Elastic deformation test system and elastic effect correction method of continuous wind tunnel model

Abstract

The invention discloses an elastic deformation test system and an elastic effect correction method of a continuous wind tunnel model, and belongs to the technical field of wind tunnel model test. In order to accurately simulate the influence on aerodynamic force after deformation, a first image acquisition device is fixed in a first air-cooled pressure-stabilizing cabin through a first fixed connection block, a second image acquisition device is fixed in a second air-cooled pressure-stabilizing cabin through a second fixed connection block, and a plurality of light sources are mounted on the side wall of a wind tunnel test section; the first air-cooling pressure-stabilizing cabin and the second air-cooling pressure-stabilizing cabin are fixedly mounted on the upper surface of the wind tunnel test section; before an elastic deformation test of the continuous wind tunnel model, the wind tunnel shafting calibration device is placed in a wind tunnel test section to carry out wind tunnel shafting calibration, and then the wind tunnel shafting calibration device is replaced with a to-be-tested model to carry out the elastic deformation test of the continuous wind tunnel model; a checkerboard calibration plate is embedded in a table top of the wind tunnel shafting calibration device, a first angle measuring instrument and a second angle measuring instrument are placed on the table top, and a supporting rod is installed on the side surface of the table top. According to the invention, the matching precision is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind tunnel model testing, and particularly relates to an elastic deformation testing system and an elastic effect correction method for a continuous wind tunnel model. Background Art

[0002] In modern fluid mechanics research, wind tunnel tests are a key means for analyzing and optimizing aerodynamic performance. Especially for the research of complex flow fields and deformable objects, the accuracy of wind tunnel models is crucial. However, the models used in traditional wind tunnel tests usually assume that the object is a rigid structure, ignoring the elastic deformation effect that the model may produce under the action of airflow. This assumption may not be accurate enough in some high-speed, high-pressure or highly complex flow fields, resulting in a large deviation between the calculated results and the actual situation. Therefore, how to accurately simulate the elastic effect of an object after being affected by airflow in a wind tunnel test has become an urgent problem to be solved in the field of fluid mechanics.

[0003] With the continuous development of computational fluid dynamics (CFD) technology, combining numerical simulation and physical experiments has become an important direction in modern fluid mechanics research. In the process of solving large-scale deformation, non-linear aerodynamic characteristics, and high-precision models, rigid models often cannot truly reflect the aerodynamic characteristics and actual performance of objects. Therefore, researching and developing effective elastic effect correction methods is of great practical significance for improving the accuracy of wind tunnel experiments and numerical simulation results.

[0004] When performing elastic effect correction, the synchronous measurement of attitude and deformation is crucial and requires high precision. In order to accurately capture the aerodynamic response of the model during the deformation process in the wind tunnel, it is necessary to synchronously measure the attitude change and deformation state of the model in real time. Due to the large range of model attitude changes, some marker points may be invisible or blocked at specific attitudes. As the model undergoes large attitude changes in the wind tunnel, some marker points may deviate from the field of view or cannot be captured by the camera due to geometric position changes, increasing the difficulty of marker point matching, thereby affecting accurate attitude matching and elastic effect correction.

[0005] To ensure the accuracy of elastic correction, the layout strategy of wing marker points becomes a key challenge. Since interpolation processing is required later, if the marker points are not arranged reasonably, it may lead to a decrease in interpolation accuracy, thereby affecting the accuracy and calculation efficiency of the correction results. Summary of the Invention

[0006] The problem to be solved by the present invention is to accurately simulate the influence on aerodynamic force after deformation, and a continuous wind tunnel model elastic deformation testing system and an elastic effect correction method are proposed.

[0007] To achieve the above object, the present invention is realized through the following technical solutions: A flexible deformation test system for a continuous wind tunnel model, comprising a first image acquisition device, a second image acquisition device, a first air-cooled pressure stabilizing chamber, a second air-cooled pressure stabilizing chamber, a first fixing block, a second fixing block and a light source; The first image acquisition device is fixed in the first air-cooled pressure stabilizing chamber through the first fixing block, the second image acquisition device is fixed in the second air-cooled pressure stabilizing chamber through the second fixing block, and a plurality of light sources are installed on the side wall of the wind tunnel test section; the first air-cooled pressure stabilizing chamber and the second air-cooled pressure stabilizing chamber are fixedly installed on the upper surface of the wind tunnel test section; Before the flexible deformation test of the continuous wind tunnel model, place the wind tunnel axis calibration device in the wind tunnel test section for wind tunnel axis calibration, and then replace the wind tunnel axis calibration device with the model to be tested for the flexible deformation test of the continuous wind tunnel model; The wind tunnel axis calibration device includes a support rod, a first angle measuring instrument, a second angle measuring instrument, a checkerboard calibration plate and a tabletop. The checkerboard calibration plate is embedded in the tabletop. The first angle measuring instrument and the second angle measuring instrument are respectively placed in the horizontal direction and the vertical direction on the tabletop. A support rod is installed on the side surface of the tabletop, and the wind tunnel axis calibration device is moved to multiple positions of the model to be tested during the wind tunnel test through the support rod.

[0008] Further, the tabletop of the wind tunnel axis calibration device is connected to the support rod through a flange.

[0009] Further, the first image acquisition device includes a camera and a lens, the second image acquisition device includes a camera and a lens, and when the brightness of the marking point excites a light source in a specific band, an optical filter that selectively transmits the excitation band and effectively filters out light of other bands is configured in front of the lens.

