A free piston shock tunnel and a ground test method thereof

Abstract

The application provides a free piston shock tunnel and a ground test method thereof, the tunnel comprises a high-pressure working medium power device, a compression pipe, a shock tube, a gas accelerating nozzle device and a test section; the high-pressure working medium power device, the compression pipe, the shock tube, the gas accelerating nozzle device and the test section are sequentially fixedly connected along the same horizontal direction; the high-pressure working medium power device is internally provided with liquid high-pressure working medium, the compression pipe is internally provided with a compression piston, and the test section is used for setting a hypersonic vehicle; the liquid high-pressure working medium can be gasified to generate gaseous high-pressure working medium B and drive the compression piston to compress the driving gas in the compression pipe to pass through the shock tube and the gas accelerating nozzle device, so as to perform a hypersonic ground simulation test on the hypersonic vehicle in the test section; the scheme provided by the application has high safety without using flammable and explosive gas, the test equipment occupies a small volume, the test efficiency of the free piston shock tunnel is effectively improved, controllability is relatively strong, and the test performance of the tunnel can be improved.

Description

Technical Field

[0001] This invention belongs to the field of free piston shock wave wind tunnel technology, specifically relating to a free piston shock wave wind tunnel and its ground testing method. Background Technology

[0002] Hypersonic vehicles exhibit complex physical phenomena due to the high-speed airflow during operation. To address this, hypersonic ground testing technology effectively simulates the real gas effects during hypersonic vehicle operation. The free-piston shock tunnel is a typical device used in high-enthalpy ground testing. Utilizing piston compression and shock tube constant-pressure drive principles, the free-piston shock tunnel employs a heavy-duty piston compressor as the high-enthalpy pulse device in the shock tube drive section. It can generate extremely high pressures and enthalpies, with the enthalpy of the airflow in the test section exceeding that of near-Earth orbit vehicles. In recent years, with optimizations and improvements to free-piston shock tunnel technology, it can now simulate the flight state of hypersonic vehicles within the atmosphere, making it an effective tool for researching hypersonic scramjet engines.

[0003] Existing free piston shock tunnels mostly use high-pressure air as the driving source. Their operating principle is based on piston compression and constant-pressure drive in the shock tube. Specifically, the high-pressure air collection device is first filled with high-pressure air, which drives the piston in the compression tube to accelerate. Through a reasonable film-breaking time, a strong shock wave is formed inside the shock tube, rapidly increasing the temperature and pressure of the air inside, subsequently generating high-enthalpy flow through the nozzle. The drawbacks of using high-pressure air as the driving source in free piston shock tunnels are as follows: Free piston shock tunnels require a huge high-pressure air collection device, increasing the overall tunnel volume and cost; the air pressure of the high-pressure air collection device is limited, restricting its driving capacity; after completing a hypersonic ground test, a significant amount of time is needed to replenish the high-pressure air collection device, extending the test cycle. Therefore, optimizing the performance of the driving source for free piston shock tunnels—in a miniaturized, high-performance, rapid, and low-cost manner—is a challenging problem that needs to be solved in this field.

[0004] Given the technical problems existing in the free piston shock tunnel mentioned above, there are currently no relevant solutions; therefore, there is an urgent need to find effective solutions to address these problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned technologies by proposing a free piston shock tunnel and its ground testing method, aiming to solve the problem of poor performance of existing free piston shock tunnels.

[0006] The present invention provides a free piston shock tunnel, which comprises a high-pressure working medium power device, a compression tube, a shock tube, a gas acceleration nozzle device and an experimental section; the high-pressure working medium power device, the compression tube, the shock tube, the gas acceleration nozzle device and the experimental section are fixedly connected in sequence along the same horizontal direction; a liquid high-pressure working medium is provided in the high-pressure working medium power device, a compression piston is provided in the compression tube, and a hypersonic wind vehicle is arranged in the experimental section; the liquid high-pressure working medium can be vaporized to generate a gaseous high-pressure working medium B, and drive the compression piston to compress the driving gas in the compression tube through the shock tube and the gas acceleration nozzle device, so as to conduct a hypersonic ground simulation test on the hypersonic wind vehicle in the experimental section.

