CN114993598B - Time calibration method and device for shock tunnel dynamic test - Google Patents
Time calibration method and device for shock tunnel dynamic test Download PDFInfo
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- CN114993598B CN114993598B CN202210553749.3A CN202210553749A CN114993598B CN 114993598 B CN114993598 B CN 114993598B CN 202210553749 A CN202210553749 A CN 202210553749A CN 114993598 B CN114993598 B CN 114993598B
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
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Abstract
The invention relates to the field of wind tunnels, in particular to a time calibration method for a shock wind tunnel dynamic test, and also relates to a time calibration device for the shock wind tunnel dynamic test, 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 initial momentum of free flight for the test model, the signal trigger is used for sending trigger signals to the pneumatic ejection device and the observation acquisition system, and the observation acquisition system is used for shooting and video-recording 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 by observing the data obtained by the acquisition system. The time calibration method is established under the original acquisition system and the real test environment of the shock tunnel dynamic test, and is accurate in time calibration, high in accuracy, high in reduction degree, simple, reliable and convenient to operate.
Description
Technical Field
The invention relates to the field of wind tunnels, in particular to a time calibration method for a shock tunnel dynamic test. The invention also relates to a time calibration device for the shock tunnel dynamic test.
Background
In general, the multi-body separation or dynamic flight characteristics test of hypersonic aircraft and other special tests are mostly carried out in conventional hypersonic tunnels.
Since the effective test time of the conventional hypersonic wind tunnel is long (about 40 s), the time required for separating and freely flying the high-speed model and the delay actuation time of the related pneumatic actuator (high-speed pneumatic ejection device) can be ignored, so the problem is not obvious and not paid attention to in the conventional wind tunnel test, but is important in the dynamic special test of the hypersonic wind tunnel with shorter effective test time (about 100 ms), and the problem is important to solve the problem that the separation or free flight time of the aircraft and the start delay time of the corresponding device in the special test of the hypersonic wind tunnel have irreplaceable advantages for the development of the important hypersonic aircraft due to the fact that the hypersonic wind tunnel has high total temperature compared with the conventional wind tunnel.
In order to obtain the above-mentioned time parameters and to control them precisely, it is necessary to calibrate them by new methods.
Disclosure of Invention
The invention aims to provide a time calibration method and a time calibration device for shock tunnel dynamic test, which aim to solve the problem of
In order to solve the technical problems, the invention specifically provides the following technical scheme:
the application provides a time calibration method for shock tunnel dynamic test, wherein the time calibration device used by the time calibration method comprises a test model, a pneumatic ejection device, a signal trigger and an observation acquisition system, wherein the ejection end of the pneumatic ejection device is opposite to 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 trigger signals to the pneumatic ejection device and the observation acquisition system, and the observation acquisition system is used for shooting and video recording the test model; the time calibration method comprises the following steps:
s2, starting the signal trigger at a time t1, and sending trigger signals to the pneumatic ejection device and the observation acquisition system by the signal trigger; s3, the observation acquisition system shoots videos of the test model; s5, the pneumatic ejection device pushes the test model to enable the test model to obtain initial momentum of free flight; and S7, acquiring an initial time t5 when the test model starts to move and a termination time t7 when the test model is completely separated from an observation interval of the observation acquisition system according to an acquisition result of the observation acquisition system, and obtaining a model flight time dt4 by using a formula dt4 = t7-t 5.
Preferably, the pneumatic ejection device comprises an ejection driving part, a cylinder body, a piston rod and an ejection executing part, wherein 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 in 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, and a second pressure sensor is connected to a part, close to the air outlet end, of the cylinder body and is connected with a pressure signal acquisition system through a pressure sensor signal acquisition circuit; the time calibration method further comprises the following steps:
s6, the pressure signal acquisition system acquires a voltage signal transmitted by the second pressure sensor through the pressure sensor signal acquisition circuit, the moment when the signal trigger sends a trigger signal to the ejection driving part is set as t3, the moment when the second pressure sensor sends a signal is set as t5, and the ejection action delay time dt3 is obtained by using a formula dt3 = t5-t 3.
Preferably, a first pressure sensor is connected to a part of the cylinder body, which is close to the air inlet end, and the first pressure sensor is connected with the pressure signal acquisition system through a pressure sensor signal acquisition circuit; step S6 further comprises the steps of:
the pressure signal acquisition system acquires the voltage signal transmitted by the first pressure sensor through the pressure sensor signal acquisition circuit, and the time when the first pressure sensor sends out the signal is t4.
Preferably, the time calibration method further comprises the following steps:
and S4, after the time t1, starting the shock tunnel at the ignition signal time t2 after the ignition delay time dt1 to obtain the wind tunnel air outlet time t6 and the wind tunnel effective test time t.
Preferably, the time calibration device further comprises a signal controller; step S2 further includes:
at the time t1, the signal trigger sends a trigger signal to the signal controller; step S5 further includes:
after the time t1, the ejection start delay time dt2 passes, and at the time t3, the signal controller 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 taking an average value, and adjusting the ignition delay time dt1 and the ejection starting delay time dt2 to enable the ignition delay time dt1 and the ejection starting delay time dt2 to meet the following conditions, so that the calibration of the ignition delay time dt1 and the ejection starting delay time dt2 is completed:
if the model flight time dt4 is less than the wind tunnel effective test time t, making the initial time t5=the wind tunnel air outlet time t6; if the model flight time dt4 is greater than the wind tunnel effective test time t, the initial time t5 is greater than the wind tunnel air outlet time t6.
Preferably, the time calibration device further comprises a wind tunnel test cabin, and the test model and the pneumatic ejection device are both arranged in the wind tunnel test cabin; the time calibration method further comprises the following steps:
s1, vacuumizing the inside of the wind tunnel test cabin before the time t 1.