[0010] A flexible effect correction method for a continuous wind tunnel model, implemented relying on a flexible deformation test system for a continuous wind tunnel model, includes the following steps: S1. Arrange the flexible deformation test system for the continuous wind tunnel model described above; S2. Use the wind tunnel axis calibration device to calibrate the flexible deformation test system for the continuous wind tunnel model, including parameter calibration of the camera and wind tunnel axis calibration; S3. Arrange marking points on the model to be tested, arrange marking points on the fuselage of the model to be tested for attitude identification, and arrange marking points on the wing part of the model to be tested for identifying the flexible deformation of the wing; S4. Use the first image acquisition device and the second image acquisition device to perform image acquisition, and acquire the reference image and test image of the model to be tested; S5. Perform marking point recognition and matching on the reference image and test image of the model to be tested collected in step S4; S6. Calculate the deformation and current attitude of the wing of the model to be tested under different working conditions; S7. Correct the influence of the elastic deformation of the model under test.

[0011] Furthermore, the specific implementation method of step S2 includes the following steps: S2.1. By adjusting the attitude of the support rod, place the tabletop at multiple positions of the model under test during the wind tunnel test. Collect images of the checkerboard calibration board through the first image acquisition device and the second image acquisition device, and solve the internal and external parameters of the camera based on the Zhang's calibration method. S2.2. Wind tunnel axis system calibration: By adjusting the angle of the support rod of the wind tunnel mechanism, collect images of the calibration board by the first image acquisition device and the second image acquisition device at different pitch angles. Based on corner detection, obtain the corner image coordinates of the collected calibration board images. Combining with the internal camera parameters and external parameters to obtain the three-dimensional coordinates of the corners of the checkerboard calibration board at different pitch angles. Calculate the rotation relationship between the three-dimensional coordinates of the checkerboard corners at adjacent two pitch angles through the Root-Rao Kabsch algorithm. Convert the rotation relationship into an axis vector through the Rodriguez transformation, and average it to obtain the pitch axis vector of the model under test in the wind tunnel axis system. Normalize it so that the modulus of the vector is 1 to obtain the final pitch axis vector ; then calculate the yaw axis vector and the roll axis vector ; obtain the wind tunnel axis system transformation matrix in the camera coordinate system .

[0012] Furthermore, the specific implementation method of step S3 includes the following steps: S3.1. Arrange marker points on the fuselage of the model under test, adopting an irregular distribution strategy to avoid multiple marker points collinear on the same epipolar line, so as to ensure that the matching of the marker points can be effectively realized through epipolar line constraint at different viewing angles; S3.2. Arrange marker points on the wing part of the model under test, adopting a regular distribution strategy. Arrange marker points in the wing root, leading edge and trailing edge regions of the wing. The marker points are ensured to be evenly distributed in the spanwise and chordwise directions to identify the elastic deformation of the wing.

[0013] Furthermore, the specific implementation method of step S4 includes the following steps: S4.1. Collect the reference images of the model under test: Collect the image sequences of all working conditions without wind. The image sequences collected by the first image acquisition device without wind and the image sequences collected by the second image acquisition device without wind , where m is the number of working conditions, is the image captured by the first image acquisition device under the m-th working condition without wind, is the image captured by the second image acquisition device under the m-th working condition without wind, and record the attitude information sequence without wind and the image captured by the first image acquisition device when the attitude of the model to be measured is 0 without wind and the image captured by the second image acquisition device , where is the attitude information under the m-th working condition without wind; S4.2. Collect the test images of the model to be measured: Collect the image sequences of all working conditions during the test. The image sequence captured by the first image acquisition device during the test is , and the image sequence captured by the second image acquisition device during the test , n is the number of working conditions during the test, and record the attitude information sequence during the test , set m greater than or equal to n, where is the image captured by the first image acquisition device under the n-th working condition during the test, is the image captured by the second image acquisition device under the n-th working condition during the test, is the attitude information under the n-th working condition during the test.

[0014] Furthermore, the specific implementation method of step S5 includes the following steps: S5.1. Identify and match the same-name marked points in the images captured by the first image acquisition device and the second image acquisition device, including fuselage marked point matching and wing marked point matching; S5.1.1. The fuselage marked points are matched through epipolar constraint to obtain the sequence of matched fuselage marked points without wind; S5.1.2. The wing marked points are mainly matched through image correlation to obtain the sequence of matched wing marked points without wind , where l is the number of marked points on the wing, is the image coordinate of the l-th marked point on the wing in the image captured by the first image acquisition device, is the image coordinate of the l-th marked point on the wing in the image captured by the second image acquisition device; S5.1.3. Based on the internal and external camera parameters obtained in step S2 combined with , through triangulation, reconstruct the three-dimensional coordinates of the matched fuselage marked points without wind and the three-dimensional coordinates of the matched wing marked points without wind ; S5.1.4. Based on the wind tunnel axis transformation matrix obtained in S2 , obtain the sequence of three-dimensional coordinates of the fuselage in the wind tunnel coordinate system without wind The three-dimensional coordinate sequences of the wing marker points in the wind tunnel coordinate system when there is no wind ; S5.2. Perform the matching of the marker points in all working conditions in the images collected by the first image acquisition device and the second image acquisition device with the marker points when the attitude is 0, including the matching of the fuselage marker points and the wing marker points; S5.2.1. For the marker points on the fuselage, use the three-dimensional point cloud matching method based on distance matching and singular value decomposition to obtain the matching result sequence of the marker points on the fuselage under any test working condition and the marker points when the attitude is 0 ; S5.2.2. The wing marker points are matched for two-dimensional points according to image correlation and then converted into three-dimensional coordinates in the wind tunnel coordinate system to obtain the wing marker points on the wing under any test working condition and the marker points when the attitude is 0, as well as the marker point matching sequence under the corresponding working condition when there is no wind .

