A system and method for wind tunnel model ejection testing

Abstract

A kind of wind tunnel model launching test system and test method belong to model wind tunnel dynamic test technical field.Solve the problem that cannot give consideration to gravity launching and with initial velocity launching function in prior art.Technical points: tail brace bending knife is arranged on wind tunnel test section, tail brace transmission is arranged on tail brace bending knife, test model and tail brace transmission are connected by tail brace support rod, the top of launching model is fixedly connected with test model, binocular vision position measuring system is arranged outside wind tunnel test section;elastic energy-absorbing protective pad is arranged on the wall of wind tunnel test section, blocking protection net is arranged behind tail brace bending knife.The present application realizes the switching of force direction and the adjustment of launching speed by electromagnetic control, and the launching action is responsive and controllable, and the high-speed camera is used to record the time sequence curve of the position and posture of the launching model, to provide complete and accurate dynamic data support for wind tunnel test.

Description

Technical Field

[0001] This invention relates to the field of dynamic testing technology for model wind tunnels, specifically to a system and method for deploying wind tunnel models for testing. Background Technology

[0002] When an aircraft releases external objects, the separated body passes through an extremely complex turbulent flow field and experiences a strong unsteady and nonlinear aerodynamic environment. The aerodynamic changes during this process are extremely drastic and may produce unpredictable collision risks. In the early days, flight tests were the main method, which was costly and risky. With the advancement of wind tunnel equipment and testing technology, wind tunnel model release tests have gradually become a standard procedure and play an extremely important role in the design and development cycle.

[0003] Wind tunnel model drop tests are a type of unsteady testing method. During the test, the main model is held in place by a support, while the separated model is in free flight after deployment, thus obtaining reliable separation trajectory data. Wind tunnel drop separation tests are based on similarity theory, reproducing the physical process of separation through scaled-down model tests. According to the deployment method, they can be divided into gravity deployment and deployment with initial velocity, which are achieved by the wind tunnel deployment mechanism.

[0004] Existing wind tunnel model deployment testing equipment struggles to precisely control initial velocity, initial angular velocity, and attitude angles, resulting in large launch errors and significant discrepancies between ground calibration and actual wind tunnel conditions. Scaled-down models often fail to achieve full-scale Reynolds number similarity, leading to deviations in boundary layer and separation characteristics from real flight. Furthermore, most models are custom-designed, requiring redesign and manufacturing for different models, resulting in long lead times and high costs. They are also ill-suited for adapting to multiple sizes, configurations, and separation modes. Wind tunnel operation is energy-intensive, requires long preparation times, and results in high costs and low frequency of single tests.

[0005] Therefore, there is an urgent need to propose a wind tunnel model deployment test system and test method to solve the problem that the existing technology cannot simultaneously achieve gravity deployment and deployment with initial velocity. Summary of the Invention

[0006] In view of the above facts, in order to solve the problem that the existing technology cannot simultaneously achieve gravity-based deployment and deployment with initial velocity, the present invention designs a wind tunnel model deployment test system and test method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] Option 1: A system for wind tunnel model deployment testing, comprising a wind tunnel test section, a tail support rod, a tail support bevel, a tail support transmission, a test model, a barrier net, a deployment model, and a binocular vision positioning system;

[0009] The wind tunnel test section is equipped with a tail support bevel, the tail support drive is installed on the tail support bevel, the test model and the tail support drive are connected by the tail support rod, the top of the drop model is fixedly connected to the test model, the binocular vision positioning system is set outside the wind tunnel test section, and the barrier net is set behind the tail support bevel.

[0010] The deployment model includes a hanger, an electromagnet, an electromagnet cover plate, a limiter track, and a deployment object model;

[0011] The top surface of the bracket is fixedly connected to the test model. The bottom of the bracket has two openings, and an electromagnet is installed inside each of the two openings. Two electromagnet cover plates are installed at the bottom of the bracket, corresponding to the two electromagnets respectively. A limiter track is set between the two openings.

[0012] The delivery model includes a head section, a front magnetic section, a neodymium magnet with a countersunk hole, a middle section, a rear magnetic section, a tail section, and a limiter.