[0007] Furthermore, a heating agent is also provided in the high-pressure working medium power device, and a plurality of heating agents are fixed in the liquid high-pressure working medium; the heating agent is also electrically connected to a chemical reaction control device outside the high-pressure working medium power device through a signal line; in the unexcited state, the heating agent and the liquid high-pressure working medium are separated by a film respectively, and in the excited state, the heating agent completes deflagration, causing the film to rupture, so as to excite the liquid high-pressure working medium to complete phase change conversion.

[0008] Furthermore, the liquid high-pressure working medium is encapsulated in the high-pressure working medium power device through a burst pressure relief valve plate; the burst pressure relief valve plate faces the compression piston; the gaseous high-pressure working medium B generated by the vaporization of the liquid high-pressure working medium can break through the burst pressure relief valve plate under a preset pressure, and push the compression piston to compress the driving gas; a high-pressure working medium injection valve is also provided on the high-pressure working medium power device.

[0009] Furthermore, the number of the heating agents is N, and N satisfies 1≤N≤8; one end of the high-pressure working medium power device is hermetically connected to one end of the compression tube through a flange; the other end of the compression tube is hermetically connected to one end of the shock tube through a flange; the other end of the shock tube is hermetically connected to one end of the gas acceleration nozzle device through a flange; the other end of the gas acceleration nozzle device is hermetically connected to one end of the experimental section through a flange.

[0010] Furthermore, the length of the chamber is L1, and the inner diameter of the chamber in the high-pressure working medium power device is d1; the thickness of the burst pressure relief valve plate is h, and h satisfies 4mm < h < 10mm; the diameter of the burst pressure relief valve plate is d3, and d3 satisfies 0.8d < L1 < 2d; the length of the rupture throat in the high-pressure working medium power device is L3, and L3 satisfies L3 = 3h; the diameter of the rupture throat in the high-pressure working medium power device is d, and d satisfies d4 = d3; the diameter of the pressure relief port of the high-pressure working medium power device is d4, and d4 satisfies 0.6d < d4 < d1; the length of the expansion section of the high-pressure working medium power device is L4, and L4 satisfies 0.6L2 < L4 < L2.

[0011] Further, the inner diameter of the compression tube is d5, and d5 satisfies d5 = d4; the diameter of the compression piston is equal to the inner diameter of the compression tube; the diameter of the outlet of the compression tube is d6, and d6 satisfies 0.6d5 < d6 < 2d5; the inner diameter of the shock tube, the diameter of the air inlet of the gas acceleration nozzle device, and the diameter d6 of the outlet of the compression tube are equal.

[0012] Further, the inner diameter of the chamber in the high-pressure working medium power device is d1, and the value range of d1 is 300 mm to 1500 mm; the length of the chamber is L1, and L1 satisfies: 6d1 < L1 < 10d1; the length 2L of the contraction section in the high-pressure working medium power device, and L2 satisfies 0.3L < L2.

[0013] Further, the shock tube is a single-stage or multi-stage diaphragm shock tube; the compressed driving gas forms a moving shock wave in the shock tube, and the compressed driving gas is heated and pressurized.

[0014] Further, the liquid high-pressure working medium is liquid nitrogen, liquid ammonia or liquid carbon dioxide.

[0015] Further, the driving gas is argon, helium or hydrogen.

[0016] Correspondingly, in combination with the above solutions, the present invention also provides a ground test method for a free piston shock tunnel, using the free piston shock tunnel described above; the ground test method conducts a hypersonic ground simulation test for a hypersonic vehicle and simulates the real gas effect during the operation of the hypersonic vehicle; the ground test method includes the following processes:

[0017] S1: Fix the heating agent in the high-pressure working medium power device, connect the agent reaction control device with a signal line, and inject the liquid high-pressure working medium into the high-pressure working medium power device through the high-pressure working medium injection valve;

[0018] S2: The agent reaction control device starts the heating agent to release a large amount of heat, so that the liquid high-pressure working medium in the high-pressure working medium power device is quickly vaporized to generate gaseous high-pressure working medium B;

[0019] S3: The vaporized liquid high-pressure working medium B breaks through the explosion-proof valve piece and pushes the compression piston to compress the driving gas;

[0020] S4: The compressed driving gas forms a moving shock wave in the shock tube, and the compressed driving gas is heated and pressurized;

[0021] S5: The high-temperature and high-pressure driving gas is accelerated and expanded in the gas acceleration nozzle device to form an ultra-high-speed and high-enthalpy fluid and enters the experimental section, and acts on the hypersonic vehicle, completing the entire ground experiment simulation process of the hypersonic vehicle.

