A model deformation measurement method for high temperature hypersonic flow fields

Abstract

The present invention discloses a model deformation measurement method for high-temperature hypersonic flow fields, which relates to the field of wind tunnel experiments. The method utilizes a calibration plate and front-illuminated light imaging, does not require the setting of artificial marking points, and can directly obtain the test model boundary. The test model boundary is utilized to realize the positioning of the head of the simulation model, thereby realizing the displacement and deformation measurement of the simulation model. The method solves the pain point problem that the existing visual measurement method cannot be used in a high-temperature flow field without setting artificial marking points. The method can be used in a hypersonic flow field scene, and solves the shock wave interference problem of the existing schlieren measurement method.

Description

Technical Field

[0001] The invention relates to the field of wind tunnel experiments, and in particular to a model deformation measurement method for high-temperature hypersonic flow fields. Background Art

[0002] In wind tunnel experiments, the test model will deform or move its head under the action of aerodynamic loads. In normal temperature and low-speed wind tunnels, visual measurement methods are usually used to measure the posture and deformation of wind tunnel models. In the prior art, artificial marking points are usually pasted on the surface of the test model, and these artificial marking points are photographed by a camera, and the three-dimensional coordinates of the artificial marking points are calculated. The deformation of the test model is calculated based on these three-dimensional coordinates.

[0003] This method is difficult to use in high-temperature / hypersonic wind tunnels because the temperature of the wind tunnel is very high, reaching 1000°C, and the pasted artificial marking points are easily burned. In addition, in order to achieve the displacement measurement of the test model head, the schlieren measurement system is generally used. In the absence of shock waves, the model boundary image can be obtained. In the presence of laser, the head is covered by the shock wave and subsequent measurements cannot be performed. Summary of the invention

[0004] The purpose of the present invention is to measure the deformation of a test model in a hypersonic wind tunnel or a high-temperature wind tunnel, and to overcome the influence of shock wave interference.

[0005] To achieve the above object, the present invention provides a model deformation measurement method for high-temperature hypersonic flow fields, the method comprising:

[0006] Step 1: installing a test model in a wind tunnel, wherein the wind tunnel is a hypersonic wind tunnel or a high temperature wind tunnel;

[0007] Step 2: Install the light source and image acquisition device on the same side of the test model;

[0008] Step 3: defining a first measurement plane coordinate system of the test model based on a calibration plate;

[0009] Step 4: testing the test model in the wind tunnel, and using the image acquisition device to take a number of images in chronological order to obtain an image set;

[0010] Step 5: Select a reference image from the image set, select a preset point position to be measured from the reference image, and calculate first position coordinate information of the preset point position in the first measurement plane coordinate system according to the calibration result of the image acquisition device;

[0011] Step 6: Selecting a first image after the reference image in the image set, and finding the position of the preset point in the first image;

[0012] Step 7: Calculate the second position coordinate information of the preset point position in the first image in the first measurement plane coordinate system;

[0013] Step 8: Based on the first position coordinate information and the second position coordinate information, calculate and obtain the displacement of the preset point position, and obtain the deformation of the test model based on the displacement.

[0014] Among them, the principle of this method is: in order to solve the problems raised in the background technology, the present invention proposes a front light imaging method. Through front light illumination, using the prior knowledge that there is strong reflection on the surface of the test model, an image with clear model boundaries can be obtained, which can be used for model deformation measurement based on the model edge.

[0015] Front-light imaging: the camera and the light source are located on the same side, the light source projects strong light onto the surface of the object to be measured, the object to be measured reflects the light to the camera, and the camera receives the light from the surface of the object to be measured, so that the brightness of the object to be measured and the background can be separated, and then the image we obtain can be captured; compared with the schlieren imaging method: the light source is located on the back of the object to be measured, the camera is located in front of the object to be measured, and the light source and the camera are not located on the same side; therefore, after the light source passes through the flow field, it will be disturbed by the shock wave; on the contrary, front-light imaging, after being projected from this object, is directly reflected by the object to be measured, and the energy of the reflected light is stronger and is not affected by the shock wave; further: compared with the traditional method of pasting artificial marking points, this method uses a calibration plate, which does not require pasting artificial marking points on the surface of the object to be measured and is not affected by high-temperature airflow; therefore, on this basis, by obtaining a high-contrast target image and using the target's contour information, feature matching and positioning can be completed, and model displacement, deformation, posture and other measurements can be achieved.

