Turbine vector engine tail flame angle measurement method, electronic equipment and storage medium

Abstract

The present invention proposes a method for measuring the tail flame angle of a turbine vector engine suitable for a wind tunnel, and belongs to the technical field of wind tunnel tests. The method comprises: S1, installing an infrared camera with an adjustable pitch angle for shooting tail flame images, and placing an infrared calibration plate in the test area; S2, selecting corner points on the infrared calibration plate, and calculating the number of millimeters per pixel of the image within the shooting range of the infrared camera according to the Euclidean distance of the corner points in the image coordinate system and the number of checkerboards between the corner points and the infrared calibration plate, and performing camera attitude correction; S3, collecting the tail flame image of the engine nozzle during the test; S4, removing the interfering background area in the tail flame image during the test, and obtaining a set of test tail flame images under a standard viewing angle after removing the interfering background area; S5, solving the tail flame angle. A method for obtaining an accurate tail flame angle during a wind tunnel test is provided, which is of great significance for engineers to optimize the nozzle design and improve the control accuracy of the thrust vector.

Description

Technical Field

[0001] The invention relates to a method for measuring the tail flame angle of a turbine vector engine, electronic equipment and a storage medium, and belongs to the technical field of wind tunnel testing. Background Art

[0002] The turbine vectoring engine is a key technology in modern aviation engine technology, which enables the aircraft to maintain excellent maneuverability and control performance under extreme flight conditions. By controlling the engine nozzle, the thrust direction of the aircraft is dynamically adjusted. The introduction of this technology greatly expands the maneuverability range of the aircraft.

[0003] The development of turbine vectoring engines is inseparable from precise and complex wind tunnel tests. Wind tunnel tests provide a controlled environment in which the engine design, aerodynamic characteristics, and thrust vector control systems can be evaluated and optimized before actual flight. By simulating different flight conditions, researchers can understand in detail the performance of the engine in various operating environments and promptly identify and resolve possible design defects. This type of test is a necessary step to ensure that the reliability and performance of the engine meet strict military standards.

[0004] The measurement of tail plume (or nozzle wake) is a key step in wind tunnel testing, which involves a detailed analysis of the hot air flow and pressure field emitted by the engine. The angle and shape of the tail plume directly affect the thrust efficiency of the aircraft and the stability of the subsequent airflow, which has a direct impact on the overall performance and maneuverability of the aircraft. Accurately measuring the tail plume can help engineers optimize the nozzle design and improve the control accuracy of the thrust vector, making the aircraft more stable and efficient in complex maneuvers.

[0005] In wind tunnel tests of turbine vectoring engines, accurate measurement of the tail flame angle is crucial to verifying and optimizing engine performance. However, the measurement of the tail flame angle faces multiple challenges in practice, which stem from the limitations of the measurement method and the complexity of the experimental environment. Traditionally, the measurement method of the tail flame angle includes using physical measuring tools (such as angle rulers or turntables) to directly measure the jet angle at the nozzle outlet, or using simple photography techniques to record the shape of the tail flame and then analyze it. The advantages of these methods are intuitive operation and low cost, but there are obvious shortcomings in accuracy and practicality.

[0006] With the advancement of technology, optical measurement methods have become the first choice for measuring tail flame angles. These methods can provide real-time, continuous tail flame images, supporting the accurate capture of the dynamic characteristics of the tail flame. Optical methods can provide higher spatial and temporal resolution, and can also perform non-contact measurements of temperature, velocity and other important physical quantities in the tail flame. Although optical methods are superior in theory, in practical applications, conventional optical images are still difficult to obtain clear, high-quality tail flame images in high-speed, high-temperature wind tunnel environments. The spatial limitations and environmental interference in the wind tunnel may make it difficult for the camera to remain strictly parallel to the ground, resulting in a deviation between the measured tail flame angle and the true angle. Summary of the invention

[0007] A brief overview of the present invention is provided below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0008] In view of this, in order to solve the technical problems that it is still difficult to obtain clear and high-quality tail flame images with conventional optical images in the high-speed and high-temperature wind tunnel environment in the prior art, and that the space limitation and environmental interference in the wind tunnel may make it difficult for the camera to remain strictly parallel to the ground, thereby causing the measured tail flame angle to deviate from the true angle, the present invention provides a method for measuring the tail flame angle of a turbine vector engine. The present invention is suitable for measuring the tail flames of various turbine vector engine models under the Mach number range of 0-4 Mach.

