Energy storage compressed gas driven underwater vehicle based on supercavitation drag reduction and driving method thereof

Abstract

The application discloses an underwater vehicle driven by energy storage compressed gas based on supercavitation drag reduction and a driving method thereof. The application uses a power system of compressed gas expansion to provide power for the underwater vehicle, and meanwhile, waste gas of the power system generates a supercavitation to reduce the drag of the vehicle, so that the traditional lithium battery underwater vehicle power system is replaced. The method of coupling the power system and the drag reduction system increases the compactness of the system, reduces the navigation resistance, effectively improves the navigation speed, the endurance time and the high-speed maneuverability of the underwater vehicle, and good benefits are obtained.

Description

Technical Field

[0001] This invention relates to the field of underwater vehicle power and drag reduction technology, specifically to an underwater vehicle and driving method based on supercavitation drag reduction using energy storage compressed gas. Background Technology

[0002] With the advancement of related technologies, underwater vehicles are beginning to perform more tasks, such as marine environmental surveys, seabed measurements, and real-time communication.

[0003] Endurance and speed are key performance indicators for the planning and execution of underwater vehicles. Currently, most underwater vehicles have speeds below 6 knots, with a few reaching 6–12 knots. To meet the needs of future marine operations and improve the mission execution and underwater survivability of underwater vehicles, there is an urgent need to enhance their overall performance in terms of high speed, long endurance, and high maneuverability, especially high-speed navigation capabilities above 20 knots and high maneuverability exceeding 2 m / s².

[0004] The propulsion system is one of the core elements affecting speed, endurance, and maneuverability, and it places high demands on the mass or volumetric energy density of the energy storage medium. Lithium-ion batteries are widely used as the energy storage medium for both light and heavy underwater vehicles due to their high energy density, wide operating temperature range, and long cycle life. Current research on the propulsion performance of lithium-ion batteries for underwater vehicles is relatively comprehensive. However, the endurance of underwater vehicles decreases significantly during high-speed maneuvers, primarily due to the substantial increase in drag at high speeds. Therefore, underwater drag reduction technology is also a key technology for improving the speed, endurance, and high-speed maneuverability of underwater vehicles.

[0005] Current research on underwater drag reduction technologies mainly includes microstructure drag reduction, superhydrophobic surface drag reduction, and supercavitation drag reduction. Microstructure drag reduction technology suffers from drawbacks such as low manufacturing precision, poor dynamic adaptability, and insufficient research on drag reduction performance. Hydrostatic pressure, underwater chemicals, and pollutants can reduce the lifespan of the air layer on superhydrophobic surfaces, making superhydrophobic surface drag reduction difficult to apply to marine environments. Supercavitation drag reduction technology reduces drag by generating a stable gas phase around the vehicle, placing lower demands on the vehicle's structure and achieving drag reduction rates exceeding 90%. Supercavitation drag reduction is divided into natural supercavitation drag reduction and artificially ventilated supercavitation drag reduction. The former requires sufficiently high speeds, is difficult to achieve, and has poor stability; the latter requires an air source and can be used for drag reduction in underwater vehicles. Using artificially ventilated supercavitation in lithium-ion battery-powered underwater vehicles is expected to significantly reduce drag, but artificial ventilation systems occupy a large amount of limited space. It is necessary to explore other novel propulsion systems to meet the high speed, long endurance, and high maneuverability performance requirements of future underwater vehicles.

[0006] Systems that use compressed gas as the energy storage medium for underwater vehicles and power the vehicle through its expansion have advantages such as rapid inflation and high safety. They have shown promising application prospects in vehicles and other equipment. Furthermore, the hydrostatic pressure of seawater provides excellent conditions for achieving isobaric expansion, which helps reduce... Therefore, it is possible to effectively apply compressed gas propulsion systems to underwater vehicles, and to share a gas source with artificial ventilation supercavitation systems. Through effective coupling of the two, the space occupancy rate can be effectively reduced.

[0007] A search revealed no prior art related to the compressed gas-powered underwater vehicle capable of generating supercavitation drag reduction, as described in this invention, within the field of underwater vehicle propulsion and drag reduction technology. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing an underwater vehicle driven by supercavitation drag reduction energy storage compressed gas and its driving method.