[0016] Preferably, the method uses the visual measurement principle to obtain the conversion relationship between the spatial coordinates and the pixel coordinates in the image, and then calculates the first position coordinate information and the second position coordinate information based on the conversion relationship between the spatial coordinates and the pixel coordinates in the image.

[0017] Preferably, the conversion relationship between the spatial coordinates and the pixel coordinates in the image is:

[0018]

[0019] Among them, z c is the scale factor, u is the image horizontal coordinate, v is the image vertical coordinate, c x is the abscissa of the optical center, c y is the ordinate of the optical center, x w is the horizontal coordinate in the wind tunnel coordinate system, y w is the ordinate in the wind tunnel coordinate system, z wis the vertical coordinate in the wind tunnel coordinate system, M1 is the internal parameter of the image acquisition device, M2 is the external parameter of the image acquisition device, M is the projection matrix, R is the rotation matrix, T is the translation vector, and f u =f·s x and f v =f·s y They represent the equivalent pixel focal length of the image acquisition device in the u and v directions, f is the equivalent focal length, s x and y is the scale factor.

[0020] Preferably, the calibration plate comprises a plate body, and a plurality of calibration points are evenly distributed on the plate body. The plate body can be used in a hypersonic wind tunnel or a high temperature wind tunnel, and the coordinate system can be established and calibrated by using the distributed calibration points.

[0021] Preferably, in order to efficiently and accurately find the position of the preset point in the subsequent image, the method finds the position of the preset point in the first image by an image content matching method or an image shape matching method.

[0022] Preferably, the method calculates the corresponding displacement by the change of the coordinate information of the preset point position in the previous and next images. The method calculates the displacement of the preset point position in the following manner:

[0023] The first position coordinates are (X0, Y0), and the second position coordinates are (X t , Y t );

[0024]

[0025]

[0026]

[0027] Among them, D y is the displacement in the y direction in the wind tunnel coordinate system, D x is the displacement in the x direction in the wind tunnel coordinate system, D xy is the displacement in the x and y planes in the wind tunnel coordinate system.

[0028] Preferably, the method uses a direct linear transformation method, a RAC two-step method, or a Zhang Zhengyou calibration method to calibrate the image acquisition device.

[0029] Preferably, in order to eliminate image noise, after the image acquisition device acquires the image, the method uses an image processing method to process the image:

[0030] The image is denoised by median filtering, and the sub-pixel precision image edge extraction is performed on the denoised image. The extracted edge image is fitted to find the measurement target position of the test model.

[0031] Preferably, the method finds the preset point position image in the first image by the following image matching method: taking the measuring point as the center, setting a rectangle along the axis of the test model, selecting an image block from the reference image as a reference module based on the rectangle, and then searching for the optimal matching image based on the criterion adopted by the reference module in the image to be matched, which is the decentralized normalized cross-correlation criterion.

[0032] Among them, the criterion used is the decentralized normalized cross-correlation criterion - ZNCC criterion, which can better solve the problem of image brightness change. Therefore, even if the image brightness is dimmed due to water mist during the test, matching can be achieved. Under the ZNCC criterion, the optimal matching pixel has a large correlation coefficient.

[0033] Preferably, in order to realize the measurement of the bending deformation of the test model, a number of preset point positions distributed along the axial direction of the test model are selected from the reference image, the first angle information of the line connecting two adjacent preset point positions is calculated in the reference image, the second angle information of the line connecting two adjacent preset point positions is calculated in the first image, the corresponding line angle change is calculated based on the second angle information and the corresponding first angle information, and the bending deformation of the test model is obtained based on the line angle change.

