A high-temperature wind tunnel with shock wave thermal loading and its test method

Abstract

This invention discloses a high-temperature wind tunnel and testing method under shock wave thermal loading, relating to the technical field of high-temperature wind tunnel testing equipment. The method includes: a shock tube, a wind tunnel testing system, a pressure acquisition system, and an intake and exhaust system. It utilizes secondary shock wave reflection heating to obtain a high-temperature, high-pressure gas source, resulting in a higher total temperature of the heated gas source. The high-temperature wind tunnel achieves gas heating and pressurization entirely through shock wave flow, requiring no additional electricity or fuel gas, thus reducing the cost per test. The high-temperature wind tunnel test gas is premixed, enabling precise control of the test gas components and ensuring their purity. This invention can obtain high-temperature, high-pressure subsonic flow fields and even supersonic flow fields covering a wide range of operating conditions. It can be used for visual testing and diagnosis of fuel atomization and auto-ignition processes under high-temperature crosswinds, accurately characterizing physicochemical parameters such as fuel atomization characteristics, auto-ignition characteristics, and flame propagation characteristics, providing experimental data support for the combustion organization of engine combustion chamber atomization.

Description

Technical Field

[0001] This invention relates to the field of high-temperature wind tunnel testing equipment technology, and more specifically to a high-temperature wind tunnel and testing method with shock wave thermal loading. Background Technology

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

[0003] Conventional high-temperature wind tunnels cannot cover the current combustion chamber operating parameters and meet the requirements 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 covered, and their temperature boundaries are difficult to match the current combustion chamber temperature range; staged combustion heating wind tunnels have a single operating temperature, making it difficult to control the operating conditions, and inevitably resulting in combustion product pollution; compared with the time scale of basic research on fuel atomization combustion, conventional high-temperature wind tunnels have excessive operating time, resulting in high operating costs, and 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 test gas, after being compressed by the shock wave, experiences a rapid increase in temperature and pressure, and then quickly develops into a supersonic flow through steady expansion in the nozzle. This technology is widely used in supersonic testing. However, because the test section of a shock tunnel is often connected to the driven section, and its initial state is a vacuum environment, the high-temperature, high-pressure test gas after shock wave compression often spontaneously develops into a supersonic flow state, leading to difficulties in subsonic testing applications. Furthermore, during the steady expansion of the test gas, as the gas velocity increases, the temperature and pressure of the test gas rapidly decrease, resulting in a certain difference between the test gas state in the test section and the operating conditions of the engine combustion chamber.

[0005] Therefore, how to provide a high-temperature wind tunnel and testing method for shock wave thermal loading that matches the transonic intake state of various combustion chambers is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

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

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-temperature wind tunnel subjected to shock wave thermal loading includes: a shock tube, a wind tunnel testing system, a pressure acquisition system, and an intake and exhaust system; the shock tube is connected to the wind tunnel testing system, the pressure acquisition system, and the intake and exhaust system respectively; the wind tunnel testing system is connected to the pressure acquisition system.

[0009] The shock tube utilizes the pressure difference between the driving gas and the experimental gas to form an incident shock wave that compresses the experimental gas once. The incident shock wave is reflected at the end face of the shock tube, compressing the experimental gas a second time, thus providing a high-temperature and high-pressure gas source that meets the requirements for the wind tunnel test system.

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

[0011] The pressure acquisition system is used to collect, store, and analyze the pressure changes of the shock tube and wind tunnel test system.

[0012] The intake and exhaust system supplies driving gas and test gas to the shock tube, and realizes gas intake and exhaust and pressure control.

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

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

[0015] Optionally, the pressure acquisition system includes a pressure sensor, a computer, and a data acquisition unit. 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 acquired by the data acquisition unit and saved to the computer.

[0016] Optionally, the 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 via gas supply lines. The high-pressure gas cylinder includes a helium cylinder, a nitrogen cylinder, and an oxygen cylinder. The helium cylinder and the nitrogen cylinder supply driving gas to the drive section via gas supply lines. The gas distribution tank is connected to the driven section via gas supply lines and is used to configure and supply test gas to the drive section. The vacuum pump is used to evacuate the drive section, the jacketed section, the driven section, and the gas distribution tank.