[0013] The head section, front magnetic section, middle section, rear magnetic section, and tail section of the model are sequentially spliced ​​and fixed. The front magnetic section and the rear magnetic section of the model are provided with mounting slots. The top mounting slot closest to the bracket is filled with a neodymium magnet with a countersunk hole, and the other mounting slots are filled with counterweights. The limiter is set on the middle section of the model, and the limiter is in rolling contact with the limiter track.

[0014] The bracket is equipped with an electromagnet circuit.

[0015] The electromagnet is magnetically attracted to the neodymium magnet with a countersunk hole.

[0016] Furthermore: a set of electronic switch groups is placed on each of the left and right sides of the electromagnet circuit. Each set of electronic switch groups has two electronic switches arranged vertically. The electromagnet is placed between the two sets of electronic switch groups. The electromagnet and each set of electronic switch groups form two half-bridges. The freewheeling diode is connected in parallel with the electronic switch in the opposite direction.

[0017] Furthermore, the end faces of the head section, middle section, and tail section of the model are all provided with slots, and the end faces of the front magnetic section and rear magnetic section of the model are all provided with buckles, which are spliced ​​and fixed with the slots.

[0018] Furthermore, the electromagnet is a square electromagnet.

[0019] Furthermore, the electromagnet cover plate is provided with four screw holes, which are used to install it on the bottom of the bracket.

[0020] Furthermore, the binocular vision positioning system includes two high-speed cameras.

[0021] Furthermore, the walls of the wind tunnel test section are equipped with elastic energy-absorbing protective pads.

[0022] Furthermore, the two electromagnets are controlled by a series circuit, and the coils of each electromagnet are wound in the same direction.

[0023] Option 2: A method for wind tunnel model deployment testing, implemented using a wind tunnel model deployment testing system as described in Option 1, specifically as follows:

[0024] S1: Experimental design;

[0025] S2: Installation of the test model;

[0026] S21: Install the head section, front magnetic section, neodymium magnet with countersunk hole, middle section, rear magnetic section, and tail section of the model onto the outer surface of each section for a smooth transition;

[0027] S22: Correctly affix the checkerboard identification label to the assembled delivery model and secure the bracket to the test model with screws;

[0028] S23: When the electromagnet circuit is energized, the two electromagnets generate magnetic force and attract and fix the object model with the neodymium magnet with the countersunk hole. The relative position is adjusted by the limiter track and the limiter until the object model is in the correct position.

[0029] S3: Binocular vision positioning system equipment layout;

[0030] S4: Begin wind tunnel model deployment test;

[0031] S41: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started.

[0032] S42: When the wind tunnel wind speed reaches the set value, the electromagnet circuit is closed. After the power is cut off, the magnetic force disappears, and the instantaneous state of the object model is free fall.

[0033] S43: The binocular vision positioning system records a series of images showing the change in pose of the object model over time during the deployment process;

[0034] S44: After the test is completed, the low-speed recirculation wind tunnel is shut down, and the deployed object model is retrieved and captured by the barrier net.

[0035] S5: Begin the wind tunnel dynamic separation test with initial velocity;

[0036] S51: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started.

[0037] S52: When the wind tunnel wind speed reaches the set value, the current in the electromagnet circuit is changed to the opposite direction, the direction of the magnetic force generated by the electromagnet is reversed, and electromagnetic repulsion is generated with the neodymium magnet with the sinker hole, which ejects the object model at the calibrated initial velocity.

[0038] S53: A binocular vision positioning system records a series of images showing the change in pose of the object model over time during the deployment process;

[0039] S54: After the test is completed, the low-speed recirculation wind tunnel is shut down, and the deployed object model is retrieved and captured by the barrier net;

[0040] S6: According to the test plan, change the magnitude of the current of the neodymium magnet with countersunk hole or electromagnet to change the initial velocity of the release, repeat S2-S5, and continue the test process;

[0041] S7: Experimental data analysis.

[0042] Further: In S7, based on the real-time coordinates of the object fed back by the binocular vision positioning system, the marked point images obtained by the model posture in each test process are used to establish a perspective transformation imaging model of the high-speed camera using the principle of three-dimensional stereo vision, the intrinsic and extrinsic parameter matrices of the high-speed camera are calibrated, and the mapping relationship between spatial points and image points is established.

[0043] Based on the inherent constraints between the parameters of the high-speed camera, the intrinsic parameter matrix and extrinsic parameter matrix of the high-speed camera are obtained through matrix factorization algorithm. Based on the camera distortion model, the nonlinear distortion parameters of the camera are calibrated, and the distortion of the original image is corrected.

