Method for measuring wide-temperature-range three-dimensional pressure field in extreme wind tunnel environment

Abstract

The invention discloses a wide-temperature-range three-dimensional pressure field measurement method in an extreme wind tunnel environment, and the method achieves the high-precision reconstruction of a three-dimensional pressure field in a whole temperature range from low temperature to high temperature through the fusion of a digital image correlation (DIC) technology and a multi-mode sensing technology, specifically, in a low-temperature environment, pressure-sensitive paint and temperature-sensitive paint are used for joint calibration, and the measurement precision of a wide-temperature-range three-dimensional pressure field is improved. A laser light source and double cameras are synchronously triggered through a binocular vision system, fluorescence lifetime signals are captured, temperature interference is eliminated through a double-gating gain function ratio, a three-dimensional shape is reconstructed in combination with a DIC technology, and non-contact pixel-level pressure field mapping is achieved. In a high-temperature environment, pressure measuring point layout is optimized through CFD simulation, discrete pressure data are acquired by adopting a high-temperature-resistant pressure sensor array, sensor space coordinates are acquired in combination with a binocular DIC system, a two-dimensional pressure field is reconstructed by utilizing a Kriging interpolation algorithm, and a three-dimensional pressure field is obtained through pixel-level mapping and three-dimensional point cloud fusion. And a high-resolution three-dimensional pressure field in a high-temperature environment is generated.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-dimensional reconstruction, and more specifically, relates to a method for measuring a three-dimensional pressure field over a wide temperature range in an extreme wind tunnel environment. Background Art

[0002] With the rapid development of aerospace, high-speed transportation and other fields, the demand for aerodynamic performance testing of complex structures such as cross-domain transformable aircraft and aircraft engine blades under extreme temperature and high-speed flow conditions is becoming increasingly urgent. High-precision measurement of surface pressure field is a key means to evaluate aerodynamic characteristics and optimize design, but traditional measurement technology has significant limitations in the application of wide temperature range (low temperature to high temperature). This has led to the separation of low-temperature and high-temperature measurement technologies, and the lack of a unified framework for continuous measurement over the entire temperature range. In addition, the pixel-level mapping of pressure field and three-dimensional morphology is affected by environmental deformation and projection errors, making it difficult to ensure full-field consistency.

[0003] In recent years, pressure-sensitive paint (PSP) technology has been widely used in wind tunnel testing and flight test research. Pressure-sensitive paint technology is a high-resolution non-contact pressure field measurement technology developed by using the oxygen quenching reaction of luminescent molecules in an excited state. This technology coats pressure-sensitive paint on the surface of the test specimen, excites it with a laser of the corresponding wavelength, and uses image acquisition devices such as CCD cameras to collect images of the pressure-sensitive paint. Finally, the pressure field on the surface of the test piece is obtained by processing and analyzing the image. However, since the pressure-sensitive paint itself does not have the property of high temperature resistance, it is challenging to use pressure-sensitive paint to measure the pressure field in a high temperature environment. In addition, the pressure-sensitive paint will be affected by temperature in the test environment, resulting in inaccurate pressure measurement. Pressure sensors can work in higher temperature environments than pressure-sensitive paint. However, when using traditional pressure sensors to measure pressure, the selection of pressure measurement points often depends on the experience of the measurement personnel. In addition, although distributed pressure sensors can obtain accurate pressure distribution, it is difficult to obtain complete pressure field information on the surface of the test piece because the measurement data is discrete.

