Shock wave heat loading high-temperature wind tunnel and test method

Abstract

The invention discloses a shock wave heat loading high-temperature wind tunnel and a test method, and relates to the technical field of high-temperature wind tunnel test equipment. The shock wave heat loading high-temperature wind tunnel comprises a shock tube, a wind tunnel test system, a pressure acquisition system and an air intake and exhaust system; a high-temperature and high-pressure gas source is obtained in a secondary shock wave reflection heating mode, and the total temperature of the obtained heating gas source is higher; the high-temperature wind tunnel realizes gas heating and pressurization completely through shock wave flow, extra electric power and gas requirements are not needed, and the cost of a single test is lower; the high-temperature wind tunnel test gas is premixed, so that the components of the test gas can be accurately controlled, and the purity of the components of the test gas is ensured; the device can obtain a high-temperature high-pressure subsonic flow field and even a supersonic flow field covering wide-range working conditions, can be used for visualization test diagnosis of spray fuel atomization and spontaneous combustion processes under high-temperature crosswind, accurately characterizes physical and chemical characteristic parameters such as fuel atomization characteristics, self-ignition characteristics, flame propagation characteristics and the like, and has a wide application prospect. And test data support is provided for engine combustion chamber spray atomization combustion organization.

Description

Technical Field

[0001] The present invention relates to the technical field of high temperature wind tunnel test equipment, and more particularly to a high temperature wind tunnel with shock wave thermal loading and a test method. Background Art

[0002] At present, the atomization and combustion organization inside the combustion chamber is the focus of aero-engine design and iteration. The inlet conditions of aero-engine afterburner and ramjet combustion chambers are harsh, and it is difficult to match the residence time of fuel in the combustion chamber with its atomization and combustion time scale, which restricts the development of the next generation of high-Mach aero-engines with a wide speed range. There is an urgent need to conduct in-depth research on the fuel atomization and combustion process under the actual combustion chamber flow field state, which relies on a wide range of controllable high-temperature wind tunnel test technology.

[0003] Conventional high-temperature wind tunnels are difficult to cover the current combustion chamber operating parameters and meet the needs of atomization combustion tests under high-temperature and high-speed flow fields. This is reflected in the following aspects: high-temperature wind tunnels that rely on electric heating have limited operating conditions, and the temperature boundary is difficult to match the current combustion chamber temperature range; the operating temperature of the graded combustion heating wind tunnel is single, the operating conditions are difficult to control, and there is inevitable pollution from combustion products; compared with the time scale of basic research on fuel atomization combustion, the operating time of conventional high-temperature wind tunnels exceeds the limit, and the operating cost is high. At the same time, the long-term active heating of the wind tunnel places stringent requirements on the thermal protection and cooling of the equipment.

[0004] A device that uses shock wave compression to generate high-speed test gas is called a shock tunnel. The temperature and pressure of the test gas compressed by the shock wave rises extremely fast, and after the steady expansion of the nozzle, it quickly develops into a supersonic airflow, which is widely used in the field of supersonic tests. Since the test section of the shock tunnel is often connected to the driven section, its initial state is a vacuum environment. The high-temperature and high-pressure test gas after the reflected shock wave compression often spontaneously develops into a supersonic flow state, which causes difficulties in the application of shock tunnels in subsonic tests. At the same time, during the steady expansion of the test gas, as the test gas speed increases, the test gas temperature and pressure drop rapidly, and there is a certain gap between the state of the test gas in the test section and the operating conditions of the engine combustion chamber.

[0005] Therefore, how to provide a high-temperature wind tunnel and test method for shock wave heat loading that matches the transonic intake state of multiple combustion chambers is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of this, the present invention provides a high-temperature wind tunnel and a test method for shock wave thermal loading to solve the problems existing in the background technology.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A high-temperature wind tunnel with shock wave thermal loading, comprising: a shock tube, a wind tunnel test system, a pressure collection system, and an intake and exhaust system; the shock tube is respectively connected to the wind tunnel test system, the pressure collection system, and the intake and exhaust system; the wind tunnel test system is connected to the pressure collection system;

[0009] The shock tube uses the pressure difference between the driving gas and the experimental gas to form an incident shock wave to compress the experimental gas once, and the incident shock wave is reflected at the end surface of the shock tube to compress the experimental gas twice, thereby providing a high-temperature and high-pressure gas source that meets the requirements for the wind tunnel test system;

[0010] The wind tunnel test system is used to visualize and observe test phenomena, measure changes in test airflow pressure, absorb the test airflow to maintain the stability of the gas parameters in the test section, and eliminate gas flow noise;

[0011] The pressure acquisition system is used to collect pressure changes in the shock tube and wind tunnel test system and store and analyze them;

[0012] The air intake and exhaust system delivers driving gas and test gas to the shock tube and realizes gas intake and output and pressure control.