[0017] Optionally, diaphragms are provided on both sides of the membrane section. Under the pressure difference between the driving section and the driven section, the diaphragms break and form an incident shock wave in the driven section. The incident shock wave is reflected and compresses the test gas at the end face of the driven section, forming a certain amount of test gas at the end face of the driven section, which serves as the gas source for the wind tunnel test system.

[0018] Optionally, the driven section end face 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 opens directionally under pressure, and the test gas flows through the small hole to the nozzle and the test section. The directional membrane rupture structure is driven by the pressure difference between the driven section and the test section and can only open 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 remains closed.

[0019] Optionally, it also includes modifying the nozzle design parameters according to the target test conditions, and switching between subsonic and supersonic flow fields by switching between a converging nozzle and a converging-expanding nozzle.

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

[0021] Multiple pressure sensors are disposed on the side wall of the driven section, and the axial distance between adjacent pressure sensors is equal, for collecting gas pressure changes in the driven section and for calculating the incident shock wave velocity.

[0022] All pressure sensor data is output to the data acquisition unit and finally stored in the computer. Based on the analysis of the pressure signals, the shock wave velocity, total temperature and total pressure of the test flow, and the dynamic 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 under shock wave thermal loading includes:

[0024] Before the test, design the test gas composition according to the target working conditions, open the valve of the gas mixing tank, and then open the valves of the oxygen cylinder and nitrogen cylinder in sequence to introduce gas into the gas mixing tank. After the gas is introduced, close all valves and let it stand until the test gas in the gas mixing tank is fully mixed to obtain a mixed test gas with a preset ratio.

[0025] Before the test, the initial inlet pressures in the driving section, driven section, and test section were designed based on the gas state parameters of the incoming flow under the target operating condition. Based on the one-dimensional steady flow relationship, the initial back pressure of the test section and the total temperature and pressure of the gas after being heated and pressurized by the secondary reflected shock wave at the end face of the driven section were calculated using the target incoming flow parameters. Based on the ideal shock wave theory, the initial gas pressures of the driving section and driven section were calculated using the total temperature and pressure of the gas at the end face of the driven section.

[0026] Diaphragms are installed on both sides of the membrane section to separate the drive section, membrane section and driven section cavity. The directional membrane breaking structure is closed to separate the driven section and the nozzle and test section cavity. The vacuum pump valve and the valves of the drive section, membrane section, driven section and buffer tank are opened to evacuate the shock tube body and wind tunnel test cavity. After the shock tube body and wind tunnel test cavity reach vacuum, the vacuum pump is turned off.

[0027] Open the nitrogen cylinder, helium cylinder, and valves of the drive section and membrane section respectively to input drive gas into the drive section and membrane section. After the membrane section reaches half of the target initial pressure of the drive section, close the membrane section valve. Keep the drive section valve open and continue to input gas into the drive section until the target pressure is reached, then close all valves. Open the gas distribution tank valve and the driven section valve to input test gas into the driven section until the target pressure is reached, then close all valves. Open the nitrogen cylinder and buffer tank valves to input inert gas into the nozzle, test section, and buffer tank until the target pressure is reached, then close all valves. Since the pressure in the test section is often higher than the pressure in the driven section, the directional membrane breaking structure remains closed during the test gas inlet phase.

[0028] Set the data acquisition unit to trigger-ready mode to receive pressure transition signals and begin data acquisition. Open the valve connecting to the outdoor pipeline, and then instantly open the valve of the jacketed section. The driving gas in the jacketed section is discharged, causing a sudden pressure drop in the jacketed section and creating a pressure difference with the driving section. When the pressure difference between the driving section and the jacketed section exceeds the allowable pressure of the diaphragm, the diaphragm ruptures and breaks through the diaphragm between the jacketed section and the driven section, forming a shock wave. At this time, the incident shock wave propagates towards the end face of the driven section, and at the same time, a rarefaction wave is generated and propagates towards the driving section. At the moment of rupture, the contact surface between the driving gas and the test gas coincides with the shock wave surface. During propagation, the distance between the contact surface and the shock wave surface continuously increases. 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 towards the driving section and further increases the temperature and pressure of the gas in the test section, achieving the designed target operating 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. Therefore, the directional membrane breaking structure opens in a directional manner, 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 pressure change inside the tube and outputs a pressure transition signal, which triggers the data acquisition unit to continue data acquisition and obtain the pressure change curves inside the shock tube and the wind tunnel test chamber. Based on the pressure change curves acquired by the data acquisition unit, the total pressure of the test gas at the driven section is obtained. Based on the pressure transition time acquired by the pressure sensors arranged at equal intervals, the incident shock wave velocity is calculated, and then the total temperature of the test gas at the end face of the driven section is calculated.