[0009] Solution 1: Method for measuring tail flame angle of turbine vectoring engine, including:

[0010] S1. An infrared camera with adjustable pitch angle is installed on the upper wall of the wind tunnel to capture the tail flame image. An infrared calibration plate is placed in the test area before the test begins.

[0011] S2. Select a corner point on the infrared calibration board, calculate the number of millimeters per pixel of the image within the range of the infrared camera according to the Euclidean distance of the corner point in the image coordinate system and the number of checkerboards between the corner point and the infrared calibration board, obtain the change relationship, perform camera posture correction, and obtain a correction matrix;

[0012] S3, taking out the infrared calibration plate, starting the test, and collecting the image of the engine nozzle tail flame during the test;

[0013] S4, removing the interfering background area in the tail flame image during the test, aligning the test tail flame image to a standard viewing angle, and obtaining a set of test tail flame images at the standard viewing angle with the interfering background area removed;

[0014] S5. Calculate the tail flame angle.

[0015] Preferably, it also includes sorting the test tail flame images after collecting them during the test in S3, and retaining the test tail flame images containing the tail flames. The specific steps include: screening by the average gray value of the image, invalid data is data with insufficient temperature or no tail flame. Due to the particularity of infrared images, the average gray value of the invalid data is much smaller than the gray value of the valid data, so the image threshold is set. , when the gray value of the image is less than Delete the image when

[0016] Preferably, it also includes drawing a fitting straight line in the image in the test to display the tail flame trend, and the specific steps include: , is an integer, as the v value, substituted into =b+k In the equation, we get the coordinate sequence of the points on the line { }, For when given When , the coordinates of the point on the straight line in the u direction; Indicates the row number of the first row of the tail flame area. Indicates the number of the last row of the tail flame area; according to the point coordinate sequence on the image { }, draw a straight line on the test tail flame image, and the image collection collected during the test Draw a straight line on it; where k is the slope of the straight line equation, b is the intercept on the v axis, u represents the horizontal axis coordinate in the image coordinate system, and v represents the vertical axis coordinate in the image coordinate system.

[0017] Preferably, S2 comprises the following steps:

[0018] Set the corner points on the infrared calibration board by corner point detection or manual selection to obtain the image coordinates of the four corner points , , , ;

[0019] Calculate corner point 1 and corner point 2 Euclidean distance in pixel coordinates = , according to the actual spacing of each chessboard grid , and the number of checkerboard squares between corner 1 and corner 2 , calculate the number of millimeters per pixel of the image within the range of the infrared camera k = , where K represents the number of millimeters per pixel in the image within the range of the infrared camera.

[0020] Preferably, the step of performing camera posture correction to obtain a correction matrix includes:

[0021] In the plane of the infrared calibration plate, considering the positional relationship in the plane, the coordinates of corner point 1 are set to (0,0), then the coordinates of corner point 2, corner point 3 and corner point 4 are expressed as (0, ), ( ,0), ( , ), is the number of chessboard squares between corner point 1 and corner point 3;

[0022] Define that in the image of the infrared calibration plate at a standard viewing angle, the horizontal axis of the infrared calibration plate plane is parallel to the horizontal axis of the image coordinate system, and the vertical axis is parallel to the vertical axis of the image coordinate system. Then, in the standard plane state, the image coordinates of corner points 1, 2, 3, and 4 are based on the number of millimeters per pixel in the image within the range of the infrared camera k and the coordinates of corner point 1 in the image. get:

[0023] = + = ;

[0024] = + =( , + );

[0025] = + =( , );

[0026] = =( , + );

[0027] Will - , mapped to by affine transformation - , get the transformation relationship of camera calibration, that is, the transformation relationship from the current perspective to the standard perspective, that is, construct each point on the image To the image coordinates under the standard viewing angle The transformation matrix relationship:

[0028] ;

[0029] in, Expressed as - The coordinates of any point in ;

[0030] a, b, c, d, e are the transformation coefficients to be solved. A matrix relationship is constructed for each point and organized into a system of equations. The solution is based on the least squares method, then R = is the correction matrix to be solved.

[0031] Preferably, the step of removing the nozzle area in the test tail flame image comprises:

[0032] The method of filtering and obtaining the nozzle profile according to the following rules is: histogram equalization of the image without flame spraying;

[0033] The Otsu method is used to automatically calculate the binarization threshold of the image, and all pixels with values ​​higher than the threshold are set to 1, and the remaining pixel values ​​are set to 0, thus obtaining a rough binarized image.

[0034] Use the Canny edge detection algorithm to extract the contours in the binary image, obtain multiple contours, and give the upper limit of the contour size threshold and lower limit , if the contour size is larger than Small life If it is large, the profile is not a nozzle profile;

[0035] The method for obtaining the test tail flame image without the nozzle area is: set the approximation accuracy parameter, use the Ramer-Douglas-Peucker algorithm to reduce the number of contour points; iteratively delete the point with the shortest distance on the line segment until the distance from all points to their corresponding line segments does not exceed the set approximation accuracy parameter, and obtain the minimum contour points. Based on this, the simplified polygonal nozzle contour is obtained and the mask is constructed. , set the value of the nozzle contour area to 0, and the value of the non-nozzle area to 1; all subsequent test images are The test tail flame image with the nozzle area removed is obtained by multiplication.

[0036] Preferably, the step of calculating the tail flame angle comprises:

[0037] Test tail flame image with the nozzle area data removed , whose image size is , that is, in the image coordinate system, the horizontal pixel range is 0- , the vertical pixel range is 0- ; Set the tail flame interval in the vertical direction , where up is the initial row number and down is the end row number. Let the coordinate set of all pixels in any row of the tail flame interval on the infrared image be , , take the pixel with the largest gray value coordinate , then the image point coordinate sequence with the maximum gray value in each row is obtained in the tail flame interval , according to the coordinates of the image points, fit a straight line;

[0038] According to the coordinates of the image points, the steps of fitting a straight line include: calculating the average values ​​of all horizontal and vertical coordinates: = , = ;

[0039] The formula for calculating the slope of a straight line is:

[0040] k= ;

[0041] The formula for calculating the intercept of a line is:

[0042] b= -k ;

[0043] Calculate the angle between the straight line and the vertical direction, that is, the angle between the tail flame and the horizontal direction: .

[0044] Solution 2: An electronic device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for measuring the tail flame angle of a turbine vector engine described in Solution 1 are implemented.

[0045] Solution three: A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for measuring the tail flame angle of a turbine vector engine described in Solution one.

[0046] The beneficial effects of the present invention are as follows: the tail flame of the nozzle is photographed through germanium glass by an infrared camera to obtain a clear, high-quality image with high and low temperature characteristics, and the infrared calibration plate suitable for the infrared camera is used to calibrate the camera when it is not installed perpendicular to the ground, so as to eliminate the problem of projection angle in the directly measured angle caused by the tilt of the installation position. In addition, the nozzle model area is extracted from the collected infrared image through ostu adaptive binarization, Canny edge detection, and Ramer-Douglas-Peucker algorithm, and the corresponding area mask is extracted to ensure that the nozzle in the image will not interfere with the settlement of the tail flame angle; the straight line used to describe the tail flame is extracted through the gray value of the tail flame, so as to settle the tail flame angle. The present invention can obtain accurate tail flame angles during wind tunnel tests, which is of great significance for engineers to optimize nozzle design and improve the control accuracy of thrust vectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1 The flowchart of the method for measuring the tail flame angle of a turbine vectoring engine is as follows;

