Shock tunnel plasma sheath and wake light radiation characteristic measurement system and method

Abstract

The application discloses a high-enthalpy shock tunnel test model plasma sheath and wake light radiation characteristic measurement system and method, and belongs to the field of hypersonic aerodynamics test. By using a large-size high-enthalpy shock tunnel, a suspension type heavy model electromagnetic synchronous release system is adopted to realize the free flight of the heavy model without disturbing the wake, a heating device and related design are adopted to realize the heating of the heavy model to simulate the ablation model, a spectrometer system and a radiometer system are adopted to realize the transient light radiation characteristic test, and then the measurement of the light radiation characteristic of the plasma sheath and the wake thereof is realized. The application can not only study the light radiation characteristic of the plasma sheath in the leading edge region of the model, but also can study the light radiation characteristic of the wake of the model, and can accurately measure the light radiation characteristic of the plasma sheath and the wake of the ablation model.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-enthalpy shock tunnel model plasma sheath and wake light radiation characteristic measurement system and method, and belongs to the field of hypersonic aerodynamics testing. BACKGROUND

[0002] When a high-speed vehicle flies at a super high speed in the near space, the surrounding gas is heated by a shock wave or decelerated by viscous resistance, so that the energy of the random motion of the molecules is increased, a high temperature of thousands of degrees is generated to cause the vibration excitation and dissociation of the gas molecules, and even ionization, resulting in that the hypersonic gas presents the properties of a real gas, and the physical phenomena of mechanics, heat, optics and electricity are generated by the interaction between the vehicle and the air. The light radiation physical phenomena generated by the vehicles with different characteristics and their flow fields are not completely the same. The limitations in the understanding of the physical phenomena of hypersonic flow lead to the inappropriateness of the physical modeling, and further lead to the uncertainty of the numerical calculation, so it is very important to study the hypersonic flow law through experiments.

[0003] At present, when the radiation characteristic law is studied in a high-enthalpy shock tunnel, a fixed support mode is generally adopted, the model is disturbed by the support mechanism, the difficulty of measuring the flow field parameters is increased, and the measurement accuracy and accuracy of the photoelectric characteristics of the model plasma sheath wake are affected. In addition, the current measurement is only carried out for a common model, lacks the measurement of an ablative model, and cannot accurately simulate the light radiation characteristics of a high-temperature model under flight conditions. SUMMARY

[0004] The technical problem solved by the present application is to overcome the shortcomings of the prior art, provide a high-enthalpy shock tunnel model plasma sheath and wake light radiation characteristic measurement system and method, and solve the problem that the light radiation characteristics of the plasma sheath and wake of a high-speed vehicle are difficult to accurately measure.

[0005] The technical solution of the present application is:

[0006] In a first aspect, the present application provides a shock tunnel plasma sheath and wake light radiation characteristic measurement system, comprising a high-enthalpy shock tunnel, a spectrometer system, a radiometer system, a suspension heavy model electromagnetic synchronous release system, a pressure sensor, a synchronous acquisition system and a calculation processing system.

[0007] The high-enthalpy shock tunnel is used to provide a flow field for a vehicle test model.

[0008] The suspension heavy model electromagnetic synchronous release system suspends the vehicle test model in the wind tunnel before the wind tunnel starts, releases the vehicle test model after receiving the release signal after the wind tunnel starts, and recovers the vehicle test model.

[0009] Pressure sensor: installed on the compression tube and shock tube of the high-enthalpy shock tunnel, used to collect the pressure signals of the compression tube and shock tube after the wind tunnel runs, and send them to the synchronous acquisition system;

[0010] Synchronous acquisition system: after receiving the pressure signals, simultaneously sends a release signal to the electromagnetic synchronous release system of the suspended heavy model, and sends a start signal to the spectrometer system and the radiometer system;

[0011] Spectrometer system: after starting, collects the spectral information of the model's plasma sheath and wake, and sends it to the calculation processing system; Radiometer system: after starting, collects the light radiation information of the model's plasma sheath and wake, and sends it to the calculation processing system;

[0012] Calculation processing system: processes the spectral information and radiation information, and obtains the light radiation characteristics of the aircraft test model's plasma sheath and wake.

[0013] Preferably, the electromagnetic synchronous release system of the suspended heavy model is located in the test section of the high-enthalpy shock tunnel, and includes a model release device fixed above the angle of attack mechanism and a buffer capture model device fixed below the angle of attack mechanism;

[0014] Model release device: suspends the aircraft test model in the wind tunnel before the wind tunnel starts; after the wind tunnel starts, releases the aircraft test model after receiving the release signal;

[0015] Buffer capture model device: realizes the lossless recovery of the aircraft test model.

