CN114993598A

CN114993598A - Time calibration method and device for shock tunnel dynamic test

Info

Publication number: CN114993598A
Application number: CN202210553749.3A
Authority: CN
Inventors: 汪运鹏; 王粤; 姜宗林
Original assignee: Institute of Mechanics of CAS
Current assignee: Institute of Mechanics of CAS
Priority date: 2022-05-20
Filing date: 2022-05-20
Publication date: 2022-09-02
Anticipated expiration: 2042-05-20
Also published as: CN114993598B

Abstract

The invention relates to the field of wind tunnels, in particular to a time calibration method for a dynamic test of a shock tunnel, and further relates to a time calibration device for the dynamic test of the shock tunnel, wherein the time calibration device comprises a test model, a pneumatic ejection device, a signal trigger and an observation acquisition system, the pneumatic ejection device is used for pushing the test model to provide the test model with initial momentum of free flight, the signal trigger is used for sending a trigger signal to the pneumatic ejection device and the observation acquisition system, and the observation acquisition system is used for shooting and recording a video of the test model; the time calibration method comprises the following steps: and the running time calibration device calculates each time of the shock tunnel dynamic test through data obtained by observing the acquisition system. The time calibration method is carried out under the original collection system of the shock tunnel dynamic test and the real test environment, and is accurate in time calibration, high in accuracy, high in reduction degree, simple, reliable and convenient to operate.

Description

Time calibration method and device for shock tunnel dynamic test

Technical Field

The invention relates to the field of wind tunnels, in particular to a time calibration method for a dynamic test of a shock tunnel. The invention also relates to a time calibration device for the dynamic test of the shock tunnel.

Background

Generally, the test of the multi-body separation or dynamic flight characteristics of hypersonic aircrafts and other special tests are mostly carried out in conventional hypersonic wind tunnels.

The problem is not obvious and does not bring enough attention in the conventional wind tunnel test because the effective test time of the conventional hypersonic wind tunnel is very long (about 40s), the time required by the separation and free flight of the high-speed model and the delayed actuation time of a related pneumatic actuating element (a high-speed pneumatic ejection device) can be ignored, but the problem is very important in the dynamic special test of the shock wind tunnel with short effective test time (about 100ms), and the problem of solving the aircraft separation or free flight time in the shock wind tunnel special test and the start delay time of the corresponding device are very important in considering that the shock wind tunnel has irreplaceable advantages for the development of a great hypersonic aircraft compared with the conventional wind tunnel due to the fact that the shock wind tunnel has high total temperature.

In order to obtain the above time parameters and to control them precisely, it is necessary to calibrate them by a new method.

Disclosure of Invention

The invention aims to provide a time calibration method and a time calibration device for a dynamic test of a shock tunnel, and aims to solve the problem that

In order to solve the technical problems, the invention specifically provides the following technical scheme:

the application provides a time calibration method for a shock tunnel dynamic test, wherein a time calibration device used in the time calibration method comprises a test model, a pneumatic ejection device, a signal trigger and an observation acquisition system, an ejection end of the pneumatic ejection device is over against the test model, the pneumatic ejection device is used for pushing the test model to provide initial momentum of free flight for the test model, the signal trigger is used for sending a trigger signal to the pneumatic ejection device and the observation acquisition system, and the observation acquisition system is used for shooting and recording a video of the test model; the time calibration method comprises the following steps:

s2, starting the signal trigger at a time t1, wherein the signal trigger sends trigger signals to the pneumatic ejection device and the observation and collection system; s3, the observation acquisition system shoots and records the test model; s5, the pneumatic ejection device pushes the test model to enable the test model to obtain the initial momentum of free flight; and S7, obtaining an initial time t5 when the test model starts to move and an end time t7 when the test model completely departs from an observation interval of the observation acquisition system through the acquisition result of the observation acquisition system, and obtaining a model flight time dt4 by using a formula dt4-t 7-t 5.

Preferably, the pneumatic ejection device comprises an ejection driving part, a cylinder body, a piston rod and an ejection executing part, the ejection driving part is used for providing high-pressure gas, the cylinder body is provided with an air inlet end and an air outlet end, the air inlet end is connected with the ejection driving part, the piston and the piston rod are coaxially connected inside the cylinder body, the ejection executing part is connected with the piston rod, the ejection executing part pushes the test model under the action of kinetic energy provided by the piston, a second pressure sensor is connected to a position, close to the air outlet end, on the cylinder body, and the second pressure sensor is connected with a pressure signal collecting system through a pressure sensor signal collecting line; the time calibration method also comprises the following steps:

and S6, the pressure signal acquisition system acquires the voltage signal transmitted by the second pressure sensor through the pressure sensor signal acquisition line, the time when the signal trigger sends a trigger signal to the ejection driving part is set as t3, the time when the second pressure sensor sends a signal is set as t5, and the ejection actuation delay time dt3 is obtained by using a formula dt 3-t 5-t 3.

Preferably, a first pressure sensor is connected to a position, close to the air inlet end, on the cylinder body of the air cylinder, and the first pressure sensor is connected with the pressure signal acquisition system through a pressure sensor signal acquisition circuit; step S6 further includes the steps of:

the pressure signal acquisition system acquires the voltage signal transmitted by the first pressure sensor through the pressure sensor signal acquisition line, and the time when the first pressure sensor sends out a signal is t 4.

Preferably, the time calibration method further comprises the following steps:

and S4, after the time t1, starting the shock tunnel at an ignition signal time t2 after an ignition delay time dt1 to obtain a wind tunnel air-out time t6 and a wind tunnel effective test time t.

Preferably, the time calibration device further comprises a signal control instrument; step S2 further includes:

at the time t1, the signal trigger sends a trigger signal to the signal control instrument; step S5 further includes:

after the time t1, the ejection start delay time dt2 elapses, and at the time t3, the signal control unit sends a start signal to the pneumatic ejection device.

Preferably, the time calibration method further comprises the following steps:

s8, repeating the steps S2-S7 for a plurality of times and averaging, and adjusting the ignition delay time dt1 and the ejection starting delay time dt2 to meet the following conditions, thereby completing the calibration of the ignition delay time dt1 and the ejection starting delay time dt 2:

if the model flight time dt4 is less than the wind tunnel effective test time t, making the initial time t5 equal to the wind tunnel air-out time t 6; and if the model flight time dt4 is greater than the wind tunnel effective test time t, enabling the initial time t5 to be greater than the wind tunnel air-out time t 6.

Preferably, the time calibration device further comprises a wind tunnel test cabin, and the test model and the pneumatic ejection device are both placed in the wind tunnel test cabin; the time calibration method further comprises the following steps:

and S1, before the time t1, vacuumizing the interior of the wind tunnel test chamber.

and S1, before the time t1, vacuumizing the interior of the wind tunnel test chamber, the interior of the cylinder body and the connection part of the air inlet end and the ejection driving part.