[0022] The technical solution provided by the present invention has the following technical effects:

[0023] First, the solution provided by the present invention uses a liquid high-pressure working fluid as a driving source. The liquid high-pressure working fluid is instantly converted into a gaseous high-pressure working fluid through a high-pressure working fluid power device, generating ultra-high pressure and driving the piston to do work on the driving gas in the compression tube, so that the driving gas is rapidly heated and pressurized. The driving gas enters the shock tube and forms a shock wave in the tube, which heats and pressurizes the gas in the driven section of the shock tube. The gas in the driven section expands and accelerates through the nozzle device, forming the high enthalpy flow required by the missile or aerospace vehicle.

[0024] Secondly, the solution provided by this invention uses a liquid high-pressure working fluid as a driving source. By reasonably selecting the amount of heating agent, the liquid high-pressure working fluid in the high-pressure working fluid power device can be fully vaporized and pressurized. Different driving pressures can be obtained by adjusting the amount of liquid high-pressure working fluid and the thickness of the explosion relief valve plate. The amount of liquid high-pressure working fluid controls the working time, and the thickness of the explosion relief valve plate controls the maximum acceleration of the piston. Different working conditions can be met without complicated operations.

[0025] Third, the solution provided by this invention has strong controllability; the entire experimental process does not use flammable or explosive gases, resulting in high safety; the experiment uses liquid high-pressure working fluid for driving, which reduces operating costs; it can realistically reproduce the actual operating environment of hypersonic wind turbines; the high-pressure working fluid driving source can generate extremely high pressure, thus obtaining extremely high experimental performance parameters; the small volume of the liquid high-pressure working fluid can effectively reduce the volume of the entire experimental system. Attached Figure Description

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] The present invention will be further described below with reference to the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of the free piston shock tunnel before the start of this invention;

[0029] Figure 2 This is a schematic diagram of the free piston shock tunnel after the invention has been started;

[0030] Figure 3 This is a schematic diagram of a free piston shock wave wind tunnel according to the present invention.

[0031] In the diagram: 1. High-pressure working fluid power unit; 2. Compression pipe; 3. Shock tube; 4. Gas acceleration nozzle device; 5. Experimental section; 6. Heating agent; 7. High-pressure working fluid injection valve; 8. Agent reaction control equipment; 9. Liquid high-pressure working fluid; 10. Explosion relief valve; 11. Compression piston; 12. Driving gas; 13. Hypersonic winder; A. High-enthalpy fluid; B. Gaseous high-pressure working fluid; N. Quantity of heating agent; h. Thickness of explosion relief valve; d1. Inner diameter of high-pressure working fluid power unit chamber; d2. Outer diameter of high-pressure working fluid power unit; d3. Diameter of explosion relief valve; d4. Diameter of high-pressure working fluid power unit pressure relief port; d5. Inner diameter of compression pipe; d6. Diameter of compression pipe outlet; L1. Length of high-pressure working fluid power unit chamber; L2. Length of contraction section; L3. Length of rupture throat; L4. Length of expansion section. Detailed Implementation

