Measuring system and testing method for three-dimensional track of sand dust particles in particle separator

Abstract

The invention discloses a measuring system and a testing method for a three-dimensional track of sand dust particles in a particle separator. The measuring system comprises the particle separator, two high-speed cameras and a sand throwing system, sand and dust particles at the specified speed and angle are projected into the particle separator through the sand throwing system; the two cameras are used for shooting the flow direction view field and the spanwise view field of the particle separator at the same time; calculating pixel coordinates of the sand dust particles at each instantaneous moment by using an image processing method, and then calculating real coordinates of the sand dust particles at each moment in two visual fields by using parameters calibrated by a camera; and finally obtaining the three-dimensional motion trail of the sand dust particles. The measuring system is simple in overall structure, sand dust particles at different speeds and angles can be simulated, and high adaptability and flexibility are achieved; the three-dimensional motion trail of the sand dust particles is obtained by capturing the images of the sand dust particles in the two visual fields and processing the images, the real motion characteristics of the sand dust particles are restored, and a foundation is laid for research of the particle separator.

Description

Technical Field

[0001] The present invention relates to the technical field of particle motion trajectory measurement, and in particular to a measurement system and a test method for three-dimensional trajectories of sand and dust particles in a particle separator. Background Art

[0002] As a vertical take-off and landing aircraft, helicopters often have to operate in various complex environments. When helicopters operate in particle-rich environments such as deserts and seas, especially when the engine takes off and lands at close to full power, they usually inhale a large amount of high-inertia particle flow. If the engine does not take any protective measures, these sand and dust particles will cause very serious damage to the engine, such as: corrosion of the compressor blades, resulting in a decrease in engine power, and in severe cases, engine blade stall; the cooling channel of the turbine blades is easily blocked by particles, causing the turbine blades to overheat and even causing the engine to stop in the air. Therefore, in order to better protect the helicopter engine, a helicopter particle separator is usually installed in front of the engine. In order to better design the particle separator and predict the sand separation efficiency of the particle separator, it is particularly important to study the movement trajectory of the sand and dust particles inside the particle separator.

[0003] At present, the measurement of the trajectory of sand and dust particles inside the particle separator is concentrated on the two-dimensional measurement of a single field of view. However, the movement of sand and dust particles has significant three-dimensional characteristics. It is difficult to show the true movement characteristics of sand and dust particles by only performing two-dimensional measurement of the particle movement trajectory. Therefore, in order to show the true movement trajectory of sand and dust particles, it is particularly important to propose an effective three-dimensional movement trajectory measurement system and test method for measuring particles in a particle separator. Summary of the invention

[0004] Purpose of the invention: In view of the current shortcoming that the three-dimensional motion trajectory of particles in a particle separator cannot be measured, the present invention provides a measurement system and test method for the three-dimensional trajectory of sand and dust particles in a particle separator.

[0005] Technical solution: To solve the above problems, the present invention adopts a system for measuring the three-dimensional trajectory of sand and dust particles in a particle separator, including a bracket, a particle separator, a flow light source, a span light source, a sand throwing system, a flow field of view camera, a span field of view camera, and a data processing system. The particle separator is installed on the bracket, and the particle separator is made of transparent material; the flow light source is used to provide a light source for the flow direction of the particle separator, and the span light source is used to provide a light source for the span direction of the particle separator; the flow field of view camera is used to capture the flow field of the particle separator, the span field of view camera is used to capture the span field of the particle separator, and the sand throwing system is used to throw sand into the particle separator; the data processing system is used to receive and process camera data and output the three-dimensional trajectory of sand and dust particles.

[0006] Furthermore, the sand throwing system includes an air compressor, a pressure regulating valve, an air storage tank, a pressure gauge, a solenoid valve, and a sand gun which are connected in sequence through a hose; the solenoid valve is also connected to a programmable logic controller through a wire, the programmable logic controller is connected to a control switch, and the control switch is connected to a power supply.

[0007] Furthermore, the sand gun includes an electric angle position platform, a sand gun bracket installed on the electric angle position platform, a sand gun barrel installed on the sand gun bracket, and an egg tray installed in the sand gun barrel, wherein the egg tray is used to hold sand and dust particles, and an inclinometer is also provided on the sand gun bracket.

[0008] Furthermore, the control switch is also connected to the flow field camera and the span field camera via a camera synchronization line.

[0009] Furthermore, the flow direction light source is installed on a bracket, and the span direction light source is arranged on the top outside the particle separator.