[0049] Figure 2 This is a schematic diagram of the structure for measuring the tail flame angle of a turbine vectoring engine;

[0050] Figure 3 It is the infrared image field of view;

[0051] Figure 4 This is a schematic diagram of the infrared calibration board;

[0052] Figure 5 Schematic diagram of the corner points of the infrared calibration plate;

[0053] Figure 6 Schematic diagram of infrared images during the test.

[0054] In the figure, 1-nozzle; 2-tail flame; 3-first L-shaped block; 4-second L-shaped block; 5-germanium glass; 6-infrared camera; 7-; 8-infrared calibration plate; 9-roll adjustable bracket; 10-screw; 11-angle piece; 12-electric lifting platform; 13-high-precision inclinometer. DETAILED DESCRIPTION

[0055] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0056] Example 1: Reference Figure 1 The present embodiment is described as follows: a method for measuring the tail flame angle of a turbine vectoring engine, characterized by comprising:

[0057] S1. An infrared camera with adjustable pitch angle is installed on the upper wall of the wind tunnel to capture the tail flame image. An infrared calibration plate is placed in the test area before the test begins.

[0058] Reference Figure 2 As shown in the figure, the specific operation process of installing an infrared camera with adjustable pitch angle on the upper wall of the wind tunnel is as follows: a threaded hole is processed on the rib plate of the upper wall plate of the wind tunnel, and the first L-shaped block 3 is installed on the rib plate by screws; the second L-shaped block 4 is installed on the first L-shaped block 3 by screws, and the camera pitch direction angle is adjusted according to the installation position. The infrared camera 6 is installed on the second L-shaped block 4 by screws, and the camera side sliding direction angle is adjusted according to the installation position. After adjustment, the nozzle 1 is located on the central axis of the field of view. Figure 3 As shown, a relatively complete tail flame 2 can be observed through the germanium glass 5.

[0059] An infrared calibration plate is placed in the test area to calibrate the infrared camera and eliminate the problem that the calculated angle is not the actual deflection angle due to the lens being perpendicular to the ground after the camera is installed.

[0060] The infrared calibration plate 8 is composed of a checkerboard pattern made of materials with different reflectivities, which can clearly display each grid under an infrared camera. The grids include black and white; the white grids are made of high-reflective materials, which are preferably metals or special reflective coatings; the black grids reflect infrared light and are made of low-reflectivity materials, preferably plastic or materials coated with special absorption coatings, which are used to absorb reflected infrared light.

[0061] Reference Figure 4As shown, the infrared calibration plate 8 is placed on a bracket 9 with adjustable pitch and roll. The adjustable bracket 9 is adjusted by screws 10 on the bracket, and the infrared calibration plate is fixed to the adjustable bracket 9 by corner pieces 11. The high-precision inclinometer 13 is placed at the center of the calibration plate, and the screws 10 on the bracket are adjusted so that the angles of the high-precision inclinometer 13 in the pitch direction and the roll direction are both 0 degrees, so that the infrared calibration plate 8 is parallel to the wind tunnel floor. The height of the infrared calibration plate 8 is adjusted by the electric lifting platform 12 so that the height of the infrared calibration plate is consistent with the height of the nozzle in the 0 attitude state.

[0062] After adjusting the position, take away the high-precision inclinometer 13, and use the installed infrared camera to take an image of the infrared calibration plate.