[0032] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0033] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0035] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] 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 a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] like Figures 1 to 3 As shown, this invention provides a free piston shock tunnel, which includes a high-pressure working fluid power unit 1, a compression pipe 2, a shock pipe 3, a gas acceleration nozzle device 4, and an experimental section 5; wherein, the high-pressure working fluid power unit 1, the compression pipe 2, the shock pipe 3, the gas acceleration nozzle device 4, and the experimental section 5 are sequentially and fixedly connected in the same horizontal direction; further, the high-pressure working fluid power unit 1 contains a liquid high-pressure working fluid 9, which serves as the power source; further, the compression pipe 2 contains a compression piston 11, which is used to compress the driving gas 12 under pressure; further, the experimental section 5 is used to house a hypersonic wind vehicle 13, which can be a missile or a spacecraft; specifically, the liquid high-pressure working fluid 9 can vaporize to generate a gaseous high-pressure working fluid B, which drives the compression piston 11 to compress the driving gas 12 in the compression pipe 2 through the shock pipe 3 and the gas acceleration nozzle device 4, thereby conducting a hypersonic ground simulation test on the hypersonic wind vehicle 13 in the experimental section 5; further, the shock pipe 3 utilizes motion The shock wave compresses the driven gas, causing it to rapidly heat up and pressurize. The gas acceleration nozzle 4 accelerates the high-temperature, high-pressure driven gas after it leaves the shock tube 3, forming the high-enthalpy flow required by missiles and aerospace vehicles. The experimental section 5 is used to install the hypersonic flight device to be tested. The free piston shock wave wind tunnel provided by this invention uses a high-pressure working fluid as the driving source. The instantaneous heating and phase change of the high-pressure working fluid can instantly generate a high-energy shock wave and a high-pressure gas to produce a huge driving force. This enables the miniaturization and lightweighting of the free piston shock wave wind tunnel driving source, increases the upper limit of the driving source pressure, obtains extremely high experimental performance parameters, and can also meet the requirements of high-frequency testing, effectively improving the testing efficiency of the free piston shock wave wind tunnel. It also has strong controllability. The entire experimental process does not use flammable or explosive gases, ensuring high safety. The experiment uses a liquid high-pressure working fluid for driving, resulting in low operating costs. It can realistically reproduce the actual operating environment of hypersonic wind vehicles. The high-pressure working fluid driving source can generate extremely high pressure, thus obtaining extremely high experimental performance parameters. The experimental equipment occupies a small volume, improving the testing performance of the wind tunnel.

[0038] Preferably, in combination with the above schemes, such as Figures 1 to 3As shown, the high-pressure working fluid power unit 1 is also equipped with a heating agent 6, and multiple heating agents 6 are fixed in the liquid high-pressure working fluid 9; furthermore, the heating agent 6 is also electrically connected to the agent reaction control device 8 outside the high-pressure working fluid power unit 1 through a signal line; specifically, in the unactivated state, the heating agent 6 and the liquid high-pressure working fluid 9 are separated by a thin film; in the activated state, the heating agent 6 completes deflagration, causing the thin film to rupture, thereby stimulating the liquid high-pressure working fluid 9 to complete the phase change transformation.

[0039] Preferably, in combination with the above schemes, such as Figures 1 to 3 As shown, the liquid high-pressure working fluid 9 is encapsulated in the high-pressure working fluid power unit 1 through the explosion relief valve plate 10; further, the explosion relief valve plate 10 faces the compression piston 11; the gaseous high-pressure working fluid B generated by the vaporization of the liquid high-pressure working fluid 9 can break through the explosion relief valve plate 10 when the preset pressure is reached, and push the compression piston 11 to compress the driving gas 12; further, the high-pressure working fluid power unit 1 is also provided with a high-pressure working fluid injection valve 7 for injecting the liquid high-pressure working fluid 9.

[0040] Preferably, in combination with the above schemes, such as Figures 1 to 3 As shown, the quantity of heating agent 6 is N, where N satisfies 1≤N≤8. All heating agents 6 must be completely encapsulated in the liquid high-pressure working fluid 9. By reasonably selecting the quantity N of heating agent, the liquid high-pressure working fluid 9 in the high-pressure working fluid power device 1 can be fully vaporized and pressurized. Different driving pressure states can be obtained by adjusting the quantity of liquid high-pressure working fluid 9 and the thickness h of the explosion relief valve plate 10. The quantity of liquid high-pressure working fluid controls the work time, and the thickness h of the explosion relief valve plate 10 controls the maximum acceleration of the compression piston 11. Furthermore, the high-pressure working fluid power device 1... One end of the compression pipe 2 is sealed to one end of the compression pipe 2 via a flange; the other end of the compression pipe 2 is sealed to one end of the shock pipe 3 via a flange; the other end of the shock pipe 3 is sealed to one end of the gas acceleration nozzle device 4 via a flange; the other end of the gas acceleration nozzle device 4 is sealed to one end of the experimental section 5 via a flange; furthermore, the cooperation of the heating agent 6, the liquid high-pressure working medium 9, the explosion relief valve plate 10, the compression piston 11 and the driving gas 12 should ensure that the compression piston 23 does not collide with the compression pipe 2 when the speed is reduced to 0.