[0013] Optionally, the shock tube body includes a coaxially connected driving section, a membrane section and a driven section; the membrane section is a double-membrane pressure difference rupture structure, and two diaphragms are arranged on both sides of the membrane section to separate the driving section, the membrane section and the driven section.

[0014] Optionally, the wind tunnel test system includes a directional film rupture structure, a nozzle, a test section, a buffer tank and a dynamic pressure measuring device, wherein the directional film rupture structure is located on the end face of the driven section and is coaxially connected to the driven section, the directional film rupture structure is driven to open directionally by a pressure difference, and is used to control the unidirectional flow of the test gas from the driven section pipe body to the nozzle, the nozzle is connected to the test section for accelerating the test gas, the test section is used to visualize the observation of the test phenomena, the buffer tank is connected to the outlet of the test section for absorbing non-ideal airflow and maintaining the stability of the gas parameters in the test section, and the dynamic pressure measuring device is located inside the cavity of the test section, and is used to measure the dynamic pressure of high-speed airflow.

[0015] Optionally, the pressure acquisition system includes a pressure sensor, a computer and a data collector. The pressure sensor is used to convert the pressure changes in the driven section and the test section of the shock tube into electrical signals. The output signal of the pressure sensor is collected by the data collector and saved in the computer.

[0016] Optionally, the air intake and exhaust system includes a vacuum pump, a gas distribution tank and a high-pressure gas cylinder, which are connected to the shock tube body through a gas pipeline. The high-pressure gas cylinder includes a helium cylinder, a nitrogen cylinder and an oxygen cylinder. The helium cylinder and the nitrogen cylinder convey driving gas to the driving section through the gas pipeline. The gas distribution tank is connected to the driven section through the gas pipeline and is used to configure and convey test gas to the driving section. The vacuum pump is used to evacuate the driving section, the membrane clamping section, the driven section and the gas distribution tank.

[0017] Optionally, diaphragms are provided on both sides of the diaphragm section. Under the action of the pressure difference between the driving section and the driven section, the diaphragms are broken and form an incident shock wave at the driven section. The incident shock wave is reflected at the end surface of the driven section to compress the test gas, and a certain amount of test gas is formed at the end surface of the driven section as the gas source of the wind tunnel test system.

[0018] Optionally, the end face of the driven section is connected to the directional membrane rupture structure, and a small hole is opened at the center of the end face. When the internal pressure of the driven section increases, the directional membrane rupture structure is opened directionally under the drive of the pressure, and the test gas flows to the nozzle and the test section through the small hole; wherein the directional membrane rupture structure is driven by the pressure difference between the driven section and the test section, and can only be opened in one direction, that is, when the pressure of the driven section is higher than that of the test section, the directional membrane rupture structure opens, and when the pressure of the test section is higher than that of the driven section, the directional membrane rupture structure opens and remains closed.

[0019] Optionally, the nozzle design parameters are modified according to the target test conditions, and the switching between subsonic and supersonic flow fields is achieved by switching between a converging nozzle and a converging-expanding nozzle.

[0020] Optionally, the tip of the dynamic pressure measuring device is coaxially installed with the nozzle, and two pressure sensors are arranged therein. Small holes are respectively opened at the tip of the dynamic pressure measuring device and the cylindrical wall surface to connect to the pressure sensors, so as to measure the dynamic pressure and static pressure of the test flow field respectively, so as to calculate the flow velocity of the test flow field;

[0021] A plurality of pressure sensors are arranged on the side wall of the driven section, and the axial distances between adjacent pressure sensors are equal, and are used to collect the pressure change of the gas in the driven section and to calculate the incident shock wave velocity;

[0022] All pressure sensor data are output to the data acquisition device and finally saved in the computer. Based on the analysis of the pressure signal, the shock wave velocity, the total temperature and total pressure of the test flow, the flow pressure and static pressure of the test flow are obtained, and the test state parameters are further calculated.