Preferably, the time calibration device further comprises a wind tunnel test cabin, and the test model and the pneumatic ejection device are both arranged in the wind tunnel test cabin; the time calibration method further comprises the following steps:
s1, before the time t1, vacuumizing the inside of the wind tunnel test cabin, the inside of the cylinder body of the air cylinder 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, wherein 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; the step S1 specifically comprises the following steps:
before the time t1, vacuumizing the inside of the wind tunnel test cabin, and simultaneously opening the vacuum source, wherein the vacuum source pumps out gas in the cylinder body and at the connection part of the air inlet end and the three-way joint through the three-way joint.
Preferably, the vacuum source is connected with the three-way joint through a valve and a vacuum gauge; step S1 further comprises the steps of: the vacuum gauge displays a negative pressure condition and the reading is stable, closing the vacuum source and the valve.
The application also provides a time calibration device for shock tunnel dynamic test, including test model, pneumatic ejection device, signal trigger and survey acquisition system, pneumatic ejection device's ejection end just to test model, pneumatic ejection 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 ejection device with survey acquisition system sends trigger signal, survey acquisition system is used for to test model shoots the video recording, and gathers initial moment t5 that test model began to move, and test model breaks away from completely survey acquisition system's observation interval's termination moment t7.
Preferably, the time calibration device further comprises a wind tunnel test cabin, the test model and the pneumatic ejection device are both placed inside the wind tunnel test cabin, and before the signal trigger sends out the trigger signal, the inside of the wind tunnel test cabin is in a vacuum state.
Compared with the prior art, the application has the following beneficial effects:
1. the time calibration method is established under the original acquisition system and the real test environment of the shock tunnel dynamic test, and is accurate in time calibration, high in accuracy, high in reduction degree, simple, reliable and convenient to operate.
2. According to the time calibration method, various time parameters in the shock tunnel dynamic test can be accurately calibrated, so that the test model can accurately and smoothly finish 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 will be apparent to those of ordinary skill in the art that the drawings in the following description are exemplary only and that other implementations can be obtained from the extensions of the drawings provided without inventive effort.
FIG. 1 is a schematic diagram of a free flight test process of a multi-body separation wind tunnel;
FIG. 2 is a block diagram of one embodiment of a shock tunnel simulation test apparatus performing a multi-body split free flight test;
FIG. 3 is a block diagram of another embodiment of a shock tunnel simulation test apparatus for performing free flight tests;
FIG. 4 is a block diagram of a time calibration device;
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 of time calibration in a vacuum environment;
reference numerals in the drawings are respectively as follows:
1-a wind tunnel test cabin; 1 a-a curved knife; 1 b-model struts; 1 c-a first flange; 1 d-a second flange plate;
2-a 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 reducing valve; 4 b-solenoid valve; 4 c-a control module; 4c 1-signal flip-flop; 4c 2-signal controller; 4c 3-a first trigger signal conductor; 4c 4-voltage signal output wires; 4 d-a first hose; 4 e-a second hose; 4 f-tee joint; 4 g-third hose; 4 h-vacuum source; 4 i-valve; 4 j-vacuum gauge;
5-a power conversion section; 5 a-cylinder block; 5a 1-an air inlet end; 5a 2-the air outlet end; 5 b-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-an ejection executing part;
7-an observation acquisition system; 7 a-a second trigger signal conductor.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The principle of the free flight test of the common wind tunnel model is as follows:
when the model freely flies under the action of wind tunnel airflow, a high-speed camera is used for recording a free flight image, the time histories of the motion trail, the attitude angle and the angular speed of the model are obtained through image interpretation, and a parameter fitting or parameter identification data processing method is adopted to obtain aerodynamic force and aerodynamic derivative of the model.
The method has the advantages that the method has no support interference, can truly simulate the actual flight state of the aircraft, is an advantage of the free flight test of the wind tunnel model, and the test model in the free flight test of the common wind tunnel model is free to fly without being supported at all.
The principle of the multi-body separation wind tunnel free flight test is that an aircraft model which locks all the separation bodies into a whole in advance is enabled to emit in the windward direction in a wind tunnel flow field, when the aircraft model flies freely to an observation window, a separation unlocking device triggers unlocking, so that the separation of the separation bodies is realized, meanwhile, recording equipment such as high-speed shooting is used for shooting and recording the separation process of the separation bodies and the flying track before and after the separation, and the research of the interference characteristic and the movement track during the separation of the separation bodies is realized.
As shown in fig. 1, the whole test process can be divided into four stages, such as a multi-body separation wind tunnel free flight test process schematic diagram with interstage separation as an example.
The first stage, the model is launched into the flow field as a whole by the launching device against the wind tunnel airflow direction; step II, the model freely flies into the range of the observation window, the 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 not separated at the moment; step III, unlocking the separation unlocking mechanism, and starting separation of the front stage and the rear stage of the model; and IV, finishing the separation process, and enabling the front stage and the rear stage of the model to fly out of the observation window 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 the unique requirements, and the difficulty is higher than that of the wind tunnel free flight test technology.
The method strictly simulates the appearance of the aircraft and the motion parameters of each separation body, including mass center, mass, inertia, unlocking mode, size and form of separation force and the like, and each separation body in the test can fly freely according to the motion law similar to the real flight without restriction, can fully reflect the motion and pneumatic coupling law of the multi-body separation process, and is a ground simulation test method very close to the pneumatic characteristics of the real flight.
The simulation of transient aerodynamic force at the separation moment is only comparable to that of a wind tunnel throwing model test technology, but the simulation of the interference characteristics of the separation bodies in the separation process of the multi-body of the aircraft in the free flight state is not realized.
The test device for the free flight test of the multi-body separation wind tunnel can be divided into two main items, namely:
wind tunnel free flight test device and separation release mechanism.