[0063] S2, select a corner point on the infrared calibration board, calculate the number of millimeters per pixel of the image within the range of the infrared camera according to the Euclidean distance of the corner point in the image coordinate system and the number of checkerboards between the corner point and the infrared calibration board, obtain the transformation relationship, perform camera posture correction, and obtain the correction matrix;

[0064] Set 4 corner points on the infrared calibration board by corner point detection or manual selection to obtain the reference Figure 5 The image coordinates of the 4 corner points shown , , , ,In the figure, x represents the horizontal direction and y represents the vertical direction;

[0065] Calculate corner point 1 and corner point 2 Euclidean distance in pixel coordinates = , according to the actual spacing of each chessboard grid , and the number of checkerboard squares between corner point 1 and corner point 2 , calculate the number of millimeters per pixel of the image within the range of the infrared camera K = , K represents the number of millimeters per pixel of the image within the range of the infrared camera.

[0066] The steps to calibrate the camera posture and obtain the correction matrix include:

[0067] In the plane of the infrared calibration plate, considering the positional relationship in the plane, the coordinates of corner point 1 are set to (0,0), then the coordinates of corner point 2, corner point 3 and corner point 4 can be expressed as (0, ), ( ,0), ( , ), is the number of chessboard squares between corner point 1 and corner point 3;

[0068] Definition: Under the standard viewing angle, the horizontal axis of the infrared calibration plate plane is parallel to the horizontal axis of the image coordinate system, and the vertical axis is parallel to the vertical axis of the image coordinate system, that is, the infrared camera lens is completely perpendicular to the ground, that is, the direction from corner point 1 to corner point 2 is vertical, that is, perpendicular to the ground, and the direction from corner point 1 to corner point 3 is horizontal, that is, parallel to the ground, such as Figure 4 As shown; then in the standard plane state, the image coordinates of corner points 1, 2, 3 and 4 are based on the number of millimeters per pixel in the image within the range of the infrared camera and the coordinates of corner point 1 in the image get:

[0069] = + = ;

[0070] = + =( , + );

[0071] = + =( , );

[0072] = =( , + );

[0073] Will - , mapped to by affine transformation - , get the transformation relationship of camera calibration, that is, the transformation relationship from the current perspective to the standard perspective, and construct the transformation relationship of each point on the image Coordinates to the standard perspective The transformation matrix relationship:

[0074] ;

[0075] in, Expressed as - The coordinates of any point in ;

[0076] a, b, c, d, e are the transformation coefficients to be solved. A matrix relationship is constructed for each point and organized into a system of equations. The solution is based on the least squares method, then R = is the correction matrix to be solved.

[0077] S3, taking out the infrared calibration plate, starting the test, and collecting the test tail flame image during the test;

[0078] When the test starts, the infrared calibration plate is taken out. During the test, the test angle state is reached first, and then the flame spraying is started and the test tail flame image is collected after the flow field is stable. After the flame spraying stops, the collection of the test tail flame image is stopped.

[0079] S4, removing the interfering background area in the tail flame image during the test, aligning the test tail flame image to a standard viewing angle, and obtaining a set of test tail flame images at the standard viewing angle with the interfering background area removed;

[0080] Obtain the nozzle area mask data to eliminate the nozzle area of ​​the test data and avoid the nozzle area interfering with the settlement angle. Figure 6 As shown in the figure, when the flame is sprayed, the temperature of the nozzle is very high, which will interfere with the extraction of complete tail flame data. Therefore, this area is removed; the histogram equalization of the image without flame spraying is used to improve the contrast of the image and make the distinction between the nozzle model and the wind tunnel background more obvious; because the reflectivity of the model is inconsistent with the wind tunnel wall, the Otsu method can be used to automatically calculate the threshold of the binarization of the test tail flame image, and all pixel values ​​​​higher than the threshold are set to white (or 1), and the rest are set to black (or 0) to obtain a rough binarized image. The Canny edge detection algorithm is used to extract the contour of the test tail flame image, and the contour is screened, and the upper limit of the contour size threshold is given. and lower limit , if the contour size is larger than Smaller or smaller If the distance between the points is too large, the contour is not the nozzle contour. The polygonal approximation method is used to smooth the contour line and reduce the jaggedness of the contour. Specifically, the approximation accuracy parameter is set first (generally the distance threshold is selected), and the Ramer-Douglas-Peucker algorithm is used to reduce the number of contour points. The algorithm iteratively deletes the point with the shortest distance on the line segment until the distance between all points and their corresponding line segments does not exceed the set threshold, and finally generates a simplified polygonal contour. Then construct a mask , set the value of the nozzle contour area to 0 and the value of the non-nozzle area to 1;