[0023] A test method for a high temperature wind tunnel with shock wave thermal loading, comprising:

[0024] Before the test, design the test gas composition according to the target working conditions, open the gas tank valve, and open the valves of the oxygen cylinder and nitrogen cylinder in sequence to let gas into the gas tank. After the gas intake is completed, close each valve and let it stand, waiting for the test gas in the gas tank to be fully mixed to obtain the mixed test gas with the preset ratio;

[0025] Before the test, the initial air inlet pressures in the driving section, driven section and test section are designed according to the gas state parameters of the target working condition flow. According to the one-dimensional steady flow relationship, the initial back pressure of the test section and the total temperature and pressure of the gas after the secondary reflected shock wave heating and pressurization at the end face of the driven section are calculated by the target flow parameters; according to the ideal shock wave theory, the initial gas pressures of the driving section and driven section are calculated by the total temperature and pressure of the gas at the end face of the driven section;

[0026] Install diaphragms on both sides of the membrane section to separate the driving section, the membrane section and the driven section cavity, close the directional membrane breaking structure, separate the driven section and the nozzle and test section cavity, open the vacuum pump valve and the driving section, the membrane section, the driven section and the buffer tank valve, evacuate the shock tube body and the wind tunnel test cavity, and turn off the vacuum pump after the shock tube body and the wind tunnel test cavity reach vacuum;

[0027] Open the nitrogen bottle, helium bottle, driving section and membrane section valves respectively, input driving gas to the driving section and membrane section, close the membrane section valve after the membrane section reaches half of the target initial pressure of the driving section, keep the driving section valve open and continue to supply air to the driving section until the target pressure is reached, and close all valves; open the gas distribution tank valve and the driven section valve, input test gas to the driven section until the target pressure is reached, and close all valves; open the nitrogen bottle and buffer tank valve, input inert gas to the nozzle, test section and buffer tank until the target pressure is reached, and close all valves. Since the test section pressure is often higher than the driven section pressure, the directional membrane rupture structure is kept closed during the test air intake stage;

[0028] The data collector is set to the waiting trigger mode, ready to receive the pressure jump signal to start collecting data, open the valve connected to the outdoor pipeline, and then instantly open the valve of the diaphragm section. The driving gas in the diaphragm section is discharged, causing the pressure in the diaphragm section to drop sharply, forming a pressure difference with the driving section. The pressure difference between the driving section and the diaphragm section exceeds the allowable pressure of the diaphragm, causing the diaphragm to rupture and break through the diaphragm between the diaphragm section and the driven section to form a shock wave. At this time, the incident shock wave propagates toward the end face of the driven section, and at the same time, a sparse wave is generated to propagate toward the driving section. At the moment of rupture, the contact surface of the driving gas and the test gas coincides with the shock wave surface. During the propagation process, the distance between the contact surface and the shock wave surface continues to expand; when the incident shock wave propagates to the end face of the driven section, it will be reflected, generating a secondary reflected shock wave that propagates toward the driving section, and again increasing the temperature and pressure of the test part of the gas to achieve the designed target working condition;

[0029] When the test gas at the end face of the driven section is subjected to two shock waves, the gas pressure exceeds the initial pressure of the wind tunnel test section and the buffer tank, so the directional membrane rupture structure opens directionally, and the test gas that meets the requirements flows from the driven section to the test section and the buffer tank, forming the test target flow field;

[0030] When the incident shock wave flows through the pressure sensor after the membrane is broken, the pressure sensor senses the sudden change of pressure in the tube and outputs a pressure transition signal, triggering the data acquisition device to continue data acquisition, and obtain the pressure change curve inside the shock tube body and the wind tunnel test chamber. According to the pressure change curve collected by the data acquisition device, the total pressure of the test gas at the driven section surface is obtained, and the incident shock wave velocity is calculated according to the pressure transition time collected by the pressure sensors arranged at equal intervals, and then the total temperature of the test gas at the end surface of the driven section is calculated;

[0031] After the test is completed and the gas inside the shock tube body and the wind tunnel test chamber is stable, open the vacuum pump valve and the valves of the driving section, membrane section, driven section and buffer tank, evacuate the shock tube body and the wind tunnel test chamber, discharge the test exhaust gas and close the vacuum pump valve, open the outdoor pipeline valve, balance the pressure inside the shock tube body and the wind tunnel test chamber with the atmospheric environment pressure, and after the pressure of the shock tube body and the wind tunnel test chamber reaches the atmospheric environment pressure, disassemble and clean all parts of the high-temperature wind tunnel.

[0032] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a high-temperature wind tunnel and test method for shock wave thermal loading, which has the following beneficial effects:

[0033] 1. The present invention uses secondary shock wave reflection heating to obtain a high-temperature and high-pressure gas source, and the total temperature of the gas source can reach more than 3000K, and the flow field temperature can reach more than 2000K. Compared with high-temperature wind tunnels such as electric heating, arc heating, and staged combustion heating, the total temperature of the heated gas source is higher; at the same time, the proposed high-temperature wind tunnel completely realizes gas heating and pressurization by shock wave flow, without the need for additional electricity and gas, so its cost is only the pre-filling of inert gas, oxygen, etc. in the shock tube body and the wind tunnel test chamber, and its single test cost is lower; due to the shock wave movement in the shock tube, its effective test time is at the millisecond level, the test platform does not need additional thermal protection measures, and the test device has better safety and operability;