[0044] Based on the matching data of image points, a 3D reconstruction was performed to calculate the curve of the spatial coordinates of the centroid of the cone sleeve as a function of the oscillation time.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. This invention realizes the connection of the experimental model before separation, the free release of the objects, and the release of the objects with initial velocity, ensuring close contact between the objects and simulating the real separation process.

[0047] 2. This invention can ensure that there is no external interference during the delivery process, and the magnitude and direction of the repulsive force are stable and reliable when the object is delivered with initial velocity, which is easy to calibrate.

[0048] 3. This invention achieves both gravity-based and initial velocity-based deployment functions, with controllable force direction and deployment speed, and a large envelope range.

[0049] 4. This invention relates to a system with few components, a simple structure, and the ability to achieve rapid installation.

[0050] 5. This invention flexibly achieves switching of force direction and adjustment of release speed through electromagnetic control, resulting in rapid release response and strong controllability. Combined with a high-speed camera, it synchronously records the temporal change curve of the released object model, providing complete and accurate dynamic data support for wind tunnel testing. Attached Figure Description

[0051] Figure 1 This is a front view of the test deployment system in this invention;

[0052] Figure 2 This is an isometric view of the test system used in this invention;

[0053] Figure 3 This is an isometric view of the model deployed in this invention;

[0054] Figure 4 This is a schematic diagram of the circuit principle of the deployment model in this invention;

[0055] Figure 5 This is a diagram of the high-speed camera imaging model in this invention;

[0056] Figure 6 This is a schematic diagram of the binocular vision principle of the present invention.

[0057] In the diagram: 1-Hanging bracket, 2-Electromagnet, 3-Screw hole, 4-Electromagnet cover plate, 6-Limiter track, 7-Model head section, 8-Model front magnetic section, 9-Neodymium magnet with countersunk hole, 10-Snap fastener, 11-Mounting slot, 12-Model middle section, 13-Model rear magnetic section, 14-Slot, 15-Model tail section, 16-Limiter, 17-Wind tunnel test section, 18-Tail support rod, 19-Tail support bevel, 20-Tail support transmission, 21-Elastic energy-absorbing protective pad, 22-Test model, 23-Barrier protection net, 25-Binocular vision positioning system. Detailed Implementation

[0058] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0059] The terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0060] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0061] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0062] Example 1: Reference Figures 1 to 4 This embodiment describes a wind tunnel model deployment test system, which includes a wind tunnel test section 17, a tail support rod 18, a tail support bevel 19, a tail support transmission 20, a test model 22, a barrier net 23, a deployment model, and a binocular vision positioning system 25.

[0063] The wind tunnel test section 17 is equipped with a tail boom cutter 19, and a tail boom drive 20 is installed on the tail boom cutter 19. The test model 22 and the tail boom drive 20 are connected by a tail boom support rod 18. The test state of the test model 22 is changed through the tail boom drive 20. The deployed model is fixedly connected to the test model 22. The binocular vision positioning system 25 is installed outside the wind tunnel test section 17 to detect the flight trajectory of the test model 22 after deployment. An arresting net 23 is installed behind the tail boom cutter 19.

[0064] The deployment model includes a hanger 1, an electromagnet 2, an electromagnet cover plate 4, a limiter track 6, and a deployment object model;

[0065] The top surface of the bracket 1 is fixedly connected to the test model 22. The bottom of the bracket 1 has two openings, and an electromagnet 2 is installed inside each of the two openings. Two electromagnet cover plates 4 are installed at the bottom of the bracket 1 respectively, corresponding to the two electromagnets. A limiter track 6 is set between the two openings.

[0066] The delivery model includes a head section 7, a front magnetic section 8, a neodymium magnet with a countersunk hole 9, a middle section 12, a rear magnetic section 13, a tail section 15, and a limiter 16.

[0067] The head section 7, front magnetic section 8, middle section 12, rear magnetic section 13, and tail section 15 of the model are sequentially spliced ​​and fixed. The front magnetic section 8 and the rear magnetic section 13 of the model are both provided with mounting slots 11. The mounting slot 11 closest to the bracket 1 at the top is filled with a neodymium magnet 9 with a countersunk hole to provide magnetic force for the object model. The other mounting slots 11 are filled with counterweights to balance the weight and rotational inertia distribution of the object model. The limiter 16 is set on the middle section 12 of the model and makes rolling contact with the limiter track 6 to determine the installation position of the object model.