Preferably, the ejection driving part comprises an air supply source, an electromagnetic valve, a three-way joint and a vacuum source, the air supply source, the electromagnetic valve, the three-way joint and the air inlet end are sequentially connected, and the remaining interface of the three-way joint is connected with the vacuum source; step S1 specifically includes the following steps:

before the time t1, vacuumizing the interior of the wind tunnel test cabin, and simultaneously opening the vacuum source, wherein the vacuum source extracts gas in the cylinder body of the air cylinder and at the connecting part of the air inlet end and the tee joint through the tee joint.

Preferably, the vacuum source is connected with the three-way joint through a valve and a vacuum meter; step S1 further includes the steps of: when the vacuum meter displays the negative pressure state and the reading is stable, the vacuum source and the valve are closed.

The application still provides a time calibration device for shock tunnel dynamic test, including test model, pneumatic jettison device, signal trigger and observation collection system, pneumatic jettison device's ejection end is just right test model, pneumatic jettison device is used for promoting test model is in order to give test model provides the initial momentum of free flight, signal trigger be used for to pneumatic jettison device with it sends trigger signal to observe collection system, it is right to observe collection system is used for the video recording is shot to test model, and gathers test model initial moment t5 of starting motion, and test model breaks away from completely observe collection system's observation interval's termination time t 7.

Preferably, the time calibration device further comprises a wind tunnel test cabin, the test model and the pneumatic ejection device are both placed in the wind tunnel test cabin, and before the signal trigger sends the trigger signal, the interior of the wind tunnel test cabin is in a vacuum state.

This application compares with prior art has following beneficial effect:

1. the time calibration method is carried out under the original collection system of the shock tunnel dynamic test and the real test environment, and is accurate in time calibration, high in accuracy, high in reduction degree, simple, reliable and convenient to operate.

2. The time calibration method can accurately calibrate various time parameters in the shock tunnel dynamic test, so that the test model can accurately and smoothly complete separation or free flight in the short effective test time of the shock tunnel.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary and that other implementation drawings may be derived from the provided drawings by those of ordinary skill in the art without inventive effort.

FIG. 1 is a schematic diagram of a principle of a free flight test process of a multi-body separation wind tunnel;

FIG. 2 is a block diagram of an embodiment of a shock tunnel simulation test apparatus for performing a multiple-body separation free flight test;

FIG. 3 is a block diagram of another embodiment of a shock tunnel simulation test apparatus for performing a free-flight test;

FIG. 4 is a block diagram of a time calibration apparatus;

FIG. 5 is a schedule of a time calibration process;

FIG. 6 is a flow chart of a method of time calibration in a ground environment;

FIG. 7 is a flow chart of a method for time calibration in a vacuum environment;

the reference numerals in the drawings denote the following, respectively:

1-wind tunnel test chamber; 1 a-a curved knife; 1 b-a model strut; 1 c-a first flange; 1 d-a second flange plate;

2-test model;

3-a pneumatic ejection device;

4-ejection driving part; 4 a-a gas supply source; 4a 1-gas cylinder; 4a 2-cylinder valve switch; 4a 3-pressure relief valve; 4 b-a solenoid valve; 4 c-a control module; 4c 1-signal trigger; 4c 2-signal control instrument; 4c3 — first trigger signal conductor; 4c 4-voltage signal output conductor; 4 d-a first hose; 4 e-a second hose; 4 f-three-way joint; 4 g-a third hose; 4 h-vacuum source; 4 i-valve; 4 j-vacuum gauge;

5-a power conversion section; 5 a-a cylinder block; 5a 1-inlet end; 5a 2-outlet end; 5 b-a piston; 5 c-a piston rod; 5 d-a first pressure sensor; 5 e-a second pressure sensor; 5 f-a pressure sensor signal acquisition circuit; 5 g-a pressure signal acquisition system;

6-ejection executing part;

7-observation acquisition system; 7 a-second trigger signal conductor.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The principle of the common wind tunnel model free flight test is as follows:

when the model flies freely under the action of wind tunnel airflow, a high-speed camera is used for recording free flight images, the time history of the motion trail, the attitude angle and the angular speed of the model is obtained through image interpretation, and the aerodynamic force and the aerodynamic derivative of the model are obtained by adopting a parameter fitting or parameter identification data processing method.

The method has the advantages that the method has no support interference, can truly simulate the actual flight state of the aircraft, and is the advantage of the wind tunnel model free flight test, and the test model in the common wind tunnel model free flight test can fly freely without being supported.

The principle of the multi-body separation wind tunnel free flight test is that each separation body is locked into an integral aircraft model in advance, the aircraft model is launched in the wind tunnel flow field in the direction of the airflow, when the aircraft model flies to an observation window freely, a separation unlocking device triggers unlocking, so that each separation body is separated, meanwhile, recording equipment such as high-speed camera shooting is used for shooting and recording the separation process of each separation body and the flight tracks before and after separation, and the research on the interference characteristic and the motion track during separation among the bodies is realized.

As shown in fig. 1, the whole test process can be divided into four stages, and a schematic diagram of a principle of a multi-body separation wind tunnel free flight test process taking interstage separation as an example is shown.

In the stage I, the model as a whole is emitted into a flow field by an emitting device along the direction of the air flow of the wind tunnel; in the stage II, the model freely flies into the range of an observation window, high-speed photography starts to shoot and record the flight track of the model, and the front stage and the rear stage of the model are still not separated; in the stage III, the separation unlocking mechanism unlocks, and the front stage and the rear stage of the model start to be separated; and IV, completing the separation process, and enabling the front stage and the rear stage of the model to fly out of the observation windows respectively.

The multi-body separation wind tunnel free flight test technology not only has all the characteristics of the wind tunnel free flight test technology, but also has unique requirements and greater difficulty than the latter.

The method strictly simulates the appearance of the aircraft and the motion parameters of each separating body, including the mass center, the mass, the inertia, the unlocking mode, the magnitude and the form of the separating force and the like, each separating body flies unrestrained and freely according to the motion rule similar to the real flight in the test, the motion and pneumatic coupling rule of a multi-body separating process can be fully reflected, and the method is a ground simulation test method which is very close to the pneumatic characteristic of the real flight.

The simulation of the transient aerodynamic force at the separating moment is only comparable to the wind tunnel release model test technology, but the simulation of the interference characteristic between the separated bodies in the multi-body separating process of the aircraft in the free flight state cannot be realized by the wind tunnel release model test technology.

The test device for the multi-body separation wind tunnel free flight test can be divided into two items, namely:

the device comprises a wind tunnel free flight test device and a separation unlocking mechanism.