[0034] 2. The high-temperature wind tunnel test gas proposed in the present invention can achieve precise control of the test gas components through premixing configuration. Compared with wind tunnels such as arc heating and staged combustion heating, there is no pollution from components such as nitrogen oxides produced by arc breakdown and combustion products produced by combustion heating, thereby ensuring the purity of the test gas components; the proposed high-temperature wind tunnel controls the test flow field state parameters by controlling the pre-charge pressure of each section, and can achieve flexible control of a wide range of gas state parameters. The temperature, pressure and flow rate control range is wide and the limit is high. The flow field temperature can cover 800-2000K, the pressure covers 1-10atm, and the flow rate can achieve subsonic to supersonic.

[0035] 3. The present invention can obtain high-temperature and high-pressure subsonic flow fields and even supersonic flow fields covering a wide range of working conditions, which can be used for visualization test diagnosis of spray fuel atomization and spontaneous combustion process under high-temperature crosswind, accurately characterize physical and chemical characteristic parameters such as fuel atomization characteristics, self-ignition characteristics and flame propagation characteristics, and provide experimental data support for the spray atomization combustion organization of the engine combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the high temperature wind tunnel system structure provided by the present invention;

[0038] Among them, 1-driving section, 2-film clamping section, 3-driven section, 4-directional film breaking structure, 5-nozzle, 6-test section, 7-buffer tank, 8-dynamic pressure measuring device, 9-pressure sensor, 10-computer, 11-data acquisition device, 12-outdoor pipeline, 13-vacuum pump, 14-gas distribution tank, 15-oxygen cylinder, 16-nitrogen cylinder, 17-helium cylinder. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The embodiment of the present invention discloses a high temperature wind tunnel with shock wave thermal loading, such as Figure 1 As shown, it includes shock tube, wind tunnel test system, pressure acquisition system, intake and exhaust system;

[0041] The shock tube body comprises a coaxially connected driving section (1), a diaphragm section (2) and a driven section (3); the diaphragm section (2) is a double-diaphragm pressure difference rupture structure, which is arranged between the driving section (1) and the driven section (3), and two diaphragms are arranged on both sides of the diaphragm section (2) to separate the driving section (1), the diaphragm section (2) and the driven section (3);

[0042] The wind tunnel test system comprises a directional film rupture structure (4), a nozzle (5), a test section (6), a buffer tank (7) and a dynamic pressure measuring device (8). The directional film rupture structure (4) is located at the end face of the driven section (3) and is coaxially connected to the driven section (3). The directional film rupture structure (4) is driven to open in a directional manner by a pressure difference and is used to control the unidirectional flow of the test gas from the tube body of the driven section (3) to the nozzle (5). The nozzle (5) is connected to the test section (6) and is used to accelerate the test gas. The test section (6) is used to visualize the test phenomenon. The buffer tank (7) is connected to the outlet of the test section (6) and is used to absorb non-ideal airflow and maintain the stability of the gas parameters in the test section (6). The dynamic pressure measuring device (8) is located inside the cavity of the test section (6) and is used to measure the dynamic pressure of the high-speed airflow.

[0043] The pressure acquisition system comprises a pressure sensor (9), a computer (10) and a data acquisition device (11); the pressure sensor (9) is used to convert the pressure changes of the driven section (3) and the test section (6) of the shock tube into electrical signals; the output signal of the pressure sensor (9) is collected by the data acquisition device (11) and stored in the computer (10);

[0044] The air intake and exhaust system comprises a vacuum pump (13), a gas distribution tank (14) and a high-pressure gas cylinder, which are connected to the shock tube body through a gas transmission pipeline. The high-pressure gas cylinder comprises an oxygen cylinder (15), a nitrogen cylinder (16) and a helium cylinder (17). The oxygen cylinder (15) and the nitrogen cylinder (16) transmit driving gas to the driving section through the gas transmission pipeline. The gas distribution tank (14) is connected to the driven section (3) through the gas transmission pipeline and is used to configure and transmit test gas to the driving section (3). The vacuum pump (13) is used to evacuate the driving section (1), the film clamping section (2), the driven section (3) and the gas distribution tank (14).

[0045] In a specific embodiment, diaphragms are installed on both sides of the clamping section (2). Under the action of the pressure difference between the driving section (1) and the driven section (3), the diaphragms are broken and an incident shock wave is formed at the driven section (3). The incident shock wave is reflected at the end surface of the driven section (3) to compress the test gas, and a certain amount of high-temperature and high-pressure test gas is formed at the end surface of the driven section (3). As a high-temperature wind tunnel gas source, the total temperature of the test gas can reach above 3000K.