[0015] Furthermore, the specific implementation method of step S6 includes the following steps: S6.1. For the h-th working condition, h , calculate the attitude of the wing of the model to be measured. Based on the rigid body assumption, the obtained expression is: ; where, is and the rotation matrix of the transformation between, is and the translation vector of the transformation between; Solve and by using the calculation of the generalized inverse matrix or the singular value decomposition method, and the expression is: ; ; where, - correspond to the elements of the first row and first column, second row and first column, third row and first column, first row and second column, second row and second column, third row and second column, first row and third column, second row and third column, and third row and third column of the rotation matrix respectively, - represent the first, second, and third components of the translation vector; Convert to the pitch angle , yaw angle , roll angle , , , ; Then obtain the attitude sequences under all test conditions ; S6.2. For the h-th condition, h , calculate the deformation of the wing of the model to be measured; For , calculate to rotation matrix and translation matrix, then the three-dimensional coordinates of the wing marker points in the h-th condition without wind under 0 attitude after registration are + , and the three-dimensional coordinates of the wing marker points in the h-th condition during the test are + , then the deformation amount of the marker points in the model coordinate system is - ;

[0016] Then obtain the wing deformations under all conditions .

[0017] Furthermore, the specific implementation method of step S7 includes the following steps: S7.1. Aerodynamic force calculation of the original rigid model: Use PointWise software to generate the unstructured hybrid grid of the model to be measured before deformation, import the grid into the CFD solver, based on input the attitude information of the model to be measured, and set the oncoming flow conditions, and then obtain the aerodynamic force coefficients such as lift and drag of the model to be measured before deformation after solving the flow field; S7.2. Select interpolation points on the surface grid of the model to be measured, and based on , interpolate to obtain the surface grid of the deformed model to be measured, and then use the grid deformation program to automatically generate the grid of the deformed model; S7.3. Calculate the aerodynamic force of the deformed model to be measured based on the CFD solver, realize the correction of the influence of elastic deformation, and compare it with the aerodynamic force before deformation to obtain the influence amount of elastic deformation on the aerodynamic force.

[0018] Advantages of the present invention:

[0019] A method for correcting the elastic effect of a continuous wind tunnel model of the present invention realizes real-time high-precision measurement of model deformation by building a deformation measurement system suitable for continuous wind tunnel tests and combining advanced devices such as high-speed cameras, air-cooled pressure stabilizing cabins, and light sources. To ensure the accuracy of measurement data, a marker point layout strategy is specifically designed to optimize the geometric distribution during data acquisition. This method accurately registers images from different perspectives or different working conditions, significantly improving the accuracy of image correlation calculations. During the marker point matching process, a three-dimensional point cloud optimization algorithm based on distance matching and singular value decomposition (SVD) is adopted to ensure the accurate matching of marker points in different postures, thereby realizing synchronous high-precision measurement of posture and deformation.

[0020] A method for correcting the elastic effect of a continuous wind tunnel model of the present invention further updates and corrects the aerodynamic grid through precise measurement results, successfully realizing the precise correction of the elastic effect of the model, thereby providing a more reliable basis for aerodynamic characteristics and optimization design for wind tunnel test data. Brief Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of an elastic deformation test system for a continuous wind tunnel model of the present invention;

[0022] Figure 2 It is a schematic diagram of a wind tunnel axis calibration device of the present invention;

[0023] Figure 3 It is a flowchart of a method for correcting the elastic effect of a continuous wind tunnel model of the present invention. Detailed Description of the Specific Embodiment

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only a part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention usually described and shown in the drawings here can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0025] Therefore, the detailed description of the specific embodiments of the present invention provided in the accompanying drawings below is not intended to limit the scope of the claimed present invention, but only represents the selected specific embodiments of the present invention. All other specific embodiments obtained by those skilled in the art based on the specific embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0026] To further understand the content, features and effects of the present invention, the following specific embodiments are exemplified and described in detail in conjunction with the attached Figure 1 - Attachment Figure 3 as follows:

[0027] Embodiment 1: An elastic deformation test system for a continuous wind tunnel model, comprising a first image acquisition device 1, a second image acquisition device 2, a first air-cooled pressure stabilizing chamber 3, a second air-cooled pressure stabilizing chamber 4, a first fixing block 5, a second fixing block 6 and a light source 7; The first image acquisition device 1 is fixed in the first air-cooled pressure stabilizing chamber 3 through the first fixing block 5, the second image acquisition device 2 is fixed in the second air-cooled pressure stabilizing chamber 4 through the second fixing block 6, and a plurality of light sources 7 are installed on the side wall of the wind tunnel test section 9; the first air-cooled pressure stabilizing chamber 3 and the second air-cooled pressure stabilizing chamber 4 are fixedly installed on the upper surface of the wind tunnel test section 9; Before the elastic deformation test of the continuous wind tunnel model, the wind tunnel axis calibration device is placed in the wind tunnel test section 9 for wind tunnel axis calibration, and then the wind tunnel axis calibration device is replaced with the model 8 to be tested for the elastic deformation test of the continuous wind tunnel model; The wind tunnel axis calibration device comprises a support rod 10, a first angle measuring instrument 11, a second angle measuring instrument 12, a checkerboard calibration plate 13 and a table top 14. The checkerboard calibration plate 13 is embedded in the table top 14. The first angle measuring instrument 11 and the second angle measuring instrument 12 are respectively placed in the horizontal and vertical directions on the table top 14. A support rod 10 is installed on the side surface of the table top 14, and the wind tunnel axis calibration device is moved to multiple positions of the model 8 to be tested during the wind tunnel test through the support rod 10.