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

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

[0033] 1. This invention utilizes a secondary shock wave reflection heating method to obtain a high-temperature and high-pressure gas source, achieving a total gas source temperature of over 3000K and a flow field temperature of over 2000K. Compared with high-temperature wind tunnels using electric heating, electric arc heating, or staged combustion heating, this invention achieves a higher total gas source temperature. Furthermore, the proposed high-temperature wind tunnel achieves gas heating and pressurization entirely through shock wave flow, requiring no additional electricity or fuel. Therefore, its cost is limited to the shock tube body and the pre-filled inert gas and oxygen within the wind tunnel test chamber, resulting in lower per-test cost. Due to the shock wave motion within the shock tube, the effective test time is on the order of milliseconds, eliminating the need for additional thermal protection measures on the test platform, thus improving the safety and operability of the test device.

[0034] 2. The high-temperature wind tunnel test gas proposed in this invention, through premixing, enables precise control of the test gas components. Compared with wind tunnels using electric arc heating or staged combustion heating, it eliminates contamination from components such as nitrogen oxides generated by electric arc breakdown and combustion products generated by combustion heating, ensuring the purity of the test gas components. The proposed high-temperature wind tunnel, by controlling the pre-charge pressure of each section to control the test flow field state parameters, can achieve flexible control of a wide range of gas state parameters. The temperature, pressure, and flow rate control ranges are wide and have high limits. The flow field temperature can cover 800-2000K, the pressure can cover 1-10 atm, and the flow rate can reach subsonic to supersonic speeds.

[0035] 3. This invention can obtain high-temperature and high-pressure subsonic flow fields, and even supersonic flow fields, covering a wide range of operating conditions. It can be used for visual test diagnosis of fuel atomization and auto-ignition processes under high-temperature crosswinds, accurately characterizing physicochemical parameters such as fuel atomization characteristics, auto-ignition characteristics and flame propagation characteristics, and providing test data support for the combustion organization of atomized combustion in engine combustion chambers. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the high-temperature wind tunnel system provided by the present invention;

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

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention discloses a high-temperature wind tunnel subjected to shock wave thermal loading, such as... Figure 1 As shown, it includes a shock tube, a wind tunnel testing system, a pressure acquisition system, and an intake and exhaust system;

[0041] The shock tube body includes a coaxially connected driving section (1), a membrane section (2), and a driven section (3); the membrane section (2) is a double membrane pressure differential membrane breaking structure, which is set between the driving section (1) and the driven section (3), and two membranes are set on both sides of the membrane section (2) to separate the driving section (1), the membrane section (2), and the driven section (3);

[0042] The wind tunnel test system includes a directional membrane breaking structure (4), a nozzle (5), a test section (6), a buffer tank (7), and a dynamic pressure measuring device (8). The directional membrane breaking structure (4) is located on the end face of the driven section (3) and is coaxially connected to the driven section (3). The directional membrane breaking structure (4) is driven by pressure difference to open directionally and is used to control the test gas to flow unidirectionally from the pipe 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 and observe the test phenomena. 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 includes a pressure sensor (9), a computer (10) and a data acquisition unit (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 acquired by the data acquisition unit (11) and saved to the computer (10).

[0044] The intake and exhaust system includes 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 supply line. The high-pressure gas cylinder includes an oxygen cylinder (15), a nitrogen cylinder (16), and a helium cylinder (17). The oxygen cylinder (15) and the nitrogen cylinder (16) supply driving gas to the drive section through the gas supply line. The gas distribution tank (14) is connected to the driven section (3) through the gas supply line and is used to configure and supply test gas to the drive section (3). The vacuum pump (13) is used to evacuate the drive section (1), the jacketed 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 membrane section (2). Under the pressure difference between the driving section (1) and the driven section (3), the diaphragms break and form an incident shock wave in the driven section (3). The incident shock wave is reflected and compresses the test gas at the end face of the driven section (3), forming a certain amount of high temperature and high pressure test gas at the end face of the driven section (3) as a high temperature wind tunnel gas source. The total temperature of the test gas can reach more than 3000K.