[0068] The bracket 1 is equipped with an electromagnet circuit inside.

[0069] The electromagnet 2 is magnetically attracted to the neodymium magnet 9 with a countersunk hole.

[0070] More specifically: a set of electronic switch groups is placed on each of the left and right sides of the electromagnet circuit. Each set of electronic switch groups has two electronic switches arranged vertically. Electromagnet 2 is placed in the middle of the two sets of electronic switch groups, and electromagnet 2 and each set of electronic switch groups form two half bridges.

[0071] More specifically: the end faces of the head section 7, the middle section 12, and the tail section 15 of the model are all provided with slots 14, and the end faces of the front magnetic section 8 and the rear magnetic section 13 of the model are all provided with buckles 10, which are spliced ​​and fixed with the slots 14.

[0072] More specifically: the electromagnet 2 is a square electromagnet.

[0073] More specifically: the electromagnet cover plate 4 is provided with four screw holes 3, which are installed at the bottom of the bracket 1 by screws.

[0074] More specifically: the binocular vision positioning system 25 includes two high-speed cameras.

[0075] More specifically: the wind tunnel test section 17 is provided with an elastic energy-absorbing protective pad 21 on the tunnel wall to prevent the test model 22 from being damaged by uncontrolled free flight after being deployed.

[0076] More specifically: the electronic switch is a power transistor.

[0077] More specifically: the bracket 1 is a box-type aluminum alloy structure.

[0078] Example 2: A method for wind tunnel model deployment testing, implemented using a wind tunnel model deployment testing system as described in Example 1, specifically as follows:

[0079] S1: Experimental design;

[0080] S2: Installation of the test model;

[0081] S21: Install the head section 7, front magnetic section 8, neodymium magnet with countersunk hole 9, middle section 12, rear magnetic section 13, and tail section 15 of the model onto the outer surface of each section for a smooth transition.

[0082] S22: Correctly affix the checkerboard identification label to the surface of the assembled delivery model, and fix the bracket 1 to the test model 22 with screws;

[0083] S23: The electromagnet circuit is energized, causing the two electromagnets 2 to generate magnetic force and attract and fix the object model with the neodymium magnet 9 with the countersunk hole. The relative position is adjusted by the limiter track 6 and the limiter 16 until the object model is in the correct position.

[0084] S3: Binocular vision positioning system 25 equipment layout;

[0085] S4: Begin wind tunnel model deployment test;

[0086] S41: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started.

[0087] S42: When the wind tunnel wind speed reaches the set value, the electromagnet circuit is closed. After the power is cut off, the magnetic force disappears, and the instantaneous state of the object model is free fall.

[0088] S43: The binocular vision positioning system 25 records a series of image sequences showing the change in pose of the object model over time during the placement process;

[0089] S44: After the test is completed, the low-speed recirculation wind tunnel is shut down, and the deployed object model is retrieved and captured by the barrier net 23;

[0090] S5: Begin the wind tunnel dynamic separation test with initial velocity;

[0091] S51: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started.

[0092] S52: When the wind tunnel wind speed reaches the set value, the current in the electromagnet circuit is changed to the opposite direction. The magnetic force generated by electromagnet 2 is reversed and generates electromagnetic repulsion with the neodymium magnet 9 with a countersunk hole, which ejects the object model at the calibrated initial velocity.

[0093] S53: The binocular vision positioning system 25 records a series of image sequences showing the change in pose of the object model over time during the placement process;

[0094] S54: After the test is completed, the low-speed recirculation wind tunnel is shut down, and the deployed object model is retrieved and captured by the barrier net 23;

[0095] S6: According to the test plan, change the current of the neodymium magnet 9 with countersunk hole or electromagnet 2 to change the initial velocity of the release, repeat S2-S5, and continue the test process;

[0096] S7: Experimental data analysis.