[0046] In a specific embodiment, the end face of the driven section (3) is connected to the directional membrane rupture structure (4), and a small hole is opened at the center of the end face. When the internal pressure of the driven section (3) increases, the directional membrane rupture structure (4) opens directionally under the pressure drive, and the test gas flows through the small hole to the nozzle (5) and the test section (6), and develops into a test flow with a certain flow rate, temperature and pressure.

[0047] In a specific embodiment, the directional membrane rupture structure (4) is driven by the pressure difference between the driven section (3) and the test section (6), and can only be opened in one direction, that is, when the pressure of the driven section (3) is higher than that of the test section (6), the directional membrane rupture structure (4) is opened, and when the pressure of the test section (6) is higher than that of the driven section (3), the directional membrane rupture structure (4) is opened and remains closed, so that the test gas stably flows from the driven section (3) to the test section (6).

[0048] In a specific embodiment, according to the target test conditions, the design parameters of the nozzle (5) can be modified, including but not limited to the length, throat area, gradient curve, etc., and the switching between subsonic and supersonic flow fields can be achieved by switching between the converging nozzle and the converging-expanding nozzle.

[0049] In a specific embodiment, two visualization windows are arranged on the two side walls of the test section (6) in the horizontal direction, and a large-sized visualization end cover window is arranged on the end face, and a high-speed camera can shoot the test process through the visualization windows in two directions.

[0050] Furthermore, the buffer tank (7) is connected to the outlet of the test section (6) and is used to absorb the shock wave at the head of the flow field and maintain the stability of the gas pressure in the test section (6) during the effective test time.

[0051] Furthermore, the tip of the dynamic pressure measuring device (8) is coaxially installed with the nozzle (5), and two pressure sensors (9) are arranged therein. Small holes are opened at the tip of the device and the cylindrical wall respectively and connected to the pressure sensors (9), so as to measure the dynamic pressure and static pressure of the test flow field respectively, so as to calculate the flow velocity of the test flow field.

[0052] Furthermore, there are seven pressure sensors (9), five of which are arranged on the side wall of the driven section (3), and the axial distances between adjacent pressure sensors (9) are equal, and are used to collect the gas pressure changes in the driven section (3) for calculating the incident shock wave velocity. Two are arranged in the dynamic pressure measuring device (8) for measuring the dynamic pressure and static pressure of the test flow. All pressure sensor (9) data are output to the data acquisition device (11) and finally stored in the computer (10). According to the analysis of the pressure signal, the shock wave velocity, the total temperature and total pressure of the test flow, the flow pressure and static pressure of the test flow can be obtained, and the state parameters such as the test flow velocity can be further calculated.

[0053] A test method for a high temperature wind tunnel with shock wave thermal loading, comprising:

[0054] Before the test, the test gas composition is designed according to the target working conditions. The valve of the gas distribution tank (14) is opened, and the valves of the oxygen cylinder (15) and the nitrogen cylinder (16) are opened in sequence to allow gas to enter the gas distribution tank (14). After the gas intake is completed, each valve is closed and left to stand, waiting for the test gas in the gas distribution tank (14) to be fully mixed, so as to obtain a mixed test gas of a certain proportion.

[0055] Before the test, the initial inlet pressures in the driving section (1), the driven section (3) and the test section (6) are designed according to the gas state parameters of the target working condition. According to the one-dimensional steady flow relationship, the initial back pressure of the test section (6) and the total temperature and pressure of the gas after the secondary reflected shock wave heating and pressurization at the end face of the driven section (3) are calculated by the target flow parameters. According to the ideal shock wave theory, the initial gas pressures of the driving section (1) and the driven section (3) are calculated by the total temperature and pressure of the gas at the end face of the driven section (3).

[0056] Diaphragms are installed on both sides of the membrane section (2) to separate the driving section (1), the membrane section (2) and the driven section (3) cavities, the directional membrane breaking structure (4) is closed, the driven section (3) and the nozzle (5) and the test section (6) cavities are separated, the vacuum pump (13) valve and the driving section (1), the membrane section (2), the driven section (3) and the buffer tank (7) valves are opened, the shock tube body and the wind tunnel test chamber are evacuated, and after the shock tube body and the wind tunnel test chamber reach a vacuum, the vacuum pump (13) is closed.