[0046] In a specific embodiment, the end face of the driven section (3) is connected to the directional membrane breaking 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 breaking structure (4) opens directionally under pressure. 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 one 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) remains closed. Therefore, the test gas flows stably from the driven section (3) to the test section (6).

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

[0049] In one specific embodiment, two visualization windows are provided on the horizontal side walls of the test section (6), and a large-size visualization end cap window is provided on the end face. A high-speed camera can capture the test process through the visualization windows in both directions.

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

[0051] Furthermore, the tip of the dynamic pressure measuring device (8) is coaxially mounted with the nozzle (5), and two pressure sensors (9) are arranged inside it. Small holes are opened on the tip of the device and the cylindrical wall respectively to connect to the pressure sensors (9) to measure the dynamic pressure and static pressure of the test flow field, which are used to calculate the flow velocity of the test flow field.

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

[0053] A test method for a high-temperature wind tunnel under shock wave thermal loading includes:

[0054] Before the test, design the test gas composition according to the target working conditions. Open the valve of the gas mixing tank (14), and then open the valves of the oxygen cylinder (15) and nitrogen cylinder (16) in sequence to introduce gas into the gas mixing tank (14). After the gas is introduced, close all valves and let it stand until the test gas in the gas mixing tank (14) is fully mixed to obtain a certain proportion of mixed test gas.

[0055] Before the test, the initial inlet pressures in the driving section (1), driven section (3), and test section (6) were designed based on the gas state parameters of the incoming flow under the target operating conditions. Based on 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 being heated and pressurized by the secondary reflected shock wave at the end face of the driven section (3) were calculated using the target incoming flow parameters. Based on the ideal shock wave theory, the initial gas pressures of the driving section (1) and driven section (3) were calculated using 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), membrane section (2) and driven section (3) cavity. The directional membrane breaking structure (4) is closed to separate the driven section (3) and nozzle (5) and test section (6) cavity. The vacuum pump (13) valve and the valves of the driving section (1), membrane section (2), driven section (3) and buffer tank (7) are opened to evacuate the shock tube body and wind tunnel test cavity. After the shock tube body and wind tunnel test cavity reach vacuum, the vacuum pump (13) is closed.

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

[0058] Set the data acquisition unit (11) to the trigger-ready mode, prepare to receive the pressure transition signal and start collecting data, open the valve (12) connecting the outdoor pipeline, and then open the valve of the membrane section (2) instantly. The driving gas in the membrane section (2) is discharged, causing the pressure in the membrane section (2) to drop sharply and form a huge pressure difference with the driving section (1). The pressure difference between the driving section (1) and the membrane section (2) exceeds the allowable pressure of the membrane, causing the membrane to rupture and break through the membrane between the membrane section (2) and the driven section (3) to form a shock wave. At this time, the incident shock wave propagates towards the end face of the driven section (3), and at the same time, a rarefaction wave is generated and propagates towards the driving section (1). At the moment of membrane rupture, the contact surface of the driving gas and the test gas and the shock wave surface are basically coincident. 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 towards the driven section (1) and further increases the temperature and pressure of the gas in the test section 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). Therefore, the directional membrane breaking structure (4) is opened in a directional manner, 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, which is the test target flow field.

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

[0061]

[0062] A dynamic pressure measuring device (8) is installed in the test section (6), which has two pressure sensors (9) arranged inside. It can measure the static and dynamic pressure of the flow field in the test section (6). According to the isentropic flow theory, the flow field velocity and flow field temperature and other state parameters can be calculated.

[0063] After the test is completed and the gas inside the shock tube and the wind tunnel test chamber is stable, open the valves of the vacuum pump (13), the drive section (1), the jacket section (2), the driven section (3) and the buffer tank (7) to evacuate the shock tube and the wind tunnel test chamber. After the test exhaust gas is discharged, close the valve of the vacuum pump (13) and open the valve of the outdoor pipeline (12) to balance the pressure inside the shock tube and the wind tunnel test chamber with the atmospheric environment. After the pressure inside the shock tube and the wind tunnel test chamber reaches the atmospheric environment pressure, disassemble and clean each part of the high temperature wind tunnel.