[0016] Preferably, the model release device includes a signal processing device, an electromagnetic valve, a power supply, and an electromagnet; the power supply is connected to the electromagnet through the electromagnetic valve, the electromagnet is used to attract the aircraft test model, and the signal processing device is connected to the electromagnetic valve; when the signal processing device receives the release signal, it controls the electromagnetic valve to be disconnected, and the electromagnet loses the magnetic force to release the aircraft test model;

[0017] The buffer capture model device is a flexible steel wire mesh.

[0018] Preferably, the aircraft test model is made of metal or non-metal material; if the aircraft test model is made of non-metal material, an alloy material element is placed in the cavity of the aircraft test model.

[0019] In the second aspect, the present application provides a method for measuring the light radiation characteristics of the plasma sheath and wake of a shock tunnel, which comprises:

[0020] Calibrate the spectrometer system and the radiometer system;

[0021] According to the effective test time and the size of the uniform flow field of the high-enthalpy shock tunnel, determine the size of the aircraft test model, and design the aircraft test model;

[0022] The aircraft test model is hung in the test section of the high-enthalpy shock tunnel by using the suspension heavy model electromagnetic synchronous release system, so that the aircraft test model does not move simultaneously with the wind tunnel during the operation of the wind tunnel;

[0023] Pressure sensors are installed at corresponding positions of the compression pipe and the shock tube, and the pressure sensors are connected with the synchronous acquisition system;

[0024] The wind tunnel is started, and the pressure signals collected by the pressure sensors are sent to the synchronous acquisition system;

[0025] After receiving the pressure signals, the synchronous acquisition system simultaneously sends a release signal to the suspension heavy model electromagnetic synchronous release system and sends a start signal to the spectrometer system and the radiometer system;

[0026] After receiving the release signal, the suspension heavy model electromagnetic synchronous release system freely releases the aircraft test model into the stable flow field of the wind tunnel; the spectrometer system collects the spectrum information of the plasma sheath and the wake of the model and sends the information to the calculation processing system; the radiometer system collects the light radiation information of the plasma sheath and the wake of the model and sends the information to the calculation processing system; and the suspension heavy model electromagnetic synchronous release system recovers the aircraft test model;

[0027] The calculation processing system processes the collected spectrum information and radiation information to obtain the light radiation characteristics of the plasma sheath and the wake of the aircraft test model.

[0028] In a third aspect, the present application provides a method for measuring the light radiation characteristics of the plasma sheath and the wake of a shock tunnel, which comprises:

[0029] The spectrometer system and the radiometer system are calibrated;

[0030] According to the effective test time and the size of the uniform flow field of the high-enthalpy shock tunnel, the size of the aircraft test model is determined, and the aircraft test model is designed;

[0031] The aircraft test model is hung in the test section of the high-enthalpy shock tunnel by using the suspension heavy model electromagnetic synchronous release system, so that the aircraft test model does not move simultaneously with the wind tunnel during the operation of the wind tunnel;

[0032] Pressure sensors are installed at corresponding positions of the compression pipe and the shock tube, and the pressure sensors are connected with the synchronous acquisition system;

[0033] The aircraft test model is heated to a predetermined temperature by using a heating device to simulate an ablative model;

[0034] The wind tunnel is started, and the pressure signals collected by the pressure sensors are sent to the synchronous acquisition system;

[0035] The synchronous acquisition system receives the pressure signal and simultaneously sends a release signal to the suspension heavy model electromagnetic synchronous release system, and sends a start signal to the spectrometer system and the radiometer system;

[0036] The suspension heavy model electromagnetic synchronous release system receives the release signal and freely releases the aircraft test model into the stable flow field of the wind tunnel, the spectrometer system acquires the spectrum information of the model plasma sheath and wake, and sends the information to the computing processing system, the radiometer system acquires the light radiation information of the model plasma sheath and wake, and sends the information to the computing processing system, and the suspension heavy model electromagnetic synchronous release system recovers the aircraft test model.

[0037] The computing processing system processes the acquired spectrum information and radiation information, and obtains the light radiation characteristics of the plasma sheath and wake of the aircraft test model.

[0038] Preferably, the heating device comprises a direct current power supply placed at the top of the test section of the wind tunnel, an electrode connected with the direct current power supply, and a driving device; when heating, the driving device drives the electrode to move downward and contact the aircraft test model, the direct current power supply is turned on, the aircraft test model is heated by the electrode, and after reaching a predetermined temperature, the driving device drives the electrode to move upward and separate from the aircraft test model.

[0039] Preferably, the surface temperature of the aircraft test model is measured by using a thermal environment infrared thermal imaging technology, and the measurement method is as follows:

[0040] A surface source black body is used to calibrate the infrared thermal imager on site, and when calibrating, the surface source black body is installed on the center line of the test section of the wind tunnel, and the radiation surface is at the center of the field of view of the infrared thermal imager.