[0009] The objective of this invention is achieved through the following technical solution: an underwater vehicle driven by compressed gas based on supercavitation drag reduction, comprising a gas working medium passage, a seawater working medium passage, and a torque rotation shaft;

[0010] The gas working medium passage includes a compressed gas storage tank, a pneumatic switch valve, a cavitation unit at the head of the aircraft, and N expansion heat exchange units consisting of a control valve, an expander, a heat exchanger, and a tee connector.

[0011] The heat exchanger of each expansion heat exchange unit is connected to the outlet I of the control valve and the expander via a three-way connector. The outlet of the expander is connected to the heat exchanger of the next expansion heat exchange unit. The outlet II of the control valve of each expansion heat exchange unit is connected to the inlet of the control valve of the next expansion heat exchange unit.

[0012] The gas outlet of the compressed gas storage tank is connected to the heat exchanger of the first expansion heat exchange unit through a pneumatic switch valve; after the compressed gas is expanded and heat exchanged through several expansion heat exchange units, the outlet of the expander of the Nth expansion heat exchange unit is connected to the cavitation unit at the head of the aircraft through a gas pipeline, and the gas is discharged into the external flow field of the aircraft to form supercavitation and achieve drag reduction.

[0013] The seawater working medium passage is the seawater inlet and outlet passage of the heat exchanger in each expansion heat exchange unit.

[0014] The torque drive shaft includes an expander, a gearbox, and a propulsion device for the expansion heat exchange unit; the expanders of two adjacent expansion heat exchange units are connected by a gearbox; the expander of the Nth expansion heat exchange unit is connected to the propulsion device through the Nth gearbox to provide thrust to the spacecraft.

[0015] Furthermore, the first expansion heat exchange unit does not include a tee joint, and the heat exchange of the first expansion heat exchange unit is directly connected to the expander through the outlet I of the control valve; the Nth expansion heat exchange unit does not include a control valve, the outlet II of the control valve in the (N-1)th expansion heat exchange unit is directly connected to the tee joint of the Nth expansion heat exchange unit, and the expander of the Nth expansion heat exchange unit is directly connected to the gas pipeline.

[0016] Furthermore, the compressed gas storage tank stores air, carbon dioxide, or nitrogen, and the pressure of the compressed gas is 0.5 to 100 MPa.

[0017] Furthermore, the number of expansion heat exchange units is 1 to 10.

[0018] Furthermore, the heat exchanger used in each expansion heat exchange unit is a shell-and-tube heat exchanger or a microchannel heat exchanger, the heat source of the heat exchanger is seawater, and the temperature of the heat source of the heat exchanger is -2 to 30°C.

[0019] Furthermore, the expander used in each expansion heat exchange unit includes at least one of piston expander, screw expander, scroll expander, or turbine expander.

[0020] Furthermore, the gearbox in the torque drive shaft is of at least one type, including an AT gearbox, a CVT gearbox, an AMT gearbox, or a DCT gearbox, and the gearbox includes a clutch.

[0021] Furthermore, the propulsion device is a fixed-pitch propeller or a variable-pitch propeller.

[0022] Furthermore, the cavitation device at the nose of the aircraft is a disc cavitation device or a conical cavitation device.

[0023] On the other hand, the present invention also provides a driving method for an energy storage compressed gas-powered underwater vehicle based on supercavitation drag reduction, the driving method including a gas expansion and ventilation process and a torque transmission process.

[0024] The gas expansion and ventilation process includes: the compressed gas storage tank releases high-pressure gas, and the gas temperature decreases during the release process. The high-pressure gas flow rate is controlled by a pneumatic switch valve. After the gas exchanges heat with seawater in the heat exchanger of the first expansion heat exchange unit and is heated, it expands and does work through the expander in the first expansion heat exchange unit, and the gas temperature decreases. Then it enters the second expansion heat exchange unit. After going through N expansion heat exchange units, the process of heat exchange, heating and expansion is repeated. Finally, the gas flows through the gas pipeline to the cavitation device at the head of the vehicle and is discharged into the external flow field of the vehicle, forming supercavitation to achieve drag reduction. If the compressed gas pressure in the compressed gas storage tank is lower than the set cutoff pressure of the expander in the i-th expansion heat exchange unit, the expanders in the first to the i-th expansion heat exchange units stop operating. After the gas is released from the compressed gas storage tank, it passes through the control valve outlet II in the first to the i-th expansion heat exchange units in sequence and enters the (i+1)-th expansion heat exchange unit for heat exchange, heating and expansion.

