A double-piston shock tube

Abstract

The present invention discloses a double-piston shock tube, which comprises an experimental section, a low-pressure section and a high-pressure section connected in sequence; the high-pressure section includes a high-pressure cylinder and a vacuum cylinder. An anti-high-pressure tube is provided in the high-pressure cylinder, and an anti-low-pressure tube is provided in the vacuum cylinder. One end of the anti-low-pressure tube is communicated with one end of the anti-high-pressure tube, and a solenoid valve is provided at the other end of the anti-low-pressure tube. The anti-low-pressure tube is also connected to a gas driving cylinder outside the vacuum cylinder, and the inner cavity of the vacuum cylinder is also connected to an air pump; a main piston is provided at the other end of the anti-high-pressure tube, and a sub-piston is further provided in the inner cavity of the anti-high-pressure tube to divide the inner cavity of the anti-high-pressure tube into a first cavity and a second cavity. The first cavity and the second cavity are communicated through a pipeline, and the second cavity is provided with a through hole communicated with the inner cavity of the high-pressure cylinder, and the second cavity is also communicated with the inner cavity of the vacuum cylinder; an impact receiving block is provided on the inner wall of the high-pressure cylinder at the end connected to the low-pressure section, the impact receiving block is opposite to the main piston, and the inner cavity of the high-pressure cylinder is also connected to a high-pressure pressure gauge. The shock wave generated by this shock tube is pure, the cooling time is short, and the experimental efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamics or fluid mechanics, and specifically to a double-piston shock tube. Background Art

[0002] Gas shock waves are an important physical phenomenon in supersonic airflows. A shock tube is an experimental device for generating shock waves. It generates shock waves by creating a pressure difference between its high-pressure section and low-pressure section. Most shock tubes at home and abroad use membrane-breaking shock tubes to generate shock waves, such as single-membrane breaking, double-membrane structure, needle-breaking membrane and other types of shock tubes. Although such shock tubes can generate incident shock wave Mach numbers within a relatively wide range, during the process of generating shock waves by breaking the membrane in such shock tubes, membrane-breaking fragments will be generated to interfere with the flow field, and the membrane needs to be replaced every time an experiment is completed, resulting in low experimental efficiency. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a double-piston shock tube, which can generate relatively pure shock waves, has a short cooling time, and higher experimental efficiency.

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

[0005] A double-piston shock tube includes an experimental section, a low-pressure section, and a high-pressure section connected in sequence from left to right;

[0006] The high-pressure section includes a high-pressure cylinder and a vacuum cylinder. An anti-high-pressure tube is provided in the high-pressure cylinder, and an anti-low-pressure tube is provided in the vacuum cylinder. One end of the anti-low-pressure tube is connected to one end of the anti-high-pressure tube. A solenoid valve is provided at the other end of the anti-low-pressure tube. The anti-low-pressure tube is also connected to a first gas driving cylinder outside the vacuum cylinder through a pipeline. A first valve is provided on the pipeline connecting the anti-low-pressure tube and the first gas driving cylinder outside the vacuum cylinder. The inner cavity of the vacuum cylinder is also connected to a first air pump through a pipeline. A second valve is provided on the pipeline connecting the inner cavity of the vacuum cylinder and the first air pump; A main piston is provided at the other end of the anti-high-pressure tube. A sub-piston is also provided in the inner cavity of the anti-high-pressure tube to divide the inner cavity of the anti-high-pressure tube into a first cavity and a second cavity. The first cavity and the second cavity are connected through a pipeline. The second cavity has a through hole communicating with the inner cavity of the high-pressure cylinder. The second cavity is also connected to the inner cavity of the vacuum cylinder through a pipeline; On the inner wall of the end of the high-pressure cylinder connected to the low-pressure section, an impact-receiving block is provided, which is opposite to the main piston. The inner cavity of the high-pressure cylinder is also connected to a high-pressure pressure gauge through a third valve;

[0007] One end of the low-pressure section is connected to the high-pressure cylinder, and the other end is connected to the experimental section. The inner cavity of the low-pressure section is respectively connected to a second gas driving cylinder, a low-pressure pressure gauge, and a waste cylinder through pipelines. Fourth valves and fifth valves are respectively provided on the pipelines connecting the low-pressure section to the second gas driving cylinder and the low-pressure pressure gauge. The waste cylinder is also connected to an air extraction pump. A sixth valve is provided on the pipeline connecting the waste cylinder and the air extraction pump.

[0008] The described main piston and auxiliary piston can move axially within the second cavity.

[0009] The described main piston and auxiliary piston are made of nylon material.

[0010] The described solenoid valve is a normally open solenoid valve, which is convenient for the vacuum cylinder to dissipate heat when in a vacuum state.

[0011] The described experimental section is provided with a perspective window for observing, measuring and studying the generated shock waves.

[0012] The described high-pressure cylinder and vacuum cylinder are connected by a flange.