The separation unlocking mechanism is a special test device required by a multi-body separation wind tunnel free flight test, the separation unlocking mechanism can ensure that each separation body is reliably locked before unlocking, the unlocking mechanism can rapidly realize unlocking after triggering, and the requirements of separation parameters such as the relative speed, the relative posture and the like of each separation body at the moment of separation are met.
The multi-body separation wind tunnel free flight test is a special form of the wind tunnel free flight test, so that the test devices of the wind tunnel free flight test are all required by the test, such as a model launching mechanism, a recording device, a synchronous control device, a light path system and the like, and are all required by the test and the same as the requirements of the common wind tunnel free flight test.
If a high-speed camera is generally adopted to record the separation process and the flight track of the separation body, the separation process is a transient dynamic process, and generally only tens of milliseconds; in order to more accurately observe and record the separation process, a double optical path is adopted to better shoot; and a synchronous controller is adopted to realize synchronous starting control of the model transmitting system and the high-speed camera.
The prior art has given the structure of the model launching mechanism, but in hypersonic wind tunnel dynamic test, higher requirements are put on the existing model launching mechanism.
In the field of aerospace basic research, a hypersonic wind tunnel dynamic test technology makes great contribution to research on 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 wind tunnels.
Conventional hypersonic tunnels are tested by adopting arc heating and downward blowing type airflow, the effective test time is often tens of seconds, a track capturing system (Captive Trajectory Simulation System, CTS) can be used for a multi-body separation test, but the CTS multi-body separation test belongs to a quasi-steady test in principle and is not a real dynamic simulation test.
On the other hand, the resident chamber of the conventional hypersonic tunnel adopts devices such as electric arcs to heat test gas, so that the test gas is not pure air, the heating capacity is limited, the high total temperature cannot be realized, the high-temperature real gas effect under the hypersonic flight condition is reflected, and the higher test Mach number cannot be reached.
More dawn was studied for aircraft dynamics at high mach numbers into the shock pulse wind tunnel.
The shock pulse wind tunnel can reach higher total temperature and simulate high-temperature real gas effect under the flight condition of higher Mach number, but the effective test time of the shock wind tunnel is shorter and can reach 130ms at most, and the shock wind tunnel can refer to JF12 shock wind tunnel of the department of science mechanics.
If the dynamic separation or free flight test of the hypersonic vehicle is to be studied, a high-speed ejection device capable of being used for the shock tunnel is needed, and the test model is enabled to be subjected to high-speed dynamic separation or free flight ejection in the 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 tunnel, so that the test is a quasi-static separation simulation test and is a dynamic separation simulation test under a non-real flight condition; the free-flying test throwing device of the model mainly adopts a suspension type and a transmitting type, and the two methods have advantages and disadvantages.
The suspension type throwing device is favorable for 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 supersonic or hypersonic wind tunnel, and the suspension is very firm, but the suspension type throwing device has contradiction with the sudden and interference-free requirements when the release is required.
For the launching type launching device, the model is installed in the launching tube, more test periods can be obtained, the defects are that the model is required to be high in acceleration in the launching process, the flow field disturbance at the outlet of the launching tube is added, the initial state of the model has certain disturbance, and strong pneumatic disturbance exists under the hypersonic velocity inflow condition, so that the initial movement gesture of the model is not easy to determine, and the other defects are that the launching tube device is required 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 the axisymmetric large slenderness ratio aircraft.
In order to solve the technical problem that the existing model launching mechanism is not suitable for a shock tunnel, as shown in fig. 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, wherein the inside of the wind tunnel test chamber 1 is in a vacuum state (about 30 Pa) during the test; before the test starts, the wind tunnel test chamber 1 is connected with a spray pipe of the shock tunnel in a sealing way, then a vacuum unit of the shock tunnel starts to work, and the inside of the wind tunnel test chamber 1 is vacuumized.
The test model 2 is arranged in the wind tunnel test cabin 1; the test pattern 2 is placed towards the jet pipe of the shock tunnel, the height of the test pattern 2 has a certain limit, it needs to be launched out, and it cannot land for the effective test time of the shock tunnel, and the weight of the test pattern 2 is 26kg.
The pneumatic ejection device 3, the ejection end of the pneumatic ejection device 3 is opposite to the test model 2 and faces the wind outlet direction of the shock tunnel, the pneumatic ejection device 3 is used for pushing the test model 2 to provide initial momentum for the test model 2 to fly, when a wind field of the shock tunnel is formed at the inlet of the wind tunnel test cabin 1, the pneumatic ejection device 3 already executes ejection work, the test model 2 is free to fly for 10-20 ms, and then the test model 2 carries out high-speed multi-body separation free flight or common free flight test after the wind tunnel test air flow V infinity is established at the speed V; 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:
the inside of the wind tunnel test chamber 1 is provided with the bent blade 1a and the model supporting rod 1b, the wind tunnel test chamber 1, the bent blade 1a and the model supporting rod 1b are sequentially connected, and the model supporting rod 1b is used for placing the 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 used only for placing the test model 2, and no rigid/flexible connection structure or magnetic attraction exists between the model strut 1b and the test model 2 during the test; in the multi-body separation test, the unlocking mechanism is unlocked during the flight after the test model 2 is separated from the model strut 1b, and the structure of the unlocking mechanism is already disclosed in the prior art, which is not described here.
Further, the present embodiment provides an implementation of the pneumatic ejection device 3:
the pneumatic ejection device 3 comprises an ejection driving part 4, wherein the ejection driving part 4 is used for providing high-pressure gas; the ejection driving part 4 can output high-pressure gas through the modes of releasing the high-pressure gas cylinder, burning gunpowder and 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; the ejection executing part 6, the ejection executing part 6 is connected with the power converting part 5, and the ejection executing part 6 pushes the test model 2 to move along the straight line direction under the function provided by the power converting part 5 and fly freely under the inertia effect.
