A non-structured grid-based wind tunnel pressure data interpolation method

Abstract

The application belongs to the technical field of wind tunnel test, and discloses a wind tunnel pressure measurement data interpolation method based on unstructured grids. The wind tunnel pressure measurement data interpolation method based on unstructured grids comprises the following steps: reading in unstructured grid information, and obtaining normal vectors of grid points; reading in test data, and calculating normal vectors of test data points; obtaining n test data points closest to the grid points; performing pressure measurement data interpolation on the grid points, and obtaining aircraft surface pressure distribution and aerodynamic force. The wind tunnel pressure measurement data interpolation method based on unstructured grids can obtain the overall pressure distribution of the aircraft by interpolating irregular pressure measurement data points to the unstructured grids, and the method is simple and has engineering practical value.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, specifically relating to a wind tunnel pressure measurement data interpolation method based on unstructured grids. Background Technology

[0002] Wind tunnel pressure testing is used to obtain the pressure distribution on the surface of an aircraft. Traditional wind tunnel pressure testing requires setting up pressure measurement points in advance, numbering these points, and then obtaining the pressure at each point through wind tunnel testing. Due to limitations such as space and the number of pressure measurement points, the arrangement of these points is often irregular, making it difficult to obtain the overall pressure distribution of the aircraft.

[0003] Currently, there is an urgent need to develop a wind tunnel pressure measurement data interpolation method based on unstructured grids. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a wind tunnel pressure measurement data interpolation method based on unstructured grids to overcome the defects of the prior art.

[0005] The wind tunnel pressure measurement data interpolation method based on unstructured grids of the present invention includes the following steps: S10. Read in the unstructured mesh information and obtain the normal vectors of the mesh points; S20. Read in the experimental data and calculate the normal vector of the experimental data points; S30. Obtain the n test data points closest to the grid points; S40. Interpolate the pressure measurement data at the grid points to obtain the pressure distribution and aerodynamic forces on the aircraft surface.

[0006] Furthermore, S10 includes the following: The unstructured mesh information of the aircraft surface is read in. The unstructured mesh information of the aircraft surface includes the coordinate values ​​(X,Y,Z) of each mesh point, as well as the number and distribution of triangular meshes. Find the normal vector of each grid point; for grid point A, there are 4 triangles around it, namely triangle I, triangle II, triangle III, and triangle IV; the three grid points surrounding triangle I are grid point A, grid point B, and grid point C. Find the normal vector of triangle I. Continue to find the normal vectors of triangles II, III, and IV; obtain the normal vector of grid point A by area weighted average; finally, find the normal vectors of all grid points.

[0007] Furthermore, S20 includes the following: The test data is divided into M data segment and N data segment; the M data segment is the wind tunnel parameter segment, which includes, from front to back, the test vehicle number, Mach number, angle of attack, sideslip angle, velocity pressure and Reynolds number; the N data segment is the measurement data segment, which includes, from front to back, the pressure measurement point number and the pressure coefficient of the pressure measurement point. Input the coordinates of the test data points; the first row and first column are the component names, the first row and second column are the coordinate transformation indicators, 1 indicates that coordinate transformation is required, and 0 indicates that coordinate transformation is not required; the first row and third column y indicates the reverse sign of the coordinate y value; the second row contains the pressure point number and the pressure point coordinates (X, Y, Z); the pressure point numbers can be consecutive or non-consecutive. Calculate the distance between the test data point and the centers of all triangles, find the triangle closest to the test data point, and use the normal vector of the closest triangle as the normal vector of the test data point.

[0008] Furthermore, S30 includes the following: Based on the requirement that the angle between the data points and the normal vector of grid point A is within a pre-defined range, find the 8 test data points that are closest to grid point A.

[0009] Furthermore, S40 includes the following: S41. Interpolate the pressure measurement data at the grid points; The pressure measurements from the n closest test data points to grid point A are weighted by inverse distance, and the pressure data at grid point A is interpolated to obtain the pressure value at grid point A. : ; in, is the pressure value at grid point A; n is the number of test data points participating in the reverse distance weighting. It is the first Pressure measurements at each test data point; , It is the first The distance from each test data point to grid point A It is a positive number of acts; S42. Obtain the surface pressure distribution and aerodynamic forces of the aircraft; The pressure values ​​corresponding to grid points A, B, and C of triangle I are PA, PB, and PC, respectively. The average value P1 is taken as the pressure value of triangle I, P1 = (PA + PB + PC) / 3. Then, the pressure values ​​of all triangular grids are obtained, and a pressure distribution cloud map of the aircraft surface is drawn. Because the normal vector of triangle I The area of ​​triangle I Then the aerodynamic force of triangle I ; The aerodynamic forces of all triangles are summed to obtain the aerodynamic forces of the aircraft.