[0041] The calibrated infrared thermal imager acquires the surface level values of the aircraft test model at different times, and sends the values to a data processor;

[0042] The data processor fits the temperature-level curve of the infrared thermal imager according to the calibration data, and obtains the surface temperature of the aircraft test model at different times according to the surface level values acquired by the infrared thermal imager.

[0043] Preferably, the aircraft test model is made of metal material or non-metal material; if the aircraft test model is made of non-metal material, an alloy material element is placed in the cavity of the aircraft test model.

[0044] Preferably, a high-temperature black body furnace is used to calibrate the relative radiation intensity of each wavelength measurement band of the spectrometer system, and the relative response rate of each pixel of the CCD in different measurement bands is obtained.

[0045] Preferably, during the spectral measurement, the grating incident angle is calculated according to the wavelength range to be measured, and the grating angle of the spectrometer is adjusted to meet the requirement of the grating incident angle.

[0046] Preferably, the radiometer system comprises an infrared radiometer, an infrared radiation imaging system, an ultraviolet radiometer and a visible light radiometer.

[0047] The infrared radiometer is calibrated by a medium-temperature cavity blackbody furnace; the infrared radiation imaging system is calibrated by a large-area blackbody furnace; the ultraviolet radiometer and the visible light radiometer are calibrated by a high-brightness broadband white light source.

[0048] Preferably, the length L of the aircraft test model is determined by the following formula:

[0049] L≤(10~20)tV ∞

[0050] wherein t is the effective test time of the high-enthalpy shock tunnel, V ∞ is the free stream velocity at the outlet of the nozzle.

[0051] Preferably, after the aircraft test model is freely dropped into the stable flow field of the wind tunnel, the schlieren photograph of the aircraft test model is obtained by using the laser schlieren technique, the detached shock wave distance and the wake of the aircraft test model are measured, and it is determined whether the time for the flow field to flow through the model is greater than the time for forming two wake periods; if yes, the test is continued; if no, the operating state of the wind tunnel is adjusted until the time for the flow field to flow through the model is greater than the time for forming two wake periods.

[0052] Preferably, the proportional relationship between the detached shock wave distance Δ, the diameter D of the aircraft test model and the pixels of the schlieren photograph is as follows:

[0053]

[0054] wherein Pe1 is the pixel of the detached distance of the shock wave along the horizontal center line of the aircraft test model, and Pe2 is the pixel of the diameter of the model interpreted along the vertical center line of the aircraft test model.

[0055] Preferably, the response time t1 of the suspended heavy model electromagnetic synchronous release system, the operating time t2 of the wind tunnel and the time t3 required for the pressure sensor to collect the pressure signal and send it to the synchronous acquisition system satisfy the following relationship

[0056] t1<t3-t2.

[0057] Preferably, the suspended heavy model electromagnetic synchronous release system is located in the test section of the high-enthalpy shock tunnel, and comprises a released model device fixed above the angle of attack mechanism and a buffer captured model device fixed below the angle of attack mechanism.

[0058] Release model device: Before the wind tunnel is started, the aircraft test model is suspended in the wind tunnel; after the wind tunnel is started and a release signal is received, the aircraft test model is released.

[0059] Buffer capture model device: Enables lossless recovery of aircraft test models.

[0060] Preferably, the model release device includes a signal processing device, a solenoid valve, a power supply, and an electromagnet; the power supply is connected to the electromagnet through the solenoid valve, the electromagnet is used to adsorb the aircraft test model, and the signal processing device is connected to the solenoid valve; when the signal processing device receives a release signal, it controls the solenoid valve to open, the electromagnet loses its magnetic force, and the aircraft test model is released.

[0061] The buffer capture model device is a flexible steel wire mesh.

[0062] This invention provides a system and method for measuring the optical radiation characteristics of a plasma sheath and wake in a high-enthalpy shock wind tunnel model. The advantages compared to existing technologies are:

[0063] This invention utilizes a large-size high-enthalpy shock tunnel and employs a suspended heavy model electromagnetic synchronous release system to achieve free flight of the aircraft test model without interference contrails, thus solving the problem of interference from the model support mechanism to the contrails. A spectrometer system and a radiometer system are used to test transient optical radiation characteristics, ensuring the accuracy and precision of the photoelectric characteristics measurement of the model's plasma sheath contrails.

[0064] This invention designs a heating device to heat an aircraft test model to simulate an ablation model, thereby achieving accurate simulation of the light radiation characteristics of the high-temperature model under flight conditions.

[0065] This invention can not only study the optical radiation characteristics of the plasma sheath in the leading edge region of the model, but also conduct research on the optical radiation characteristics of the model's wake. At the same time, it can accurately measure the optical radiation characteristics of the plasma sheath and wake of the ablation model. Attached Figure Description

[0066] Figure 1 This invention relates to a schematic diagram of the method for measuring the optical radiation characteristics of a high-enthalpy shock tunnel model plasma sheath and wake.