[0010] Furthermore, a reflector and an angle adjustment plate for adjusting the angle of the reflector are also provided on the bracket, and the reflector refracts the spanwise field of view of the particle separator to a direction parallel to the flowwise field of view.

[0011] The present invention also provides a testing method for the measurement system, comprising the following steps:

[0012] Step 1: Build a test bench;

[0013] Step 2: calibrate the streamwise view camera and the spanwise view camera to obtain the internal parameter matrix and the external parameter matrix of the two cameras;

[0014] Step 3, the sand throwing system throws sand;

[0015] Step 4: The flow field camera and the span field camera capture photos of the corresponding fields of view respectively, and perform image processing to identify sand and dust particles, and obtain the pixel coordinates of the sand and dust particles on the photos;

[0016] Step 5: According to the camera's internal parameter matrix, external parameter matrix and pixel coordinates of the dust particles, the real coordinates of the dust particles at each instant in the flow field of view and the span field of view are calculated respectively;

[0017] Step 6: According to the real coordinates of the sand and dust particles in the flow field and the span field at the instantaneous moment, the three-dimensional coordinates of the sand and dust particles are obtained; each instantaneous moment image is processed to obtain the three-dimensional motion trajectory of the sand and dust particles.

[0018] Furthermore, the calibration adopts the "Zhang Zhengyou calibration method".

[0019] Furthermore, the specific method of performing image processing to identify sand and dust particles is as follows:

[0020] Step 4.1, read the photo and convert it into grayscale image;

[0021] Step 4.2, take the average of all photo pixels as the background image;

[0022] Step 4.3, subtract the pixels of each photo from the background image;

[0023] Step 4.4, set the threshold of the gray value of the photo;

[0024] Step 4.5, convert the differenced image into a binary image by thresholding;

[0025] Step 4.6, marking the connected domains in the binary image;

[0026] Step 4.7, calculate the area of ​​each connected domain;

[0027] Step 4.8: The centroid of the connected domain with the largest area is used as the pixel coordinate of the dust.

[0028] Furthermore, the specific calculation method of the real coordinates of the sand and dust particles is as follows:

[0029]

[0030] In the formula, the camera intrinsic parameters and camera extrinsic parameters are obtained by calibration, where f is the focal length of the camera, dx, dy represents the physical size of each pixel on the horizontal axis x and the vertical axis y, and Z c is the scale factor, u and v are the pixel coordinates of the center of the area of ​​the dust particle, W ,Y W ,Z W are the real coordinates of the dust particles, R and T are the translation and rotation matrices respectively.

[0031] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: (1) the overall structure of the measurement system is simple, which can simulate sand and dust particles of different speeds and angles and has high adaptability and flexibility; (2) by capturing the images of sand and dust particles in two fields of view, the three-dimensional motion trajectory of the sand and dust particles is obtained, and the real motion characteristics of the sand and dust particles are restored, laying a foundation for the research of particle separators. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the measurement system of the present invention;

[0033] Figure 2 It is a schematic diagram of the overall structure of the sand-casting system of the present invention;

[0034] Figure 3 It is a schematic diagram of the overall process of the testing method of the present invention;

[0035] Figure 4 It is a schematic diagram of the process of image processing to identify sand and dust particles according to the present invention. DETAILED DESCRIPTION

[0036] like Figure 1 As shown, a system and test method for measuring the three-dimensional trajectory of sand and dust particles in a particle separator in this embodiment include a bracket 17, a particle separator 18, a flow direction light source 19, a span direction light source 20, a sand throwing system, a flow direction field of view camera 21, a span direction field of view camera 22, and a data processing system. The bracket 17 is welded from aluminum profiles, and the particle separator 18 is mounted on the bracket 17. The particle separator 18 is made of transparent material. The flow direction light source 19 is mounted on the bracket 17 to provide a light source for the flow direction of the particle separator; the span direction light source 20 is arranged on the outer top of the particle separator 18 to provide a light source for the span direction of the particle separator. A reflector 23 and an angle adjustment plate 24 for adjusting the angle of the reflector are also provided on the bracket 17. The reflector and the bottom surface of the particle separator are at an angle of 45°, which is used to refract the span direction field of view of the particle separator to a direction parallel to the flow direction field of view. The flow field camera 21 and the span field camera 2 are installed in parallel on the same side of the particle separator. The flow field camera is used to capture the flow field of the particle separator, and the span field camera is used to capture the span field of the particle separator. The two cameras maintain the same frame rate. The sand throwing system is used to throw sand into the particle separator. The data processing system is used to receive and process camera data and output the three-dimensional trajectory of sand and dust particles.