[0010] The wind tunnel pressure measurement data interpolation method based on unstructured grids of the present invention obtains the overall pressure distribution of the aircraft by interpolating irregular pressure measurement data points onto an unstructured grid. The method is simple and has practical engineering value. Attached Figure Description

[0011] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0012] Figure 1 This is a flowchart of the wind tunnel pressure measurement data interpolation method based on unstructured grids according to the present invention; Figure 2 For unstructured meshes on the surface of the aircraft; Figure 3 This is a schematic diagram of the grid points; Figure 4 The normal vector of the grid point; Figure 5 A schematic diagram for determining the normal vectors of experimental data points; Figure 6 These are the 8 nearest test data points corresponding to each grid point; Figure 7 The pressure distribution cloud map on the surface of the aircraft (Mach number M2.0, α=10°, pressure coefficient cp); Figure 8 The Cyt-α curve of the aircraft at Mach number 2 obtained for the example; Figure 9 The Mz-α ​​curve of the aircraft at Mach number 2 obtained for the example is shown. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] Example: Figure 1 As shown, the wind tunnel pressure measurement data interpolation method based on unstructured grids in this embodiment includes the following steps: S10. Read in the unstructured mesh information and obtain the normal vectors of the mesh points; S20. Read in the experimental data and calculate the normal vector of the experimental data points; S30. Obtain the n test data points closest to the grid points; S40. Interpolate the pressure measurement data at the grid points to obtain the pressure distribution and aerodynamic forces on the aircraft surface.

[0015] Furthermore, S10 includes the following: Reading in Figure 2 The unstructured mesh information of the aircraft surface shown includes the coordinates (X, Y, Z) of each mesh point, as well as the number and distribution of triangular meshes. Find the normal vector for each grid point; for example Figure 3 As shown, for grid point A, there are four triangles surrounding grid point A: triangle I, triangle II, triangle III, and triangle IV. Figure 4 As shown, the three grid points surrounding triangle I are grid point A, grid point B, and grid point C. The normal vector of triangle I is... Continue to find the normal vectors of triangles II, III, and IV; obtain the normal vector of grid point A by area weighted average; finally, find the normal vectors of all grid points.

[0016] Furthermore, S20 includes the following: As shown in Table 1, the test data is divided into M data segment and N data segment; the M data segment is the wind tunnel parameter segment, which consists of the test vehicle number, Mach number, angle of attack, sideslip angle, velocity pressure and Reynolds number from front to back; the N data segment is the measurement data segment, which consists of the pressure measurement point number and pressure coefficient of the pressure measurement point from front to back. Table 1. Experimental Data Format ; As shown in Table 2, input the coordinates of the test data points; the first row and first column are the component names, the first row and second column are the coordinate transformation indicators, 1 indicates that coordinate transformation is required, and 0 indicates that coordinate transformation is not required; the first row and third column y indicates the reverse sign of the coordinate y value; the second row contains the pressure point number and the pressure point coordinates (X, Y, Z); the pressure point numbers can be consecutive or non-consecutive. Table 2. Format of test data point coordinates ; like Figure 5 As shown, the distance between the test data point and the center of all triangles is calculated, the triangle with the closest distance is obtained, and the normal vector of the triangle with the closest distance is used as the normal vector of the test data point.

[0017] Furthermore, S30 includes the following: like Figure 6 As shown, based on the requirement that the angle between the data points and the normal vector of grid point A is within a pre-defined angle range, the eight test data points closest to grid point A are found. In this embodiment, the angle range is within 10°.