Further, the application also provides a test method of the shock tunnel simulation test device, as shown in fig. 4, comprising the following steps:
step 100, controlling and adjusting the gas pressure output by the ejection driving part 4, and entering a preparation work; step 200, extracting gas between the ejection driving part 4 and the power conversion part 5; step 300, vacuumizing the inside of the wind tunnel test cabin 1; step 400, detecting whether the ejection driving part 4 and the power conversion part 5 are in a vacuum state or not, otherwise, returning to the execution step 200 again, and stopping vacuumizing and entering the next step if the ejection driving part 4 and the power conversion part are in the vacuum state; step 500, detecting whether the wind tunnel test cabin 1 is in a vacuum state, if so, carrying out the next step, otherwise, returning to the execution step 300; step 600, igniting the shock tunnel, and forming a wind field at the inlet of the wind tunnel test cabin 1 after a period of time; step 700, the ejection driving part 4 is delayed to be started, high-pressure gas is provided for the power conversion part 5, the power conversion part 5 converts the internal energy of the high-pressure gas into kinetic energy, and the ejection execution part 6 ejects the test model 2, so that the test model 2 is in a free flight state when a wind field is formed at the inlet of the wind tunnel test cabin 1.
It should be noted that, in the multi-body separation test, the method further includes step 800, after the ejection executing portion 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.
The method comprises the following steps:
before the test, the ejection execution part 6 is in non-contact with the test model 2, the end part of the ejection execution part 6 is connected with a round cake-shaped impact block, and 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 freely flying, 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 within 116ms (within JF12 effective test time), the maximum speed can reach about 10m/s, the CTS system test simulation used in the conventional high-altitude wind tunnel belongs to a quasi-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 separation test model has no interference of a tail support rod in the separation process.
And two,:
before the test, the ejection execution part 6 is abutted with the tail part of the test model 2, a blind hole matched with the ejection execution part 6 in an inserting way is formed at the tail part of the test model 2, the test model 2 and the ejection execution part 6 move together during the test, and when the ejection execution part 6 reaches the end of the travel, the test model 2 and the ejection execution part 6 are separated and fly freely under the action of inertia.
The interference of the pushing process on the test model is greatly reduced (even no interference) compared with the interference of the traditional sleeve launching mode, the sudden performance 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 implementation of the ejection driving portion 4:
the ejector driving portion 4 includes a gas supply source 4a, and the gas supply source 4a is preferably a 15MPa high-pressure nitrogen gas source.
And an electromagnetic valve 4b arranged in the wind tunnel test chamber 1, wherein the electromagnetic valve 4b is preferably a direct-current quick-opening high-voltage pilot type normally-closed electromagnetic valve (voltage 24V, withstand voltage 15MPa, diameter 10mm, opening time less than 20ms and closing time 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 inside of the second hose 4e and the inside of the power conversion part 5 are in a vacuum state during test, and the first hose 4d and the second hose 4e are preferably high-pressure ventilation hoses (with an inner diameter of 6mm and a pressure resistance of 28 MPa).
Specific:
the wind tunnel test chamber 1 is connected with a first flange plate 1c, a first hose 4d penetrates through the 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 no leakage point.
The air supply source 4a enables the air inlet ends of the first hose 4d and the electromagnetic valve 4b to have pressure all the time, after the electromagnetic valve 4b is opened, high-pressure air is transmitted to the power conversion part 5 through the second hose 4e, and the power conversion part 5 converts the internal energy of the high-pressure air into kinetic energy.
The air supply source 4a includes a gas cylinder 4a1, a gas cylinder valve switch 4a2 and a pressure reducing valve 4a3 connected in sequence, the gas cylinder 4a1 is used for storing high-pressure nitrogen, the gas cylinder valve switch 4a2 is used for opening and closing the gas cylinder 4a1, the pressure reducing valve 4a3 is connected with the electromagnetic valve 4b through the first hose 4d, and the pressure reducing valve 4a3 is used for stabilizing the pressure of the nitrogen output to the inside of the first hose 4d so that the use pressure is 9MPa.
Further, the present embodiment provides an implementation 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 wire 4c3, the signal controller 4c2 is connected with the electromagnetic valve 4b through a voltage signal output wire 4c4, when the shock tunnel ignites, the signal trigger 4c1 sends a trigger signal to the electromagnetic valve 4b, 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 400 ms-450 ms, and specific data can be determined according to test results, so long as the following conditions are satisfied:
when the wind field of the shock wind tunnel is formed at the inlet of the wind tunnel test cabin 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 solenoid valve 4b to the power conversion portion 5, to reduce uncontrollable factors of the test:
the electromagnetic valve 4b is provided inside the wind tunnel test chamber 1 and near the power conversion section 5.
If the electromagnetic valve 4b is located outside the wind tunnel test chamber 1, the length of the first hose 4d is longer, after the electromagnetic valve 4b is opened, the high-pressure gas needs to pass through a longer time to reach the power conversion part 5, so that the 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 yet when the effective test time of the shock tunnel is over may be caused.
Further, the present embodiment provides an embodiment of the power conversion section 5:
the power conversion part 5 comprises a cylinder body 5a, a piston 5b and a piston rod 5c, wherein 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 inside of the wind tunnel test chamber 1, the piston 5b is coaxially connected with the piston rod 5c in the cylinder body 5a, the stroke of the piston 5b is 150mm, the diameter is 63mm, the piston rod 5c is connected with the ejection execution part 6, and when the ejection driving part 4 outputs high-pressure gas into 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.
Further, since the air outlet end 5a2 is communicated with the inside of the wind tunnel test chamber 1, the section of the inside of the cylinder body 5a, which is close to the air outlet end 5a2, is kept in a vacuum negative pressure state in synchronization with the wind tunnel test chamber 1, while the section of the inside of the second hose 4e and the cylinder body 5a, which is close to the air inlet end 5a1, is kept at a certain pressure (up to one atmosphere pressure) before the test, both sides of the piston 5b are subjected to a thrust force, so that the piston rod 5c extends outwards, the stroke operation of the cylinder is completed before the test is started, the model cannot be ejected, and the test is stopped.