[0004] In recent years, the synchronous measurement technology of pressure fields for complex structures in high-speed motion scenarios has gradually attracted the attention of researchers, and several new methods have been proposed. Dong et al. proposed a pressure paint system integrated with speckle patterns in "Pressure-sensitive paint integrated with digital image correlation for instantaneous measurement on rotating blades". This method combines single-pulse lifetime emission with stereo digital image correlation technology for synchronous measurement of surface pressure and deformation of high-speed rotating blades. However, this method is affected by the working temperature range of the pressure-sensitive paint and cannot meet the requirements for pressure field measurement in high-temperature environments. Wei Chunhua et al. disclosed a method and device for synchronous measurement of three-dimensional surface profile and surface pressure of a model based on a phase-shifting profiler and pressure-sensitive paint in the invention patent "Method and device for synchronous measurement of three-dimensional surface profile and surface pressure of a model". This method sprays pressure-sensitive paint on the model surface and projects fringe light with a structured light generator to excite the coating, synchronously exciting the excitation light source and the camera to capture four phase-shifted images, and then calculating the surface pressure value and 3D surface profile of the model through parallel data processing. However, this method uses a phase measurement method based on the phase-shifting method, and multiple images require a long acquisition time. In addition, the fringe phase information in this method is affected by pressure pulsation, which will reduce the accuracy of three-dimensional pressure measurement. Zhao Xuan et al. proposed a method for accurately reconstructing the pressure distribution curve by fusing sparse wind tunnel test data and CFD data in "Refined reconstruction method of airfoil surface pressure based on multi-source data fusion" to solve the problem that it is difficult to arrange sufficient pressure measurement holes on the surface of complex models in wind tunnel tests to obtain complete pressure distribution information. However, the pressure measurement results obtained by this method are not three-dimensional pressure field distributions.

[0005] In summary, there is an urgent need for a high-precision measurement method for three-dimensional pressure fields based on multi-modal sensing fusion and adaptable to a wide temperature range to support the aerodynamic design and performance verification of complex equipment such as cross-domain variable-configuration aircraft. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for measuring three-dimensional pressure fields in a wide temperature range in an extreme wind tunnel environment. By fusing digital image correlation (DIC) technology and multi-modal sensing technology, high-precision reconstruction of three-dimensional pressure fields in the full temperature range from low temperature to high temperature is achieved.

[0007] To achieve the above invention purpose, a method for measuring three-dimensional pressure fields in a wide temperature range in an extreme wind tunnel environment according to the present invention is characterized by including the following steps:

[0008] (1) Build a binocular vision system;

[0009] Install two high-resolution cameras CCD-1 and CCD-2 on a fixed instrument to form a binocular camera. Adjust the shooting angles of CCD-1 and CCD-2 to ensure that the fields of view of the two cameras completely cover the surface of the test piece, and there is a common field of view area; install a speckle projection device and a laser generator on the fixed instrument between CCD-1 and CCD-2, and ensure that the speckle image projected by the speckle projection device and the lasers of different wavelengths projected by the laser generator can cover the common area determined by CCD-1 and CCD-2;

[0010] (2) Calibrate the binocular camera using the Zhang's calibration method to obtain the internal and external parameters of the left camera CCD-1 and the right camera CCD-2, as well as the relative pose relationship between the two;

[0011] (3) In the test environment, turn on the speckle projection device. The speckle projection device projects speckles onto the surface of the test piece to form speckle features. Then, use the calibrated CCD-1 and CCD-2 cameras to take pictures of the test piece to obtain img1 and img2; perform image matching on img1 and img2 using the stereo matching method according to the image speckle features, and perform three-dimensional reconstruction according to the calibration parameters of the binocular camera to obtain the three-dimensional morphology of the test piece;

[0012] (4) Detect the temperature of the test environment, compare the environmental temperature with the temperature threshold. If the environmental temperature is less than or equal to the temperature threshold, enter the low-temperature domain measurement in step (5); otherwise, enter the high-temperature domain measurement in step (6);

[0013] (5) Low-temperature domain measurement;

[0014] (5.1) Coat the pressure-sensitive paint PSP and the temperature-sensitive paint TSP on the surface of the test piece;

[0015] (5.2) Trigger the laser generator to emit pulsed laser suitable for the measurement band of the pressure-sensitive paint to excite the pressure-sensitive paint on the surface of the test piece to generate PSP fluorescence signal, synchronously trigger the CCD-1 camera to take the fluorescence image of the surface of the test piece, record it as img3, and then take the fluorescence image img4 again after a delay time t; then, trigger the laser generator to emit pulsed laser suitable for the measurement band of the temperature-sensitive paint to excite the temperature-sensitive paint on the surface of the test piece to generate TSP fluorescence signal, synchronously trigger the CCD-1 camera to take the fluorescence image of the surface of the test piece, record it as img5, and then take the fluorescence image img6 again after a delay time t;