[0018] Furthermore, S40 includes the following: S41. Interpolate the pressure measurement data at the grid points; The pressure measurements from the n closest test data points to grid point A are weighted by inverse distance, and the pressure data at grid point A is interpolated to obtain the pressure value at grid point A. : ; in, is the pressure value at grid point A; n is the number of test data points participating in the reverse distance weighting, and in this embodiment, n=8; It is the first Pressure measurements at each test data point; , It is the first The distance from each test data point to grid point A It is a positive number of episodes; in this embodiment, it is taken as... ; S42. Obtain the surface pressure distribution and aerodynamic forces of the aircraft; The pressure values ​​corresponding to grid points A, B, and C in triangle I are PA, PB, and PC, respectively. The average value P1 is taken as the pressure value of triangle I, where P1 = (PA + PB + PC) / 3. Then, the pressure values ​​of all triangular grids are obtained and plotted as follows. Figure 7 The image shows a cloud map of the pressure distribution on the surface of the aircraft. Because the normal vector of triangle I The area of ​​triangle I Then the aerodynamic force of triangle I ; The aerodynamic forces of all triangles are summed to obtain the aerodynamic forces of the aircraft.

[0019] This embodiment obtains as follows: Figure 8 The Cyt-α curve of the aircraft shown is as follows: Figure 9 The figure shows the Mz-α ​​curve of the aircraft; in the figure, Cyt is the lift coefficient, Mz is the pitch moment coefficient, and α is the angle of attack of the aircraft. Figure 8 , Figure 9 It can be seen that the aerodynamic forces and force measurements of the aircraft obtained by the wind tunnel pressure measurement data interpolation method based on unstructured grids of the present invention have good consistency, which has a positive effect on the use and research of wind tunnel pressure measurement data.

[0020] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A wind tunnel pressure measurement data interpolation method based on unstructured grids, characterized in that, Includes the following steps: S10. Read in the unstructured mesh information and obtain the normal vectors of the mesh points; The unstructured mesh information of the aircraft surface is read in. The unstructured mesh information of the aircraft surface includes the coordinate values ​​(X, Y, Z) of each mesh point, as well as the number and distribution of triangular meshes. Find the normal vector of each grid point; for grid point A, there are 4 triangles around it, namely triangle I, triangle II, triangle III, and triangle IV; the three grid points surrounding triangle I are grid point A, grid point B, and grid point C. Find the normal vector of triangle I. Continue to find the normal vectors of triangles II, III, and IV; obtain the normal vector of grid point A by area-weighted averaging; finally, find the normal vectors of all grid points. S20. Read in the experimental data and calculate the normal vector of the experimental data points; The test data is divided into M data segment and N data segment; the M data segment is the wind tunnel parameter segment, which includes, from front to back, the test vehicle number, Mach number, angle of attack, sideslip angle, velocity pressure and Reynolds number; the N data segment is the measurement data segment, which includes, from front to back, the pressure measurement point number and the pressure coefficient of the pressure measurement point. Input the coordinates of the test data points; the first row and first column are the component names, the first row and second column are the coordinate transformation indicators, 1 indicates that coordinate transformation is required, and 0 indicates that coordinate transformation is not required; the first row and third column y indicates the reverse sign of the coordinate y value; the second row contains the pressure point number and the pressure point coordinates (X, Y, Z); the pressure point numbers can be consecutive or non-consecutive. Find the distance between the test data point and the center of all triangles, obtain the triangle with the closest distance, and use the normal vector of the triangle with the closest distance as the normal vector of the test data point; S30. Obtain the n test data points closest to the grid points; S40. Interpolate the pressure measurement data at the grid points to obtain the pressure distribution and aerodynamic forces on the aircraft surface; the specific steps are as follows: S41. Interpolate the pressure measurement data at the grid points; The pressure measurements from the n closest test data points to grid point A are weighted by inverse distance, and the pressure data at grid point A is interpolated to obtain the pressure value at grid point A. : ； in, is the pressure value at grid point A; n is the number of test data points participating in the reverse distance weighting. It is the first Pressure measurements at each test data point; , It is the first The distance from each test data point to grid point A It is a positive number of acts; S42. Obtain the surface pressure distribution and aerodynamic forces of the aircraft; The pressure values ​​corresponding to grid points A, B, and C of triangle I are PA, PB, and PC, respectively. The average value P1 is taken as the pressure value of triangle I, P1 = (PA + PB + PC) / 3. Then, the pressure values ​​of all triangular grids are obtained, and a pressure distribution cloud map of the aircraft surface is drawn. Because the normal vector of triangle I The area of ​​triangle I Then the aerodynamic force of triangle I ; The aerodynamic forces of all triangles are summed to obtain the aerodynamic forces of the aircraft.

2. The wind tunnel pressure measurement data interpolation method based on unstructured grids according to claim 1, characterized in that, S30 includes the following: Based on the requirement that the angle between the data points and the normal vector of grid point A is within a pre-defined range, find the 8 test data points that are closest to grid point A.

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