[0057] Open the nitrogen bottle (16), helium bottle (17) and valves of the driving section (1) and the membrane section (2) respectively, input driving gas to the driving section (1) and the membrane section (2), close the valve of the membrane section (2) after the membrane section (2) reaches half of the target initial pressure of the driving section (1), keep the valve of the driving section (1) open and continue to supply gas to the driving section (1) until the target pressure is reached, and close all valves. Open the valve of the gas distribution tank (14) and the valve of the driven section (3), input test gas to the driven section (3) until the target pressure is reached, and close all valves. Open the valve of the nitrogen bottle (16) and the buffer tank (7), input inert gas to the nozzle (5), the test section (6) and the buffer tank (7) until the target pressure is reached, and close all valves. Since the pressure of the test section (6) is often higher than that of the driven section (3), the directional membrane rupture structure (4) is kept closed during the test gas supply stage.

[0058] The data acquisition device (11) is set to a trigger waiting mode, ready to receive a pressure jump signal to start collecting data, and the valve (12) connected to the outdoor pipeline is opened, and then the valve of the diaphragm section (2) is instantly opened. The driving gas in the diaphragm section (2) is discharged, causing the pressure in the diaphragm section (2) to drop sharply, forming a huge pressure difference with the driving section (1). The pressure difference between the driving section (1) and the diaphragm section (2) exceeds the allowable pressure of the diaphragm, causing the diaphragm to rupture and break through the diaphragm between the diaphragm section (2) and the driven section (3) to form a shock wave. At this time, the incident shock wave propagates toward the end face of the driven section (3), and at the same time, a sparse wave is generated to propagate toward the driving section (1). At the moment of rupture, the contact surface between the driving gas and the test gas and the shock wave surface are basically overlapped. During the propagation process, the movement speed of the contact surface is less than the propagation speed of the shock wave, so the distance between the contact surface and the shock wave surface continues to expand. When the incident shock wave propagates to the end face of the driven section (3), it will be reflected, generating a secondary reflected shock wave that propagates in the direction of the driving section (1) and further increases the temperature and pressure of the test part gas to achieve the designed target working condition.

[0059] When the test gas at the end face of the driven section (3) is subjected to two shock waves, the gas pressure exceeds the initial pressure of the wind tunnel test section (6) and the buffer tank (7), so the directional membrane rupture structure (4) opens directionally, and the high-temperature and high-pressure test gas flows from the driven section (3) to the test section (6) and the buffer tank (7), forming a high-temperature and high-speed flow field, i.e., the test target flow field.

[0060] When the incident shock wave flows through the pressure sensor (9) after the membrane is broken, the pressure sensor (9) senses the sudden change in pressure inside the tube and outputs a pressure jump signal, triggering the data acquisition device (11) to continue data acquisition, and obtain the pressure change curve inside the shock tube body and the wind tunnel test chamber. According to the pressure change curve acquired by the data acquisition device (11), the total pressure of the test gas at the end face of the driven section (3) can be directly obtained. According to the pressure jump time acquired by the pressure sensors (9) arranged at equal known intervals, the incident shock wave velocity, that is, the incident shock wave Mach number, can be calculated. According to the ideal shock wave theory, the total temperature after the secondary shock wave compression at the end face of the driven section (3) can be calculated using the initial temperature of the experimental gas in the driven section (3) and the incident shock wave Mach number, where T total is the total temperature of the experimental gas after the reflected shock wave heating, where T0 is the initial inlet temperature of the driven section, M s is the incident shock wave Mach number, γ1 is the adiabatic index of the experimental gas.

[0061]

[0062] A dynamic pressure measuring device (8) is provided in the test section (6), and two pressure sensors (9) are arranged inside the dynamic pressure measuring device (8) to measure the static pressure and dynamic pressure of the flow field in the test section (6). State parameters such as the flow field velocity and flow field temperature can be calculated based on the isentropic flow theory.

[0063] After the test is completed and the gas inside the shock tube body and the wind tunnel test chamber is stable, open the vacuum pump (13) valve and the valves of the driving section (1), the diaphragm section (2), the driven section (3) and the buffer tank (7), evacuate the shock tube body and the wind tunnel test chamber, discharge the test exhaust gas, close the vacuum pump (13) valve, open the outdoor pipeline (12) valve, balance the shock tube body and the wind tunnel test chamber with the atmospheric pressure, and after the pressure of the shock tube body and the wind tunnel test chamber reaches the atmospheric pressure, disassemble and clean the various parts of the high-temperature wind tunnel.