In order to solve the above problems, it is necessary to evacuate the second hose 4e and the gas remaining in the power conversion section 5 before the start of the test, so that when the interior of the wind tunnel test chamber 1 is evacuated, the second hose 4e and the interior of the power conversion section 5 have no internal energy available for the conversion of the piston 5b, and the piston 5b is prevented from moving before the start of the test.
Embodiment 1 in which the second hose 4e and the power conversion unit 5 are evacuated:
a micropore (not shown) communicating with the inside of the wind tunnel test chamber 1 is formed in one end of the cylinder body 5a near the air inlet end 5a 1.
The micro-holes refer to holes with a diameter of 1mm or less, and although the high-pressure gas is overflowed through the micro-holes in the process that the high-pressure gas enters the inside of 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 lost internal energy of the high-pressure gas is almost negligible, the negative effect on the movement of the piston 5b is negligible, but the micro-holes have the advantages that:
before the test starts, when the vacuum unit of the shock tunnel vacuumizes the wind tunnel test chamber 1, 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 pumped out, so that the vacuum is formed in the wind tunnel test chamber 1, and meanwhile, the vacuum is also formed in the second hose 4e and the cylinder body 5 a.
Embodiment 2 in which the second hose 4e and the power conversion unit 5 are evacuated:
the solenoid valve 4b is connected with the first hose 4d through a three-way joint 4f, the remaining joint of the three-way joint 4f is connected with a vacuum source 4h through a third hose 4g, the vacuum source 4h is preferably an air pump, and the third hose 4g is preferably a high-pressure ventilation hose (inner diameter 6mm, pressure resistance 28 MPa).
The vacuum source 4h is for drawing gas between the solenoid valve 4b and the power conversion portion 5 to form a vacuum.
Specifically, be connected with second ring flange 1d on wind tunnel test chamber 1, voltage signal output wire 4c4 and third hose 4g all pass the casing of wind tunnel test chamber 1 through second ring flange 1d, and second ring flange 1d is used for connecting wind tunnel test chamber 1 and voltage signal output wire 4c4, third hose 4g and ensures the no gas leakage point.
The above-described structure can also achieve the effect of evacuating the inside of the second hose 4e and the cylinder 5a before the start of the test, in order to make the operation of the vacuum source 4h controllable, in this embodiment, the valve 4i and the vacuum gauge 4j are mounted on the third hose 4g, wherein, in order to facilitate the operation of the staff, both the valve 4i and the vacuum gauge 4j are located outside the wind tunnel test chamber 1, the vacuum source 4h operates to evacuate the gas inside the second hose 4e and the cylinder 5a through the three-way joint 4f before the start of the test, the staff observes the readings of the vacuum gauge 4j, judges whether the second hose 4e and the cylinder 5a are in a vacuum state (about 10 kPa) and remains stable, and if so, closes the vacuum source 4h and the valve 4i.
Further, the present embodiment provides two implementations of the ejection execution portion 6:
the ejection executing portion 6 is a connecting rod connected to the piston rod 5c for contacting the test model 2, and specifically, the ejection executing portion 6 is coaxially connected to an end portion of the piston rod 5 c.
The ejection executing portion 6 follows the high-speed movement of the piston rod 5c to push the test pattern 2 at a high speed and bring it into a free flight state.
Further, in order to be able to observe the course of the test:
the shock tunnel simulation test device further comprises an observation collection system 7, the observation collection system 7 is connected with a signal trigger 4c1 through a second trigger signal wire 7a, the observation collection system 7 is used for observing the motion track of the test model 2 in a shock tunnel flow field, and the signal trigger 4c1 is used for sending a trigger signal to the observation collection 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 zone of the observation and collection system 7 is the area that can be observed by an observation window, and the working time of the observation and collection system 7 is continued from the shock tunnel ignition until the test model 2 falls to the ground.
After solving the technical problem of how to eject the test model 2 in a shock tunnel, there are other technical problems to be solved:
the effective test time (up to 100ms, millisecond level) of the shock tunnel is very short compared with the effective test time (40 s, second level) of a hypersonic conventional wind tunnel, so that if dynamic special tests such as free flight or multi-body separation of a model are carried out in the shock tunnel, a high-speed pneumatic ejection device is needed, the model can be ejected out in the effective test time of the shock tunnel, the time for accurately ejecting and separating the model or free flight is needed, the delay time of the high-speed pneumatic ejection device is needed, and the signal delay time of starting the high-speed pneumatic ejection device in the test is needed, so that the effective test time of the shock tunnel can be utilized to the greatest extent by the separation and free flight of the model, and reliable test data are obtained.
In general, the multi-body separation or dynamic flight characteristics test of hypersonic aircraft and other special tests are mostly carried out in conventional hypersonic tunnels.
Because the effective test time of the conventional hypersonic wind tunnel is long, the time required by the separation and free flight of the high-speed model and the delay actuation time of the related pneumatic actuator (high-speed pneumatic ejection device) can be ignored, so the problem is not highlighted and not paid attention to in the conventional wind tunnel test, but is important in the dynamic special test of the hypersonic wind tunnel with shorter effective test time, and the problem is important to solve the problem that the separation or free flight time of the aircraft and the start delay time of the corresponding device in the hypersonic wind tunnel special test because the hypersonic wind tunnel has irreplaceable advantages for the development of a great hypersonic aircraft compared with the conventional wind tunnel due to the high total temperature of the hypersonic wind tunnel is considered.
Because the effective test time of the shock tunnel is short, the test hopes to observe the separation movement of the model in the wind tunnel observation window in the effective time period of the wind tunnel, so that the separation movement time of the model is less than the effective test time of the wind tunnel as much as possible, and therefore, the time or moment needs to be calibrated more accurately.