[0016] (5.3) Calculate the gated intensity integral ratio of the PSP fluorescence signals recorded in img3 and img4 pixel by pixel and the gated intensity integral ratio of the TSP fluorescence signals recorded in img5 and img6 Among them, i represents the serial number index of the pixel point, respectively representing the gated intensity integrals of the i-th pixel point in the images img3, img4, img5, and img6;

[0017] (5.4) Use a pressure calibration system to calibrate the sensitivities of the pressure-sensitive paint and the temperature-sensitive paint, and obtain the calibration curves of gated intensity integral ratio - pressure and gated intensity integral ratio - temperature;

[0018] (5.5) Use a quadratic curve to fit the ratio of the gated intensity integral ratios of TSP under the reference condition and the test condition in the radial and chordal directions of the test piece, to obtain the fitting curves varying with the radial and chordal positions;

[0019] (5.6) According to the calibration curve in step (5.4) and the fitting curve in step (5.5), remove the variation caused by temperature change in to obtain the corrected PSP gated intensity integral ratio for each pixel point

[0020]

[0021] where k(T) is the temperature sensitivity ratio between PSP and TSP;

[0022] (5.7) Establish the relationship between the pressure value P i at each pixel point and the gated intensity integral ratio as:

[0023]

[0024] Calculate the true pressure value P i at each pixel point according to the above relationship to obtain the two-dimensional pressure field distribution;

[0025]

[0026] where A(T) and B(T) are calibration coefficients related to the temperature T, which can be obtained from the calibration process, and P ref is the reference pressure in the calibration process;

[0027] (6) High-temperature domain measurement;

[0028] (6.1) Simulate the test environment in the actual situation in the CFD simulation, then extract the surface pressure coefficient gradient curve of the test piece based on the CFD simulation, and dynamically allocate the number of pressure measurement points in the high-pressure gradient and low-pressure gradient regions according to the pressure coefficient gradient curve;

[0029] (6.2) Arrange the same pressure sensors on the test piece according to the number of pressure measurement points determined by the simulation. Then, during the test, use CCD-1 to capture the distribution image of the pressure sensors on the surface of the test piece, denoted as img7, and determine the pixel coordinate positions of each sensor in img7 to establish the mapping relationship between the pressure sensors and the pixel coordinates;

[0030] (6.3) Conduct a pressure test in the test environment, collect the pressure values on each sensor, and map the pressure values to img7 through the mapping relationship between the pressure sensors and the pixel coordinates to obtain a discrete pressure distribution map, denoted as img8;

[0031] (6.4) In the two-dimensional image pixel coordinate system determined by img8, use the sensor projection points as known data points, construct a spatial variation function based on the Kriging interpolation algorithm, and generate a high-resolution two-dimensional pressure field distribution covering the entire image domain by solving the weight coefficients;

[0032] (7) Fuse the two-dimensional pressure field distribution with the three-dimensional topography point cloud reconstructed by binocular DIC through the pixel-level mapping relationship to generate a high-resolution three-dimensional pressure field in the full temperature range.

[0033] The invention object of the present invention is realized as follows:

[0034] A method for measuring a three-dimensional pressure field in a wide temperature range in an extreme wind tunnel environment of the present invention realizes high-precision reconstruction of the three-dimensional pressure field in the full temperature range from low temperature to high temperature by fusing digital image correlation (DIC) technology and multi-modal sensing technology. Specifically, in a low-temperature environment, combined calibration of pressure-sensitive paint and temperature-sensitive paint is adopted. The laser light source and the dual cameras are synchronously triggered by a binocular vision system to capture the fluorescence lifetime signal. The temperature interference is eliminated by using the ratio of the double-gated gain functions. The three-dimensional topography is reconstructed by combining DIC technology to realize non-contact pixel-level pressure field mapping; in a high-temperature environment, the pressure measurement point layout is optimized by CFD simulation. A high-temperature-resistant pressure sensor array is used to collect discrete pressure data. The spatial coordinates of the sensors are obtained by combining with a binocular DIC system. The two-dimensional pressure field is reconstructed by using the Kriging interpolation algorithm, and a high-resolution three-dimensional pressure field in the high-temperature environment is generated through pixel-level mapping and three-dimensional point cloud fusion.