[0013] Beneficial effects: A double-piston shock tube provided by the present invention can generate relatively pure shock waves, has a short cooling time, higher experimental efficiency, and the solenoid valve is a normally open solenoid valve, which is beneficial for the vacuum cylinder to dissipate heat in a vacuum state; in the selection of pistons, both the main piston and the auxiliary piston use nylon material. Nylon is lighter than metal in mass and can also ensure the high strength of the piston. It can withstand loads for a long time, has good resilience, maintains toughness, and resists repeated impacts; the impact block is fixed on the inner wall of the high-pressure cylinder, reducing the impact of the rapid movement of the piston on the cylinder and increasing the service life of the shock tube. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of a double-piston shock tube in the inflated state;

[0015] Figure 2 It is a schematic structural diagram of a double-piston shock tube in the deflated state;

[0016] In the figure: 1. Experimental section 2. Perspective window 3. Low-pressure section 4. Second gas driving cylinder 5. Fourth valve 6. Third valve 7. High-pressure pressure gauge 8. Impacted block 9. High-pressure cylinder 10. Auxiliary piston 11. Vacuum cylinder 12. Normally open solenoid valve 13. Second valve 14. First air pump 15. First gas driving cylinder 16. First valve 17. Anti-low-pressure tube 18. Anti-high-pressure tube 19. First cavity 20. Second cavity 21. Through hole 22. Main piston 23. Sixth valve 24. Second air pump 25. Low-pressure pressure gauge 26. Fifth valve. Detailed Embodiments

[0017] The following further elaborates on the content of the present invention in conjunction with the drawings and embodiments, but it is not a limitation to the present invention.

[0018] Embodiment:

[0019] As Figure 1As shown, a double-piston shock tube includes an experimental section 1, a low-pressure section 3, and a high-pressure section connected sequentially from left to right;

[0020] The high-pressure section includes a high-pressure cylinder 9 and a vacuum cylinder 11. An anti-high-pressure pipe 18 is provided in the high-pressure cylinder 9, and an anti-low-pressure pipe 17 is provided in the vacuum cylinder 11. One end of the anti-low-pressure pipe 17 is connected to one end of the anti-high-pressure pipe 18, and the other end of the anti-low-pressure pipe 17 is provided with an electromagnetic valve 12. The anti-low-pressure pipe 17 is also connected to the first gas-driven cylinder 15 outside the vacuum cylinder through a pipeline. A first valve 16 is provided on the pipeline connecting the anti-low-pressure pipe 17 and the first gas-driven cylinder 15 outside the vacuum cylinder 11. The inner cavity of the vacuum cylinder 11 is also connected to the first air pump 14 through a pipeline. The inner cavity of the vacuum cylinder 11 is connected to the first air pump 14 on the pipeline. A second valve 13 is provided; a main piston 22 is provided at the other end of the anti-high-pressure tube 18, and a secondary piston 10 is further provided in the inner cavity of the anti-high-pressure tube 18 to divide the inner cavity of the anti-high-pressure tube 18 into a first cavity 19 and a second cavity 20. The first cavity 19 and the second cavity 20 are connected by a pipe. The second cavity 19 is provided with a through hole 21 and communicates with the inner cavity of the high-pressure cylinder 9. The second cavity 20 is also connected to the inner cavity of the vacuum cylinder 11 through a pipe; an impact block 8 is provided on the inner wall of the end connected to the low-pressure section 3, and the impact block 8 is opposite to the main piston 22. The inner cavity of the high-pressure cylinder 9 is also connected to the high-pressure pressure gauge 7 through a third valve 6;

[0021] One end of the low-pressure section 3 is connected to the high-pressure cylinder 9, and the other end is connected to the experimental section 1. The inner cavity of the low-pressure section 3 is connected to the second gas-driven cylinder 4, the low-pressure air pressure gauge 25 and the exhaust gas cylinder 24 through pipelines. The pipelines connecting the low-pressure section 3 with the second gas-driven cylinder 4 and the low-pressure air pressure gauge 25 are respectively provided with a fourth valve and a fifth valve. The exhaust gas cylinder is also connected to an exhaust pump, and a sixth valve is provided on the pipeline connecting the exhaust gas cylinder and the exhaust pump.

[0022] The primary piston 22 and the secondary piston 10 can move axially in the second cavity 20 .

[0023] The main piston 22 and the auxiliary piston 8 are made of nylon.

[0024] The solenoid valve 12 is a normally open solenoid valve, which facilitates the cooling of the vacuum cylinder 11 when the vacuum cylinder 11 is in a vacuum state.

[0025] The experimental section 1 is provided with a perspective window 2 for observing, measuring and studying the generated shock wave.