[0064] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0065] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-temperature wind tunnel subjected to shock wave thermal loading, characterized in that, include: Shock tube, wind tunnel testing system, pressure acquisition system, intake and exhaust system; The shock tube is connected to the wind tunnel testing system, the pressure acquisition system, and the intake and exhaust system, respectively; the wind tunnel testing system is connected to the pressure acquisition system. The shock tube utilizes the pressure difference between the driving gas and the experimental gas to form an incident shock wave that compresses the experimental gas once. The incident shock wave is reflected at the end face of the shock tube, compressing the experimental gas a second time, thus providing a gas source that meets the requirements for the wind tunnel test system. The wind tunnel testing system is used to visualize and observe test phenomena, measure changes in test air pressure, absorb test airflow to maintain stable gas parameters in the test section, and eliminate gas flow noise. The pressure acquisition system is used to collect, store, and analyze the pressure changes of the shock tube and wind tunnel test system. The intake and exhaust system supplies driving gas and test gas to the shock tube, and realizes gas intake and exhaust and pressure control. The wind tunnel testing system includes a directional membrane breaking structure, a nozzle, a test section, a buffer tank, and a dynamic pressure measuring device. The directional membrane breaking structure is located at the end face of the driven section and is coaxially connected to the driven section. The directional membrane breaking structure is driven by pressure difference to open directionally, and is used to control the test gas to flow unidirectionally from the driven section tube to the nozzle. The nozzle is connected to the test section for accelerating the test gas. The test section is used for visual observation of test phenomena. The buffer tank is connected to the outlet of the test section for absorbing non-ideal airflow and maintaining stable gas parameters in the test section. The dynamic pressure measuring device is located inside the cavity of the test section and is used to measure the dynamic pressure of the high-speed airflow. It also includes the connection between the end face of the driven section and the directional membrane 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 membrane breaking structure opens directionally under pressure drive, and the test gas flows through the small hole to the nozzle and the test section. 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 remains closed.

2. The high-temperature wind tunnel under shock wave thermal loading according to claim 1, characterized in that, The shock tube body includes a driving section, a membrane-clamping section, and a driven section connected coaxially; the membrane-clamping section is a double-membrane differential pressure rupture structure, with two membranes on both sides of the membrane-clamping section to separate the driving section, the membrane-clamping section, and the driven section.

3. The high-temperature wind tunnel under shock wave thermal loading according to claim 1, characterized in that, The pressure acquisition system includes a pressure sensor, a computer, and a data acquisition unit. 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 acquired by the data acquisition unit and saved to the computer.

4. A high-temperature wind tunnel subjected to shock wave thermal loading according to claim 1, characterized in that, The 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 via gas supply lines. The high-pressure gas cylinder includes a helium cylinder, a nitrogen cylinder, and an oxygen cylinder. The helium and nitrogen cylinders supply driving gas to the driving section via gas supply lines. The gas distribution tank is connected to the driven section via gas supply lines and is used to configure and supply test gas to the driving section. The vacuum pump is used to evacuate the driving section, the jacketed section, the driven section, and the gas distribution tank.

5. A high-temperature wind tunnel subjected to shock wave thermal loading according to claim 2, characterized in that, The membrane section has diaphragms on both sides. Under the pressure difference between the driving section and the driven section, the diaphragms break and form an incident shock wave in the driven section. The incident shock wave is reflected and compresses the test gas at the end face of the driven section, forming a certain amount of test gas at the end face of the driven section, which serves as the gas source for the wind tunnel test system.

6. A high-temperature wind tunnel subjected to shock wave thermal loading according to claim 1, characterized in that, It also includes modifying the nozzle design parameters according to the target test conditions, and switching between subsonic and supersonic flow fields by switching between tapered nozzles and tapered-expanding nozzles.