The separation unlocking mechanism is a special test device required by a free flight test of the multi-body separation wind tunnel, and can ensure that each separation body is reliably locked before unlocking, and can quickly realize unlocking after being triggered, and meet the requirements of separation parameters such as relative speed, relative attitude and the like of each separation body at the moment of separation.

Because the multi-body separation wind tunnel free flight test is a special form of the wind tunnel free flight test, the test device of the wind tunnel free flight test is required by the test, such as a model transmitting mechanism, a recording device, a synchronous control device, an optical path system and the like, and the requirements of the wind tunnel free flight test are the same as those of the common wind tunnel free flight test.

If a high-speed camera is usually adopted to record the separation process and the flight track of the separation body, the separation process is a transient dynamic process and is generally only tens of milliseconds; in order to observe and record the separation process more accurately, double light paths are adopted for shooting better; and a synchronous controller is adopted to realize synchronous starting control and the like of the model transmitting system and the high-speed camera.

The structure of the model launching mechanism is already given in the prior art, but in a hypersonic wind tunnel dynamic test, higher requirements are put forward on the existing model launching mechanism.

In the field of aerospace basic research, the hypersonic wind tunnel dynamic test technology makes great contribution to the research of dynamic flight characteristics and multi-body separation dynamic characteristics of hypersonic aircrafts.

At present, hypersonic wind tunnels are mainly divided into conventional hypersonic heating wind tunnels and shock wave wind tunnels.

The conventional hypersonic wind tunnel adopts electric arc heating and downward blowing type airflow to carry out tests, the effective test time is often dozens of seconds, a track capture System (CTS) can be used for carrying out multi-body separation tests, but the CTS multi-body separation tests belong to quasi-steady tests in principle and are unreal dynamic Simulation tests.

On the other hand, the conventional hypersonic wind tunnel is used for heating test gas in a room by adopting devices such as electric arcs and the like, so that the test gas is not pure air, the heating capacity is limited, the high total temperature cannot be reached, the high-temperature real gas effect under the hypersonic flight condition is reflected, and the higher test Mach number cannot be reached.

More of the eosin of the aircraft dynamics at high mach numbers is studied into the shock impulse tunnel.

The shock wave pulse wind tunnel can reach higher total temperature and simulate high-temperature real gas effect under the condition of higher Mach number flight, but the effective test time of the shock wave wind tunnel is shorter, the longest time can reach 130ms, and the shock wave wind tunnel can refer to the JF12 shock wave wind tunnel of the institute of mechanics of Chinese academy of sciences.

If a dynamic separation or free flight test of a hypersonic vehicle needs to be researched, a high-speed ejection device which can be used for a shock tunnel is needed, and a test model can be subjected to high-speed dynamic separation or ejection free flight within short effective test time of the shock tunnel.

At present, a CTS track simulation system is generally adopted for a multi-body separation test in a hypersonic wind tunnel, and the test is a quasi-static separation simulation test and a dynamic separation simulation test under an unreal flight condition; the model free flight test putting device mainly adopts a suspension type and a launching type, and the two methods have respective advantages and disadvantages.

The suspension type throwing device is beneficial to better controlling the initial posture of the model, but the airflow impact force is too large in the process of establishing the flow field of the pulse type supersonic speed or hypersonic speed wind tunnel, the suspension is very firm, and the conflict exists between the burstiness and the non-interference requirement when the release is required.

For the launching type launching device, a model is installed in a launching tube, so that more test periods can be obtained, the defects are that the requirement of high acceleration in the launching process of the model is met, certain disturbance exists in the initial state of the model due to the disturbance of a flow field at the outlet of the launching tube, strong pneumatic interference exists under the condition of hypersonic incoming flow, the initial attitude of the model is not easy to determine, and the other defect is that the launching tube needs to be matched with the model, and the interchangeability is poor.

And the current wind tunnel free flight test is limited to the shaping test of an axisymmetric aircraft with a large slenderness ratio.

In order to solve the technical problem that the existing model launching mechanism is not suitable for a shock tunnel, as shown in figures 2-3, the application provides a shock tunnel simulation test device based on a high-speed pneumatic ejection technology, which comprises:

the wind tunnel test chamber 1 is in a vacuum state (about 30 Pa) in the test; before the test is started, the wind tunnel test cabin 1 is hermetically connected with a spray pipe of a shock tunnel, then a vacuum unit of the shock tunnel starts to work, and the interior of the wind tunnel test cabin 1 is pumped into a vacuum state.

The test model 2 is placed in the wind tunnel test cabin 1; the test model 2 is placed towards a spray pipe of the shock tunnel, the height of the test model 2 is limited to a certain extent, the test model needs to be emitted out and cannot fall to the ground within the effective test time of the shock tunnel, and the weight of the test model 2 is 26 kg.

The device comprises a pneumatic ejection device 3, wherein an ejection end of the pneumatic ejection device 3 is over against a test model 2 and faces the air outlet direction of a shock tunnel, the pneumatic ejection device 3 is used for pushing the test model 2 to provide initial momentum for flight for the test model 2, so that when a wind field of the shock tunnel is formed at the inlet of a wind tunnel test cabin 1, the pneumatic ejection device 3 executes ejection work, the test model 2 flies for 10-20 ms freely, and then the test model 2 is built in a wind tunnel test airflow V infinity at a speed V to perform a high-speed multi-body separation free flight or common free flight test; and after 1-3 seconds, the wind tunnel test is finished, and all the equipment is closed.

Further, in order to make the test model 2 have a certain height inside the wind tunnel test chamber 1:

a bent knife 1a and a model supporting rod 1b are placed in a wind tunnel test cabin 1, the bent knife 1a and the model supporting rod 1b are sequentially connected, and the model supporting rod 1b is used for placing a test model 2, so that the test model 2 has a height which does not fall to the ground before the test is finished.

In the free flight test, the model strut 1b is only used for placing the test model 2, and in the test, no rigid/flexible connecting structure or magnetic attraction exists between the model strut 1b and the test model 2; in the multi-body separation test, during the flight after the test model 2 is separated from the model strut 1b, the unlocking mechanism is unlocked, and the structure of the unlocking mechanism is disclosed in the prior art and is not described in detail herein.

Further, the present embodiment provides an implementation manner of the pneumatic ejection device 3:

the pneumatic ejection device 3 comprises an ejection driving part 4, and the ejection driving part 4 is used for providing high-pressure gas; the ejection driving section 4 can output high-pressure gas by means of release of a high-pressure gas cylinder, combustion of gunpowder, or the like.