[0037] like Figure 2 As shown, the sand throwing system includes an air compressor 1, a pressure regulating valve 3, an air storage tank 4, a pressure gauge 5, a solenoid valve 11, and a sand gun, which are connected in sequence through a hose 2. The solenoid valve 11 is also connected to a programmable logic controller 10 through a wire 6, and the programmable logic controller 10 is connected to a control switch 8, and the control switch 8 is connected to a variable frequency power supply 7. The pressure gauge is also connected to the variable frequency power supply 7 through a wire 6. The control switch 8 is also connected to a flow field camera 20 and a span field camera 21 through a camera synchronization line 9, so that the sand throwing system and the camera work synchronously. The sand gun includes an electric angle table 12, a sand gun bracket 14 installed on the electric angle table 12, a sand gun barrel 15 installed on the sand gun bracket 14, and an egg tray 16 installed in the sand gun barrel 15, and the egg tray is used to hold sand dust particles. The sand gun bracket 14 is also provided with an inclinometer 13 for reading the inclination data of the sand gun bracket.

[0038] The sand throwing system uses the air compressor 1 to fill the gas tank 2 with high-pressure gas, and by adjusting the opening of the pressure regulating valve 3, the pressure in the gas tank 2 is stabilized at a value, and the solenoid valve 11 is made to work only for a specific time each time through the programmable logic controller 10, so as to ensure that the gas pressure and mass flow rate of the sand gun barrel 15 passing through each time are the same, and the sand dust particles can be accelerated at the same time. The impact of the sand gun jet on the flow field can also be reduced. The angle of the sand gun barrel 15 is automatically adjusted and displayed through the electric angle table 12 and the inclinometer 13, and the sand dust particles are thrown out with the egg tray as the carrier. By adjusting the pressure of the gas tank in the sand gun system and the angle of the barrel in the sand gun system, it can project sand dust particles at a specified speed and angle into the particle separator.

[0039] like Figure 3 As shown, the testing method of the system for measuring the three-dimensional trajectory of sand and dust particles in the particle separator of the present invention specifically includes the following steps:

[0040] Step 1: Build a test bench.

[0041] Step 2: Use the camera calibration plate to calibrate the streamwise view camera and the spanwise view camera, specifically using the “Zhang Zhengyou calibration method” to obtain the internal parameter matrix and external parameter matrix of the two cameras.

[0042] Step 3: Set the speed and angle of the sand-feeding system and start sand-feeding.

[0043] Step 4: The flow view camera and the span view camera capture photos of the corresponding fields of view respectively, and perform image processing to identify sand and dust particles, and obtain the pixel coordinates of the sand and dust particles on the photos. Figure 4 As shown, the specific method of image processing to identify sand and dust particles is as follows:

[0044] Step 4.1, read the photo and convert it into grayscale image;

[0045] Step 4.2, take the average of all photo pixels as the background image;

[0046] Step 4.3, subtract the pixels of each photo from the background image;

[0047] Step 4.4, set the threshold of the gray value of the photo;

[0048] Step 4.5, convert the differenced image into a binary image by thresholding;

[0049] Step 4.6, marking the connected domains in the binary image;

[0050] Step 4.7, calculate the area of ​​each connected domain;

[0051] Step 4.8: The centroid of the connected domain with the largest area is used as the pixel coordinate of the dust.

[0052] Step 5: According to the camera's internal parameter matrix, external parameter matrix and the pixel coordinates of the dust particles, the real coordinates of the dust particles at each instant in the flow field of view and the span field of view are calculated. The specific calculation method is as follows:

[0053]

[0054] In the formula, the camera intrinsic parameters and camera extrinsic parameters are obtained by calibration, where f is the focal length of the camera, dx, dy represents the physical size of each pixel on the horizontal axis x and the vertical axis y, and Z c is the scale factor, u and v are the pixel coordinates of the center of the area of ​​the dust particle, W ,Y W ,Z W are the real coordinates of the dust particles, R and T are the translation and rotation matrices respectively.

[0055] The real coordinates of the dust particles in the flow field of view are calculated based on the data of the flow field of view [X L ,Y L The real coordinates of the dust particles in the spanwise field of view are calculated based on the spanwise field of view data [X Z ,Z Z ].

[0056] Step 6: According to the real coordinates of the dust particles in the flow field of view and the span field of view at the instant, the three-dimensional coordinates of the dust particles [X L ,Y L ,Z z ]; process the image at each instant to obtain the three-dimensional motion trajectory of the sand and dust particles.