[0025] The torque transmission process includes: the gas expands and outputs torque in the expander of the first expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the first gearbox, the gas passes through the expanders and gearboxes in the second expansion heat exchange unit. After passing through the expanders and gearboxes in N expansion heat exchange units, the gas expands and outputs torque in the expander of the Nth expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the Nth gearbox, the torque is transmitted to the propulsion device. The propulsion device provides thrust to the spacecraft. If the pressure of the compressed gas in the compressed gas storage tank is lower than the set cutoff pressure of the expander in the i-th expansion heat exchange unit, the expanders in the first to the i-th expansion heat exchange units stop operating, and the clutches in the first to the i-th gearboxes work to disengage the drive shaft of the expander in the corresponding expansion heat exchange unit from the main shaft, and the gas expands and outputs torque in the (i+1)-th expansion heat exchange unit.

[0026] Compared with the prior art, the beneficial effects of this invention are as follows:

[0027] 1. This invention proposes an underwater vehicle driven by compressed gas based on supercavitation drag reduction. Compressed gas is used as the energy storage medium for the underwater vehicle's power system, replacing the traditional underwater vehicle power system that uses lithium batteries as the energy storage medium and the system that separates power and drag reduction. At the same time, to address the problems of low speed, short endurance, and poor high-speed maneuverability of lithium battery systems, this invention proposes a method of coupling ventilated supercavitation drag reduction technology with the compressed gas power system. This satisfies the underwater vehicle's power requirements while reducing the vehicle's drag by applying underwater supercavitation drag reduction technology. It effectively utilizes the work capacity of compressed gas and the exhaust gas after expansion, making the system more compact and improving the underwater vehicle's speed, endurance, and high-speed maneuverability. In this embodiment, the compressed gas storage tank stores air at 100 MPa and 15°C, with a mass energy density of up to 135 Wh / kg. The seawater temperature is 15°C. The gas is expanded and does work through a four-stage expansion system. The system flow is established on the MATLAB / Simulink platform, and a supercavitating flow hydrodynamic model is established on the Fluent platform. The joint simulation calculation shows that, compared with the lithium iron phosphate battery system, this dynamic drag reduction system can improve the endurance by 2.73% to 458.20% at speeds of 1 to 60 knots with the same energy storage, and by 42.02% to 148.96% at speeds of 30 to 60 knots with the same energy storage mass.

[0028] 2. In the embodiment, the cavitation device is a disc cavitation device with a diameter of 80mm, and the vehicle is a lightweight underwater vehicle with a diameter of 324mm. It can achieve a maximum drag reduction rate of about 84%. At high speeds, the system coupling characteristics show that the maximum drag reduction rate can generally be achieved, which can greatly improve the speed of the underwater vehicle and its high-speed maneuverability.

[0029] 3. Since the compressed gas power system and the supercavitation drag reduction system share the same gas source in this invention, the overall compactness of the system can be improved and the system mass can be reduced. Using the exhaust gas of the power system for drag reduction can improve energy utilization efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an underwater vehicle and its driving method based on supercavitation drag reduction and energy storage compressed gas, as shown in the embodiment. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] See Figure 1 An underwater vehicle driven by compressed gas based on supercavitation drag reduction in this embodiment includes a gas working medium passage, a seawater working medium passage, and a torque rotation shaft.

[0033] The gas working medium passage includes a compressed gas storage tank 1, a pneumatic switch valve 2, a cavitation device 14 at the head of the aircraft, and N expansion heat exchange units consisting of a control valve, an expander, a heat exchanger, and a tee connector.

[0034] The heat exchanger of each expansion heat exchange unit is connected to the outlet I of the control valve and the expander via a three-way connector. The outlet of the expander is connected to the heat exchanger of the next expansion heat exchange unit. The outlet II of the control valve of each expansion heat exchange unit is connected to the inlet of the control valve of the next expansion heat exchange unit.