In order to solve the above technical problems, it is first required to calibrate the ejection separation or free flight time of the test model (hereinafter referred to as model flight time dt 4) so as to determine whether the model flight time dt4 is less than the effective test time of the shock 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. 4-7, the present application provides:
the 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 the 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 initial momentum of free flight for the test model 2, the signal trigger 4c1 is used for sending trigger signals to the pneumatic ejection device 3 and the observation acquisition system 7, and the observation acquisition system 7 is used for shooting and video recording the test model 2; the time calibration method comprises the following steps:
s2, starting a 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 acquisition system 7 shoots videos of the test model 2; s5, the pneumatic ejection device 3 pushes the test model 2, so that the test model 2 obtains initial momentum of free flight; and S7, obtaining an initial time t5 when the test model 2 starts to move and a final time t7 when the test model 2 is completely separated from an observation interval of the observation and acquisition system 7 through an acquisition result of the observation and acquisition system 7, and obtaining a model flight time dt4 by using a formula dt4 = t7-t 5.
In order to be able to maximize the utilization of the wind tunnel effective test time t, the model flight time dt4 should satisfy the following conditions:
1. model flight time dt4 < wind tunnel effective test time t; 2. initial time t5=time when the wind tunnel uniformly flows to reach the nozzle outlet after the shock tunnel ignites and a wind field is formed in front of the test model 2 (hereinafter referred to as wind tunnel air-out time t 6).
If the above conditions cannot be satisfied, namely:
and the model flight time dt4 is greater than the effective test time t of the wind tunnel, and t5 is less than t6, so that the model moves in advance, and the time for the test model to move in advance is dt 4-t.
Further, after the initial time t5 when the test model 2 starts to move is calibrated, it is also 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 required for the process of sending a start signal to the pneumatic ejection device 3 to output kinetic energy to the test model 2 by the pneumatic ejection device 3 (hereinafter referred to as ejection actuation delay time dt 3), so as to precisely control the moment when the pneumatic ejection device 3 pushes the power conversion part 5, and further precisely control the initial time t5 when the test model 2 enters the observation interval of the observation collection system 7, for this purpose, the present application firstly provides an embodiment of the pneumatic ejection device 3, and then provides a calibration method for the actuation time of the pneumatic ejection device 3 in the embodiment:
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, wherein the ejection driving part 4 is used for providing high-pressure gas, 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 piston 5b and the piston rod 5c are coaxially connected in 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 second pressure sensor 5e is connected to a part, close to the air outlet end 5a2, of the cylinder body 5a, and 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 further comprises the following steps:
s6, the pressure signal acquisition system 5g acquires a voltage signal transmitted by the second pressure sensor 5e through the pressure sensor signal acquisition circuit 5f, the moment when the signal trigger 4c1 sends a trigger signal to the ejection driving part 4 is set as t3, the moment when the second pressure sensor 5e sends a signal is set as t5, and the ejection action delay time dt3 is obtained by using a formula dt3 = t5-t 3.
It should be noted that the process of calibrating dt3 cannot be performed in a vacuum environment, but can be performed only in a ground environment, when the piston 5b starts to move, the pressure inside the section formed by the portion of the interior of the cylinder block 5a near the air outlet end 5a2 increases, and the air overflows through the air outlet end 5a2, so that the signal of the second pressure sensor 5e jumps, that is, the signal jump time of the second pressure sensor 5 e=the time when the piston 5b starts to move=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 wind tunnel is not required to be started, so that the signal controller 4c2 is not required, and there is no time for the signal controller 4c2 to delay sending out the signal, so that it can be regarded as t3=0, dt3=t5-0, and in the formal test, since the pneumatic ejection device 3 needs to be started up to the time t3 through the signal controller 4c2, dt3=t5-t 3.
Further, the ejection delay time dt3 includes a time from when the solenoid valve is opened to when the second hose 4e is full of gas, and also includes a time from when the air pressure forms a certain pressure at a portion of the cylinder 5a near the air inlet end 5a1 to when the piston 5b starts to move, so that the two times can be calibrated respectively for making dt3 more accurate:
the part of the cylinder body 5a, which is 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 comprises 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 circuit 5f, and the time when the first pressure sensor 5d sends out the signal is t4.
Wherein t4-t3 can obtain the time (electromagnetic valve opening time+air path ventilation time) required by the gas to be transmitted from the ejection driving part 4 to the air inlet end 5a1, t5-t4 can obtain the time (cylinder actuation delay time) for converting the internal energy of the high-pressure gas into the kinetic energy of the piston motion, and the time are added to obtain the actuation delay time dt3 of the whole pneumatic ejection device 3.
Further, to control the wind outlet time t6 of the wind tunnel, the ignition initiation time of the shock wind tunnel (hereinafter referred to as the ignition signal time t 2) must be calibrated, for this purpose:
the time calibration method further comprises the following steps:
and S4, after the time t1, starting the shock tunnel at the ignition signal time t2 after the ignition delay time dt1 to obtain the wind tunnel air outlet time t6 and the wind tunnel effective test time t.
Further, after the wind tunnel wind outlet time t6 is calibrated, in order to ensure that the initial time t5 is less than or equal to the wind tunnel wind outlet time t6, the time t3 for starting the pneumatic ejection device 3 should also be controlled, and since the pneumatic ejection device 3 is started by receiving the signal of the signal trigger 4c1, the starting time of the pneumatic ejection device 3 is controlled:
the time calibration device also comprises a signal controller 4c2; 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, it is known that dt 2=t3-t 1, and thus accurately calibrating and controlling the ejection start time t3 is equivalent to accurately calibrating and controlling the ejection start delay time dt2.