[0034] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0035] Compared with the prior art, the present invention does not need to set artificial marking points, can directly obtain the test model boundary, use the test model boundary to realize the test model head positioning, and then realize the test model displacement and deformation measurement; it solves the pain point problem that the existing visual measurement method cannot be used in high temperature flow field without setting artificial marking points;

[0036] The present invention can be used in hypersonic flow field scenarios to solve the shock wave interference problem existing in existing schlieren measurement methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation on the embodiments of the present invention;

[0038] Figure 1 It is a flow chart of a model deformation measurement method for high temperature hypersonic flow field;

[0039] Figure 2 It is a schematic diagram of the principle of visual measurement in the present invention;

[0040] Figure 3 It is a structural schematic diagram of the calibration plate in the present invention;

[0041] Figure 4 It is a schematic diagram of the calibration plate and the test model measuring side being placed parallel to each other in the present invention;

[0042] Figure 5 is a schematic diagram of the extracted test model boundary results;

[0043] Figure 6 Schematic diagram of the angle calculation method for the line connecting two points AB. DETAILED DESCRIPTION

[0044] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those within the scope of this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0046] Embodiment 1

[0047] Please refer to Figure 1 , Figure 1 The present invention is a flow chart of a method for measuring deformation of a model in a high-temperature hypersonic flow field. Embodiment 1 of the present invention provides a method for measuring deformation of a model in a high-temperature hypersonic flow field. The method includes:

[0048] Step 1: installing a test model in a wind tunnel, wherein the wind tunnel is a hypersonic wind tunnel or a high temperature wind tunnel;

[0049] Step 2: Install the light source and image acquisition device on the same side of the test model;

[0050] Step 3: defining a first measurement plane coordinate system of the test model based on a calibration plate;

[0051] Step 4: testing the test model in the wind tunnel, and using the image acquisition device to take a number of images in chronological order to obtain an image set;

[0052] Step 5: Select a reference image from the image set, select a preset point position to be measured from the reference image, and calculate first position coordinate information of the preset point position in the first measurement plane coordinate system according to the calibration result of the image acquisition device;

[0053] Step 6: Selecting a first image after the reference image in the image set, and finding the position of the preset point in the first image;

[0054] Step 7: Calculate the second position coordinate information of the preset point position in the first image in the first measurement plane coordinate system;

[0055] Step 8: Based on the first position coordinate information and the second position coordinate information, calculate and obtain the displacement of the preset point position, and obtain the deformation of the test model based on the displacement.

[0056] Among them, the displacement amounts in different directions and positions reflect the deformation amounts of the test model at different positions or directions. The corresponding deformation amounts can be calculated according to the specific displacement amounts. The specific position or direction to calculate the displacement amount can be designed according to the specific deformation amount calculation requirements, and the present invention does not make specific limitations.

[0057] Among them, in the embodiment of the present invention, the light source can be a corresponding lighting device or apparatus, such as an LED lighting lamp, etc., and the image acquisition device can be a video camera or a camera, etc., and the present invention does not make specific limitations.

[0058] Among them, a hypersonic wind tunnel refers to a wind tunnel with a flow field speed exceeding 5 Ma, and a high-temperature wind tunnel refers to a wind tunnel with a flow field speed exceeding normal temperature.

[0059] In the embodiment of the present invention, the test model is tested in the wind tunnel. The test model can be a model of any shape, which is not specifically limited in the present invention.

[0060] Among them, the basic principle of measuring the deformation of the test model in the present invention is:

[0061] Visual measurement is to measure the 3D or 2D spatial position and displacement of the object to be measured by visual imaging method according to the camera pinhole imaging model. In the present invention, the visual measurement method is used to realize the deformation measurement of the model in the 2D plane.

[0062] The following is a brief introduction to the principles of visual measurement. Figure 2 As shown in the figure, a point P in the physical space is imaged as P' in the camera imaging plane. Then point P and the corresponding point P' in the image need to undergo three coordinate transformations:

[0063] (1) Conversion from world coordinates to camera coordinates

[0064] The world coordinate system is used as a spatial reference system. It is generally selected to be easy to describe the spatial geometric dimensions of an object. The world coordinate system is marked as O w X w Y w Z w , where Ow is the origin, X w , Y w , Z w are the three axes of the coordinate system. The world coordinates of any point in space are marked as (x w ,y w ,z w ), where x w is the x coordinate of the world coordinate, y w is the y coordinate of the world coordinate system, z w is the z coordinate of the world coordinate. The camera coordinate system is based on the optical center of the camera lens O c is the coordinate origin, X c O c Y c plane is parallel to the image plane, Z c The axis coincides with the optical axis. The spatial point can be expressed in camera coordinates as:

[0065]

[0066] Among them, X c is the x coordinate in the camera coordinate system, y c is the y coordinate in the camera coordinate system, z c is the z coordinate in the camera coordinate system, R is the rotation matrix, and T is the translation vector.