[0035] The gas outlet of the compressed gas storage tank 1 is connected to the heat exchanger 3 of the first expansion heat exchange unit via a pneumatic switch valve 2. The heat exchanger 3 of the first expansion heat exchange unit is connected to the control valve 4 of the first expansion heat exchange unit. The outlet I of the control valve 4 of the first expansion heat exchange unit is connected to the heat exchanger 6 of the second expansion heat exchange unit via the expander 5 of the first expansion heat exchange unit. The heat exchanger 6 of the second expansion heat exchange unit is connected to the tee connector 7 of the second expansion heat exchange unit. The outlet II of the control valve 4 of the first expansion heat exchange unit is connected to the control valve 8 of the second expansion heat exchange unit. The outlet I of the control valve 8 of the second expansion heat exchange unit is connected to the second expansion heat exchange unit via the tee connector 7 of the second expansion heat exchange unit. The expander 9 of the second expansion heat exchange unit is connected to the heat exchanger 10 of the third expansion heat exchange unit; and so on. After the compressed gas is expanded and heat exchanged by several expansion heat exchange units, the control valve of the (N-1)th expansion heat exchange unit is directly connected to the three-way connector 11 of the Nth expansion heat exchange unit; the Nth three-way connector 11 is connected to the expander 12 of the Nth expansion heat exchange unit; the outlet of the expander 12 of the Nth expansion heat exchange unit is connected to the cavitation device 14 at the head of the vehicle through the gas pipeline 13; the gas is discharged into the external flow field of the vehicle to form supercavitation and achieve drag reduction; the seawater working medium passage is the seawater inlet and outlet passage of the heat exchanger in each expansion heat exchange unit.

[0036] The torque drive shaft includes an expander of the expansion heat exchange unit, a gearbox, and a propulsion device 18; the expander 5 of the first expansion heat exchange unit is connected to the expander 9 of the second expansion heat exchange unit through the first gearbox 15, the expander 9 of the second expansion heat exchange unit is connected to the expander of the third expansion heat exchange unit through the second gearbox 16; and so on, the expander 12 of the Nth expansion heat exchange unit is connected to the propulsion device 18 through the Nth gearbox 17 to provide thrust for the vehicle.

[0037] Combination Figure 1 The underwater vehicle propulsion method based on supercavitation drag reduction and energy storage compressed gas in this embodiment adopts the above-mentioned underwater vehicle propulsion method based on supercavitation drag reduction and energy storage compressed gas.

[0038] The supercavitation drag reduction-based compressed gas propulsion underwater vehicle drive method in this embodiment includes a gas expansion and ventilation process and a torque transmission process.

[0039] The gas expansion and ventilation process includes: the compressed gas storage tank 1 releases high-pressure gas, and the gas temperature decreases during the release process. The high-pressure gas flow rate is controlled by the pneumatic switch valve 2. After the gas exchanges heat with seawater in the heat exchanger 3 of the first expansion heat exchange unit and is heated, it enters the expander 5 of the first expansion heat exchange unit through the outlet I of the control valve 4 in the first expansion heat exchange unit to expand and do work, and the gas temperature decreases. Then, it exchanges heat with seawater in the heat exchanger 6 of the second expansion heat exchange unit and is heated. Then, it enters the expander 9 of the second expansion heat exchange unit through the three-way connector 7 in the second expansion heat exchange unit to expand and do work, and the gas temperature decreases. This process is repeated through N expansion heat exchange units. Finally, it expands and does work through the expander 12 of the Nth expansion heat exchange unit. Then, it flows through the gas pipeline 13 to the cavitation unit 14 at the head of the vehicle and is discharged into the external flow field of the vehicle, forming supercavitation to achieve drag reduction.

[0040] If the pressure of compressed gas in compressed gas storage tank 1 is lower than the set cut-off pressure of the expander in the i-th expansion heat exchange unit, the expanders in the first to the i-th expansion heat exchange units will all stop running. After the gas is released from compressed gas storage tank 1, it will pass through the control valve outlet II in the first to the i-th expansion heat exchange units in sequence, and enter the (i+1)-th expansion heat exchange unit for heat exchange, temperature rise and expansion to do work.

[0041] The torque transmission process includes: the gas expands and outputs torque in the expander 5 of the first expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the first gearbox 15, the gas is coaxial with the expander 9 in the second expansion heat exchange unit. The gas expands and outputs torque in the expander 9 of the second expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the gearbox 16 in the second expansion heat exchange unit, the process continues. After passing through the expanders and gearboxes in N expansion heat exchange units, the gas expands and outputs torque in the expander 12 of the Nth expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the Nth gearbox 17, the torque is transmitted to the propulsion device 18, and the propulsion device 18 provides thrust to the spacecraft.

[0042] If the pressure of compressed gas in compressed gas storage tank 1 is lower than the set cut-off pressure of the expander in the i-th expansion heat exchange unit, then the expanders in the first to the i-th expansion heat exchange units will all stop running, and the clutches in the first to the i-th gearboxes will work to disengage the drive shaft of the expander in the corresponding expansion heat exchange unit from the main shaft, so that the (i+1)-th expansion heat exchange unit can expand and do work to output torque.