[0064] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0065] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high temperature wind tunnel with shock wave thermal loading, characterized in that: include: Shock tube, wind tunnel test system, pressure collection system, intake and exhaust system; The shock tube is connected to the wind tunnel test system, the pressure collection system, and the intake and exhaust system respectively; the wind tunnel test system is connected to the pressure collection system; The shock tube uses the pressure difference between the driving gas and the experimental gas to form an incident shock wave to compress the experimental gas once, and the incident shock wave is reflected at the end surface of the shock tube to compress the test gas twice, thereby providing a gas source that meets the requirements for the wind tunnel test system; The wind tunnel test system is used to visualize and observe test phenomena, measure changes in test airflow pressure, absorb the test airflow to maintain the stability of the gas parameters in the test section, and eliminate gas flow noise; The pressure acquisition system is used to collect pressure changes in the shock tube and wind tunnel test system and store and analyze them; The air intake and exhaust system delivers driving gas and test gas to the shock tube and realizes gas intake and output and pressure control.

2. A high temperature wind tunnel with shock wave thermal loading according to claim 1, characterized in that: The shock tube body comprises a coaxially connected driving section, a diaphragm section and a driven section; the diaphragm section is a double-diaphragm pressure difference rupture structure, and two diaphragms are arranged on both sides of the diaphragm section to separate the driving section, the diaphragm section and the driven section.

3. A high temperature wind tunnel with shock wave thermal loading according to claim 1, characterized in that: The wind tunnel test system includes a directional film rupture structure, a nozzle, a test section, a buffer tank and a dynamic pressure measuring device. The directional film rupture structure is located at the end face of the driven section and is coaxially connected to the driven section. The directional film rupture structure is driven to open in a directional manner by a pressure difference and is used to control the unidirectional flow of the test gas from the driven section pipe body to the nozzle. The nozzle is connected to the test section and is used to accelerate the test gas. The test section is used to visualize and observe the test phenomena. The buffer tank is connected to the outlet of the test section and is used to absorb non-ideal airflow and maintain the stability of the gas parameters in the test section. The dynamic pressure measuring device is located inside the test section cavity and is used to measure the dynamic pressure of high-speed airflow.

4. A high temperature wind tunnel with shock wave thermal loading according to claim 1, characterized in that: The pressure acquisition system includes a pressure sensor, a computer and a data collector. The pressure sensor is used to convert the pressure changes in the driven section and the test section of the shock tube into electrical signals. The output signal of the pressure sensor is collected by the data collector and saved in the computer.

5. A high temperature wind tunnel with shock wave thermal loading according to claim 1, characterized in that: The air intake and exhaust system includes a vacuum pump, a gas distribution tank and a high-pressure gas cylinder, which are connected to the shock tube body through a gas pipeline. The high-pressure gas cylinder includes a helium cylinder, a nitrogen cylinder and an oxygen cylinder. The helium cylinder and the nitrogen cylinder convey driving gas to the driving section through the gas pipeline. The gas distribution tank is connected to the driven section through the gas pipeline and is used to configure and convey test gas to the driving section. The vacuum pump is used to evacuate the driving section, the membrane clamping section, the driven section and the gas distribution tank.

6. A high temperature wind tunnel with shock wave thermal loading according to claim 2, characterized in that: Diaphragms are arranged on both sides of the clamping section. Under the pressure difference between the driving section and the driven section, the diaphragms are broken and form an incident shock wave in the driven section. The incident shock wave is reflected and compressed at the end surface of the driven section, and a certain amount of test gas is formed at the end surface of the driven section, which serves as the gas source of the wind tunnel test system.

7. A high temperature wind tunnel with shock wave thermal loading according to claim 3, characterized in that: The end face of the driven section is connected to the directional film-breaking structure, and a small hole is opened at the center of the end face. When the internal pressure of the driven section increases, the directional film-breaking structure opens directionally under the pressure drive, and the test gas flows to the nozzle and the test section through the small hole; The directional membrane rupture structure is driven by the pressure difference between the driven section and the test section and can only be opened in one direction, that is, when the pressure in the driven section is higher than that in the test section, the directional membrane rupture structure opens, and when the pressure in the test section is higher than that in the driven section, the directional membrane rupture structure opens and remains closed.

8. A high temperature wind tunnel with shock wave thermal loading according to claim 3, characterized in that: It also includes modifying the nozzle design parameters according to the target test conditions, and achieving switching between subsonic and supersonic flow fields by switching between convergent nozzles and divergent nozzles.

9. A high temperature wind tunnel with shock wave thermal loading according to claim 3, characterized in that: The tip of the dynamic pressure measuring device is coaxially installed with the nozzle, and two pressure sensors are arranged inside it. Small holes are opened at the tip of the dynamic pressure measuring device and the cylindrical wall respectively, which are connected to the pressure sensors to measure the dynamic pressure and static pressure of the test flow field respectively, so as to calculate the flow velocity of the test flow field; A plurality of pressure sensors are arranged on the side wall of the driven section, and the axial distances between adjacent pressure sensors are equal, and are used to collect the pressure change of the gas in the driven section and to calculate the incident shock wave velocity; All pressure sensor data are output to the data acquisition device and finally saved in the computer. Based on the analysis of the pressure signal, the shock wave velocity, the total temperature and total pressure of the test flow, the flow pressure and static pressure of the test flow are obtained, and the test state parameters are further calculated.