[0035] At the same time, a method for measuring a three-dimensional pressure field in a wide temperature range in an extreme wind tunnel environment of the present invention also has the following

[0036] Beneficial effects:

[0037] (1) Continuous measurement ability across the entire temperature range: By integrating DIC technology and multi-modal sensing technology, a unified measurement framework is constructed to achieve continuous measurement of the three-dimensional pressure field across the entire temperature range from low temperature to high temperature. This solves the problem of discontinuous data caused by temperature range fragmentation in traditional methods and improves the measurement adaptability of complex equipment such as cross-domain variable configuration aircraft under extreme temperature conditions.

[0038] (2) High-precision anti-interference characteristics: In a low-temperature environment, the combined calibration of PSP and TSP and the ratio correction technology of the double-gated gain function are used to effectively eliminate temperature sensitivity errors and achieve non-contact pixel-level pressure field mapping, improving the pressure measurement accuracy; in a high-temperature environment, the dynamic layout of pressure measurement points is optimized based on CFD simulation, and the high-resolution pressure field is reconstructed by combining the Kriging interpolation algorithm, which can overcome the gradient distortion caused by high-temperature deformation and greatly enhance the measurement reliability.

[0039] (3) Deep integration of three-dimensional topography and pressure field: The three-dimensional topography point cloud is synchronously reconstructed through a binocular DIC system, and the two-dimensional pressure field is accurately projected into three-dimensional space using the pixel-level mapping relationship, providing highly consistent data support for the study of fluid-structure coupling effects.

[0040] (4) Wide engineering applicability: The present invention can be efficiently applied to the aerodynamic performance testing and flow field analysis of complex structures such as cross-domain variable configuration aircraft, aeroengine blades, and high-speed trains, reducing the dependence on experience for sensor layout and providing an efficient technical means for aerodynamic optimization design. Description of the Drawings

[0041] Figure 1 is a flowchart of a method for measuring a wide-temperature-range three-dimensional pressure field in an extreme wind tunnel environment according to the present invention;

[0042] Figure 2 is a diagram of the measurement architecture of the wide-temperature-range three-dimensional pressure field. Detailed Embodiments

[0043] The following describes the detailed embodiments of the present invention with reference to the drawings, so that those skilled in the art can better understand the present invention. It should be particularly noted that in the following description, when the detailed description of known functions and designs may obscure the main content of the present invention, these descriptions will be omitted here.

[0044] Embodiment

[0045] In this embodiment, as Figure 1 shown, a method for measuring a wide-temperature-range three-dimensional pressure field in an extreme wind tunnel environment according to the present invention includes the following steps:

[0046] (1) Build a binocular vision system;

[0047] In this embodiment, asFigure 2 As shown in Figure 2 , two high-resolution cameras CCD-1 and CCD-2 are installed on a fixed instrument to form a binocular camera. The shooting angles of CCD-1 and CCD-2 are adjusted to ensure that the fields of view of the two cameras completely cover the surface of the test piece, and there is a common field of view area; the speckle projection device and the laser generator are installed on the fixed instrument between CCD-1 and CCD-2, and it is ensured that the speckle image projected by the speckle projection device and the lasers with different wavelengths projected by the laser generator can cover the common area determined by CCD-1 and CCD-2;

[0048] In this embodiment, the speckle projection device is used to project laser speckles on the surface of the test piece to provide conditions for constructing the three-dimensional point cloud of the measured model, and the laser generator is used to emit lasers with wavelengths of 395nm and 620nm to achieve the excitation of TSP and PSP.

[0049] (2) Calibrate the binocular camera using the Zhang's calibration method to obtain the internal and external parameters of the left camera CCD-1 and the right camera CCD-2 and the relative pose relationship between the two;

[0050] (3) Turn on the speckle projection device in the test environment. The speckle projection device projects speckles onto the surface of the test piece to form speckle features. Then, use the CCD-1 and CCD-2 cameras after binocular calibration to capture the test piece, thereby obtaining img1 and img2; perform image matching on img1 and img2 using the stereo matching method according to the image speckle features, and perform three-dimensional reconstruction according to the binocular camera calibration parameters to obtain the three-dimensional topography of the test piece;

[0051] (4) Detect the temperature of the test environment, compare the environmental temperature with the temperature threshold. If the environmental temperature is less than or equal to the temperature threshold, enter the low-temperature domain measurement in step (5); otherwise, enter the high-temperature domain measurement in step (6); in this embodiment, the temperature threshold is generally set to 200°C;