[0067] ⑵ Transformation from camera coordinate system to image physical coordinate system

[0068] The center point of the camera coordinate system (x c ,y c ,z c ) is projected in image coordinates as (x, y), and the perspective transformation of the camera projection is:

[0069]

[0070] f is the equivalent focal length, that is, the distance between the camera plane and the object of interest. The above formula is converted into the following matrix relationship:

[0071]

[0072] ⑶Conversion of image physical coordinates to computer pixel coordinate system

[0073] The unit of image physical coordinates is usually mm. The origin of the coordinates is also called the image principal point coordinates, which is usually at the center of the image. x ,c y ), while computer images are often expressed in pixels. The origin of the coordinates is usually at the upper left corner of the image. The pixel coordinates represent the row and column positions of the image points, recorded as (u, v). The conversion relationship between image physical coordinates and pixel coordinates is:

[0074]

[0075] (s x ,s y ) are scale factors, representing the number of pixels per unit distance in the x and y directions in the image coordinates.

[0076] Combining the above coordinate transformations, we can get the direct conversion relationship between spatial coordinates and pixel coordinates:

[0077]

[0078] Among them, z c is the scale factor, u is the image horizontal coordinate, v is the image vertical coordinate, c x is the abscissa of the optical center, c y is the ordinate of the optical center, x w is the horizontal coordinate in the wind tunnel coordinate system, y w is the ordinate in the wind tunnel coordinate system, z w is the vertical coordinate in the wind tunnel coordinate system, M1 is the internal parameter of the image acquisition device, M2 is the external parameter of the image acquisition device, M is the projection matrix, R is the rotation matrix, T is the translation vector, and f u =f·s x and f v =f·s y They represent the equivalent pixel focal length of the image acquisition device in the u and v directions, f is the equivalent focal length, s x and y is the scale factor.

[0079] The above is a linear imaging model under an ideal state. In practice, the optical imaging system will inevitably bring about corresponding optical distortion due to the errors in lens design and assembly, mainly radial distortion, eccentric distortion and thin prism distortion. In general, radial distortion and eccentric distortion are considered, and the radial distortion model is adopted in the present invention.

[0080] Therefore, through the above three coordinate transformations, the connection between a point P in space and a point P' in the image is established. As can be seen from Formula 5, the three-dimensional coordinates of the space cannot be determined using only one point in the image, because in order to obtain the real three-dimensional coordinates, two cameras are generally required to provide two sets of image coordinates, and then the three-dimensional coordinates in the world coordinate system are estimated according to the least squares. For the application of the present invention, it is assumed that the wind tunnel model is displaced in the observation plane, that is, the three-dimensional coordinates of the space (x w ,y w ,z w ), z w is a known term and a constant, so the image coordinates (u, v) can be used to measure the displacement of the object under test in a two-dimensional plane.

[0081] Model deformation measurement principle:

[0082] Will Figure 3 The calibration plate shown, Figure 3 1 is the body of the calibration plate, 2 is the marking point, where the calibration plate can be made of transparent glass, and the calibration point can be a black circle, which can be added to the calibration plate by painting. The marking plate is used to define the world coordinate system (x w ,y w ,z w ). When the world coordinate system is defined based on the calibration plate, the center point of the marker plate can be used as the origin. For two-dimensional deformation measurement, set the measurement object z w =0, the model measurement coordinate system (X, Y) is defined accordingly.

[0083] To reduce the interference of perspective distortion, such as Figure 4 As shown, Figure 4 Where a is the distance between the marking points. Before the test, the calibration plate is placed parallel to the measurement side of the test model. The camera tries to shoot the current calibration plate image straight on, and the model measurement plane coordinate system (X, Y) is defined by the calibration plate image.