[0097] More specifically: In S1, the wind tunnel model deployment test involves the coupling between fluid (air) and solid (deployed model), and must meet the conditions of flow similarity criteria and structural dynamic similarity criteria;

[0098] The flow similarity criterion is derived from the Wiener-Stokes equations. For unsteady, compressible, viscous, and perfectly air-flow conditions, the model flow field and the real flow field must satisfy the following similarity criterion:

[0099] Ma = v3 / c;

[0100] Re = ρv4 / μ1;

[0101] Fr=v5 / ;

[0102] Where: Ma is the Mach number;

[0103] v3 is the object's velocity;

[0104] c represents the speed of sound;

[0105] Re is the Reynolds number;

[0106] ρ is the fluid density;

[0107] v4 represents the characteristic flow velocity;

[0108] l is the characteristic length;

[0109] μ1 is the hydrodynamic viscosity;

[0110] Fr is a Froude number;

[0111] v5 represents the fluid velocity;

[0112] g1 is the acceleration due to gravity;

[0113] Like other wind tunnel model drop test techniques, wind tunnel model drop tests cannot simultaneously satisfy all of the above similarity criteria. They can only analyze the main contradictions and achieve partial simulation. Ma is a measure of the influence of gas compressibility on flow. In the low-speed range, the compressibility of gas is negligible. Re is a similarity criterion that reflects the influence of fluid viscosity on flow. For general wind tunnels, given the limitations of wind tunnel size and test wind speed, for low-speed external object drop tests, practice has shown that the Ma number and Re number have little impact and can generally be ignored.

[0114] The Fr similarity criterion is the ratio of inertial force to gravity, which characterizes the effect of gravity on flow. The St similarity criterion is the ratio of unsteady inertial force to inertial force, which characterizes the unsteadiness of the fluid. Since the trajectory of the test object is related to gravity and release time, it is necessary to simulate these two similarity criteria.

[0115] The wind tunnel model drop test is to obtain the motion trajectory of the dropped object model. The structural dynamic similarity criterion is related to the gravity and aerodynamic forces acting on the dropped object.

[0116] The position (x, y, z) of the center of mass of the launcher model at any given time and its attitude angle θ are related to the following physical quantities: the angle of attack of the launcher model. m The sideslip angle β of the project model m The velocity v of the launched object model m The average aerodynamic chord length c of the delivery platform Am Air density of the object model m Viscosity of the delivery model m The diameter d of the object model m The mass m of the object model m The model size d of the object being placed m The moment of inertia I of the object model m The gravitational acceleration g of the object model m The time t of the delivery model m The deployment speed v of the deployment model sm This leads to the following relation:

[0117] (x, y, z, θ) = f(α) m ,β m v m c Am , m , m d m m m I m g m , t m v sm );

[0118] According to the similarity theorem, to make the cone trajectory obtained from the wind tunnel model drop test similar to that in actual flight, all dimensionless quantities on the right-hand side of the equation must be equal. The parameters of the model and test conditions during the wind tunnel model drop test are shown in Table 1.

[0119] Table 1

[0120]

[0121] Where, ρ s The air density of the original size object;

[0122] d s The model dimensions are those of the original physical object;

[0123] t s The time required for the original size physical object;

[0124] v ss The speed at which the original-size physical objects are deployed;

[0125] a m The acceleration of the object being placed;

[0126] a s This is the acceleration of the original-sized object;

[0127] v s The speed of the original size object;

[0128] q m For the velocity and pressure of the object being placed;

[0129] q s Rapid pressing of the original size object;

[0130] I s The moment of inertia of the original-sized object;

[0131] If a drop test with initial velocity is to be carried out, it is necessary to further calculate the magnetic force of the neodymium magnet 9 with a countersunk hole and the current of the electromagnet 2 installed on the drop model, and to carry out ground calibration work.

[0132] More specifically: In S2, the wind tunnel model deployment test is a dynamic unsteady test.

[0133] More specifically: In S2, the freewheeling diode D1 is connected in reverse parallel with the power transistor Q1. When it is turned on, the upper node of the power transistor Q1 in the load is driven to be in line with the battery supply voltage V. bat Equal potential levels;

[0134] The freewheeling diode D2 is connected in reverse parallel with the power transistor Q2. When it is turned on, it drives the lower node of the power transistor Q2 to a potential level equal to the reference ground.