Further, in order to accurately calibrate the above-described time:
the time calibration method further comprises the following steps:
s8, repeating the steps S2-S7 for a plurality of times and taking an average value, and adjusting the ignition delay time dt1 and the ejection starting delay time dt2 to enable the ignition delay time dt1 and the ejection starting delay time dt2 to meet the following conditions, so that the calibration of the ignition delay time dt1 and the ejection starting delay time dt2 is completed:
if the model flight time dt4 is less than the wind tunnel effective test time t, making the initial time t5=the wind tunnel air outlet time t6; if the model flight time dt4 is greater than the wind tunnel effective test time t, the initial time t5 is greater than the wind tunnel air outlet time t6.
Those skilled in the art know how the ignition delay time dt1 and the ejection start delay time dt2 should be set as long as they satisfy the above conditions.
Further, considering that the separation time or the movement time of the model in the vacuum environment in the actual wind tunnel test is different from the separation time or the 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 further comprises a wind tunnel test cabin 1, and the test model 2 and the pneumatic ejection device 3 are both arranged in the wind tunnel test cabin 1; the time calibration method further comprises the following steps:
s1, vacuumizing the inside of the wind tunnel test chamber 1 before the time t 1.
Further, as described above, the main body of the pneumatic ejection device 3 used in the present embodiment is the power conversion portion 5, when the interior of the wind tunnel test chamber 1 is vacuumized, the portion of the interior of the cylinder body 5a communicating with the air outlet end 5a2 is vacuumized, and the portion of the interior of the cylinder body 5a communicating with the air inlet end 5a1 and the second hose 4e remain with air at one atmosphere, which results in that the piston 5b reaches the end of the stroke before the time t1, so that the test cannot be performed, and this results in:
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 arranged in the wind tunnel test cabin 1; the time calibration method further comprises the following steps:
S1, before the time t1, the inside of the wind tunnel test chamber 1, the inside of the cylinder body 5a, and the connection portion between the air inlet end 5a1 and the ejection driving portion 4 are vacuumized.
The ejection start delay time dt2 'and the model flight time dt4' calibrated by the test in the vacuum environment still need to satisfy the following conditions:
if the model flight time dt4 '> the wind tunnel effective test time t, the ejection start delay time dt 2=t6-dt 3- (dt 4' -t) is such that the initial time t5 is less than the wind tunnel air outlet time t6.
If the model flight time dt4 '< the wind tunnel effective test time t, the ejection start delay time dt2' =t6-dt 3, so that the initial time t5=the wind tunnel air outlet time t6.
Further, the specific method for vacuuming the connection part between the air inlet end 5a1 and the ejection driving part 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, wherein 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 remaining interface of the three-way joint 4f is connected with the vacuum source 4 h; the step S1 specifically comprises the following steps:
before the time t1, the inside of the wind tunnel test chamber 1 is vacuumized, a vacuum source 4h is turned on, and the vacuum source 4h pumps out gas in the cylinder body 5a and at the connection part of the air inlet end 5a1 and the three-way joint 4f through the three-way joint 4 f.
Further:
the vacuum source 4h is connected with the three-way joint 4f through the valve 4i and the vacuum meter 4 j; step S1 further comprises the steps of:
vacuum gauge 4j shows the negative pressure condition and the reading is stable, vacuum source 4h and valve 4i are closed.
As shown in fig. 5, based on the above time calibration method, the conclusion after the test is:
model flight time dt 4=117 ms, wind tunnel effective test time t=100 ms, model advance motion time dt 4-t=17 ms, wind tunnel air outlet time t 5=530 ms, solenoid valve delay time=t4-t3=20 ms, cylinder delay time=t5-t4=59 ms, ejection actuation delay time=solenoid valve delay time+cylinder delay time=t5-t3=79 ms, and finally ejection start delay time dt 2=t6-dt 3- (dt 4-t) =530-79- (117-100) =434 ms.
The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application, the scope of which is defined by the claims. Various modifications and equivalent arrangements may be made to the present application by those skilled in the art, which modifications and equivalents are also considered to be within the scope of the present application.
Claims (7)
1. A time calibration method for shock tunnel dynamic test 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 (4 c 1) and an observation acquisition system (7), wherein the 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 initial momentum for free flight for the test model (2), the signal trigger (4 c 1) is used for sending trigger signals to the pneumatic ejection device (3) and the observation acquisition system (7), and the observation acquisition system (7) is used for shooting and video-recording the test model (2);
the pneumatic ejection device (3) comprises an ejection driving part (4), a cylinder body (5 a), a piston (5 b), a piston rod (5 c) and an ejection executing part (6), wherein the ejection driving part (4) is used for providing high-pressure gas, the cylinder body (5 a) is provided with an air inlet end (5 a 1) and an air outlet end (5 a 2), the air inlet end (5 a 1) is connected with the ejection driving part (4), the piston (5 b) and the piston rod (5 c) are coaxially connected inside the cylinder body (5 a), the ejection executing part (6) is connected with the piston rod (5 c), the ejection executing part (6) pushes the test model (2) under the action of kinetic energy provided by the piston (5 b), a second pressure sensor (5 e) is connected to a part, close to the air outlet end (5 a 2), of the second pressure sensor (5 e) is connected with a pressure signal acquisition system (5 g) through a pressure sensor signal acquisition line (5 f);
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 arranged in the wind tunnel test cabin (1);
the time calibration method comprises the following steps:
s1, before a time t1, vacuumizing the inside of the wind tunnel test cabin (1), the inside of the cylinder body (5 a) and the connection part of the air inlet end (5 a 1) and the ejection driving part (4);
s2, starting the signal trigger (4 c 1) at a time t1, wherein the signal trigger (4 c 1) sends trigger signals to the pneumatic ejection device (3) and the observation acquisition system (7);
s3, the observation acquisition system (7) shoots videos of the test model (2);
s4, after the time t1, starting a shock tunnel at the ignition signal time t2 after the ignition delay time dt1 to obtain a tunnel air outlet time t6 and a tunnel effective test time t;
s5, the pneumatic ejection device (3) pushes the test model (2) so that the test model (2) obtains initial momentum of free flight;
s6, the pressure signal acquisition system (5 g) acquires a voltage signal transmitted by the second pressure sensor (5 e) through the pressure sensor signal acquisition circuit (5 f), the moment when the signal trigger (4 c 1) sends a trigger signal to the ejection driving part (4) is set as t3, the moment when the second pressure sensor (5 e) sends the signal is set as t5, and the ejection action delay time dt3 is obtained by using a formula dt3 = t5-t 3;
S7, acquiring an initial time t5 when the test model (2) starts to move and a final time t7 when the test model (2) is completely separated from an observation interval of the observation acquisition system (7) according to an acquisition result of the observation acquisition system (7), and obtaining a model flight time dt4 by using a formula dt4 = t7-t 5;
s8, repeating the steps S2-S7 for a plurality of times and taking an average value, and adjusting the ignition delay time dt1 and the ejection start delay time dt2 to enable the ignition delay time dt1 and the ejection start delay time dt2 to meet the following conditions, so that the calibration of the ignition delay time dt1 and the ejection start delay time dt2 is completed:
if the model flight time dt4 is less than the wind tunnel effective test time t, making the initial time t5=the wind tunnel air outlet time t6;
if the model flight time dt4 is greater than the wind tunnel effective test time t, the initial time t5 is greater than the wind tunnel air outlet time t6.