[0067] Figure 2 This is a schematic diagram of the high-enthalpy shock wind tunnel model plasma sheath and wake light radiation characteristic measurement system involved in the present invention; wherein (a) is a horizontal cross-section and (b) is a vertical cross-section;

[0068] Among them, 1-compression tube, 2-shock tube, 3-spectrometer system and radiometer system, 4-grating, 5-computation processing system, 6-synchronous acquisition system, 7-release model device, 8-aircraft test model, 9-buffered capture model device. Detailed Implementation

[0069] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0070] This invention presents a system and method for measuring the optical radiation characteristics of a plasma sheath and contrail in a high-enthalpy shock wind tunnel model. It provides an experimentally verified and feasible approach for the accurate measurement of the optical radiation characteristics of the plasma sheath and contrail in a clean, interference-free model. The aircraft test model used in this invention employs a heavy model to ensure that the model's displacement in the flow field is minimized and that the airflow does not affect the model's attitude angles.

[0071] This invention utilizes a large-size high-enthalpy shock tunnel, combined with interference-free wake re-model free-flight technology, re-model heating technology, and transient optical radiation characteristic testing technology to measure the optical radiation characteristics of the plasma sheath and its wake. This invention not only enables the study of the optical radiation characteristics of the plasma sheath in the model's leading edge region but also allows for the research of the model's wake optical radiation characteristics, and simultaneously enables precise measurement of the optical radiation characteristics of the plasma sheath and wake of an ablation model.

[0072] like Figure 2 As shown, a measurement system for the plasma sheath and wake radiation characteristics of a high-enthalpy shock wind tunnel model includes a high-enthalpy shock wind tunnel, a spectrometer system and a radiometer system 3, a suspended heavy model electromagnetic synchronous release system, a pressure sensor, a synchronous acquisition system 6, and a calculation and processing system 5.

[0073] High enthalpy shock wave wind tunnel: The nozzle exit size is 1.2m to 2.5m, which is used to provide the flow field for the test model 8 of the aircraft.

[0074] Suspended heavy model electromagnetic synchronous release system: Before the wind tunnel is started, the test model 8 of the aircraft is suspended in the wind tunnel; after the wind tunnel is started, the test model 8 of the aircraft is released after receiving the release signal.

[0075] Pressure sensor: Installed on compression tube 1 and shock tube 2 of the high enthalpy shock wind tunnel, used to collect pressure signals of compression tube 1 and shock tube 2 after the wind tunnel is running and send them to synchronous acquisition system 6.

[0076] Synchronous acquisition system 6: After receiving the pressure signal, it simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and radiometer system 3.

[0077] Spectrometer system: After startup, it collects spectral information of the plasma sheath and wake of the model and sends it to the computing and processing system 5.

[0078] Radiometer system: After startup, it collects the light radiation information of the plasma sheath and wake of the model and sends it to the computing and processing system 5.

[0079] Computational processing system 5: Processes spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model.

[0080] The suspended heavy model electromagnetic synchronous release system is located in the high-enthalpy shock wave wind tunnel test section. It includes a release model device 7 fixed above the angle-of-attack mechanism and a buffer capture model device 9 fixed below the angle-of-attack mechanism. The release model device suspends the aircraft test model in the wind tunnel before wind tunnel startup; after wind tunnel startup, it releases the aircraft test model upon receiving a release signal. The buffer capture model device enables the lossless recovery of the aircraft test model.

[0081] The model release device 7 includes a signal processing unit, a solenoid valve, a power supply, and an electromagnet. The power supply is connected to the electromagnet via the solenoid valve. The electromagnet is used to attract the aircraft test model. The signal processing unit is connected to the solenoid valve. When the signal processing unit receives a release signal, it controls the solenoid valve to open, the electromagnet loses its magnetic force, and the aircraft test model is released. The buffer capture device 9 is a flexible steel wire mesh.

[0082] The aircraft test model is made of metallic or non-metallic materials; if the aircraft test model is made of non-metallic materials, alloy material components are placed inside the cavity of the aircraft test model.

[0083] The above system was used to measure the optical radiation characteristics of the model plasma sheath and its wake. The method for measuring the optical radiation characteristics of the model plasma sheath and its wake in this invention can be applied to both ordinary models and ablation models. Figure 1 The present invention relates to a method and procedure for measuring the plasma sheath and wake radiation characteristics of a high-enthalpy shock wind tunnel model.