The power conversion part 5 is connected with the ejection driving part 4, and the power conversion part 5 is used for converting the internal energy of the high-pressure gas into the kinetic energy of linear motion; and the ejection executing part 6 is connected with the power conversion part 5, and the ejection executing part 6 pushes the test model 2 to move along the linear direction under the function provided by the power conversion part 5 and flies freely under the inertia effect.

Further, the present application also provides a test method of the shock tunnel simulation test device, as shown in fig. 4, including the following steps:

step 100, controlling and adjusting the gas pressure output by the ejection driving part 4, and entering preparation work; step 200, extracting gas between the ejection driving part 4 and the power conversion part 5; step 300, vacuumizing the interior of the wind tunnel test cabin 1; step 400, detecting whether the space between the ejection driving part 4 and the power conversion part 5 is in a vacuum state, if not, returning to the step 200, if so, stopping the vacuum pumping work and entering the next step; 500, detecting whether the wind tunnel test chamber 1 is in a vacuum state, if so, performing the next step, otherwise, returning to the step 300; step 600, igniting a shock wind tunnel, and forming a wind field at an inlet of a wind tunnel test cabin 1 after a period of time; step 700, the ejection driving part 4 is started in a delayed mode, high-pressure gas is provided for the power conversion part 5, the internal energy of the high-pressure gas is converted into kinetic energy by the power conversion part 5, and the test model 2 is ejected through the ejection executing part 6, so that when a wind field is formed at the inlet of the wind tunnel test cabin 1, the test model 2 is in a free flight state.

In the multi-body separation test, the method further includes step 800, after the ejection executing part 6 impacts the test model 2, the unlocking mechanism of the test model 2 is unlocked, so that the test model 2 completes multi-body separation in the free flight process.

It should also be noted that the high-speed pushing includes the following two motion processes.

One is as follows:

before the test, the ejection execution part 6 is not in contact with the test model 2, the end part of the ejection execution part 6 is connected with a round cake-shaped impact block, during the test, the impact block of the ejection execution part 6 moves at a high speed and impacts on the test model 2, so that the test model 2 obtains initial momentum capable of flying freely, and if the test is a multi-body separation free flight test, the unlocking structure of the test model 2 is unlocked after the impact.

The impact process belongs to strict high-speed dynamic separation, the upper-level model can finish high-speed longitudinal dynamic separation in 116ms (in JF12 effective test time), the maximum speed can reach about 10m/s, the test simulation of the CTS system used in the conventional hypersonic wind tunnel belongs to a standard steady test, and the interference of the impact process on the separation model is greatly reduced compared with that of the CTS system, because the separated test model has no interference of a tail support rod in the separation process.

The second step is as follows:

before the test, the ejection executing part 6 is abutted against the tail part of the test model 2, a blind hole which is matched with the ejection executing part 6 in an inserted mode is formed in the tail part of the test model 2, during the test, the test model 2 and the ejection executing part 6 move together, and when the ejection executing part 6 reaches the end point of the stroke, the test model 2 is separated from the ejection executing part 6 and flies freely under the action of inertia.

Compared with the interference of a traditional sleeve launching mode, the interference of the pushing process on the test model is greatly reduced (even is not interfered), the burstiness is met during launching, the initial posture of the model is easy to determine during launching, the sleeve is avoided in the launching method, the model interchangeability is greatly improved, the method can be suitable for diversified complex aircraft shapes, and in addition, the cost of the test model and the cost of machining the sleeve are saved.

Further, the present embodiment provides an embodiment of the ejection driving part 4:

the ejection drive section 4 includes a gas supply source 4a, and the gas supply source 4a is preferably a 15MPa high-pressure nitrogen gas source.

And the electromagnetic valve 4b is arranged in the wind tunnel test cabin 1, and the electromagnetic valve 4b is preferably a direct-current quick-opening high-pressure pilot-operated normally-closed electromagnetic valve (voltage is 24V, withstand voltage is 15MPa, drift diameter is 10mm, opening time is less than 20ms, and closing time is 1-3 s).

And a control module 4c for controlling the opening and closing of the electromagnetic valve 4b, wherein the air supply source 4a is communicated with the electromagnetic valve 4b through a first hose 4d, the electromagnetic valve 4b is communicated with the power conversion part 5 through a second hose 4e, the interiors of the second hose 4e and the power conversion part 5 are in a vacuum state during testing, and the first hose 4d and the second hose 4e are preferably high-pressure air hoses (6 mm in inner diameter and 28MPa in pressure resistance).

Specifically, the method comprises the following steps:

the wind tunnel test chamber 1 is connected with a first flange plate 1c, a first hose 4d penetrates through a shell of the wind tunnel test chamber 1 through the first flange plate 1c, and the first flange plate 1c is used for connecting the wind tunnel test chamber 1 and the first hose 4d to ensure that no air leakage point exists.

The gas supply source 4a always supplies pressure to the gas inlet ends of the first hose 4d and the solenoid valve 4b, and after the solenoid valve 4b is opened, the high-pressure gas is transmitted to the power conversion unit 5 through the second hose 4e, and the power conversion unit 5 converts the internal energy of the high-pressure gas into kinetic energy.

The air supply source 4a includes a gas cylinder 4a1, a cylinder valve switch 4a2, and a pressure reducing valve 4a3 connected in this order, the gas cylinder 4a1 is used for storing high-pressure nitrogen gas, the cylinder valve switch 4a2 is used for opening and closing the gas cylinder 4a1, the pressure reducing valve 4a3 is connected to the solenoid valve 4b through the first hose 4d, and the pressure reducing valve 4a3 is used for stabilizing the pressure of the nitrogen gas output to the inside of the first hose 4d so that the operating pressure thereof is 9 MPa.

Further, the present embodiment provides an implementation manner of the control module 4 c:

the control module 4c comprises a signal trigger 4c1 and a signal controller 4c2, the signal trigger 4c1 is connected with the signal controller 4c2 through a first trigger signal lead 4c3, the signal controller 4c2 is connected with the electromagnetic valve 4b through a voltage signal output lead 4c4, when the shock tunnel is ignited, the signal trigger 4c1 sends a trigger signal to the electromagnetic valve 4b, and the signal controller 4c2 waits for a specified time after receiving the trigger signal and then sends a 24V direct-current voltage signal to the electromagnetic valve 4 b.

The specified time is approximately 400ms to 450ms, and specific data can be determined according to test results as long as the following conditions are met:

when the wind field of the shock tunnel is formed at the inlet of the wind tunnel test chamber 1, the pneumatic ejection device 3 already executes ejection work, and the test model 2 already flies freely for 0-20 ms.

Further, in order to shorten the time required for the high-pressure gas to pass from the electromagnetic valve 4b to the power conversion portion 5, so as to reduce the uncontrollable factors of the test:

the electromagnetic valve 4b is disposed inside the wind tunnel test chamber 1 and near the power conversion unit 5.