[0135] The freewheeling diode D3 is connected in reverse parallel with the power transistor Q3. When it is turned on, it drives the upper node of the power transistor Q3 to the same voltage as the battery supply voltage V. bat Equal potential levels;

[0136] The freewheeling diode D4 is connected in reverse parallel with the power transistor Q4. When it is turned on, it drives the lower node of the power transistor Q4 to a potential level equal to the reference ground.

[0137] More specifically: In S2, the electromagnet circuit is energized, power transistors Q1 and Q4 are turned on, and current flows from the positive terminal of the power supply through power transistor Q1 from left to right through electromagnet 2, and returns to the negative terminal of the power supply through power transistor Q4.

[0138] More specifically: In S3, a binocular vision positioning system 25 is arranged outside the wind tunnel test section 17. Displacement measurement is achieved through the binocular vision positioning system 25. The imaging model of the high-speed camera is ideally a pinhole perspective transformation model, such as... Figure 5-6 As shown, O w X w Y w Z w Using the geodetic coordinate system, O xyz Let O' be the high-speed camera coordinate system, O'x'y' be the image plane coordinate system of the high-speed camera, O'uv be the computer image coordinate system, f be the focal length, and P be the image coordinate system of the computer image system. u (x) u ',y u P is the theoretical image point on the imaging plane of the high-speed camera. d (x) d ',y d Let P be the projection position of point P in the computer image coordinate system. oz (0, 0, z) is a point on the optical axis, and the imaging point is the principal point O'. From the geodetic coordinate system O w X w Y w Z w To the high-speed camera coordinate system O xyz The transformation relationship is as follows:

[0139] ;

[0140] Where: R is the rotation orthogonal matrix;

[0141] T is the translation vector;

[0142] Binocular stereo vision utilizes the principle of stereo parallax to obtain two different images of the same 3D point P. By finding the matching image points of point P in the two images, the 3D coordinates of the point can be calculated.

[0143] The imaging relationship of spatial points in the binocular vision positioning system 25, such as... Figure 5 As shown, O w X w Y w Z wLet C1 and C2 be the geodetic coordinate system, and O1 and O2 be the optical centers of the two high-speed cameras, respectively. The pixel point P that is imaged in C1 is P1 with pixel coordinates (u1, v1), and the pixel point P that is imaged in C2 is P2 with pixel coordinates (u2, v2). When the geodetic coordinate system is established on C1, and the pinhole model is used as the imaging model of the high-speed camera, the three-dimensional coordinates of the spatial point P(x, y, z) can be derived based on the spatial geometric relationship.

[0144] For the calibration of the binocular vision positioning system 25, the three-dimensional points on the target plane are denoted as N=[X, Y, Z]. T The points on the image plane that are mapped to this point are denoted as n = [u, v]. T The homogeneous coordinates of the 3D point and the point on the image plane are respectively =[X, Y, Z, 1] T and =[u, v] T The high-speed camera is based on the pinhole model, and the mapping relationship between spatial points and images is e. =A[R,t1] ;

[0145] Where: e is an arbitrary non-zero scaling factor;

[0146] t1 is the translation vector;

[0147] A is the internal parameter matrix of the high-speed camera;

[0148] Assuming the target plane lies on the xy plane of the geodetic coordinate system, i.e., z=0, the mapping formula is expanded as follows:

[0149] ;

[0150] Where: r1 is the coordinate of the X-axis unit vector of the geodetic coordinate system in the high-speed camera coordinate system;

[0151] r2 is the coordinate of the Y-axis unit vector in the geodetic coordinate system in the high-speed camera coordinate system;

[0152] r3 is the coordinate of the Z-axis unit vector in the geodetic coordinate system in the high-speed camera coordinate system;

[0153] Based on the inherent constraints between the parameters of the high-speed camera, the intrinsic and extrinsic parameters of the high-speed camera are obtained through singular value decomposition. The intrinsic and extrinsic parameters of the binocular vision positioning system 25 are calibrated. Based on the matching data of image points, the three-dimensional coordinates of the spatial points are obtained through three-dimensional reconstruction.

[0154] ;

[0155] ;

[0156] ;

[0157] Among them, f l This is the effective focal length of the high-speed camera on the left.

[0158] f r This is the effective focal length of the high-speed camera on the right.