7. A high-temperature wind tunnel subjected to shock wave thermal loading according to claim 1, characterized in that, The tip of the dynamic pressure measuring device is coaxially mounted with the nozzle, and two pressure sensors are arranged inside it. Small holes are opened on the tip of the dynamic pressure measuring device and the cylindrical wall respectively to connect to the pressure sensors, so as to measure the dynamic pressure and static pressure of the test flow field and calculate the flow velocity of the test flow field. Multiple pressure sensors are disposed on the side wall of the driven section, and the axial distance between adjacent pressure sensors is equal, for collecting gas pressure changes in the driven section and for calculating the incident shock wave velocity. All pressure sensor data is output to the data acquisition unit and finally stored in the computer. Based on the analysis of the pressure signals, the shock wave velocity, total temperature and total pressure of the test flow, and the dynamic and static pressure of the test flow are obtained, and the test state parameters are further calculated.

8. A test method for a high-temperature wind tunnel under shock wave thermal loading, characterized in that, A high-temperature wind tunnel subjected to shock wave thermal loading as described in any one of claims 1-7, comprising: Before the test, design the test gas composition according to the target working conditions, open the valve of the gas mixing tank, and then open the valves of the oxygen cylinder and nitrogen cylinder in sequence to introduce gas into the gas mixing tank. After the gas is introduced, close all valves and let it stand until the test gas in the gas mixing tank is fully mixed to obtain a mixed test gas with a preset ratio. Before the test, the initial inlet pressures in the driving section, driven section, and test section were designed based on the gas state parameters of the incoming flow under the target operating condition. Based on the one-dimensional steady flow relationship, the initial back pressure of the test section and the total temperature and pressure of the gas after being heated and pressurized by the secondary reflected shock wave at the end face of the driven section were calculated using the target incoming flow parameters. Based on the ideal shock wave theory, the initial gas pressures of the driving section and driven section were calculated using the total temperature and pressure of the gas at the end face of the driven section. Diaphragms are installed on both sides of the membrane section to separate the drive section, membrane section and driven section cavity. The directional membrane breaking structure is closed to separate the driven section and the nozzle and test section cavity. The vacuum pump valve and the valves of the drive section, membrane section, driven section and buffer tank are opened to evacuate the shock tube body and wind tunnel test cavity. After the shock tube body and wind tunnel test cavity reach vacuum, the vacuum pump is turned off. Open the nitrogen cylinder, helium cylinder, and valves of the drive section and jacketed section respectively to input drive gas into the drive section and jacketed section. After the jacketed section reaches half of the target initial pressure of the drive section, close the jacketed section valve. Keep the drive section valve open and continue to input gas into the drive section until the target pressure is reached, then close all valves. Open the gas distribution tank valve and the driven section valve to input test gas into the driven section until the target pressure is reached, then close all valves. Open the nitrogen cylinder and buffer tank valves to input inert gas into the nozzle, test section, and buffer tank until the target pressure is reached, then close all valves. Since the pressure in the test section will be higher than the pressure in the driven section, the directional membrane breaking structure remains closed during the test gas inlet phase. Set the data acquisition unit to the trigger-ready mode, prepare to receive the pressure transition signal and start data acquisition. Open the valve connecting to the outdoor pipeline, and then instantly open the valve of the jacket section. The driving gas in the jacket section is discharged, causing a sudden drop in pressure in the jacket section and forming a pressure difference with the driving section. The pressure difference between the driving section and the jacket section exceeds the allowable pressure of the diaphragm, causing the diaphragm to rupture and break through the diaphragm between the jacket section and the driven section to form a shock wave. At this time, the incident shock wave propagates towards 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 towards the driving section and further increases the temperature and pressure of the gas in the test section to achieve the designed target operating conditions. 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 pressure change inside the tube and outputs a pressure transition signal, which triggers the data acquisition unit to continue data acquisition and obtain the pressure change curves inside the shock tube and the wind tunnel test chamber. Based on the pressure change curves acquired by the data acquisition unit, the total pressure of the test gas at the driven section is obtained. Based on the pressure transition time acquired by the pressure sensors arranged at equal intervals, the incident shock wave velocity is calculated, and then the total temperature of the test gas at the end face of the driven section is calculated. After the test is completed and the gas inside the shock tube and the wind tunnel test chamber is stable, open the vacuum pump valve and the valves of the drive section, jacket section, driven section and buffer tank to evacuate the shock tube and the wind tunnel test chamber. After the test exhaust gas is discharged, close the vacuum pump valve and open the outdoor pipeline valve to balance the pressure inside the shock tube and the wind tunnel test chamber with the atmospheric environment. After the pressure inside the shock tube 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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