2. The method for time calibration for shock tunnel dynamic test according to claim 1, wherein,
a first pressure sensor (5 d) is connected to the part, close to the air inlet end (5 a 1), of the cylinder body (5 a), and the first pressure sensor (5 d) is connected with the pressure signal acquisition system (5 g) through the pressure sensor signal acquisition circuit (5 f);
Step S6 further comprises the steps of:
the pressure signal acquisition system (5 g) acquires the voltage signal transmitted by the first pressure sensor (5 d) through the pressure sensor signal acquisition circuit (5 f), and the time when the first pressure sensor (5 d) sends out the signal is t4.
3. The method for time calibration for shock tunnel dynamic test according to claim 1, wherein,
the time calibration device also comprises a signal controller (4 c 2);
step S2 further includes: at the time t1, the signal trigger (4 c 1) sends a trigger signal to the signal controller (4 c 2);
step S5 further includes: after the time t1, the ejection start delay time dt2 passes, and at the time t3, the signal controller (4 c 2) sends a start signal to the pneumatic ejection device (3).
4. The method for time calibration for shock tunnel dynamic test according to claim 1, wherein,
the ejection driving part (4) comprises an air supply source (4 a), an electromagnetic valve (4 b), a three-way joint (4 f) and a vacuum source (4 h), wherein the air supply source (4 a), the electromagnetic valve (4 b), the three-way joint (4 f) and the air inlet end (5 a 1) are sequentially connected, and the remaining interface of the three-way joint (4 f) is connected with the vacuum source (4 h);
The step of vacuumizing the interior of the wind tunnel test cabin (1) specifically comprises the following steps:
simultaneously, the vacuum source (4 h) is opened, and the vacuum source (4 h) pumps out gas in the cylinder body (5 a) and at the connection part of the air inlet end (5 a 1) and the three-way joint (4 f) through the three-way joint (4 f).
5. The method for time calibration for shock tunnel dynamic test according to claim 4, wherein,
the vacuum source (4 h) is connected with the three-way joint (4 f) through a valve (4 i) and a vacuum meter (4 j);
step S1 further comprises the steps of:
the vacuum gauge (4 j) displays a negative pressure state and when the reading is stable, the vacuum source (4 h) and the valve (4 i) are closed.
6. A time calibration device for shock tunnel dynamic test is characterized in that,
the device comprises a test model (2), a pneumatic ejection device (3), a signal trigger (4 c 1) and an observation acquisition system (7), wherein the 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 initial momentum of free flight for the test model (2), the signal trigger (4 c 1) is used for sending trigger signals to the pneumatic ejection device (3) and the observation acquisition system (7), the observation acquisition system (7) is used for shooting and video-recording the test model (2), and acquiring initial time t5 when the test model (2) starts to move and end time t7 when the test model (2) is completely separated from an observation interval of the observation acquisition system (7);
The pneumatic ejection device (3) comprises an ejection driving part (4), a cylinder body (5 a), a piston (5 b), a piston rod (5 c) and an ejection executing part (6), wherein the ejection driving part (4) is used for providing high-pressure gas, the cylinder body (5 a) is provided with an air inlet end (5 a 1) and an air outlet end (5 a 2), the air inlet end (5 a 1) is connected with the ejection driving part (4), the piston (5 b) and the piston rod (5 c) are coaxially connected inside the cylinder body (5 a), the ejection executing part (6) is connected with the piston rod (5 c), the ejection executing part (6) pushes the test model (2) under the action of kinetic energy provided by the piston (5 b), a second pressure sensor (5 e) is connected to a part, close to the air outlet end (5 a 2), of the second pressure sensor (5 e) is connected with a pressure signal acquisition system (5 g) through a pressure sensor signal acquisition line (5 f);
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 arranged in the wind tunnel test cabin (1).
7. The time calibration device for shock tunnel dynamic test according to claim 6, wherein,
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 (4 c 1) sends out a trigger signal, the inside of the wind tunnel test cabin (1) is in a vacuum state.
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| Title |
|---|
| 激波风洞侧向喷流干扰效应试验研究;刘洪山,徐翔,孔荣宗,吕治国,刘伟雄;空气动力学学报(第03期);294-298 * |
| 高超声速风洞多体干扰与分离试验技术;吴继飞;王元靖;罗新福;钱丰学;;实验流体力学(第03期);99-102 * |
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