[0084] Specifically, the steps for measuring the plasma sheath and wake radiation characteristics of a common model are as follows:

[0085] (1) Calibrate the spectrometer system and the radiometer system;

[0086] (2) Based on the effective test time of the high enthalpy shock wind tunnel flow field calibration and the size of the uniform flow field region, determine the size of the aircraft test model and design the aircraft test model;

[0087] (3) The test model of the aircraft is suspended in the test section of the high enthalpy shock wave wind tunnel using the suspended heavy model electromagnetic synchronous release system and fixed on the angle of attack mechanism to ensure that the test model of the aircraft does not move at the same time as the wind tunnel during the wind tunnel operation.

[0088] (4) Install pressure sensors at corresponding positions on the compression tube and shock tube, and connect the pressure sensors to the synchronous acquisition system;

[0089] (5) Start the wind tunnel and the pressure sensor collects the pressure signal and sends it to the synchronous acquisition system;

[0090] (6) After receiving the pressure signal, the synchronous acquisition system simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and the radiometer system.

[0091] (7) After receiving the release signal, the suspended heavy model electromagnetic synchronous release system freely releases the aircraft test model into the stable flow field of the wind tunnel; the spectrometer system collects the spectral information of the flow field around the model and sends it to the computing and processing system; the radiometer system collects the light radiation information of the flow field around the model and sends it to the computing and processing system; after the aircraft test model is released, the suspended heavy model electromagnetic synchronous release system retrieves it.

[0092] (8) The computational processing system processes the collected spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model.

[0093] The method for measuring the optical radiation characteristics of the plasma sheath and wake of an ablation model is as follows:

[0094] (1) Calibrate the spectrometer system and the radiometer system;

[0095] (2) Based on the effective test time of the high enthalpy shock wind tunnel flow field calibration and the size of the uniform flow field region, determine the size of the aircraft test model and design the aircraft test model;

[0096] (3) The test model of the aircraft is suspended in the test section of the high enthalpy shock wave wind tunnel using the suspended heavy model electromagnetic synchronous release system and fixed on the angle of attack mechanism to ensure that the test model of the aircraft does not move at the same time as the wind tunnel during the wind tunnel operation.

[0097] (4) Install pressure sensors at corresponding positions on the compression tube and shock tube, and connect the pressure sensors to the synchronous acquisition system;

[0098] (5) Use a heating device to heat the aircraft test model to a predetermined temperature to simulate the ablation model;

[0099] (6) Start the wind tunnel and the pressure sensor collects the pressure signal and sends it to the synchronous acquisition system;

[0100] (7) After receiving the pressure signal, the synchronous acquisition system simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and the radiometer system.

[0101] (8) After receiving the release signal, the suspended heavy model electromagnetic synchronous release system freely releases the aircraft test model into the stable flow field of the wind tunnel; the spectrometer system collects the spectral information of the flow field around the model and sends it to the computing system; the radiometer system collects the light radiation information of the flow field around the model and sends it to the computing system; after the aircraft test model is released, the suspended heavy model electromagnetic synchronous release system retrieves it.

[0102] (9) The computational processing system processes the collected spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model.

[0103] When heating the aircraft test model to a predetermined temperature using a heating device, if the model is made of metal, the power supply voltage directly heats the model; for objects that cannot be directly heated by resistance, indirect resistance heating can be used, by making alloy material components from special alloy materials and placing the alloy material components inside the model cavity.

[0104] Specifically, the heating device includes a DC power supply placed at the top of the wind tunnel test section, electrodes connected to the DC power supply, and a drive device. During heating, the drive device moves the electrodes downwards to contact the aircraft test model, the DC power supply is turned on, and the aircraft test model is heated through the electrodes. After reaching the predetermined temperature, the drive device moves the electrodes upwards, separating them from the aircraft test model. During the test, the model moves downwards and enters the flow field; the electrodes remain above the test section and do not enter the flow field. The DC power supply equipment is placed at the top of the test section.

[0105] The surface temperature of the aircraft test model was measured using infrared thermal imaging technology. The infrared thermal imager observed the radiation of the blackbody through infrared glass, thus eliminating the need for corrections to the transmittance and reflectance losses of the infrared window glass. Finally, the data processor provided a fitting curve of the temperature-level values ​​from the infrared thermal imager. The specific measurement method is as follows:

[0106] (1) Use a blackbody to calibrate the infrared thermal imager on site. During calibration, the blackbody is installed on the center line of the wind tunnel test section, and its radiation surface is at the center of the infrared thermal imager's field of view.

[0107] (2) The calibrated infrared thermal imager collects the surface level values ​​of the test model of the aircraft at different times and sends them to the data processor.

[0108] (3) The data processor fits the temperature-level curve of the infrared thermal imager according to the calibration data, and obtains the surface temperature of the aircraft test model at different times according to the surface level value collected by the infrared thermal imager.