[0081] The specific processing process of removing the mask data of the nozzle area in the test tail flame image is as follows:

[0082] The method for obtaining the nozzle outline by screening according to the following rules is: performing histogram equalization on the image without flame spraying; automatically calculating the binarization threshold of the image by Otsu method, setting the values ​​of all pixels with values ​​higher than the threshold to 1, and setting the values ​​of the remaining pixels to 0, to obtain a rough binarized image;

[0083] Use the Canny edge detection algorithm to extract the contours in the binarized image and obtain multiple contours Given an upper threshold for contour size and lower limit , if the contour size is larger than Smaller or smaller If it is large, the profile is not a nozzle profile;

[0084] The method for obtaining the test tail flame image without the nozzle area is: set the approximation accuracy parameter, use the Ramer-Douglas-Peucker algorithm to reduce the number of contour points; iteratively delete the point with the shortest distance on the line segment until the distance from all points to their corresponding line segments does not exceed the set approximation accuracy parameter, and obtain the minimum contour points. Based on this, the simplified polygonal nozzle contour is obtained and the mask is constructed. , set the value of the nozzle contour area to 0 and the value of the non-nozzle area to 1.

[0085] All subsequent test images were The test tail flame image with the nozzle area removed is obtained by multiplication.

[0086] S5. Calculate the tail flame angle. Based on the transformation relationship, correct the engine nozzle tail flame image during the test to calculate the tail flame angle; remove the test tail flame image of the nozzle area data. , assuming the test tail flame image size is , that is, in the image coordinate system, the horizontal pixel range is 0- , the vertical pixel range is 0- ; Set the tail flame interval in the vertical direction , where up is the initial row number and down is the end row number, refer to Figure 6 As shown; suppose the coordinate set of all pixels in any row of the tail flame interval on the infrared image is , , take the pixel with the largest gray value coordinate , then the image point coordinate sequence with the maximum gray value in each row is obtained in the tail flame interval , according to the coordinates of the image points, fit a straight line;

[0087] According to the coordinates of the image points, the steps of fitting a straight line include: the average value of all horizontal coordinates and vertical coordinates: = , = ;

[0088] The formula for calculating the slope of a straight line is:

[0089] k= ;

[0090] The formula for calculating the intercept of a line is:

[0091] b= -k ;

[0092] Calculate the angle between the straight line and the vertical direction, that is, the angle between the tail flame and the horizontal direction: .

[0093] Embodiment 2: The difference between this embodiment and embodiment 1 is that the measurement method further comprises S6, sorting the images after collecting the test tail flame images during the test in S3, and retaining the test tail flame images including the tail flame;

[0094] Screening is performed based on the average grayscale value of the image. Data with insufficient temperature or no tail flame is regarded as invalid data. The average grayscale value of the image of invalid data is less than the average grayscale value of the image of valid data. Therefore, the threshold is set. , when the average gray value of the image is less than Delete the image when

[0095] Embodiment 3: The difference between this embodiment and embodiment 1 and embodiment 2 is that the measurement method further comprises S7, drawing a fitting straight line in the image under test to visualize the tail flame trend, and drawing a fitting straight line in the image =b+k , k is the slope of the straight line equation, b is the intercept on the v axis, u represents the horizontal axis coordinate in the image coordinate system, and v represents the vertical axis coordinate in the image coordinate system. The specific steps to achieve visualization include:

[0096] Any , is an integer, as the v value, substituted into =b+k In the equation, we get the coordinate sequence of the points on the line { }, For a given When , the coordinates of the point on the straight line in the u direction; Indicates the row number of the first row of the tail flame area. Indicates the number of the last row of the tail flame area; according to the point coordinate sequence on the image { }, draw a straight line on the test tail flame image. Similarly, the image set collected during the test Draw a straight line on.