If the electromagnetic valve 4b is located outside the wind tunnel test chamber 1, the length of the first hose 4d is long, and after the electromagnetic valve 4b is opened, the high-pressure gas can reach the power conversion part 5 only after a long time, so that the time delay between the opening of the electromagnetic valve 4b and the starting of the power conversion part 5 is too long, and even the technical problem that the power conversion part 5 is not started before the effective test time of the shock tunnel is over may be caused.

Further, the present embodiment provides an embodiment of the power conversion portion 5:

the power conversion part 5 comprises a cylinder body 5a, a piston 5b and a piston rod 5c, the cylinder body 5a is provided with an air inlet end 5a1 and an air outlet end 5a2, the air inlet end 5a1 is connected with the ejection driving part 4, the air outlet end 5a2 is communicated with the interior of the wind tunnel test chamber 1, the piston 5b and the piston rod 5c are coaxially connected inside the cylinder body 5a, the stroke of the piston 5b is 150mm, the diameter of the piston 5b is 63mm, the piston rod 5c is connected with the ejection executing part 6, and when the ejection driving part 4 outputs high-pressure gas to the interior of the cylinder body 5a through the air inlet end 5a1, the piston 5b moves towards the air outlet end 5a2 so as to convert the internal energy of the high-pressure gas into kinetic energy.

Furthermore, because the air outlet end 5a2 is communicated with the interior of the wind tunnel test chamber 1, the section of the interior of the cylinder body 5a close to the air outlet end 5a2 can keep a vacuum negative pressure state synchronously with the wind tunnel test chamber 1, while the section of the interior of the second hose 4e and the cylinder body 5a close to the air inlet end 5a1 can keep a certain pressure (which can reach an atmospheric pressure at most) before the test, and both sides of the piston 5b can be subjected to a thrust force, so that the piston rod 5c extends outwards, and before the test starts, the stroke actuation of the cylinder is completed, and the model cannot be ejected, so that the test is stopped.

In order to solve the above problem, before the test is started, the second hose 4e and the gas remaining inside the power conversion part 5 need to be evacuated, so that when the vacuum is evacuated inside the wind tunnel test chamber 1, the second hose 4e and the power conversion part 5 have no internal energy inside which the piston 5b can convert, and the piston 5b is prevented from moving before the test is started.

Embodiment 1 in which the inside of the second hose 4e and the power conversion unit 5 is evacuated:

the cylinder block 5a is formed with a micropore (not shown) at one end thereof near the air inlet end 5a1 to communicate with the interior of the wind tunnel test chamber 1.

The micropore refers to a hole with the diameter less than or equal to 1mm, although the high-pressure gas in the cylinder body 5a can overflow through the micropore in the process that the high-pressure gas enters the cylinder body 5a through the air inlet end 5a1 and drives the piston 5b to move when the ejection driving part 4 is started, the loss of the internal energy of the high-pressure gas is almost negligible, the negative effect on the movement of the piston 5b can be negligible, but the micropore has the advantages that:

before the test begins, when the vacuum unit of the shock tunnel vacuumizes the wind tunnel test chamber 1, the residual gas in the second hose 4e and the cylinder body 5a can escape into the wind tunnel test chamber 1 through the micropores and then be extracted, so that the second hose 4e and the cylinder body 5a also form vacuum when the interior of the wind tunnel test chamber 1 forms vacuum.

Embodiment 2 in which the inside of the second hose 4e and the power conversion unit 5 is evacuated:

the electromagnetic valve 4b is connected to the first hose 4d via a three-way joint 4f, and the remaining port of the three-way joint 4f is connected to a vacuum source 4h via a third hose 4g, the vacuum source 4h is preferably an air pump, and the third hose 4g is preferably a high-pressure air hose (inner diameter 6mm, pressure resistance 28 MPa).

The vacuum source 4h is for drawing gas between the electromagnetic valve 4b and the power conversion portion 5 to form a vacuum.

Specifically, the wind tunnel test chamber 1 is connected with a second flange 1d, the voltage signal output lead 4c4 and the third hose 4g penetrate through the shell of the wind tunnel test chamber 1 through the second flange 1d, and the second flange 1d is used for connecting the wind tunnel test chamber 1 with the voltage signal output lead 4c4 and the third hose 4g to ensure that no air leakage point exists.

The above structure can also achieve the effect of vacuumizing the interior of the second hose 4e and the cylinder 5a before the test is started, in order to make the operation of the vacuum source 4h controllable, in this embodiment, a valve 4i and a vacuum gauge 4j are installed on the third hose 4g, wherein, for the operation of a worker, the valve 4i and the vacuum gauge 4j are both located outside the wind tunnel test chamber 1, before the test is started, the vacuum source 4h works to pump out the gas inside the second hose 4e and the cylinder 5a through a three-way joint 4f, the worker observes the reading of the vacuum gauge 4j to judge whether the second hose 4e and the cylinder 5a are in a vacuum state (about 10 kPa) and are kept stable, and if so, the vacuum source 4h and the valve 4i are closed.

Further, the present embodiment provides two embodiments of the ejection executing part 6:

the ejection actuator 6 is a connecting rod connected to the piston rod 5c for contacting the test pattern 2, and specifically, the ejection actuator 6 is coaxially connected to an end of the piston rod 5 c.

The ejection executing part 6 follows the piston rod 5c to move at a high speed to push the test model 2 at a high speed and bring it into a free flight state.

Further, to be able to observe the course of the test:

the shock tunnel simulation test device further comprises an observation and acquisition system 7, the observation and acquisition system 7 is connected with the signal trigger 4c1 through a second trigger signal lead 7a, the observation and acquisition system 7 is used for observing and acquiring the motion trail of the test model 2 in the shock tunnel flow field, and the signal trigger 4c1 is used for sending a trigger signal to the observation and acquisition system 7 when the shock tunnel is ignited.

The observation and collection system 7 is preferably a high-speed camera/schlieren collection system, as shown in fig. 1, the collection interval of the observation and collection system 7 is an area that can be observed by the observation window, and the working time of the observation and collection system 7 is continued from the ignition of the shock tunnel until the test model 2 falls to the ground.

After solving the technical problem of how to eject the test model 2 in the shock tunnel, other technical problems remain to be solved:

the shock tunnel effective test time (the highest-100 ms, millisecond magnitude) is very short compared with the hypersonic conventional wind tunnel effective test time (40 s, second magnitude), so if dynamic special tests such as model free flight or multi-body separation and the like are developed in the shock tunnel, firstly, a high-speed pneumatic ejection device is needed, the model can be ejected out within the shock tunnel effective test time, secondly, the time for controlling the model ejection separation or free flight, the actuation delay time of the high-speed pneumatic ejection device and the signal delay time for starting the high-speed pneumatic ejection device during the test are needed, so that the effective test time of the shock tunnel can be utilized to the maximum extent by the separation and free flight of the model, and reliable test data are obtained.