[0109] During optical radiation measurements in the test section, the spectrometer and radiometer systems used require calibration. The spectrometer system has different measurement wavelength ranges. A high-temperature blackbody furnace (temperature greater than 500°C) is used to calibrate the relative radiation intensity of each wavelength range of the spectrometer, obtaining the relative responsivity of each CCD pixel in different measurement wavelength ranges. During experimental measurements, the required grating incident angle is calculated using the dispersion equation based on the wavelength range to be measured, and the angle of grating 4 is adjusted to meet the calculated incident angle requirements.

[0110] A radiometer system includes an infrared radiometer, an infrared imaging system, an ultraviolet radiometer, and a visible light radiometer. The calibration methods for radiometers vary depending on the wavelength band. Infrared radiometers are calibrated using a medium-temperature (300–500°C) cavity blackbody furnace, while infrared imaging systems use a large-area (area greater than 1m²) furnace. 2 The blackbody furnace was used for calibration, and the ultraviolet radiometer and visible radiometer were calibrated using a high-brightness (brightness greater than 1 million illuminance) broadband white light source.

[0111] In the initial model design, numerical simulations using the unsteady, multi-component, and multi-temperature Navier-Stokes equations are necessary to obtain the initial time required for the model wake to form, thereby determining the model size. The size of the experimental model is then evaluated based on the effective test time calibrated using the high-enthalpy shock tunnel flow field. When measuring the wake, the wake time needs to span at least two periods. The length of the experimental model is determined by the effective operating time and the free-flow velocity at the nozzle exit, as shown in the following equation:

[0112] L≤(10~20)tV ∞

[0113] Where t is the effective test time of the high-enthalpy shock tunnel, and V ∞ The free flow velocity is the nozzle exit velocity.

[0114] After the aircraft test model is freely deployed into the stable flow field of the wind tunnel, laser schlieren technology is used to obtain schlieren images of the aircraft test model. The distance of the detached shock wave and the wake of the aircraft test model are measured. It is determined whether the time for the flow field to pass through the model is greater than the time for forming two wake cycles. If it is greater, the test continues. If it is not greater, the wind tunnel operation is adjusted until the time for the flow field to pass through the model is greater than the time for forming two wake cycles.

[0115] The proportional relationship between the detached shock wave distance Δ, the model diameter D, and the pixels of the schlieren image is as follows:

[0116]

[0117] Where Pe1 is the distance pixel of the detachment of the stagnation shock wave along the horizontal centerline of the model, and Pe2 is the model diameter pixel read along the vertical centerline of the model.

[0118] A suspended electromagnetic synchronous release system for the heavy model is constructed to suspend the model in the wind tunnel. The electromagnetic synchronous release system for the heavy model needs to be matched with the wind tunnel operating time constraints. The response time t1 of the electromagnetic synchronous release system, the wind tunnel operating time t2, and the time t3 required for the pressure sensor to collect the pressure signal and send it to the synchronous acquisition system must satisfy the following relationship:

[0119] t1 < t3 - t2.

[0120] Establish a release model device and a buffer capture model device to achieve instantaneous release and lossless recycling of the heavy model.

[0121] Based on the pre-reserved sensor mounting interfaces in the compression tube and shock tube, a series of high-frequency, high-temperature, and high-pressure sensors are installed at corresponding positions in the compression tube and shock tube. The pressure sensors are connected to a synchronous data acquisition system; upon signal triggering, the acquired data is connected to the computing and processing system via optical fiber. The pressure sensors have a frequency greater than 1MHz, a temperature greater than 2000K, and a pressure greater than 10MPa.

[0122] To address the challenge of accurately measuring the optical radiation characteristics of the plasma sheath and contrail of high-speed aircraft, this invention utilizes a large-size high-enthalpy shock tunnel and employs a suspended heavy model electromagnetic synchronous release system to achieve free flight of the heavy model without interference contrails. A heating device and related design are used to heat the heavy model to simulate ablation. A spectrometer system and a radiometer system are employed to test transient optical radiation characteristics. This invention aims to develop a quantitative measurement method for the optical radiation characteristics of large-size aircraft models, thus solving the problem of accurately measuring the plasma sheath and contrail of models.

[0123] This invention can not only study the optical radiation characteristics of the plasma sheath in the leading edge region of the model, but also conduct research on the optical radiation characteristics of the model's wake. At the same time, it can accurately measure the optical radiation characteristics of the plasma sheath and wake of the ablation model, which is a better method.