[0052] (5) Low-temperature domain measurement;

[0053] (5.1) Coat the pressure-sensitive paint PSP and the temperature-sensitive paint TSP on the surface of the test piece;

[0054] (5.2) Trigger the laser generator to emit pulsed laser suitable for the measurement band of pressure-sensitive paint to excite the pressure-sensitive paint on the surface of the test piece to generate PSP fluorescence signal, synchronously trigger the CCD-1 camera to capture the fluorescence image of the surface of the test piece, denoted as img3, and then capture the fluorescence image img4 again after a delay time t; then, trigger the laser generator to emit pulsed laser suitable for the measurement band of temperature-sensitive paint to excite the temperature-sensitive paint on the surface of the test piece to generate TSP fluorescence signal, synchronously trigger the CCD-1 camera to capture the fluorescence image of the surface of the test piece, denoted as img5, and then capture the fluorescence image img6 again after a delay time t;

[0055] (5.3) Calculate the gated intensity integral ratio of the PSP fluorescence signal recorded in img3 and img4 pixel by pixel and the gated intensity integral ratio of the TSP fluorescence signal recorded in img5 and img6 where i represents the index number of the pixel point, respectively represent the gated intensity integrals of the i-th pixel point in images img3, img4, img5, and img6;

[0056] In this embodiment, taking image img3 as an example, the gated intensity integral of the i-th pixel point in the image can be expressed as:

[0057]

[0058] where G3(t) is a specific time-varying function, I i represents the luminescence intensity of the PSP recorded at the i-th pixel point in img3, and the luminescence intensity is determined by the gray value of the pixel point.

[0059] (5.4) Use the pressure calibration system to calibrate the sensitivity of the pressure-sensitive paint and the temperature-sensitive paint, and obtain the calibration curves of gated intensity integral ratio - pressure and gated intensity integral ratio - temperature;

[0060] In this embodiment, place the PSP and TSP samples in an independently pressure and temperature controlled calibration chamber, gradually adjust the pressure and temperature, record the fluorescence intensity response data under different conditions, and obtain the calibration curves of gated intensity integral ratio - pressure and gated intensity integral ratio - temperature;

[0061] (5.5) Use a quadratic curve to fit the ratio of the gated intensity integral values of TSP under the reference condition and the test condition in the radial and chordal directions of the test piece to obtain the fitting curve varying with the radial and chordal positions;

[0062] (5.6) According to the calibration curve in step (5.4) and the fitting curve in step (5.5), Remove the variation caused by temperature change in the middle to obtain the corrected PSP gating intensity integral ratio for each pixel point

[0063]

[0064] Among them, k(T) is the temperature sensitivity ratio between PSP and TSP;

[0065] (5.7), Establish the pressure value P at each pixel point i And the gating intensity integral ratio The relationship between them is:

[0066]

[0067] Calculate the true pressure value P at each pixel point according to the above relationship i , Obtain the two-dimensional pressure field distribution;

[0068]

[0069] Among them, A(T) and B(T) are calibration coefficients related to the temperature T, which can be obtained from the calibration process, and P ref Is the reference pressure for the calibration process;

[0070] (6), High-temperature domain measurement;

[0071] (6.1), Set the incoming flow parameters such as the air flow dynamic viscosity coefficient, Mach number, and angle of attack in the CFD simulation to simulate the test environment under real conditions, and then extract the surface pressure coefficient gradient curve of the test piece based on the CFD simulation, and dynamically allocate the number of pressure measurement points in the high-pressure gradient and low-pressure gradient regions according to the pressure coefficient gradient curve;

[0072] In this embodiment, the method for dynamically allocating the number of pressure measurement points is:

[0073] Find the minimum value and its corresponding chordwise position x on the pressure coefficient gradient curve i , And define the pressure coefficient gradient at the position x i As B i , Then set the number of pressure measurement points A at the position x i ;

[0074] After that, in order to obtain the number of pressure measurement points at other positions, through the pressure coefficient gradient B j At other chordwise positions x on the model surface j , According to int(B j / B i ) to determine the number of pressure measurement points M at these positions j, where int(*) is the rounding function; specifically, the number of measurement points M j can be expressed as follows:

[0075]

[0076] In this way, we can densely arrange pressure sensors in the high-pressure gradient area and sparsely arrange them in the low-pressure gradient area, optimize the layout of the sensor array, and reduce the influence of the pressure measurement accuracy of the pressure sensors at the measurement points.