Generally, the multi-body separation or dynamic flight characteristic test and other special tests of the hypersonic flight vehicle are mostly carried out in a conventional hypersonic wind tunnel.

The problem is not obvious and does not bring enough attention in the conventional wind tunnel test because the effective test time of the conventional hypersonic wind tunnel is very long, and the time required by the separation and free flight of the high-speed model and the delay actuation time of a related pneumatic actuating element (a high-speed pneumatic ejection device) can be ignored, but the problem is very important in the dynamic special test of the shock tunnel with short effective test time, and the problem of solving the aircraft separation or free flight time in the shock tunnel special test and the start delay time of a corresponding device is very important in consideration of the irreplaceable advantage of the high total temperature of the shock tunnel compared with the conventional wind tunnel on the major hypersonic aircraft research.

Because the effective test time of the shock tunnel is short, and the test hopes that the separation motion of the model is observed in the wind tunnel observation window in the effective time stage of the wind tunnel, the separation motion time of the model needs to be less than the effective test time of the wind tunnel as far as possible, and the time or the moment needs to be calibrated accurately.

In order to solve the above technical problem, firstly, the ejection separation or free flight time of a test model (hereinafter referred to as model flight time dt4) needs to be calibrated to determine whether the model flight time dt4 is smaller than the effective test time of the shock wind tunnel (hereinafter referred to as wind tunnel effective test time t), and further determine whether the test can be performed in an ideal state, for this reason, as shown in fig. 4 to 7, the present application provides:

a time calibration method for a shock tunnel dynamic test is disclosed, wherein a time calibration device used in the time calibration method comprises a test model 2, a pneumatic ejection device 3, a signal trigger 4c1 and an observation acquisition system 7, wherein an ejection end of the pneumatic ejection device 3 is opposite to the test model 2, the pneumatic ejection device 3 is used for pushing the test model 2 to provide the test model 2 with initial momentum of free flight, the signal trigger 4c1 is used for sending a trigger signal to the pneumatic ejection device 3 and the observation acquisition system 7, and the observation acquisition system 7 is used for shooting and recording the test model 2; the time calibration method comprises the following steps:

s2, starting the signal trigger 4c1 at the time t1, and sending a trigger signal to the pneumatic ejection device 3 and the observation and acquisition system 7 by the signal trigger 4c 1; s3, shooting and recording the test model 2 by the observation and acquisition system 7; s5, the pneumatic ejection device 3 pushes the test model 2 to enable the test model 2 to obtain the initial momentum of free flight; and S7, observing the acquisition result of the acquisition system 7, obtaining an initial time t5 when the test model 2 starts to move and a termination time t7 when the test model 2 completely departs from the observation interval of the observation acquisition system 7, and obtaining model flight time dt4 by using a formula dt4-t 7-t 5.

In order to maximize the utilization of the effective test time t of the wind tunnel, the model flight time dt4 should satisfy the following condition:

firstly, the model flight time dt4 is less than the effective test time t of the wind tunnel; second, the initial time t5 when the test model 2 starts to move is the time when the wind tunnel reaches the nozzle outlet uniformly after the shock tunnel is ignited and forms a wind field in front of the test model 2 (hereinafter referred to as wind tunnel air-out time t 6).

If the above conditions cannot be met, namely:

model flight time dt4 > wind tunnel effective test time t, and t5 < t6 should be allowed, so that the model moves in advance, and the time of the advanced motion of the test model is dt 4-t.

Further, after the initial time t5 at which the test model 2 starts to move is calibrated, it is necessary to control the initial time t5, and if the initial time t5 is to be controlled, it is necessary to calibrate the actuation time of the pneumatic ejection device 3, that is, the time (hereinafter referred to as an ejection actuation delay time dt3) required by the process of sending a start signal to the pneumatic ejection device 3 to output the kinetic energy to the test model 2, so as to accurately control the time at which the pneumatic ejection device 3 pushes the power conversion part 5, and further accurately control the initial time t5 at which the test model 2 enters the observation interval of the observation acquisition system 7, for this purpose, the application first provides an implementation mode of the pneumatic ejection device 3, and then provides a calibration method for the actuation time of the pneumatic ejection device 3 in this implementation mode:

the pneumatic ejection device 3 comprises an ejection driving part 4, a cylinder body 5a, a piston 5b, a piston rod 5c and an ejection executing part 6, the ejection driving part 4 is used for providing high-pressure gas, the cylinder body 5a is provided with a gas inlet end 5a1 and a gas outlet end 5a2, the gas inlet end 5a1 is connected with the ejection driving part 4, the piston 5b and the piston rod 5c are coaxially connected inside the cylinder body 5a, the ejection executing part 6 is connected with the piston rod 5c, the ejection executing part 6 pushes the test model 2 under the action of kinetic energy provided by the piston 5b, a part, close to the gas outlet end 5a2, of the cylinder body 5a is connected with a second pressure sensor 5e, and the second pressure sensor 5e is connected with a pressure signal collecting system 5g through a pressure sensor signal collecting line 5 f; the time calibration method further comprises the following steps:

s6, the pressure signal collection system 5g collects the voltage signal transmitted by the second pressure sensor 5e through the pressure sensor signal collection line 5f, and the ejection actuation delay time dt3 is obtained by setting the time when the signal trigger 4c1 sends the trigger signal to the ejection driving unit 4 to be t3 and the time when the second pressure sensor 5e sends the signal to be t5, using the formula dt3 to t5-t 3.

It should be noted that the process of calibrating dt3 cannot be performed in a vacuum environment, but only in a ground environment, when the piston 5b starts to move, the pressure inside the section formed by the portion inside the cylinder 5a near the gas outlet end 5a2 increases, and the gas escapes through the gas outlet end 5a2, so that the signal of the second pressure sensor 5e starts to jump, that is, the signal jump time of the second pressure sensor 5e is the time when the piston 5b starts to move, which is the initial time t5 when the test model 2 starts to move.

Meanwhile, it should be noted that in the ground ejection test, the shock tunnel does not need to be opened, so the signal controller 4c2 is not needed, and there is no time for the signal controller 4c2 to delay sending the signal, so t3 is equal to 0, and dt3 is equal to t5-0, and in the official test, the pneumatic ejection device 3 needs to be started by delaying to the time t3 through the signal controller 4c2, so dt3 is equal to t5-t 3.