[0041] Preferably, in combination with the above schemes, such as Figures 1 to 3As shown, the inner diameter of the chamber in the high-pressure working fluid power device 1 is d1, and the value range of d1 is 300 mm to 1500 mm; the length of the chamber is L1, and L1 satisfies: 6d1 < L1 < 10d1; the thickness of the explosion vent valve plate 10 is h, and h satisfies 4 mm < h < 10 mm; the diameter of the explosion vent valve plate 10 is d3, and d3 satisfies 0.8d1 < d3 < 2d1; further, the rupture throat length in the high-pressure working fluid power device 1 is L3, and L3 satisfies L3 = 3h; further, the rupture throat diameter in the high-pressure working fluid power device 1 is d4, and d4 satisfies d4 = d3; further, the relief port diameter of the high-pressure working fluid power device 1 is d4, and d4 satisfies 0.6d1 < d4 < d1; further, the expansion section length of the high-pressure working fluid power device 1 is L4, and L4 satisfies 0.6L2 < L4 < L2; the above size design is considered in combination with the overall structure and function realization of the free piston shock tunnel, and the overall stability of the free piston shock tunnel can be improved, as well as the experimental effect can be improved.

[0042] Preferably, in combination with the above scheme, as Figures 1 to 3 shown, the inner diameter of the compression tube 2 is d5, and d5 satisfies d5 = d4; the diameter of the compression piston 11 is equal to the inner diameter of the compression tube 2; further, the diameter of the outlet of the compression tube 2 is d6, and d6 satisfies 0.6d5 < d6 < 2d5; further, the inner diameter of the shock tube 3, the inlet diameter of the gas acceleration nozzle device 4, and the diameter d6 of the outlet of the compression tube 2 are equal; the above size design is considered in combination with the overall structure and function realization of the free piston shock tunnel, and the overall stability of the free piston shock tunnel can be improved, as well as the experimental effect can be improved.

[0043] Preferably, in combination with the above scheme, as Figures 1 to 3 shown, the inner diameter of the chamber in the high-pressure working fluid power device 1 is d1, and the value range of d1 is 300 mm to 1500 mm; the length of the chamber is L1, and L1 satisfies: 6d1 < L1 < 10d1; the contraction section length L2 in the high-pressure working fluid power device 1, and L2 satisfies 0.3L1 < L2; the above size design is considered in combination with the overall structure and function realization of the free piston shock tunnel, and the overall stability of the free piston shock tunnel can be improved, as well as the experimental effect can be improved.

[0044] Preferably, in combination with the above scheme, as Figures 1 to 3 shown, the shock tube 3 is a single-stage or multi-stage diaphragm shock tube; the compressed driving gas 12 forms a moving shock wave in the shock tube 3, and the compressed driving gas 12 is heated and pressurized.

[0045] Preferably, in combination with the above scheme, as Figures 1 to 3 shown, the liquid high-pressure working fluid 9 is liquid nitrogen, liquid ammonia or liquid carbon dioxide; the driving gas 12 is argon, helium or hydrogen.

[0046] Accordingly, in conjunction with the above schemes, such as Figures 1 to 3 As shown, the present invention also provides a ground testing method for a free piston shock tunnel, employing the aforementioned free piston shock tunnel; the ground testing method conducts hypersonic ground simulation tests on a hypersonic wind vehicle, simulating the real gas effects during the operation of the hypersonic wind vehicle; the ground testing method includes the following processes:

[0047] S1: The heating agent 6 is fixed inside the high-pressure working medium power device 1, and the agent reaction control device 8 is connected by a signal line. Liquid high-pressure working medium 9 is injected into the high-pressure working medium power device 1 through the high-pressure working medium injection valve 7.

[0048] S2: The reagent reaction control device 8 starts heating the reagent 6 to release a large amount of heat, which causes the liquid high-pressure working medium 9 in the high-pressure working medium power device 1 to rapidly vaporize and generate gaseous high-pressure working medium B.