[0077] (6.2) Arrange the same pressure sensors on the test piece according to the number of pressure measurement points determined by the simulation. Then, during the test, use CCD-1 to take the distribution image of the pressure sensors on the surface of the test piece, denoted as img7, and determine the pixel coordinate positions of each sensor in img7, and establish the mapping relationship between the pressure sensors and the pixel coordinates;

[0078] (6.3) Conduct a pressure test in the test environment, collect the pressure values on each sensor, and through the mapping relationship between the pressure sensors and the pixel coordinates, map the pressure values to img7 to obtain a discrete pressure distribution map, denoted as img8;

[0079] (6.4) In the two-dimensional image pixel coordinate system determined by img8, using the sensor projection points as known data points, construct a spatial variation function based on the Kriging interpolation algorithm, and generate a high-resolution two-dimensional pressure field distribution covering the entire image domain by solving the weight coefficients;

[0080] (7) Fuse the two-dimensional pressure field distribution with the three-dimensional shape point cloud reconstructed by binocular DIC through the pixel-level mapping relationship to generate a high-resolution three-dimensional pressure field under the full temperature range.

[0081] In this embodiment, since the two-dimensional pressure field distribution is constructed based on the CCD-1 image plane, each pixel position corresponds to a specific pressure value. At the same time, the three-dimensional point cloud in the generated three-dimensional shape of the test piece not only contains accurate spatial coordinate information, but also its projection position in the image is identified in pixels. Using this pixel-level correspondence relationship, the fitted two-dimensional pressure field can be mapped to the three-dimensional point cloud pixel by pixel, realizing the conversion of pressure information from the two-dimensional image domain to the three-dimensional physical space.

[0082] In summary, it can be seen that the present invention unifies the three-dimensional shape reconstruction framework through DIC technology, combines the temperature range adaptability advantages of different sensing modalities, solves problems such as large temperature sensitivity errors, dependence on experience for measuring point layout, and limited measurement in high-temperature environments in traditional methods, significantly improves the pressure field measurement accuracy and reliability of the cross-domain variable structure aircraft under complex working conditions in a wide temperature range, and provides an efficient technical support for its aerodynamic performance optimization and flow field analysis.