[0028] Further, the table top 14 of the wind tunnel axis calibration device is connected to the support rod 10 through a flange.

[0029] Further, the first image acquisition device 1 comprises a camera and a lens, and the second image acquisition device 2 comprises a camera and a lens. When the brightness of the marking point excites a light source in a specific band, an optical filter that selectively transmits the excitation band and effectively filters out light of other bands is configured in front of the lens.

[0030] Further, if the first image acquisition device 1 and the second image acquisition device 2 need to identify the marking point excited by a specific wavelength, the image acquisition device also needs to install a specific optical filter in front of the lens, which only allows the excitation light source to pass through and filters out other ambient light sources. If only conventional marking points are to be identified, there is no need to install a filter in front of the lens.

[0031] Furthermore, an air-cooled pressure stabilizing chamber is used to maintain a constant air pressure in the internal space during the continuous evacuation and negative pressure boosting of the wind tunnel, ensuring air flow through the air inlet and outlet, enabling the image acquisition device to operate under normal temperature and pressure and dissipate heat properly. The air-cooled pressure stabilizing chamber is fixedly connected to the wind tunnel test section by welding or bolt connection, etc.

[0032] Furthermore, the area of the checkerboard calibration plate is precisely designed to be absolutely horizontal to ensure the accuracy of the calibration process. Above the tabletop, two high-precision angle measuring instruments can be placed to accurately measure the angle changes of the calibration plate.

[0033] Embodiment 2: A method for correcting the elastic effect of a continuous wind tunnel model is realized relying on the elastic deformation test system of a continuous wind tunnel model in Embodiment 1, and includes the following steps: S1. Arrange an elastic deformation test system of a continuous wind tunnel model; S2. Calibrate the elastic deformation test system of the continuous wind tunnel model using a wind tunnel axis system calibration device, including parameter calibration of the camera and calibration of the wind tunnel axis system; Furthermore, the specific implementation method of step S2 includes the following steps: S2.1. By adjusting the attitude of the strut, place the tabletop at multiple positions of the model to be tested during wind tunnel tests, collect images of the checkerboard calibration plate through the first image acquisition device and the second image acquisition device, and solve the internal and external parameters of the camera based on the Zhang's calibration method; Furthermore, the parameter calibration of the camera is specifically: the internal parameters are ; the external parameters are ; where is the focal length in the u and v directions, is the radial distortion parameter, is the image principal point coordinates; R and t are the rotation matrix and translation vector from the world coordinate system to the camera coordinate system respectively.

[0034] The calibration of the wind tunnel axis system is to obtain the transformation matrix from the camera coordinate system to the wind tunnel axis system: specifically, by adjusting the angle of the strut of the wind tunnel mechanism, collect images of the calibration plate by the binocular camera at different pitch angles , based on corner detection, the corner image coordinates of the calibration plate images collected in the image acquisition devices Ⅰ and Ⅱ can be obtained, and combined with the camera internal parameters and external parameters the three-dimensional coordinates of the corners of the checkerboard calibration plate at different pitch angles can be obtained , m = 10. Calculate the rotation relationship between the three-dimensional coordinates of the checkerboard corners at adjacent two pitch angles through the Root-Rot Kabsch algorithm , the rotational relationship is converted into an axis vector through Rodriguez transformation , take the average of them to obtain the pitch axis vector of the model in the wind tunnel axis system, and normalize it so that the modulus of the vector is 1 to obtain the final pitch axis vector . Similarly, the yaw axis vector can be obtained , based on being orthogonal to the pitch axis vector , the roll axis vector is obtained ; S2.2. Wind tunnel axis system calibration: By adjusting the angle of the strut of the wind tunnel mechanism, collect the images of the calibration plate by the first image acquisition device and the second image acquisition device at different pitch angles. Based on corner detection, obtain the corner image coordinates of the collected calibration plate images, and combine the camera internal parameters and external parameters to obtain the three-dimensional coordinates of the corners of the checkerboard calibration plate at different pitch angles. Calculate the rotational relationship between the three-dimensional coordinates of the checkerboard corners at adjacent two pitch angles through the Root-R Kabsch algorithm, convert the rotational relationship into an axis vector through Rodriguez transformation, take the average of them to obtain the pitch axis vector of the model to be measured in the wind tunnel axis system, and normalize it so that the modulus of the vector is 1 to obtain the final pitch axis vector ; Then calculate the yaw axis vector , the roll axis vector ; Obtain the transformation matrix of the wind tunnel axis system in the camera coordinate system , and the expression is: .

[0035] S3. Arrange marker points on the model to be measured. Arrange marker points on the fuselage of the model to be measured for attitude recognition, and arrange marker points on the wing part of the model to be measured for identifying the elastic deformation of the wing; Furthermore, the specific implementation method of step S3 includes the following steps: S3.1. Arrange marker points on the fuselage of the model to be measured, and adopt an irregular distribution strategy to avoid multiple marker points collinear on the same epipolar line, so as to ensure that the matching of marker points can be effectively realized through epipolar line constraint under different perspectives; S3.2. Arrange marker points on the wing part of the model to be measured, and adopt a regular distribution strategy. Arrange marker points in the root, leading edge and trailing edge areas of the wing, and ensure that the marker points are evenly distributed in the spanwise and chordwise directions for identifying the elastic deformation of the wing.