[0097] Embodiment 4: The computer device of the present invention may be a device including a processor and a memory, such as a single chip microcomputer including a central processing unit, etc. Moreover, the processor is used to implement the steps of the above-mentioned turbine vector engine tail flame angle measurement method when executing the computer program stored in the memory.

[0098] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0099] The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0100] Embodiment 5: Computer readable storage medium embodiment.

[0101] The computer-readable storage medium of the present invention can be any form of storage medium that can be read by the processor of a computer device, including but not limited to non-volatile memory, volatile memory, ferroelectric memory, etc. A computer program is stored on the computer-readable storage medium. When the processor of the computer device reads and executes the computer program stored in the memory, the steps of the above-mentioned turbine vector engine tail flame angle measurement method can be implemented.

[0102] The computer program includes computer program code, which may be in source code form, object code form, executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer readable media do not include electric carrier signals and telecommunication signals.

[0103] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

Claims

1. A method for measuring the tail flame angle of a turbine vectoring engine, characterized in that: include: S1. An infrared camera with adjustable pitch angle is installed on the upper wall of the wind tunnel to capture the tail flame image during the test. An infrared calibration plate is placed in the test area before the test begins. S2, select a corner point on the infrared calibration board, calculate the number of millimeters per pixel of the image within the range of the infrared camera according to the Euclidean distance of the corner point in the image coordinate system and the number of checkerboards between the corner point and the infrared calibration board, obtain the transformation relationship, perform camera posture correction, and obtain the correction matrix; S2 includes the following steps: Set four corner points on the infrared calibration board by corner point detection or manual selection, and obtain the image coordinates of the four corner points pts1(u1,v1), pts2(u2,v2), pts3(u3,v3), pts4(u4,v4); Calculate the Euclidean distance between corner point 1pts1(u1,v1) and corner point 2pts2(u2,v2) in pixel coordinate system According to the actual spacing d of each chessboard calib , and the number of checkerboard squares n between corner point 1 and corner point 2 1→2 , calculate the number of millimeters per pixel of the image within the range of the infrared camera K = d pixel / n 1→2 ×d calib , where K represents the number of millimeters per pixel of the image within the range of the infrared camera; The steps to calibrate the camera posture and obtain the correction matrix include: In the plane of the infrared calibration plate, set the coordinates of corner point 1 to Then the coordinates of corner points 2, 3, and 4 are expressed as n 1→3 is the number of chessboard squares between corner point 1 and corner point 3; Define that in the image of the infrared calibration plate at a standard viewing angle, the horizontal axis of the infrared calibration plate plane is parallel to the horizontal axis of the image coordinate system, and the vertical axis is parallel to the vertical axis of the image coordinate system. Then, in the standard plane state, the image coordinates of corner points 1, 2, 3, and 4 are obtained based on the number of millimeters per pixel k in the image within the range of the infrared camera and the coordinates pts1(u1,v1) of corner point 1 in the image: Map pts1-pts4 to Get the transformation relationship of camera calibration and construct the image coordinates (u ′ ,v ′ )’s transformation matrix relationship: Among them, (u ′ ,v ′ )for The coordinates of any point, (u, v) are expressed as the coordinates of any point in pts1-pts4; a, b, c, d, e are the transformation coefficients to be solved. A matrix relationship is constructed for each point and organized into a system of equations. The solution is based on the least squares method. is the correction matrix to be solved; S3, take out the infrared calibration plate, start the test, and collect the tail flame image during the test; S4, removing the interfering background area in the tail flame image during the test, aligning the tail flame image during the test to a standard viewing angle, and obtaining a set of tail flame images during the test at the standard viewing angle with the interfering background area removed; S5. Calculate the tail flame angle.