[0083] Although the above description of the illustrative embodiments of the present invention has been made to facilitate understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A method for measuring a three-dimensional pressure field in a wide temperature range in an extreme wind tunnel environment, characterized in that It includes the following steps: (1) Set up a binocular vision system; Install two high-resolution cameras CCD-1 and CCD-2 on a fixed instrument to form a binocular camera. Adjust the shooting angles of CCD-1 and CCD-2 to ensure that the fields of view of the two cameras completely cover the surface of the test piece and there is a common field of view range area. Install a speckle projection device and a laser generator on the fixed instrument between CCD-1 and CCD-2, and ensure that the speckle image projected by the speckle projection device and the lasers with different wavelengths projected by the laser generator can cover the common area determined by CCD-1 and CCD-2; (2) Calibrate the binocular camera using the Zhang's calibration method to obtain the internal and external parameters of the left camera CCD-1 and the right camera CCD-2 and the relative pose relationship between the two; (3) In the test environment, turn on the speckle projection device. The speckle projection device projects speckles onto the surface of the test piece to form speckle features. Then use the CCD-1 and CCD-2 cameras after binocular calibration to shoot the test piece to obtain img1 and img2. Perform image matching on img1 and img2 using the stereo matching method according to the image speckle features, and perform three-dimensional reconstruction according to the binocular camera calibration parameters to obtain the three-dimensional morphology of the test piece; (4) Detect the temperature of the test environment, compare the environmental temperature with the temperature threshold. If the environmental temperature is less than or equal to the temperature threshold, enter the low-temperature range measurement in step (5); otherwise, enter the high-temperature range measurement in step (6); (5) Low-temperature range measurement; (5.1) Coat the pressure-sensitive paint PSP and the temperature-sensitive paint TSP on the surface of the test piece; (5.2) Trigger the laser generator to emit pulsed laser in the measurement band suitable for the pressure-sensitive paint to excite the pressure-sensitive paint on the surface of the test piece to generate PSP fluorescence signal. Synchronously trigger the CCD-1 camera to shoot the fluorescence image of the surface of the test piece, denoted as img3, and then shoot the fluorescence image img4 again after a delay time t. Then, trigger the laser generator to emit pulsed laser in the measurement band suitable for the temperature-sensitive paint to excite the temperature-sensitive paint on the surface of the test piece to generate TSP fluorescence signal. Synchronously trigger the CCD-1 camera to shoot the fluorescence image of the surface of the test piece, denoted as img5, and then shoot the fluorescence image img6 again after a delay time t; (5.3) Calculate the gated intensity integral ratio of the PSP fluorescence signals recorded in img3 and img4 pixel by pixel and the gated intensity integral ratio of the TSP fluorescence signals recorded in img5 and img6 where i represents the index of the pixel number, respectively represent the gated intensity integrals of the i-th pixel in images img3, img4, img5, and img6; (5.4) Use the pressure calibration system to calibrate the sensitivity of the pressure-sensitive paint and the temperature-sensitive paint to obtain the calibration curves of gated intensity integral ratio - pressure and gated intensity integral ratio - temperature; (5.5) Use a quadratic curve in the radial and chordal directions of the test piece to fit the ratio of the integrated gating intensity of TSP under the reference condition to that under the test condition to obtain a fitted curve that varies with the radial and chordal positions; (5.6) According to the calibration curve in step (5.4) and the fitting curve in step (5.5), remove the variation caused by temperature change in to obtain the corrected PSP gated intensity integral ratio of each pixel point where k(T) is the temperature sensitivity ratio between PSP and TSP; (5.7) Establish the pressure value P at each pixel point i AND gate intensity integration ratio The relationship between them is as follows: Calculate the true pressure value P at each pixel point according to the above relationship i , and obtain the two-dimensional pressure field distribution; where A(T) and B(T) are calibration coefficients related to the temperature T, and P ref is the reference pressure for the calibration process; (6) High-temperature range measurement; (6.1) Simulate the test environment in the real situation in the CFD simulation, then extract the surface pressure coefficient gradient curve of the test piece based on the CFD simulation, and dynamically allocate the number of pressure measurement points in the high-pressure gradient and low-pressure gradient regions according to the pressure coefficient gradient curve; (6.2) Arrange the same pressure sensors on the test piece according to the number of pressure measurement points determined by the simulation. Then, during the test, use CCD-1 to capture the distribution image of the pressure sensors on the surface of the test piece, denoted as img7, and determine the pixel coordinate positions of each sensor in img7 to establish the mapping relationship between the pressure sensors and the pixel coordinates; (6.3) Conduct a pressure test in the test environment, collect the pressure values on each sensor, and map the pressure values to img7 through the mapping relationship between the pressure sensors and the pixel coordinates to obtain a discrete pressure distribution map, denoted as img8; (6.4) In the two-dimensional image pixel coordinate system determined by img8, using the sensor projection points as known data points, construct a spatial variation function based on the Kriging interpolation algorithm, and generate a high-resolution two-dimensional pressure field distribution covering the entire image domain by solving the weight coefficients; (7) Fuse the two-dimensional pressure field distribution with the three-dimensional shape point cloud reconstructed by binocular DIC through the pixel-level mapping relationship to generate a high-resolution three-dimensional pressure field in the full temperature range.

2. The three-dimensional pressure field measurement method in a wide temperature range in an extreme wind tunnel environment according to claim 1, wherein The dynamic allocation method of the number of pressure measurement points is as follows: Find the minimum value on the pressure coefficient gradient curve and its corresponding chordwise position x i , and define the pressure coefficient gradient at the chordwise position x i as B i , and then set the number of pressure measurement points A at x i ; Obtain the number of pressure measurement points at other positions on the surface of the test piece: Extract the pressure coefficient gradient B at the other chordwise position x on the surface of the test piece j at j , and then determine the number of pressure measurement points M at the chordwise position x according to the value of int(B j / B i ) j : j ​ where, int(*) is the rounding function.

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