[0036] S4. Use the first image acquisition device and the second image acquisition device to collect images, and collect the reference image and test image of the model to be measured; Furthermore, the specific implementation method of step S4 includes the following steps: S4.1. Collect the reference images of the model to be tested: Collect the image sequences of all working conditions without wind, including the image sequence collected by the first image acquisition device without wind and the image sequence collected by the second image acquisition device without wind , where m is the number of working conditions, is the image collected by the first image acquisition device under the m-th working condition without wind, is the image collected by the second image acquisition device under the m-th working condition without wind, and record the attitude information sequence without wind and the image collected by the first image acquisition device when the attitude of the model to be tested is 0 without wind , the image collected by the second image acquisition device , where is the attitude information of the m-th working condition without wind; S4.2. Collect the test images of the model to be tested: Collect the image sequences of all working conditions during the test. The image sequence collected by the first image acquisition device during the test is , and the image sequence collected by the second image acquisition device during the test , n is the number of working conditions during the test, and record the attitude information sequence during the test , set m greater than or equal to n, where is the image collected by the first image acquisition device under the n-th working condition during the test, is the image collected by the second image acquisition device under the n-th working condition during the test, is the attitude information of the n-th working condition during the test.

[0037] S5. Identify and match the marked points in the reference images and test images of the model to be tested collected in step S4; Further, the specific implementation method of step S5 includes the following steps: S5.1. Identify and match the homologous marked points in the images collected by the first image acquisition device and the second image acquisition device, including the matching of the fuselage marked points and the wing marked points; S5.1.1. The fuselage marked points are matched through epipolar constraint to obtain the sequence of matched fuselage marked points without wind , where k is the number of marked points on the fuselage, is the image coordinate of the k-th marked point on the fuselage in the image collected by the first image acquisition device, is the image coordinate of the k-th marked point on the fuselage in the image collected by the second image acquisition device; Further, the epipolar constraint is specifically set that a certain point p in space projects onto the image of camera 1 and the image of camera 2 as and , the projection equations of the two cameras in the system are: , , is the three-dimensional coordinate of point p in space, is the scale factor, is the rotation matrix, is the translation matrix. Eliminating the scale factor can obtain the epipolar constraint equation and , where , is from defined skew-symmetric matrix, . Given in the image within the position, then in the image within the corresponding point must be located on its epipolar line in the image . That is must be on the line , and vice versa. Based on the epipolar constraint relationship, an initial candidate matching relationship is established and a symmetry test is performed. The matching that satisfies the constraint relationship in only one direction or neither direction is regarded as a false match.

[0038] S5.1.2. The matching of the wing marked points is mainly through image correlation to obtain the sequence of wing marked points matched when there is no wind , where l is the number of marked points on the wing, is the image coordinate of the l-th marked point on the wing in the image collected by the first image acquisition device, is the image coordinate of the l-th marked point on the wing in the image collected by the second image acquisition device; Further, the image correlation is specifically: registration feature point selection. For a single wing, preferably 6 points are selected. Find an end point near the fuselage along the spanwise direction of the leading edge of the wing , find an end point near the wing tip along the spanwise direction of the trailing edge of the wing , find a point near the middle position along the leading edge , find a point near the middle position along the trailing edge , find the farthest point along the spanwise direction of the wing , select a point in the middle area of the wing surface , as a supplement to local deformation. Based on this, 6 feature points characterizing the wing layout from the perspective of camera 1 can be obtained , 6 feature points characterizing the wing layout from the perspective of camera 2 .

[0039] Based on the thin plate spline deformation and the registered feature points obtained in a, construct the affine transformation relationship for transforming the image from the perspective of Camera 2 to the image from the perspective of Camera 1, that is , the mapping function The general form of is = , A is The affine transformation matrix of, which is used to describe the global linear transformation, Is the weight of the control point, which is used to describe the intensity of local distortion. Is the basis function, which represents the contribution of the distance from point x to the control point To the distortion. The preferred tail radial basis function is = , = , when solving , input And , by minimizing the error function , solve for A and , represent the distortion mapping function as a matrix equation, and finally obtain = , where K is the radial basis function, Is the regularization parameter used to control the distortion smoothness. After solving the equation, A and And b are obtained, and then Is obtained.

[0040] Based on T and Obtain the rough corresponding point coordinates of the corresponding marked points of the marked points collected by Camera 2 mapped to the image collected by Camera 1 = , at this time The position of is very close to , so the image correlation Can be used to And Are matched, and then And Are matched. Obtain the sequence of wing marked points matched when there is no wind , where k is the number of marked points on the fuselage;

[0041] S5.1.3. Based on the internal and external camera parameters obtained in step S2 combined with , through triangulation, reconstruct the three-dimensional coordinates of the matched fuselage marked points when there is no wind And the three-dimensional coordinates of the matched wing marked points when there is no wind ; S5.1.4. Based on the wind tunnel axis system transformation matrix obtained in S2 , obtain the three-dimensional coordinate sequence of the fuselage in the wind tunnel coordinate system when there is no wind and the three - dimensional coordinate sequences of the wing marked points in the wind tunnel coordinate system when there is no wind ; = , = ; wherein, is the three - dimensional coordinate of the marked point on the fuselage of the m - th working condition of the fuselage in the wind tunnel coordinate system when there is no wind, is the three - dimensional coordinate of the marked point on the wing of the m - th working condition of the fuselage in the wind tunnel coordinate system when there is no wind; Furthermore, in the same way, the three - dimensional coordinates of the fuselage and wing marked points in the wind tunnel coordinate system under the 0 - attitude of the model can be obtained , , and the three - dimensional coordinate sequences of the fuselage and marked points on the aircraft in the wind tunnel coordinate system during the test can be obtained , .