Further, the ejection actuation delay time dt3 includes the time from the solenoid valve opening to the gas filling the second hose 4e, and also includes the time from the gas pressure forming a certain pressure in the cylinder 5a near the gas inlet end 5a1 to the piston 5b starting to move, and in order to make dt3 more accurate, the two times can be calibrated respectively:

the part of the cylinder body 5a close to the air inlet end 5a1 is connected with a first pressure sensor 5d, and the first pressure sensor 5d is connected with a pressure signal acquisition system 5g through a pressure sensor signal acquisition circuit 5 f; step S6 further includes the steps of:

the pressure signal acquisition system 5g acquires the voltage signal transmitted by the first pressure sensor 5d through the pressure sensor signal acquisition line 5f, and the time when the first pressure sensor 5d sends out the signal is t 4.

The time (the opening time of the electromagnetic valve + the ventilation time of the air circuit) required for transmitting the gas from the ejection driving part 4 to the air inlet end 5a1 can be obtained at t4-t3, the time (the actuation delay time of the cylinder) for converting the internal energy of the high-pressure gas into the kinetic energy of the piston motion can be obtained at t5-t4, and the actuation delay time dt3 of the whole pneumatic ejection device 3 can be obtained by adding the two.

Further, to control the wind tunnel air-out time t6, the ignition detonation time of the shock tunnel (hereinafter referred to as the ignition signal time t2) must be calibrated, for this reason:

the time calibration method further comprises the following steps:

Further, after the wind tunnel air-out time t6 is calibrated, in order to ensure that the initial time t5 is not less than the wind tunnel air-out time t6, the time t3 for starting the pneumatic ejection device 3 should be controlled, and since the pneumatic ejection device 3 is started by receiving a signal from the signal trigger 4c1, in order to control the starting time of the pneumatic ejection device 3:

the time calibration device also comprises a signal controller 4c 2; step S2 further includes:

at the time t1, the signal trigger 4c1 sends a trigger signal to the signal controller 4c 2; step S5 further includes:

after the time t1, the ejection start delay time dt2 elapses, and at the time t3, the signal controller 4c2 sends a start signal to the pneumatic ejection device 3.

At present, dt2 is known to be t3-t1, so that the accurate calibration and control of the ejection starting time t3 is equivalent to the accurate calibration and control of the ejection starting delay time dt 2.

Further, in order to calibrate the time accurately:

the time calibration method further comprises the following steps:

The person skilled in the art knows how the ignition delay time dt1 and the launch initiation delay time dt2 should be set as long as they fulfil the above conditions.

Furthermore, considering that the separation time or movement time of the model in the vacuum environment during the real wind tunnel test is different from the separation time or movement time in the ground atmospheric environment, the delay time and the delay time set by the signal controller need to be corrected, and the correction method is as follows:

the time calibration device also comprises a wind tunnel test cabin 1, and a test model 2 and a pneumatic ejection device 3 are both arranged in the wind tunnel test cabin 1; the time calibration method further comprises the following steps:

and S1, before the time t1, vacuumizing the interior of the wind tunnel test chamber 1.

Further, as described above, the main body of the pneumatic ejection device 3 used in the present embodiment is the power conversion unit 5, when the interior of the wind tunnel test chamber 1 is evacuated, the portion of the interior of the cylinder 5a communicating with the air outlet 5a2 is also evacuated, and the portion of the interior of the cylinder 5a communicating with the air inlet 5a1 and the second hose 4e have a gas of one atmospheric pressure remaining therein, which may cause the piston 5b to reach the end of the stroke before the time t1, and thus the test cannot be performed, and therefore:

s1, before the time t1, the interior of the wind tunnel test chamber 1, the interior of the cylinder block 5a, and the connection portion between the air inlet end 5a1 and the ejection drive unit 4 are vacuumized.

The catapult starting delay time dt2 'and the model flight time dt 4' calibrated by experiments in a vacuum environment still need to meet the following conditions:

if the model flight time dt4 'is greater than the wind tunnel effective test time t, the catapulting start delay time dt2 is t6-dt 3- (dt 4' -t), so that the initial time t5 is less than the wind tunnel air-out time t 6.

If the model flight time dt4 'is less than the wind tunnel effective test time t, the catapult start delay time dt 2' is t6-dt3, so that the initial time t5 is the wind tunnel air-out time t 6.

Further, a specific method of vacuuming the connection portion between the air inlet end 5a1 and the ejection drive unit 4 is as follows:

the ejection driving part 4 comprises an air supply source 4a, an electromagnetic valve 4b, a three-way joint 4f and a vacuum source 4h, the air supply source 4a, the electromagnetic valve 4b, the three-way joint 4f and an air inlet end 5a1 are sequentially connected, and the rest of the interface of the three-way joint 4f is connected with the vacuum source 4 h; step S1 specifically includes the following steps:

before the time t1, the interior of the wind tunnel test chamber 1 is vacuumized, and the vacuum source 4h is turned on, so that the vacuum source 4h draws out the gas in the cylinder 5a and the connection portion between the air inlet 5a1 and the three-way joint 4f through the three-way joint 4 f.

And further:

the vacuum source 4h is connected with the three-way joint 4f through a valve 4i and a vacuum meter 4 j; step S1 further includes the steps of:

when the vacuum gauge 4j indicates a negative pressure state and the reading is stable, the vacuum source 4h and the valve 4i are turned off.

As shown in fig. 5, based on the above time calibration method, the following conclusions are obtained after the test is performed:

the model flight time dt4 is 117ms, the wind tunnel effective test time t is 100ms, the model advance motion time dt4-t is 17ms, the wind tunnel air-out time t5 is 530ms, the solenoid valve delay time t4-t3 is 20ms, the cylinder delay time t5-t4 is 59ms, the catapult actuation delay time t solenoid valve delay time + cylinder delay time t5-t3 is 79ms, and finally the catapult start delay time dt2 t6-dt 3- (dt 4-t) 530-79- (117) and 100) 434ms is obtained.

The above embodiments are only exemplary embodiments of the present application, and are not intended to limit the present application, and the protection scope of the present application is defined by the claims. Various modifications and equivalents may be made by those skilled in the art within the spirit and scope of the present application and such modifications and equivalents should also be considered to be within the scope of the present application.