2. The method for measuring the tail flame angle of a turbine vectoring engine according to claim 1, characterized in that: The method further includes sorting the tail flame images during the test after the tail flame images during the test are collected in S3, and retaining the tail flame images during the test including the tail flame. The specific steps include: setting an image threshold ε, and deleting the image when the gray value of the image is less than ε.

3. The method for measuring the tail flame angle of a turbine vectoring engine according to claim 1, characterized in that: The method also includes drawing a fitting straight line in the tail flame image during the test. The specific steps include: i ∈[n up , n down ],n i is an integer, as the v value, substituted into v = b + k × u, and the coordinate sequence of the points on the straight line is obtained. For a given n i When , the coordinates of the point on the straight line in the u direction; n up Indicates the row number of the first row of the tail flame area, n down Indicates the number of the last row of the tail flame area; according to the point coordinate sequence on the straight line A collection of test tail flame images collected during the test Draw a straight line on it; where k is the slope of the straight line equation, b is the intercept on the v axis, u represents the horizontal axis coordinate in the image coordinate system, and v represents the vertical axis coordinate in the image coordinate system.

4. The method for measuring the tail flame angle of a turbine vectoring engine according to claim 1, characterized in that: The steps of removing the mask data of the nozzle area in the tail flame image during the test include: The method of obtaining the nozzle profile by screening according to the following rules is: histogram equalization of the tail flame image during the test without spraying fire; The threshold of the binarization of the image is automatically calculated by the Otsu method, and the values ​​of all pixels with values ​​higher than the threshold are set to 1, and the values ​​of the remaining pixels are set to 0, so as to obtain a rough binarized image of the tail flame during the test. Use the Canny edge detection algorithm to extract the contours in the binary image and obtain multiple contours. Given the upper limit of the contour size threshold n max and lower limit n min , if the contour size is larger than n min Smaller or smaller than n max If it is large, the profile is not a nozzle profile; The method for obtaining the tail flame image when removing the nozzle area is as follows: set the approximation accuracy parameter and use the Ramer-Douglas-Peucker algorithm to reduce the number of contour points; iteratively delete the point with the shortest distance on the line segment until the distance from all points to their corresponding line segments does not exceed the set approximation accuracy parameter, and obtain the minimum contour points. Based on this, the simplified polygonal nozzle contour is obtained and the mask I is constructed. mask , set the value of the nozzle contour area to 0, and the value of the non-nozzle contour area to 1; all subsequent test images are the same as I mask The tail flame image of the test without the nozzle area is obtained by multiplication.

5. The method for measuring the tail flame angle of a turbine vectoring engine according to claim 1, characterized in that: The steps to solve the tail flame angle include: Tail flame image during the test without nozzle area data The image size is m p ×n p , that is, in the image coordinate system, the horizontal pixel range is 0-m p , the vertical pixel range is 0-n p ; Set the tail flame interval in the vertical direction [n up , n down ], where up is the initial row number and down is the final row number. Let the coordinate set of all pixels in any row of the tail flame interval on the infrared image be {(u1,n i ),…,(u mp ,n i )},n i ∈[n up , n down ], take the pixel with the largest gray value p i coordinate Then, in the tail flame interval, we get the image point coordinate sequence with the largest gray value in each row: Fit a straight line according to the coordinates of the image points; According to the coordinates of the image points, the steps of fitting a straight line include: calculating the average value of all horizontal coordinates and vertical coordinates: The formula for calculating the slope of a straight line is: The formula for calculating the intercept of a line is: The angle between the straight line and the vertical direction, that is, the angle between the tail flame and the horizontal direction is calculated to be θ = arctan (|k|).

6. An electronic device, characterized in that: It comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the method for measuring the tail flame angle of a turbine vector engine as claimed in any one of claims 1 to 5 when executing the computer program.

7. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the method for measuring the tail flame angle of a turbine vector engine according to any one of claims 1 to 5 is implemented.

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