[0042] S5.2. Perform the matching of the marked points in all working conditions in the images collected by the first image acquisition device and the second image acquisition device with the marked points in the 0 - attitude, including the matching of the fuselage marked points and the wing marked points; S5.2.1. For the marked points on the fuselage, use the three - dimensional point cloud matching method based on distance matching and singular value decomposition to obtain the matching result sequence of the marked points on the fuselage under any test working condition and the marked points in the 0 - attitude , and the expression is: ; wherein, is the three - dimensional coordinate of the marked point on the fuselage of the model to be measured in the 0 - attitude in the wind tunnel coordinate system when there is no wind, is the three - dimensional coordinate of the marked point on the fuselage of the model to be measured in the n - th working condition during the test in the wind tunnel coordinate system, and at this time, all the marked points in and are in one - to - one correspondence; Furthermore, the specific three - dimensional point cloud optimal matching method based on distance matching and singular value decomposition is as follows: For any point in , calculate its distance to all points in , and t is the number of points in . For any point in , calculate its distance to all points in , and s is the number of points in . , According to and to calculate the matching point pairs. That is, there exists , , , is the distance deviation threshold. Preferably , then it is considered that the current and are temporary matching points. And the current matching result is retained.

[0043] Repeat the above steps until all the points in and are traversed to obtain multiple groups of matching results = . is the number of matching results.

[0044] For any matching point that meets the conditions, the optimal rotation matrix R and translation vector T are calculated through singular value decomposition (SVD) such that the matching point cloud in is best aligned with the point cloud in . And calculate the error between the transformed point cloud and the target point cloud. If , then it is considered that the current matching point is the correct matching point, and the current

[0045] S5.2.2. The wing marking points perform two-dimensional point matching according to image correlation and then are converted into three-dimensional coordinates in the wind tunnel coordinate system to obtain the wing marking points of the model under test under any test condition and the marking points when the attitude is 0, as well as the matching sequence of the marking points under the corresponding condition when there is no wind. The expression is: = ; wherein is the three-dimensional coordinate of the wing marking point on the model under test when the attitude is 0 in the wind tunnel coordinate system when there is no wind, is the three-dimensional coordinate of the wing marking point on the model under test in the wind tunnel coordinate system under the nth test condition during the test, is the three-dimensional coordinate of the fuselage marking point on the model under test in the wind tunnel coordinate system corresponding to when there is no wind and under the nth test condition during the test. At this time , and all the marking points in are in one-to-one correspondence.

[0046] S6. Calculate the deformation of the wing of the model under test under different conditions and the current attitude; Furthermore, the specific implementation method of step S6 includes the following steps: S6.1. For the h-th working condition, h , calculate the attitude of the wing of the model to be tested. Based on the rigid body assumption, the obtained expression is: ; where, is and the rotation matrix for the transformation between is and the translation vector for the transformation between Solve and by using the calculation of the generalized inverse matrix or the singular value decomposition. The expression is: ; ; where, - correspond to the elements of the first row and first column, the second row and first column, the third row and first column, the first row and second column, the second row and second column, the third row and second column, the first row and third column, the second row and third column, and the third row and third column of the rotation matrix respectively. - represent the first, second, and third components of the translation vector; Convert to the pitch angle , yaw angle , and roll angle , , , ; Then obtain the attitude sequence for all test working conditions; S6.2. For the h-th working condition, h , calculate the deformation of the wing of the model to be tested; For , calculate the rotation matrix from and the translation matrix . Then the three-dimensional coordinates of the wing marked points in the h-th working condition without wind at 0 attitude after registration are , and the three-dimensional coordinates of the wing marked points in the h-th working condition during the test are + . Then the deformation amount of the marked points in the model coordinate system is - ; - ; Then obtain the wing deformations for all working conditions.

[0047] S7. Correct the influence of the elastic deformation of the model to be tested.

[0048] Further, the specific implementation method of step S7 includes the following steps: S7.1. Calculate the aerodynamic force of the original rigid model: Use PointWise software to generate the unstructured hybrid grid of the model to be tested before deformation, import the grid into the CFD solver, and based on input the attitude information of the model to be tested, set the oncoming flow conditions, and obtain the aerodynamic force coefficients such as lift and drag of the model to be tested before deformation after solving the flow field; S7.2. Select interpolation points on the surface grid of the model to be tested, and based on interpolate to obtain the surface grid of the deformed model to be tested, and then use the grid deformation program to automatically generate the grid of the deformed model; S7.3. Calculate the aerodynamic force of the deformed model to be tested based on the CFD solver, correct the influence of the elastic deformation, and compare it with the aerodynamic force before deformation to obtain the influence amount of the elastic deformation on the aerodynamic force.