[0049] S3: The vaporized high-pressure liquid working fluid B breaks through the explosion relief valve plate 10 and pushes the compression piston 11 to compress the driving gas 12;

[0050] S4: The compressed driving gas 12 causes a moving shock wave to be formed in the shock tube 3, and the compressed driving gas 12 is heated and pressurized.

[0051] S5: The high-temperature and high-pressure driving gas 12 is accelerated and expanded in the gas acceleration nozzle device 4 to form a hypersonic high-enthalpy fluid that enters the experimental section 5 and acts on the hypersonic wind vehicle 13, completing the entire ground experimental simulation process of the hypersonic wind vehicle 13.

[0052] The technical solution provided by this invention has the following technical effects:

[0053] First, the solution provided by the present invention uses a liquid high-pressure working fluid as a driving source. The liquid high-pressure working fluid is instantly converted into a gaseous high-pressure working fluid through a high-pressure working fluid power device, generating ultra-high pressure and driving the piston to do work on the driving gas in the compression tube, so that the driving gas is rapidly heated and pressurized. The driving gas enters the shock tube and forms a shock wave in the tube, which heats and pressurizes the gas in the driven section of the shock tube. The gas in the driven section expands and accelerates through the nozzle device, forming the high enthalpy flow required by the missile or aerospace vehicle.

[0054] Secondly, the solution provided by this invention uses a liquid high-pressure working fluid as a driving source. By reasonably selecting the amount of heating agent, the liquid high-pressure working fluid in the high-pressure working fluid power device can be fully vaporized and pressurized. Different driving pressures can be obtained by adjusting the amount of liquid high-pressure working fluid and the thickness of the explosion relief valve plate. The amount of liquid high-pressure working fluid controls the working time, and the thickness of the explosion relief valve plate controls the maximum acceleration of the piston. Different working conditions can be met without complicated operations.

[0055] Third, the solution provided by this invention has strong controllability; the entire experimental process does not use flammable or explosive gases, resulting in high safety; the experiment uses liquid high-pressure working fluid for driving, which reduces operating costs; it can realistically reproduce the actual operating environment of hypersonic wind turbines; the high-pressure working fluid driving source can generate extremely high pressure, thus obtaining extremely high experimental performance parameters; the small volume of the liquid high-pressure working fluid can effectively reduce the volume of the entire experimental system.

[0056] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of the present invention without departing from the scope of the present invention are within the protection scope of the present invention.

Claims

1. A free piston shock wave wind tunnel, characterized in that, The wind tunnel includes a high-pressure working fluid power device (1), a compression tube (2), a shock tube (3), a gas acceleration nozzle device (4), and an experimental section (5); the high-pressure working fluid power device (1), the compression tube (2), the shock tube (3), the gas acceleration nozzle device (4), and the experimental section (5) are fixedly connected in sequence along the same horizontal direction; a liquid high-pressure working fluid (9) is provided in the high-pressure working fluid power device (1), a compression piston (11) is provided in the compression tube (2), and a hypersonic wind vehicle (13) is arranged in the experimental section (5); the liquid high-pressure working fluid (9) can be vaporized to generate a gaseous high-pressure working fluid (B), and drive the compression piston (11) to compress the driving gas (12) in the compression tube (2) through the shock tube (3) and the gas acceleration nozzle device (4), so as to conduct a hypersonic ground simulation test on the hypersonic wind vehicle (13) in the experimental section (5); the liquid high-pressure working fluid (9) is encapsulated in the high-pressure working fluid power device (1) through a burst disc (10); the burst disc (10) faces the compression piston (11); the gaseous high-pressure working fluid (B) generated by the vaporization of the liquid high-pressure working fluid (9) can break through the burst disc (10) under a preset pressure, and push the compression piston (11) to compress the driving gas (12); a high-pressure working fluid injection valve (7) is further provided on the high-pressure working fluid power device (1); the length of the chamber in the high-pressure working fluid power device (1) is L1, and the inner diameter of the chamber in the high-pressure working fluid power device (1) is d1; the thickness of the burst disc (10) is h, and 4mm < h < 10mm; the diameter of the burst disc (10) is d3, and 0.8d3 < L1 < 2d3; the length of the rupture throat in the high-pressure working fluid power device (1) is L3, and L3 = 3h; the diameter of the rupture throat in the high-pressure working fluid power device (1) is d, and d = d3; the diameter of the pressure relief port of the high-pressure working fluid power device (1) is d4, and 0.6d1 < d4 < d1; the length of the expansion section of the high-pressure working fluid power device (1) is L4, and 0.6L2 < L4 < L2; the inner diameter of the compression tube (2) is d5, and d5 = d4; the diameter of the compression piston (11) is equal to the inner diameter of the compression tube (2); the diameter of the outlet of the compression tube (2) is d6, and d6 satisfies 0.6d5 < d6 < 2d5; the inner diameter of the shock tube (3), the inlet diameter of the gas acceleration nozzle device (4), and the diameter d6 of the outlet of the compression tube (2) are equal; the value range of d1 is 300mm to 1500mm; L1 satisfies: 6d1 < L1 < 10d1; the length L2 of the contraction section in the high-pressure working fluid power device (1), and L2 satisfies 0.3L1 < L2.