Claims

1. A time calibration method for a dynamic test of a shock tunnel is characterized in that,

the time calibration device used by the time calibration method comprises a test model (2), a pneumatic ejection device (3), a signal trigger (4c1) and an observation acquisition system (7), wherein an ejection end of the pneumatic ejection device (3) is over against the test model (2), the pneumatic ejection device (3) is used for pushing the test model (2) to provide the test model (2) with initial momentum of free flight, the signal trigger (4c1) is used for sending a trigger signal to the pneumatic ejection device (3) and the observation acquisition system (7), and the observation acquisition system (7) is used for shooting and recording the test model (2);

the time calibration method comprises the following steps:

s2, starting the signal trigger (4c1) at a time t1, wherein the signal trigger (4c1) sends trigger signals to the pneumatic ejection device (3) and the observation acquisition system (7);

s3, the observation and collection system (7) shoots and records the test model (2);

s5, the pneumatic ejection device (3) pushes the test model (2) to enable the test model (2) to obtain the initial momentum of free flight;

and S7, obtaining an initial time t5 when the test model (2) starts to move and a termination time t7 when the test model (2) completely departs from an observation interval of the observation acquisition system (7) through the acquisition result of the observation acquisition system (7), and obtaining a model flight time dt4 by using a formula dt4-t 7-t 5.

2. The time calibration method for the shock tunnel dynamic test according to claim 1,

the pneumatic ejection device (3) comprises an ejection driving part (4), a cylinder body (5a), a piston (5b), a piston rod (5c) and an ejection executing part (6), the ejection driving part (4) is used for providing high-pressure gas, the cylinder body (5a) is provided with a gas inlet end (5a1) and a gas outlet end (5a2), the gas inlet end (5a1) is connected with the ejection driving part (4), the piston (5b) and the piston rod (5c) are coaxially connected inside the cylinder body (5a), the ejection executing part (6) is connected with the piston rod (5c), the ejection executing part (6) pushes the test model (2) under the action of kinetic energy provided by the piston (5b), and a part, close to the gas outlet end (5a2), of the cylinder body (5a) is connected with a second pressure sensor (5e), the second pressure sensor (5e) is connected with a pressure signal acquisition system (5g) through a pressure sensor signal acquisition circuit (5 f);

the time calibration method also comprises the following steps:

and S6, the pressure signal acquisition system (5g) acquires a voltage signal transmitted by the second pressure sensor (5e) through the pressure sensor signal acquisition line (5f), the time when the signal trigger (4c1) sends a trigger signal to the ejection driving part (4) is set as t3, the time when the second pressure sensor (5e) sends a signal is set as t5, and the ejection actuation delay time dt3 is obtained by using a formula dt 3-t 5-t 3.

3. The time calibration method for the shock tunnel dynamic test according to claim 2,

a first pressure sensor (5d) is connected to a position, close to the air inlet end (5a1), on the cylinder body (5a), and the first pressure sensor (5d) is connected with the pressure signal acquisition system (5g) through the pressure sensor signal acquisition line (5 f);

step S6 further includes the steps of:

the pressure signal acquisition system (5g) acquires the voltage signal transmitted by the first pressure sensor (5d) through the pressure sensor signal acquisition line (5f), and the time when the first pressure sensor (5d) sends out a signal is t 4.

4. The time calibration method for the shock tunnel dynamic test according to claim 2,

the time calibration method also comprises the following steps:

and S4, after the moment t1, starting the shock wind tunnel at an ignition signal moment t2 after an ignition delay time dt1 to obtain a wind tunnel air-out moment t6 and a wind tunnel effective test time t.

5. The time calibration method for the shock tunnel dynamic test according to claim 4,

the time calibration device also comprises a signal control instrument (4c 2);

step S2 further includes: at the time t1, the signal trigger (4c1) sends a trigger signal to the signal control device (4c 2);

step S5 further includes: after the time t1, the ejection start delay time dt2 elapses, and at the time t3, the signal control unit (4c2) sends a start signal to the pneumatic ejection device (3).

6. The time calibration method for the shock tunnel dynamic test according to claim 5,

the time calibration method further comprises the following steps:

if the model flight time dt4 is less than the wind tunnel effective test time t, making the initial time t5 equal to the wind tunnel air-out time t 6;

and if the model flight time dt4 is greater than the wind tunnel effective test time t, enabling the initial time t5 to be greater than the wind tunnel air-out time t 6.

7. The time calibration method for the shock tunnel dynamic test according to claim 1,

the time calibration device further comprises a wind tunnel test cabin (1), and the test model (2) and the pneumatic ejection device (3) are both placed in the wind tunnel test cabin (1);

the time calibration method further comprises the following steps:

and S1, before the time t1, vacuumizing the interior of the wind tunnel test chamber (1).

8. The time calibration method for the shock tunnel dynamic test according to any one of claims 2 to 6,

the time calibration method further comprises the following steps:

and S1, before the time t1, vacuumizing the interior of the wind tunnel test chamber (1), the interior of the cylinder block (5a) and the connection part of the air inlet end (5a1) and the ejection driving part (4).

9. The time calibration method for the shock tunnel dynamic test according to claim 8,

the ejection driving part (4) comprises an air supply source (4a), an electromagnetic valve (4b), a three-way joint (4f) and a vacuum source (4h), the air supply source (4a), the electromagnetic valve (4b), the three-way joint (4f) and the air inlet end (5a1) are sequentially connected, and the rest of interfaces of the three-way joint (4f) are connected with the vacuum source (4 h);

step S1 specifically includes the following steps:

before the time t1, the interior of the wind tunnel test chamber (1) is vacuumized, the vacuum source (4h) is turned on, and the vacuum source (4h) pumps out the gas in the cylinder body (5a) and the connection part of the air inlet end (5a1) and the three-way joint (4f) through the three-way joint (4 f).

10. The time calibration method for the shock tunnel dynamic test according to claim 9,

the vacuum source (4h) is connected with the three-way joint (4f) through a valve (4i) and a vacuum meter (4 j);

step S1 further includes the steps of:

when the vacuum gauge (4j) shows a negative pressure state and the reading is stable, the vacuum source (4h) and the valve (4i) are closed.

11. A time calibration device for a dynamic test of a shock tunnel is characterized in that,

the device comprises a test model (2), a pneumatic ejection device (3), a signal trigger (4c1) and an observation acquisition system (7), wherein an ejection end of the pneumatic ejection device (3) is right opposite to the test model (2), the pneumatic ejection device (3) is used for pushing the test model (2) to provide the test model (2) with an initial momentum of free flight, the signal trigger (4c1) is used for sending a trigger signal to the pneumatic ejection device (3) and the observation acquisition system (7), the observation acquisition system (7) is used for shooting and recording the test model (2) and acquiring an initial moment t5 when the test model (2) starts to move and an end moment t7 when the test model (2) is completely separated from an observation interval of the observation acquisition system (7).

12. The time calibration device for the shock tunnel dynamic test according to claim 11,

the time calibration device further comprises a wind tunnel test cabin (1), the test model (2) and the pneumatic ejection device (3) are both placed inside the wind tunnel test cabin (1), and before the signal trigger (4c1) sends a trigger signal, the inside of the wind tunnel test cabin (1) is in a vacuum state.