[0084] The basic method for measuring the deformation of the test model is:

[0085] Select the position of the point to be measured in the reference frame (such as the first frame), such as the center of the model head, and calculate the position (X0, Y0) of the measurement point in the defined measurement plane according to the camera calibration result and the equation (5);

[0086] Then, the position of the selected measurement point is found in the subsequent frames through image processing algorithms, such as image content matching, image shape matching and other methods;

[0087] According to the camera calibration results and equation (5), the position of the measurement point in the defined measurement plane (X t , Y t );

[0088] According to the position results, calculate the displacement on the time axis:

[0089]

[0090]

[0091]

[0092] Among them, D y is the displacement in the y direction in the wind tunnel coordinate system, D x is the displacement in the x direction in the wind tunnel coordinate system, D xyis the displacement in the x and y planes in the wind tunnel coordinate system.

[0093] Vision measurement system calibration:

[0094] Camera Calibration

[0095] Camera calibration uses a series of reference points with known spatial positions to determine the internal and external parameters in the camera projection equation. Common camera calibration methods include direct linear transformation method, RAC two-step method, and Zhang Zhengyou calibration method. Among them, Zhang Zhengyou calibration method uses the correspondence between the world coordinates of feature points on the calibration plate at multiple different viewing angles and the image coordinates of the image points on its image to calibrate the camera, which has the advantages of simple use and high calibration accuracy. Therefore, the present invention uses the Zhang Zhengyou calibration method to perform camera calibration, and performs nonlinear distortion correction on the images taken by the camera.

[0096] The calibration accuracy analysis can be used to evaluate the calibration accuracy of the measurement system. Multiple calibration plate images can be used to perform test calibration accuracy evaluation. The specific test evaluation method is not specifically limited in the embodiment of the present invention.

[0097] in, Figure 3 The calibration plate image is collected. The calibration plate is 10*10cm in size and contains 7*7, a total of 49 circle center mark points. The distance between the mark points is 6.25mm. The calibration plate processing accuracy is 1um. The size of the calibration plate and the number and spacing of the circle center mark points can be adjusted according to actual needs, and the embodiment of the present invention does not specifically limit it.

[0098] Test model deformation measurement:

[0099] The test model head center displacement measurement of the present invention uses the test model head center as a reference to measure the displacement of the model head.

[0100] The image processing method used is: first, median filtering is performed on the image to eliminate image noise, then sub-pixel precision image edge extraction is performed, and then the center position of the head is found through circular fitting, thereby realizing head center tracking and measurement.

[0101] The sub-pixel edge extraction method used in the present invention is used to determine the model boundary. Figure 5 It is the extracted test model boundary result. Sub-pixel edge positioning can be achieved by fitting functions to image pixels at the edge, including Gaussian, polynomial, orthogonal basis fitting, etc., with a general accuracy better than 0.1 pixel.

[0102] After obtaining the model edge image, the center of the head circle can be obtained by performing least squares circular fitting on the edge, and then the image coordinates of the measurement point can be obtained. Then, based on the calibration results, the position of the measurement point in the model measurement plane can be calculated.

[0103] In the present invention, the preset point positions can be multiple, such as 5, and the axial displacement of the test model is measured at 5 points. 5 measurement points are selected along the axial direction of the model. The image matching method is: taking the measurement point as the center, along the axial direction of the model, a rectangle is set, and the image block is selected as the reference module. Then, the template image is used to search for the best matching image in the image to be matched. The matching criterion used is: ZNCC (de-centered normalized cross-correlation criterion):

[0104]

[0105] Among them, C is the correlation coefficient metric, I(u,v) is the pixel value of the template image, I'(u,v) is the pixel value in the search area of ​​the image to be matched, and I m is the template image mean, I' m The pixel values ​​in the search area of ​​the image to be matched can be well solved by using the ZNCC model, so the image brightness change problem can be well solved even when the image brightness is dimmed due to water mist during the test. Under the ZNCC criterion, the optimal matching pixel has a large correlation coefficient.

[0106] The line connecting the five measurement points is used to estimate the angle change between the two points. The angle calculation method of the line connecting the two points AB is as follows: Figure 6 As shown, calculate the angle between line AB and the horizontal axis. The counterclockwise direction is positive and the unit is radians.