[0159] t z Z is the translation vector of the right high-speed camera relative to the left high-speed camera;

[0160] r7 is the projection component of the Z-axis of the right high-speed camera coordinate system onto the X-axis of the left high-speed camera coordinate system;

[0161] r8 is the projection component of the Z-axis of the right high-speed camera coordinate system onto the Y-axis of the left high-speed camera coordinate system;

[0162] r9 is the projection component of the Z-axis of the right high-speed camera coordinate system onto the Z-axis of the left high-speed camera coordinate system;

[0163] (f) l f r () is the focal length of the binocular vision positioning system 25;

[0164] (X) l Y l () represents the coordinates of the spatial point matched on the image plane of the high-speed camera on the left.

[0165] (X) r Y r () represents the coordinates of the spatial point matched on the image plane of the high-speed camera on the right.

[0166] (u) l v l () represents the pixel coordinates of a spatial point on the acquired image.

[0167] More specifically: In S5, the current in the electromagnet circuit is reversed, power transistors Q2 and Q3 are turned on, and the current flows from right to left through electromagnet 2.

[0168] More specifically: In S7, based on the real-time coordinates of the object fed back by the binocular vision positioning system 25, the marked point images obtained by the model posture in each test process are used to establish a perspective transformation imaging model of the high-speed camera using the principle of three-dimensional stereo vision, the intrinsic and extrinsic parameter matrices of the high-speed camera are calibrated, and the mapping relationship between spatial points and image points is established.

[0169] Based on the inherent constraints between the parameters of the high-speed camera, the intrinsic parameter matrix and extrinsic parameter matrix of the high-speed camera are obtained through matrix factorization algorithm. Based on the camera distortion model, the nonlinear distortion parameters of the camera are calibrated, and the distortion of the original image is corrected.

[0170] Based on the matching data of image points, a 3D reconstruction was performed to calculate the curve of the spatial coordinates of the centroid of the cone sleeve as a function of the oscillation time.

[0171] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; as long as there is no structural conflict, the various features in the specific embodiments disclosed in this application can be combined with each other in any way, and will not cause the substance of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

[0172] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for wind tunnel model deployment testing, characterized in that, Includes wind tunnel test section (17), tail support rod (18), tail support scissor (19), tail support transmission (20), test model (22), barrier net (23), deployment model, and binocular vision positioning system (25). The wind tunnel test section (17) is equipped with a tail support bevel (19), and the tail support drive (20) is installed on the tail support bevel (19). The test model (22) and the tail support drive (20) are connected by the tail support rod (18). The drop model is fixedly connected to the test model (22). The binocular vision positioning system (25) is installed outside the wind tunnel test section (17). A barrier net (23) is installed behind the tail support bevel (19). The deployment model includes a hanger (1), an electromagnet (2), an electromagnet cover plate (4), a limiter track (6), and a deployment object model; The top surface of the bracket (1) is fixedly connected to the test model (22). The bottom of the bracket (1) has two openings, and electromagnets (2) are installed inside the two openings. Two electromagnet cover plates (4) are installed at the bottom of the bracket (1) respectively corresponding to the two electromagnets (2). A limiter track (6) is set between the two openings. The object model includes a head section (7), a front magnetic section (8), a neodymium magnet with a countersunk hole (9), a middle section (12), a rear magnetic section (13), a tail section (15), and a limiter (16). The head section (7), front magnetic section (8), middle section (12), rear magnetic section (13), and tail section (15) of the model are sequentially spliced ​​and fixed. The front magnetic section (8) and the rear magnetic section (13) of the model are provided with mounting slots (11). The mounting slot (11) closest to the bracket (1) at the top is filled with a neodymium magnet (9) with a countersunk hole. The other mounting slots (11) are filled with counterweights. The limiter (16) is set on the middle section (12) of the model. The limiter (16) is in rolling contact with the limiter track (6). The bracket (1) is equipped with an electromagnet circuit inside; The electromagnet (2) is magnetically attracted to the neodymium magnet (9) with a countersunk hole.

2. The system for wind tunnel model deployment testing according to claim 1, characterized in that, On the left and right sides of the electromagnet circuit, a set of electronic switch groups are placed. Each set of electronic switch groups has two electronic switches arranged vertically. The electromagnet (2) is placed between the two sets of electronic switch groups. The electromagnet (2) and each set of electronic switch groups form two half bridges. The freewheeling diode is connected in parallel with the electronic switch in the opposite direction.