2. The free piston shock tunnel according to claim 1, characterized in that, The high-pressure working fluid power device (1) is also equipped with a heating agent (6), and multiple heating agents (6) are fixed in the liquid high-pressure working fluid (9); the heating agent (6) is also electrically connected to the agent reaction control device (8) outside the high-pressure working fluid power device (1) through a signal line; in the unactivated state, the heating agent (6) and the liquid high-pressure working fluid (9) are separated by a thin film; in the activated state, the heating agent (6) completes deflagration, causing the thin film to rupture, thereby activating the liquid high-pressure working fluid (9) to complete phase change transformation.

3. The free piston shock tunnel according to claim 2, characterized in that, The quantity of the heating agent (6) is N, where N satisfies 1≤N≤8; one end of the high-pressure working fluid power device (1) is sealed to one end of the compression pipe (2) through a flange; the other end of the compression pipe (2) is sealed to one end of the shock pipe (3) through a flange; the other end of the shock pipe (3) is sealed to one end of the gas acceleration nozzle device (4) through a flange; the other end of the gas acceleration nozzle device (4) is sealed to one end of the experimental section (5) through a flange.

4. The free piston shock tunnel according to claim 1, characterized in that, The shock tube (3) is a single-stage or multi-stage diaphragm shock tube; the compressed driving gas (12) causes a moving shock wave to be formed inside the shock tube (3), and the compressed driving gas (12) is heated and pressurized.

5. The free piston shock tunnel according to claim 1, characterized in that, The liquid high-pressure working medium (9) is liquid nitrogen, liquid ammonia or liquid carbon dioxide; the driving gas (12) is argon, helium or hydrogen.

6. A ground testing method for a free piston shock tunnel, employing the free piston shock tunnel described in any one of claims 1 to 5; characterized in that, The ground testing method is used to conduct hypersonic ground simulation tests on the hypersonic wind vehicle and simulates the real gas effects during the operation of the hypersonic wind vehicle; the ground testing method includes the following processes: S1: The heating agent (6) is fixed inside the high-pressure working fluid power device (1), and the agent reaction control device (8) is connected by a signal line. Liquid high-pressure working fluid (9) is injected into the high-pressure working fluid power device (1) through the high-pressure working fluid injection valve (7). S2: The reagent reaction control device (8) starts the heating reagent (6) to release a large amount of heat, so that the liquid high-pressure working medium (9) in the high-pressure working medium power device (1) is rapidly vaporized to produce gaseous high-pressure working medium (B); S3: The gaseous high-pressure working fluid (B) breaks through the explosion relief valve plate (10) and pushes the compression piston (11) to compress the driving gas (12); S4: The compressed driving gas (12) causes a moving shock wave to be formed inside the shock tube (3), and the compressed driving gas (12) is heated and pressurized; S5: The high-temperature and high-pressure driving gas (12) is accelerated and expanded in the gas acceleration nozzle device (4) to form a hypersonic high-enthalpy fluid that enters the experimental section (5) and acts on the hypersonic wind vehicle (13) to complete the entire ground experimental simulation process of the hypersonic wind vehicle (13).

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