[0043] As the number of the N expansion heat exchange units increases, the power output of the system will increase accordingly, and the actual energy storage density of the compressed gas will also increase, which is beneficial to improving the speed, endurance and maneuverability of the aircraft. However, the number of components used will increase, which will lead to a larger overall weight and space occupancy of the aircraft. Therefore, it is necessary to design a reasonable number of expansion heat exchange units according to the requirements.

[0044] The system flow is established on the MATLAB / Simulink platform. In this embodiment, the compressed gas storage tank 1 stores air at a pressure of 100 MPa. The number of expansion heat exchange units N is 4, which includes a total of 4 expanders, 4 heat exchangers, 3 control valves, 3 T-joints, and 4 gearboxes. The heat exchangers used are microchannel heat exchangers, and the heat source for the heat exchangers is seawater at a temperature of 15°C. The expanders used are turbine expanders. The gearboxes used are D-type gearboxes. The CT gearbox includes a clutch; the propulsion device 18 is a controllable pitch propeller; the cavitation device 14 is a disc cavitation device with a diameter of 80 mm; a supercavitating flow hydrodynamic model was established on the Fluent platform, and calculations showed that the maximum drag reduction rate can reach about 84%. Co-simulation calculations showed that compared with the lithium iron phosphate battery system, this power drag reduction system can increase the endurance by 2.73% to 458.20% at speeds of 1 to 60 knots under the same energy storage conditions, and can increase the endurance by 42.02% to 148.96% at speeds of 30 to 60 knots under the same energy storage mass.

[0045] This invention proposes a novel solution for underwater vehicle propulsion-drag reduction systems based on supercavitation drag reduction using compressed gas. The improved power output is achieved through the rational design of the compressed gas propulsion system and the increased efficiency of its components. Furthermore, the coupling of power and drag is achieved through gas flow control, thereby enhancing the overall power output of the system and increasing speed and endurance. Compared to traditional lithium-ion battery propulsion systems, this invention results in a more compact system. At any speed, with the same energy storage capacity, the endurance of this invention is longer than that of lithium-ion battery systems. At high speeds, with the same energy storage mass, the endurance of this invention is also longer than that of lithium-ion battery systems. Overall, this system offers improved compactness, enhancing the speed, endurance, and high-speed maneuverability of underwater vehicles, and possesses significant practical application value in underwater applications.

[0046] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. An underwater vehicle driven by compressed gas with supercavitation drag reduction, characterized in that, This includes a gas working medium passage, a seawater working medium passage, and a torque drive shaft; The gas working medium passage includes a compressed gas storage tank (1), a pneumatic switch valve (2), a cavitation device (14) at the head of the aircraft, and N expansion heat exchange units consisting of a control valve, an expander, a heat exchanger, and a tee connector. The heat exchanger of each expansion heat exchange unit is connected to the outlet I of the control valve and the expander via a three-way connector. The outlet of the expander is connected to the heat exchanger of the next expansion heat exchange unit. The outlet II of the control valve of each expansion heat exchange unit is connected to the inlet of the control valve of the next expansion heat exchange unit. The gas outlet of the compressed gas storage tank (1) is connected to the heat exchanger (3) of the first expansion heat exchange unit through a pneumatic switch valve (2); after the compressed gas is expanded and heat exchanged by several expansion heat exchange units, the outlet of the expander (12) of the Nth expansion heat exchange unit is connected to the cavitation device (14) at the head of the aircraft through a gas pipeline (13), and the gas is discharged into the external flow field of the aircraft to form supercavitation and achieve drag reduction effect. The seawater working medium passage is the seawater inlet and outlet passage of the heat exchanger in each expansion heat exchange unit. The torque drive shaft includes an expander of the expansion heat exchange unit, a gearbox, and a propulsion device (18); the expanders of two adjacent expansion heat exchange units are connected by a gearbox; the expander of the Nth expansion heat exchange unit is connected to the propulsion device (18) through the Nth gearbox (17) to provide thrust to the aircraft.

