by pump (13) into the combustion chamber (14) for combustion.

3. The variable cycle hybrid propulsion system for unmanned aerial vehicles according to claim 1, characterized in that: Oxygen enters the cathode (312) of the fuel cell via pipeline (6) from oxygen tank (35), and flows through valve (5) via pipeline (6) from oxygen tank (35), bypassing combustion chamber (14) and driven by pump (13) to enter combustion chamber (14).

4. The variable cycle hybrid propulsion system for unmanned aerial vehicles according to claim 2 or 3, characterized in that: The exhaust gas from the fuel cell (31) is discharged through the pipes (6) before and after the fuel cell (31), and is then distributed to the four liquid rocket engines (1) through the combustion chamber (14) and nozzle (15).

5. The variable cycle hybrid propulsion system for unmanned aerial vehicles according to claim 4, characterized in that: The heat carried by the exhaust gas of the fuel cell (31) is transferred to the fuel and oxygen input into the fuel cell (31) through the pipeline (6).

6. The variable cycle hybrid propulsion system for unmanned aerial vehicles according to claim 1, characterized in that: Electrical energy is generated by the fuel cell (31), and one path is sent to the energy storage battery (32), and the other path is sent to the energy management system (33). The energy management system (33) distributes the electrical energy to the motor (12), which drives the pump (13) and the rotor (2) to operate.

7. A propulsion method for a variable-cycle hybrid propulsion system for an unmanned aerial vehicle as described in any one of claims 1-6, characterized in that: In cruise mode, fuel enters the cathode (312) of the fuel cell from the fuel tank (34) via the pipeline (6), and oxygen enters the anode (311) of the fuel cell from the oxygen tank (35) via the pipeline (6). The fuel and oxygen react in the fuel cell (31) to generate electrical energy, which is delivered to the energy management system (33). The energy management system (33) supplies part of the electrical energy to the energy storage battery (32) and the other part of the electrical energy to the motor (12). The motor (12) drives the rotor (2) to generate power. At the same time, the exhaust gas of the fuel cell (31) exchanges heat with the fuel and oxygen input to the fuel cell (31) via the pipeline (6) to make the fuel and oxygen input to the fuel cell (31) reach the reaction temperature conditions, and then is delivered to the combustion chamber (14) via the pipeline (6) and discharged to the nozzle (15).

8. A propulsion method for a variable-cycle hybrid propulsion system for an unmanned aerial vehicle as described in any one of claims 1-6, characterized in that: In boost mode, the electrical energy from the energy storage battery (32) is supplied to the energy management system (33). The energy management system (33) distributes the electrical energy to each motor (12), driving the pump (13) to operate. The pump (13) preheats the fuel in the fuel tank (34) and the oxygen in the oxygen tank (35) around the combustion chamber (14) while cooling the outer wall of the combustion chamber (14). Then, the fuel enters the combustion chamber (14) for combustion, and the pressure is reduced and the speed is increased through the nozzle (15) to generate thrust. At the same time, the amount of fuel and oxygen entering the combustion chamber (14) is controlled by the valve (5) to achieve omnidirectional attitude control of the UAV.

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