10. A test method for a high temperature wind tunnel with shock wave thermal loading, characterized in that: A high temperature wind tunnel for shock wave thermal loading as claimed in any one of claims 1 to 9, comprising: Before the test, design the test gas composition according to the target working conditions, open the gas tank valve, and open the valves of the oxygen cylinder and nitrogen cylinder in sequence to let gas into the gas tank. After the gas intake is completed, close each valve and let it stand, waiting for the test gas in the gas tank to be fully mixed to obtain the mixed test gas with the preset ratio; Before the test, the initial air inlet pressures in the driving section, driven section and test section are designed according to the gas state parameters of the target working condition flow. According to the one-dimensional steady flow relationship, the initial back pressure of the test section and the total temperature and pressure of the gas after the secondary reflected shock wave heating and pressurization at the end face of the driven section are calculated by the target flow parameters; according to the ideal shock wave theory, the initial gas pressures of the driving section and driven section are calculated by the total temperature and pressure of the gas at the end face of the driven section; Install diaphragms on both sides of the membrane section to separate the driving section, the membrane section and the driven section cavity, close the directional membrane breaking structure, separate the driven section and the nozzle and test section cavity, open the vacuum pump valve and the driving section, the membrane section, the driven section and the buffer tank valve, evacuate the shock tube body and the wind tunnel test cavity, and turn off the vacuum pump after the shock tube body and the wind tunnel test cavity reach vacuum; Open the nitrogen bottle, helium bottle and the valves of the driving section and the membrane section respectively, input the driving gas to the driving section and the membrane section, close the membrane section valve after the membrane section reaches half of the target initial pressure of the driving section, keep the driving section valve open and continue to supply air to the driving section until the target pressure is reached, and close all valves; open the gas distribution tank valve and the driven section valve, input the test gas to the driven section until the target pressure is reached, and close all valves; open the nitrogen bottle and the buffer tank valve, input inert gas to the nozzle, test section and buffer tank until the target pressure is reached, and close all valves. Since the pressure of the test section will be higher than that of the driven section, the directional membrane rupture structure remains closed during the test air intake stage; Set the data collector to the trigger mode, prepare to receive the pressure jump signal to start collecting data, open the valve connected to the outdoor pipeline, and then instantly open the diaphragm section valve. The driving gas in the diaphragm section is discharged, causing the pressure in the diaphragm section to drop sharply, forming a pressure difference with the driving section. The pressure difference between the driving section and the diaphragm section exceeds the allowable pressure of the diaphragm, causing the diaphragm to rupture and break through the diaphragm between the diaphragm section and the driven section to form a shock wave. At this time, the incident shock wave propagates toward the end face of the driven section. When the incident shock wave propagates to the end face of the driven section, it will be reflected, generating a secondary reflected shock wave that propagates toward the driving section, and again increasing the temperature and pressure of the test part of the gas to achieve the designed target working condition; When the test gas at the end face of the driven section is subjected to two shock waves, the gas pressure exceeds the initial pressure of the wind tunnel test section and the buffer tank, the directional membrane rupture structure opens directionally, and the test gas that meets the requirements flows from the driven section to the test section and the buffer tank, forming the test target flow field; When the incident shock wave flows through the pressure sensor after the membrane is broken, the pressure sensor senses the sudden change of pressure in the tube and outputs a pressure transition signal, triggering the data acquisition device to continue data acquisition, and obtain the pressure change curve inside the shock tube body and the wind tunnel test chamber. According to the pressure change curve collected by the data acquisition device, the total pressure of the test gas at the driven section surface is obtained, and the incident shock wave velocity is calculated according to the pressure transition time collected by the pressure sensors arranged at equal intervals, and then the total temperature of the test gas at the end surface of the driven section is calculated; After the test is completed and the gas inside the shock tube body and the wind tunnel test chamber is stable, open the vacuum pump valve and the valves of the driving section, membrane section, driven section and buffer tank, evacuate the shock tube body and the wind tunnel test chamber, discharge the test exhaust gas and close the vacuum pump valve, open the outdoor pipeline valve, balance the pressure inside the shock tube body and the wind tunnel test chamber with the atmospheric environment pressure, and after the pressure of the shock tube body and the wind tunnel test chamber reaches the atmospheric environment pressure, disassemble and clean all parts of the high-temperature wind tunnel.

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