[0124] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A shock tunnel plasma sheath and wake optical radiation characteristic measurement system, characterized in that: It includes a high-enthalpy shock wind tunnel, a spectrometer system, a radiometer system, a suspended heavy model electromagnetic synchronous release system, pressure sensors, a synchronous acquisition system, and a computing and processing system; High-enthalpy shock tunnel: used to provide flow fields for aircraft test models; The suspended heavy model electromagnetic synchronous release system is located in the high enthalpy shock wind tunnel test section and includes a release model device fixed above the angle of attack mechanism and a buffer capture model device fixed below the angle of attack mechanism. Release model device: Before the wind tunnel is started, the aircraft test model is suspended in the wind tunnel; after the wind tunnel is started and a release signal is received, the aircraft test model is released. Buffer capture model device: Enables lossless recovery of aircraft test models; Pressure sensor: Installed on the compression tube and shock tube of the high enthalpy shock wind tunnel, used to collect the pressure signals of the compression tube and shock tube after the wind tunnel is running and send them to the synchronous acquisition system; Synchronous acquisition system: Upon receiving the pressure signal, it simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and radiometer system; Spectrometer system: After startup, it collects spectral information of the model's plasma sheath and wake, and sends it to the computing and processing system; Radiometer system: After startup, it collects optical radiation information of the model's plasma sheath and wake, and sends it to the computing and processing system. Computational processing system: Processes spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model.

2. The shock tunnel plasma sheath and wake radiation characteristic measurement system according to claim 1, characterized in that: The model release device includes a signal processing device, a solenoid valve, a power supply, and an electromagnet. The power supply is connected to the electromagnet through the solenoid valve. The electromagnet is used to attract the aircraft test model. The signal processing device is connected to the solenoid valve. When the signal processing device receives a release signal, it controls the solenoid valve to open, and the electromagnet loses its magnetic force to release the aircraft test model. The buffer capture model device is a flexible steel wire mesh.

3. The shock tunnel plasma sheath and wake radiation characteristic measurement system according to claim 1, characterized in that: The aircraft test model is made of metallic or non-metallic materials; if the aircraft test model is made of non-metallic materials, alloy material components are placed inside the cavity of the aircraft test model.

4. A method for measuring the optical radiation characteristics of the plasma sheath and wake in a shock tunnel, characterized in that, include: Calibrate the spectrometer system and radiometer system; Based on the effective test time and the size of the uniform flow field region in the high-enthalpy shock tunnel flow field calibration, the size of the aircraft test model is determined and the aircraft test model is designed. The test model of the aircraft is suspended in the test section of the high enthalpy shock wind tunnel using a suspended heavy model electromagnetic synchronous release system to ensure that the test model of the aircraft does not move simultaneously with the wind tunnel during the operation of the wind tunnel. Pressure sensors are installed at corresponding positions on the compression tube and shock tube, and the pressure sensors are connected to the synchronous acquisition system. When the wind tunnel is started, the pressure sensor collects the pressure signal and sends it to the synchronous acquisition system; After receiving the pressure signal, the synchronous acquisition system simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and radiometer system. After receiving the release signal, the suspended heavy model electromagnetic synchronous release system freely releases the aircraft test model into the stable flow field of the wind tunnel; The spectrometer system collects spectral information of the model's plasma sheath and wake, and sends it to the computing system; the radiometer system collects optical radiation information of the model's plasma sheath and wake, and sends it to the computing system. The suspended heavy model electromagnetic synchronous release system recovers the aircraft test model; The computational processing system processes the collected spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model. After the aircraft test model is freely deployed into the stable flow field of the wind tunnel, laser schlieren technology is used to obtain schlieren images of the aircraft test model. The distance of the detached shock wave and the wake of the aircraft test model are measured. It is determined whether the time for the flow field to pass through the model is greater than the time for forming two wake cycles. If it is greater, the test continues. If it is not greater, the wind tunnel operation is adjusted until the time for the flow field to pass through the model is greater than the time for forming two wake cycles. The response time t1 of the suspended heavy model electromagnetic synchronous release system, the wind tunnel running time t2, and the time t3 required for the pressure sensor to collect the pressure signal and send it to the synchronous acquisition system satisfy the following relationship: 。 5. A method for measuring the optical radiation characteristics of the plasma sheath and wake in a shock tunnel, characterized in that, include: Calibrate the spectrometer system and radiometer system; Based on the effective test time and the size of the uniform flow field region in the high-enthalpy shock tunnel flow field calibration, the size of the aircraft test model is determined and the aircraft test model is designed. The test model of the aircraft is suspended in the test section of the high enthalpy shock wind tunnel using a suspended heavy model electromagnetic synchronous release system to ensure that the test model of the aircraft does not move simultaneously with the wind tunnel during the operation of the wind tunnel. Pressure sensors are installed at corresponding positions on the compression tube and shock tube, and the pressure sensors are connected to the synchronous acquisition system. The aircraft test model was heated to a predetermined temperature using a heating device to simulate an ablation model; When the wind tunnel is started, the pressure sensor collects the pressure signal and sends it to the synchronous acquisition system; After receiving the pressure signal, the synchronous acquisition system simultaneously sends a release signal to the suspended heavy model electromagnetic synchronous release system and a start signal to the spectrometer system and radiometer system. After receiving the release signal, the suspended heavy model electromagnetic synchronous release system freely releases the aircraft test model into the stable flow field of the wind tunnel; The spectrometer system collects spectral information of the model's plasma sheath and wake, and sends it to the computing system; the radiometer system collects optical radiation information of the model's plasma sheath and wake, and sends it to the computing system. The suspended heavy model electromagnetic synchronous release system recovers the aircraft test model; The computational processing system processes the collected spectral and radiation information to obtain the plasma sheath and contrail radiation characteristics of the aircraft test model. After the aircraft test model is freely deployed into the stable flow field of the wind tunnel, laser schlieren technology is used to obtain schlieren images of the aircraft test model. The distance of the detached shock wave and the wake of the aircraft test model are measured. It is determined whether the time for the flow field to pass through the model is greater than the time for forming two wake cycles. If it is greater, the test continues. If it is not greater, the wind tunnel operation is adjusted until the time for the flow field to pass through the model is greater than the time for forming two wake cycles. The response time t1 of the suspended heavy model electromagnetic synchronous release system, the wind tunnel running time t2, and the time t3 required for the pressure sensor to collect the pressure signal and send it to the synchronous acquisition system satisfy the following relationship: 。 6. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 5, characterized in that, The heating device includes a DC power supply placed at the top of the wind tunnel test section, electrodes connected to the DC power supply, and a driving device. During heating, the driving device moves the electrodes downward to contact the aircraft test model, the DC power supply is turned on, and the aircraft test model is heated through the electrodes. After reaching the predetermined temperature, the driving device moves the electrodes upward to separate from the aircraft test model.

7. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 6, characterized in that, The surface temperature of the aircraft test model was measured using thermal environment infrared thermography. The measurement method is as follows: The infrared thermal imager is calibrated on-site using a surface source blackbody. During calibration, the surface source blackbody is installed on the center line of the wind tunnel test section, with its radiating surface at the center of the infrared thermal imager's field of view. The calibrated infrared thermal imager collects surface level values ​​of the aircraft test model at different times and sends them to the data processor; The data processor fits the temperature-level curve of the infrared thermal imager based on the calibration data, and obtains the surface temperature of the aircraft test model at different times based on the surface level values ​​collected by the infrared thermal imager.

8. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 4 or 5, characterized in that, The aircraft test model is made of metallic or non-metallic materials; if the aircraft test model is made of non-metallic materials, alloy material components are placed inside the cavity of the aircraft test model.

9. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 4 or 5, characterized in that, The relative radiation intensity of each wavelength measurement band of the spectrometer system was calibrated using a high-temperature blackbody furnace, and the relative responsivity of each CCD pixel in different measurement bands was obtained.

10. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 9, characterized in that, During spectral measurements, the required grating incident angle is calculated using the dispersion equation based on the wavelength range to be measured, and the grating angle of the spectrometer is adjusted to meet the grating incident angle requirements.

11. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 4 or 5, characterized in that, The radiometer system includes an infrared radiometer, an infrared radiation imaging system, an ultraviolet radiometer, and a visible light radiometer; The infrared radiometer was calibrated using a medium-temperature cavity blackbody furnace; the infrared radiation imaging system was calibrated using a large-area blackbody furnace; and the ultraviolet radiometer and visible light radiometer were calibrated using a high-brightness broadband white light source.

12. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 4 or 5, characterized in that, Length of the aircraft test model Determined by the following formula: in t For the effective test time of high enthalpy shock wave wind tunnel, V ∞ The free flow velocity is the nozzle exit velocity.

13. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 12, characterized in that, The proportional relationship between the detached shock wave distance Δ, the diameter D of the aircraft test model, and the pixels of the schlieren image is as follows: in The distance in pixels from the detachment of the stagnation shock wave along the horizontal centerline of the aircraft test model. The model diameter pixels are determined along the vertical centerline of the aircraft test model.

14. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 4 or 5, characterized in that, The suspended heavy model electromagnetic synchronous release system is located in the high enthalpy shock wind tunnel test section and includes a release model device fixed above the angle of attack mechanism and a buffer capture model device fixed below the angle of attack mechanism. Release model device: Before the wind tunnel is started, the aircraft test model is suspended in the wind tunnel; after the wind tunnel is started and a release signal is received, the aircraft test model is released. Buffer capture model device: Enables lossless recovery of aircraft test models.

15. The method for measuring the plasma sheath and wake radiation characteristics of a shock tunnel according to claim 14, characterized in that, The model release device includes a signal processing device, a solenoid valve, a power supply, and an electromagnet. The power supply is connected to the electromagnet through the solenoid valve. The electromagnet is used to attract the aircraft test model. The signal processing device is connected to the solenoid valve. When the signal processing device receives a release signal, it controls the solenoid valve to open, the electromagnet loses its magnetic force, and the aircraft test model is released. The buffer capture model device is a flexible steel wire mesh.

Images