[0107] Data denoising

[0108] Since the available texture information on the surface of the photographed model is small, mismatching is inevitable during the matching and measurement process, resulting in erroneous measurement results. Therefore, anomaly detection is first performed on the final calculation results to eliminate erroneous matching calculation results, and then noise is eliminated through median filtering.

[0109] The present invention basically realizes the displacement measurement of the test model in the special wind tunnel by comprehensively selecting and optimizing the image processing algorithm.

[0110] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0111] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A model deformation measurement method for high temperature hypersonic flow field, characterized in that: The method comprises: Step 1: installing a test model in a wind tunnel, wherein the wind tunnel is a hypersonic wind tunnel or a high temperature wind tunnel; Step 2: Install the light source and image acquisition device on the same side of the test model; Step 3: defining a first measurement plane coordinate system of the test model based on a calibration plate; Step 4: testing the test model in the wind tunnel, and using the image acquisition device to take a number of images in chronological order to obtain an image set; Step 5: Select a reference image from the image set, select a preset point position to be measured from the reference image, and calculate first position coordinate information of the preset point position in the first measurement plane coordinate system according to the calibration result of the image acquisition device; Step 6: Selecting a first image after the reference image in the image set, and finding the position of the preset point in the first image; Step 7: Calculate the second position coordinate information of the preset point position in the first image in the first measurement plane coordinate system; Step 8: Based on the first position coordinate information and the second position coordinate information, calculate and obtain the displacement of the preset point position, and obtain the deformation of the test model based on the displacement; The method calculates the first position coordinate information and the second position coordinate information based on the conversion relationship between the spatial coordinates and the pixel coordinates in the image; The conversion relationship between spatial coordinates and pixel coordinates in the image is: Among them, z c is the scale factor, u is the image horizontal coordinate, v is the image vertical coordinate, c x is the abscissa of the optical center, c y is the ordinate of the optical center, x w is the horizontal coordinate in the wind tunnel coordinate system, y w is the ordinate in the wind tunnel coordinate system, z w is the vertical coordinate in the wind tunnel coordinate system, M1 is the internal parameter of the image acquisition device, M2 is the external parameter of the image acquisition device, M is the projection matrix, R is the rotation matrix, T is the translation vector, and f u =f·s x and f v =f·s y They represent the equivalent pixel focal length of the image acquisition device in the u and v directions, f is the equivalent focal length, s x and y is the scale factor; The calibration plate comprises a plate body, and a plurality of calibration points are evenly distributed on the plate body; The method finds the preset point position in the first image by an image content matching method or an image shape matching method; The method finds the preset point position image in the first image by the following image matching method: taking the measuring point as the center, setting a rectangle along the axial direction of the test model, selecting an image block from the reference image as a reference module based on the rectangle, and then searching for the best matching image based on the criterion adopted by the reference module in the image to be matched, which is the decentralized normalized cross-correlation criterion.

2. The model deformation measurement method for high temperature hypersonic flow field according to claim 1 is characterized in that: The method calculates the displacement of the preset point position in the following manner: The first position coordinates are (X0, Y0), and the second position coordinates are (X t , Y t ); Among them, D y is the displacement in the y direction in the wind tunnel coordinate system, D x is the displacement in the x direction in the wind tunnel coordinate system, D xy is the displacement in the x and y planes in the wind tunnel coordinate system.

3. The model deformation measurement method for high temperature hypersonic flow field according to claim 1, characterized in that: The method adopts direct linear transformation method or RAC two-step method or Zhang Zhengyou calibration method to calibrate the image acquisition device.

4. The model deformation measurement method for high temperature hypersonic flow field according to claim 1, characterized in that: After the image acquisition device acquires the image, the method processes the image using an image processing method: The image is denoised by median filtering, and the sub-pixel precision image edge extraction is performed on the denoised image. The extracted edge image is fitted to find the measurement target position of the test model.

5. The model deformation measurement method for high temperature hypersonic flow field according to claim 1, characterized in that: A number of preset point positions distributed along the axial direction of the test model are selected from the reference image, and the first angle information of the line connecting two adjacent preset point positions is calculated in the reference image. The second angle information of the line connecting two adjacent preset point positions is calculated in the first image. The corresponding line angle change is calculated based on the second angle information and the corresponding first angle information, and the bending deformation of the test model is obtained based on the line angle change.

Images