3. The system for wind tunnel model deployment testing according to claim 1, characterized in that, The end faces of the head section (7), middle section (12), and tail section (15) of the model are all provided with slots (14), and the end faces of the front magnetic section (8) and rear magnetic section (13) of the model are all provided with buckles (10). The buckles (10) are spliced ​​and fixed with the slots (14).

4. The system for wind tunnel model deployment testing according to claim 1, characterized in that, The electromagnet (2) is a square electromagnet.

5. The system for wind tunnel model deployment testing according to claim 1, characterized in that, The electromagnet cover plate (4) is provided with four screw holes (3), which are installed at the bottom of the bracket (1) by screws.

6. The system for wind tunnel model deployment testing according to claim 1, characterized in that, The binocular vision positioning system (25) includes two high-speed cameras.

7. The system for wind tunnel model deployment testing according to claim 1, characterized in that, The wind tunnel test section (17) is equipped with an elastic energy-absorbing protective pad (21) on its tunnel wall.

8. A system for wind tunnel model deployment testing according to claim 1, characterized in that, The two electromagnets (2) are controlled by a series circuit, and the coils of each electromagnet (2) are wound in the same direction.

9. A method for wind tunnel model deployment testing, implemented using the wind tunnel model deployment testing system as described in claim 1, characterized in that, Specifically: S1: Experimental design; S2: Installation of the test model; S21: Install the head section (7), front magnetic section (8), neodymium magnet with countersunk hole (9), middle section (12), rear magnetic section (13), and tail section (15) of the model onto the outer surface of each section for a smooth transition; S22: Correctly affix the checkerboard identification label to the surface of the assembled delivery model, and fix the hanger (1) to the test model (22) with screws; S23: The electromagnet circuit is energized, causing the two electromagnets (2) to generate magnetic force and attract and fix the object model with the neodymium magnet (9) with the countersunk hole. The relative position is adjusted by the limiter track (6) and the limiter (16) until the object model is in the correct position. S3: Binocular vision positioning system (25) equipment layout; S4: Begin wind tunnel model deployment test; S41: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started. S42: When the wind tunnel wind speed reaches the set value, the electromagnet circuit is closed. After the power is cut off, the magnetic force disappears, and the instantaneous state of the object model is free fall. S43: Binocular vision positioning system (25) records a series of image sequences of the pose of the object model during the placement process as time changes; S44: After the test is completed, the low-speed recirculation wind tunnel is shut down and the object model is retrieved and captured by the barrier net (23); S5: Begin the wind tunnel dynamic separation test with initial velocity; S51: At the start of the test, the electromagnet circuit is connected, and the continuous low-speed wind tunnel is started. S52: When the wind tunnel wind speed reaches the set value, the current in the electromagnet circuit is changed to the opposite direction, the direction of the magnetic force generated by the electromagnet (2) is reversed, and electromagnetic repulsion is generated with the neodymium magnet (9) with the sinker hole, which ejects the object model according to the calibrated initial velocity. S53: Binocular vision positioning system (25) records a series of image sequences of the pose of the object model during the placement process as time changes; S54: After the test is completed, the low-speed recirculation wind tunnel is shut down, and the object model is retrieved and captured by the barrier net (23); S6: According to the test plan, change the current of the neodymium magnet (9) with a countersunk hole or the electromagnet (2) to change the initial velocity of the release, repeat S2-S5, and continue the test process; S7: Experimental data analysis.

10. A method for wind tunnel model deployment testing according to claim 9, characterized in that, In S7, based on the real-time coordinates of the object fed back by the binocular vision positioning system (25), the marker point images obtained by the model posture in each test process are used to establish a high-speed camera perspective transformation imaging model using the three-dimensional stereo vision principle, and the high-speed camera internal and external parameter matrix is ​​calibrated to establish the mapping relationship between spatial points and image points. Based on the inherent constraints between the parameters of the high-speed camera, the intrinsic parameter matrix and extrinsic parameter matrix of the high-speed camera are obtained through matrix factorization algorithm. Based on the camera distortion model, the nonlinear distortion parameters of the camera are calibrated, and the distortion of the original image is corrected. Based on the matching data of image points, a 3D reconstruction was performed to calculate the curve of the spatial coordinates of the centroid of the cone sleeve as a function of the oscillation time.

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