2. The underwater vehicle driven by compressed gas based on supercavitation drag reduction as described in claim 1, characterized in that, The first expansion heat exchange unit does not include a three-way connector. The heat exchanger (3) of the first expansion heat exchange unit is directly connected to the expander through the outlet I of the control valve (4) of the first expansion heat exchange unit. The Nth expansion heat exchange unit does not include a control valve. The outlet II of the control valve in the N-1th expansion heat exchange unit is directly connected to the three-way connector of the Nth expansion heat exchange unit. The expander (12) of the Nth expansion heat exchange unit is directly connected to the gas pipeline (13).

3. The underwater vehicle driven by compressed gas based on supercavitation drag reduction as described in claim 1, characterized in that, The compressed gas storage tank (1) stores air, carbon dioxide or nitrogen, and the pressure of the compressed gas is 0.5 to 100 MPa.

4. The underwater vehicle driven by compressed gas based on supercavitation drag reduction as described in claim 1, characterized in that, The number of expansion heat exchange units is 1 to 10.

5. The underwater vehicle driven by compressed gas based on supercavitation drag reduction as described in claim 1, characterized in that, The heat exchanger used in each expansion heat exchange unit is a shell-and-tube heat exchanger or a microchannel heat exchanger, and the heat source of the heat exchanger is seawater, with a temperature of -2 to 30°C.

6. The underwater vehicle driven by compressed gas based on supercavitation drag reduction according to claim 1, characterized in that, The expander used in each expansion heat exchange unit includes at least one of the following types: piston expander, screw expander, scroll expander, or turbine expander.

7. The underwater vehicle driven by compressed gas based on supercavitation drag reduction according to claim 1, characterized in that, The gearbox in the torque drive shaft is of at least one type, including AT gearbox, CVT gearbox, AMT gearbox, or DCT gearbox, and the gearbox includes a clutch.

8. The underwater vehicle driven by compressed gas based on supercavitation drag reduction according to claim 1, characterized in that, The propulsion device (18) is a fixed-pitch propeller or a variable-pitch propeller.

9. The underwater vehicle driven by compressed gas based on supercavitation drag reduction according to claim 1, characterized in that, The cavitation device (14) at the nose of the aircraft is a disc cavitation device or a cone cavitation device.

10. A propulsion method for an underwater vehicle based on supercavitation drag reduction and energy storage compressed gas as described in any one of claims 1-9, characterized in that, The driving method includes a gas expansion and ventilation process as well as a torque transmission process; The gas expansion and ventilation process includes: the compressed gas storage tank (1) releases high-pressure gas, the gas temperature decreases during the release process, the high-pressure gas flow rate is controlled by the pneumatic switch valve (2), the gas heats up by exchanging heat with seawater in the heat exchanger (3) in the first expansion heat exchange unit, and then expands and does work through the expander in the first expansion heat exchange unit, the gas temperature decreases, and then enters the second expansion heat exchange unit. After going through N expansion heat exchange units, the gas repeatedly heats up and expands and does work, and finally flows through the gas pipeline (13) to the cavitation device (14) at the head of the aircraft and is discharged into the external flow field of the aircraft, forming supercavitation to achieve drag reduction effect; if the compressed gas pressure in the compressed gas storage tank (1) is lower than the set cut-off pressure of the expander in the i-th expansion heat exchange unit, the expanders in the first to the i-th expansion heat exchange units stop running, and the gas is released from the compressed gas storage tank (1) and passes through the control valve outlet II in the first to the i-th expansion heat exchange units in sequence, and enters the (i+1)-th expansion heat exchange unit for heat exchange, heating and expansion and work; The torque transmission process includes: the gas expands and outputs torque in the expander of the first expansion heat exchange unit, and transmits the torque to the main shaft through the drive shaft. After the speed is changed by the first gearbox (15), the gas passes through the expander (9) in the second expansion heat exchange unit. After passing through the expanders and gearboxes in N expansion heat exchange units, the gas expands and outputs torque in the expander (12) of the Nth expansion heat exchange unit. The torque is transmitted to the main shaft through the drive shaft. After the speed is changed by the Nth gearbox (17), the torque is transmitted to the propulsion device (18). The propulsion device (18) provides thrust to the aircraft. If the pressure of the compressed gas in the compressed gas storage tank (1) is lower than the set cutoff pressure of the expander in the i-th expansion heat exchange unit, the expanders in the first to the i-th expansion heat exchange units stop running. The clutches in the first to the i-th gearboxes work to disengage the drive shaft of the expander in the corresponding expansion heat exchange unit from the main shaft, and the expander in the (i+1)-th expansion heat exchange unit expands and outputs torque.

Images