[0049] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0050] Although the present application has been described above with reference to specific embodiments, various improvements can be made to it and its components can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application can be combined with each other in any way, and the lack of an exhaustive description of these combinations in this specification is only for the sake of saving space and resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A continuous wind tunnel model elastic deformation test system, characterized in that, It includes a first image acquisition device (1), a second image acquisition device (2), a first air-cooled pressure stabilizing chamber (3), a second air-cooled pressure stabilizing chamber (4), a first fixed connection block (5), a second fixed connection block (6), and a light source (7); The first image acquisition device (1) is fixed in the first air-cooled pressure stabilizing chamber (3) through the first fixed connection block (5), the second image acquisition device (2) is fixed in the second air-cooled pressure stabilizing chamber (4) through the second fixed connection block (6), and multiple light sources (7) are installed on the side wall of the wind tunnel test section (9); the first air-cooled pressure stabilizing chamber (3) and the second air-cooled pressure stabilizing chamber (4) are fixedly installed on the upper surface of the wind tunnel test section (9); Before the elastic deformation test of the continuous wind tunnel model, place the wind tunnel axis calibration device in the wind tunnel test section (9) for wind tunnel axis calibration, and then replace the wind tunnel axis calibration device with the model to be tested (8) for the elastic deformation test of the continuous wind tunnel model; The wind tunnel axis calibration device includes a strut (10), a first angle measuring instrument (11), a second angle measuring instrument (12), a checkerboard calibration plate (13), and a tabletop (14). The checkerboard calibration plate (13) is embedded in the tabletop (14). The first angle measuring instrument (11) and the second angle measuring instrument (12) are placed horizontally and vertically on the tabletop (14) respectively. A strut (10) is installed on the side surface of the tabletop (14). The wind tunnel axis calibration device is moved to multiple positions of the model to be tested (8) during wind tunnel tests through the strut (10).

2. A flexible deformation test system for a continuous wind tunnel model according to claim 1, characterized in that, The tabletop (14) of the wind tunnel axis calibration device is connected to the strut (10) through a flange.

3. A flexible deformation test system for a continuous wind tunnel model according to claim 1 or 2, characterized in that The first image acquisition device (1) includes a camera and a lens. The second image acquisition device (2) includes a camera and a lens. When the brightness of the marker point excites the light source in a specific wavelength band, an optical filter that selectively transmits the excitation wavelength band and effectively filters out light of other wavelength bands is configured in front of the lens.

4. A method for correcting the elastic effect of a continuous wind tunnel model, which is realized based on an elastic deformation test system of a continuous wind tunnel model according to one of claims 1-3, characterized in that, It includes the following steps: S1. Arrange the elastic deformation test system of the described continuous wind tunnel model; S2. Use the wind tunnel axis calibration device to calibrate the elastic deformation test system of the described continuous wind tunnel model, including camera parameter calibration and wind tunnel axis calibration; S3. Arrange marker points on the model to be tested. Arrange marker points on the fuselage of the model to be tested for attitude recognition, and arrange marker points on the wing part of the model to be tested for identifying the elastic deformation of the wing; S4. Use the first image acquisition device and the second image acquisition device to perform image acquisition, and acquire the reference image and test image of the model to be tested; S5. Perform marker point recognition and matching on the reference image and test image of the model to be tested collected in step S4; S6. Calculate the deformation and current attitude of the wing of the model to be tested under different working conditions; S7. Correct the influence of the elastic deformation of the model to be tested.

5. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 4, characterized in that, The specific implementation method of step S2 includes the following steps: S2.

1. By adjusting the attitude of the strut, place the tabletop at multiple positions of the model to be tested during wind tunnel tests. Collect images of the checkerboard calibration plate through the first image acquisition device and the second image acquisition device, and solve the internal and external parameters of the camera based on the Zhang's calibration method; S2.

2. Wind tunnel axis system calibration: By adjusting the angle of the strut of the wind tunnel mechanism, images of the calibration board are collected by the first image acquisition device and the second image acquisition device at different pitch angles. Based on corner detection, the corner image coordinates of the collected calibration board images are obtained. Combining with the camera internal parameters and external parameters to obtain the three-dimensional coordinates of the corners of the checkerboard calibration board at different pitch angles. The rotation relationship between the three-dimensional coordinates of the checkerboard corners at adjacent pitch angles is calculated by the Root-Rodrigues Kabsch algorithm. The rotation relationship is converted into an axis vector through the Rodrigues transformation, and its average value is taken to obtain the pitch axis vector of the model to be measured under the wind tunnel axis system. Normalize it so that the modulus of the vector is 1 to obtain the final pitch axis vector ; then calculate the yaw axis vector , and the roll axis vector ; obtain the wind tunnel axis system transformation matrix in the camera coordinate system , and the expression is: 。 6. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 5, characterized in that The specific implementation method of step S3 includes the following steps: S3.

1. Arrange marked points on the fuselage of the model to be tested, and adopt an irregular distribution strategy to avoid multiple marked points collinear on the same epipolar line, so as to ensure that the matching of marked points can be effectively realized through epipolar line constraints under different perspectives; S3.

2. Arrange marked points on the wing part of the model to be tested, and adopt a regular distribution strategy. Arrange marked points in the root, leading edge, and trailing edge areas of the wing. The marked points are ensured to be evenly distributed in the spanwise and chordwise directions to identify the elastic deformation of the wing.

7. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 6, characterized in that The specific implementation method of step S4 includes the following steps: S4.

1. Collect the reference images of the model to be tested: Collect the image sequences of all working conditions without wind, including the image sequence collected by the first image acquisition device without wind , and the image sequence collected by the second image acquisition device without wind , where m is the number of working conditions, is the image collected by the first image acquisition device under the m-th working condition without wind, is the image collected by the second image acquisition device under the m-th working condition without wind, and record the attitude information sequence without wind and the image collected by the first image acquisition device when the attitude of the model to be tested is 0 without wind , and the image collected by the second image acquisition device , where is the attitude information of the m-th working condition without wind; S4.

2. Collect test images of the model to be tested: Collect image sequences for all working conditions during the test. The image sequence collected by the first image acquisition device during the test is , and the image sequence collected by the second image acquisition device during the test , where n is the number of working conditions during the test, and record the pose information sequence . Set m to be greater than or equal to n, where is the image collected by the first image acquisition device for the nth working condition during the test, is the image collected by the second image acquisition device for the nth working condition during the test, is the pose information for the nth working condition during the test.

8. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 7, characterized in that The specific implementation method of step S5 includes the following steps: S5.

1. Identify and match the corresponding marked points in the images collected by the first image acquisition device and the second image acquisition device, including the matching of fuselage marked points and wing marked points; S5.1.

1. The body marking points are matched through epipolar constraint to obtain the sequence of body marking points matched under windless conditions , where k is the number of body marking points, is the image coordinate of the k-th body marking point in the image collected by the first image acquisition device, is the image coordinate of the k-th body marking point in the image collected by the second image acquisition device; S5.1.

2. The matching of the wing marking points is mainly achieved through image correlation to obtain the sequence of wing marking points matched under windless conditions , where l is the number of wing marking points, is the image coordinate of the l-th wing marking point in the image collected by the first image acquisition device, is the image coordinate of the l-th wing marking point in the image collected by the second image acquisition device; S5.1.

3. Based on the internal and external camera parameters obtained in step S2, , through triangulation, reconstruct the three-dimensional coordinates of the body marker points matched in still air and the three-dimensional coordinates of the wing marker points matched in still air ; S5.1.

4. Obtain the three-dimensional coordinate sequence of the fuselage in the wind tunnel coordinate system without wind and the three-dimensional coordinate sequence of the wing marking points in the wind tunnel coordinate system without wind based on the wind tunnel axis system transformation matrix obtained in S2 ; = ， = ； wherein, is the three-dimensional coordinate of the marked point on the fuselage of the mth working condition of the fuselage in the wind tunnel coordinate system when there is no wind, is the three-dimensional coordinate of the marked point on the wing of the mth working condition of the fuselage in the wind tunnel coordinate system when there is no wind; S5.

2. Match the marked points in the images collected by the first image acquisition device and the second image acquisition device with the marked points in the case of attitude 0 under all working conditions, including the matching of fuselage marked points and wing marked points; S5.2.

1. The marking points on the fuselage adopt a 3D point cloud matching method based on distance matching and singular value decomposition to obtain the matching result sequence of the marking points on the fuselage under any test condition and the marking points with an attitude of 0. , and the expression is: ； Among them, is the three-dimensional coordinates of the marked points on the fuselage of the model to be measured when the attitude of the model to be measured is 0 without wind in the wind tunnel coordinate system, is the three-dimensional coordinates of the marked points on the fuselage of the model to be measured under the nth working condition during the test in the wind tunnel coordinate system. At this time, and all the marked points in are in one-to-one correspondence; S5.2.

2. The wing marked points are matched for two-dimensional points according to the image correlation and then converted into three-dimensional coordinates in the wind tunnel coordinate system to obtain the wing marked points on the wing under any test working condition and the marked points in the case of attitude 0, as well as the matching sequence of marked points under the corresponding working condition without wind. The expression is: = ； Among them, is the three-dimensional coordinates of the marked points on the wing of the model to be measured in the wind tunnel coordinate system when the attitude of the model to be measured is 0 without wind. is the three-dimensional coordinates of the marked points on the wing of the model to be measured in the wind tunnel coordinate system under the nth working condition during the test. is the three-dimensional coordinates of the marked points on the fuselage of the model to be measured in the wind tunnel coordinate system corresponding to the nth working condition without wind and during the test. At this time, , and all the marked points in are in one-to-one correspondence.

9. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 8, characterized in that, The specific implementation method of step S6 includes the following steps: S6.

1. For the h-th working condition, h , calculate the attitude of the wing of the model to be measured. Based on the rigid body assumption, the obtained expression is: ； Among them, is and the rotation matrix that transforms between is and the translation vector that transforms between Solve by using the calculation of the generalized inverse matrix or the singular value decomposition and , and the expression is: ； ； Among them, - correspond to the elements of the first row and first column, second row and first column, third row and first column, first row and second column, second row and second column, third row and second column, first row and third column, second row and third column, and third row and third column of the rotation matrix, respectively. - represent the first, second, and third components of the translation vector. Convert to pitch angle , yaw angle , roll angle , , , ; Then obtain the attitude sequences for all test operating conditions ; S6.

2. For the h-th working condition, h , calculate the deformation of the wing of the model to be measured; For , calculate to rotation matrix and translation matrix , then the three-dimensional coordinates of the wing marker points in the h-th working condition without wind under the 0 attitude after registration are + , and the three-dimensional coordinates of the wing marker points in the h-th working condition during the test are + , then the deformation of the marker points in the model coordinate system is - ; Then the wing deformations under all working conditions are obtained .

10. A method for correcting the elastic effect of a continuous wind tunnel model according to claim 9, characterized in that, The specific implementation method of step S7 includes the following steps: S7.

1. Aerodynamic force calculation of the original rigid model: Use PointWise software to generate the unstructured hybrid mesh of the model to be tested before deformation, import the mesh into the CFD solver, and based on input the attitude information of the model to be tested, set the oncoming flow conditions, and obtain the aerodynamic force coefficients such as lift and drag of the model to be tested before deformation after solving the flow field; S7.

2. Select interpolation points on the surface grid of the model object to be measured. Based on , interpolate to obtain the surface grid of the deformed model object to be measured, and then use the grid deformation program to automatically generate the grid of the deformed model; S7.

3. Calculate the aerodynamic force of the deformed model to be tested based on the CFD solver, realize the correction of the influence of elastic deformation, and compare it with the aerodynamic force before deformation to obtain the influence amount of elastic deformation on the aerodynamic force.

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