[0026] The working process of the shock tube is:

[0027] First, determine the required shock wave Mach number, and then determine the predetermined pressures required for the high-pressure section and the low-pressure section 3. When the shock tube is operating, first pressurize the high-pressure section to drive the gas in the first gas driving cylinder 15 to sequentially pass through the first valve 16, the anti-low-pressure tube 17, and the anti-high-pressure tube 18 and enter the inner cavity of the high-pressure cylinder 9. At this time, the normally open solenoid valve 16 is energized and the valve port is closed. At the same time, the sixth valve 23 is closed. When the gas enters the first cavity of the anti-high-pressure tube 18, the main piston 22 and the auxiliary piston 10 will both move to the left due to the gas pressure. When the main piston 22 reaches the leftmost end, the main piston 22 collides with the impact block to block the gas flow between the high-pressure section and the low-pressure section 3. When the auxiliary piston 10 moves to the left, it will open the valve on the pipe connecting the first cavity 19 and the second cavity 20, thereby connecting the first cavity 19 and the second cavity 20, so that the driving gas enters the inner cavity of the high-pressure cylinder 9 through the through hole 21 on the second cavity 20, open the third valve 6, and observe the high-pressure pressure gauge 7. When the predetermined pressure is reached, close the first valve 16.

[0028] Subsequently, open the fourth valve 5 to drive the gas in the second gas driving cylinder 4 into the low-pressure section 3, open the fifth valve 26, and observe the low-pressure pressure gauge 25. When the predetermined pressure is reached, close the fifth valve 26. At this time, the preparatory work before generating the shock wave is completed;

[0029] Finally, open the second valve, connect and start the first air pump 14 to evacuate the vacuum cylinder 11. When the inner cavity of the vacuum cylinder 11 reaches the vacuum state, cut off the power supply of the normally open solenoid valve 12 and the valve port opens. Due to the action of the gas pressure, the main piston 22 and the auxiliary piston 10 both move quickly to the right. At this time, the high-pressure gas in the second cavity 20 is discharged into the vacuum cylinder 11 through the pipeline, and the high-pressure cylinder 9 and the low-pressure section 3 are connected. The gas in the high-pressure cylinder 9 will rush into the low-pressure section 3, and a compression wave will be generated in the low-pressure section 3, and then a shock wave will be generated. When the shock wave reaches the experimental section 1, observe, measure and study the shock wave through the perspective window 2.

[0030] After the experiment is completed, open the sixth valve 23, start the second air pump 24 to evacuate the waste gas in the shock tube, and finally close the sixth valve 23 and the second air pump 24 for the next experiment.

Claims

1. A double-piston shock tube, characterized in that: It includes the experimental section, low-pressure section and high-pressure section connected from left to right; The high-pressure section includes a high-pressure cylinder and a vacuum cylinder, an anti-high-pressure tube is provided in the high-pressure cylinder, an anti-low-pressure tube is provided in the vacuum cylinder, one end of the anti-low-pressure tube is connected to one end of the anti-high-pressure tube, and the other end of the anti-low-pressure tube is provided with an electromagnetic valve, the anti-low-pressure tube is also connected to the first gas drive cylinder outside the vacuum cylinder through a pipeline, the pipeline connecting the anti-low-pressure tube and the first gas drive cylinder outside the vacuum cylinder is provided with a first valve, the inner cavity of the vacuum cylinder is also connected to the first air pump through a pipeline, and the pipeline connecting the inner cavity of the vacuum cylinder and the first air pump is provided with a second valve; the other end of the anti-high-pressure tube is provided with a main piston, and the inner cavity of the anti-high-pressure tube is also provided with a secondary piston to divide the inner cavity of the anti-high-pressure tube into a first cavity and a second cavity, the first cavity and the second cavity are connected through a pipeline, the second cavity is provided with a through hole connected to the inner cavity of the high-pressure cylinder, and the second cavity is also connected to the inner cavity of the vacuum cylinder through a pipeline; an impact block is provided on the inner wall of the end connected to the low-pressure section, the impact block is opposite to the main piston, and the inner cavity of the high-pressure cylinder is also connected to the high-pressure pressure gauge through a third valve; One end of the low-pressure section is connected to the high-pressure cylinder, and the other end is connected to the experimental section. The inner cavity of the low-pressure section is connected to the second gas-driven cylinder, the low-pressure air pressure gauge, and the exhaust gas cylinder through pipelines. The pipelines connecting the low-pressure section with the second gas-driven cylinder and the low-pressure air pressure gauge are respectively provided with a fourth valve and a fifth valve. The exhaust gas cylinder is also connected to an air pump, and a sixth valve is provided on the pipeline connecting the exhaust cylinder and the air pump. The solenoid valve is a normally open solenoid valve; The main piston and the auxiliary piston are made of nylon; The experimental section is provided with a perspective window.

2. A double-piston shock tube according to claim 1, characterized in that: The main piston and the auxiliary piston can move axially in the second cavity.

3. A double-piston shock tube according to claim 1, characterized in that: The high-pressure cylinder and the vacuum cylinder are connected via flanges.

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