[0057] The system for measuring the three-dimensional trajectory of dust particles in the particle separator of the present invention has a simple overall structure, can simulate dust particles of different speeds and angles, and has high adaptability and flexibility. By capturing images of dust particles in two fields of view, the three-dimensional motion trajectory of the dust particles is obtained, and the real motion characteristics of the dust particles are restored, laying a foundation for the research of particle separators.

Claims

1. A system for measuring the three-dimensional trajectory of sand and dust particles in a particle separator, characterized in that: It includes a bracket, a particle separator, a flow direction light source, a span direction light source, a sand throwing system, a flow direction field of view camera, a span direction field of view camera, and a data processing system. The particle separator is installed on the bracket and is made of transparent material; the flow direction light source is used to provide light source for the flow direction of the particle separator, and the span direction light source is used to provide light source for the span direction of the particle separator; the flow direction field of view camera is used to capture the flow direction field of view of the particle separator, the span direction field of view camera is used to capture the span direction field of view of the particle separator, and the sand throwing system is used to throw sand into the particle separator; the data processing system is used to receive and process camera data and output the three-dimensional trajectory of sand and dust particles.

2. The system for measuring the three-dimensional trajectory of dust particles in a particle separator according to claim 1, characterized in that: The sand throwing system includes an air compressor, a pressure regulating valve, an air storage tank, a pressure gauge, a solenoid valve, and a sand gun which are connected in sequence through a hose; the solenoid valve is also connected to a programmable logic controller through a wire, the programmable logic controller is connected to a control switch, and the control switch is connected to a power supply.

3. The system for measuring the three-dimensional trajectory of dust particles in a particle separator according to claim 2, characterized in that: The sand gun comprises an electric angle platform, a sand gun bracket installed on the electric angle platform, a sand gun barrel installed on the sand gun bracket, and an egg tray installed in the sand gun barrel. The egg tray is used to hold sand and dust particles. An inclinometer is also provided on the sand gun bracket.

4. The system for measuring the three-dimensional trajectory of dust particles in a particle separator according to claim 2, characterized in that: The control switch is also connected to the flow-direction view camera and the span-direction view camera via a camera synchronization line.

5. The system for measuring the three-dimensional trajectory of dust particles in a particle separator according to claim 1, characterized in that: The flow direction light source is installed on a bracket, and the span direction light source is arranged on the top outside the particle separator.

6. The system for measuring the three-dimensional trajectory of dust particles in a particle separator according to claim 1, characterized in that: The bracket is also provided with a reflector and an angle adjustment plate for adjusting the angle of the reflector. The reflector refracts the spanwise field of view of the particle separator to a direction parallel to the flowwise field of view.

7. A method for testing the measurement system according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Build a test bench; Step 2: calibrate the streamwise view camera and the spanwise view camera to obtain the internal parameter matrix and the external parameter matrix of the two cameras; Step 3, the sand throwing system throws sand; Step 4: The flow field camera and the span field camera capture photos of the corresponding fields of view respectively, and perform image processing to identify sand and dust particles, and obtain the pixel coordinates of the sand and dust particles on the photos; Step 5: According to the camera's internal parameter matrix, external parameter matrix and pixel coordinates of the dust particles, the real coordinates of the dust particles at each instant in the flow field of view and the span field of view are calculated respectively; Step 6: According to the real coordinates of the sand and dust particles in the flow field and the span field at the instantaneous moment, the three-dimensional coordinates of the sand and dust particles are obtained; each instantaneous moment image is processed to obtain the three-dimensional motion trajectory of the sand and dust particles.

8. The testing method according to claim 7, characterized in that: The calibration adopts the "Zhang Zhengyou calibration method".

9. The testing method according to claim 7, characterized in that: The specific method of performing image processing to identify sand and dust particles is as follows: Step 4.1, read the photo and convert it into grayscale image; Step 4.2, take the average of all photo pixels as the background image; Step 4.3, subtract the pixels of each photo from the background image; Step 4.4, set the threshold of the gray value of the photo; Step 4.5, convert the differenced image into a binary image by thresholding; Step 4.6, marking the connected domains in the binary image; Step 4.7, calculate the area of ​​each connected domain; Step 4.8: The centroid of the connected domain with the largest area is used as the pixel coordinate of the dust.

10. The testing method according to claim 7, characterized in that: The specific calculation method of the real coordinates of the sand and dust particles is as follows: In the formula, the camera intrinsic parameters and camera extrinsic parameters are obtained by calibration, where f is the focal length of the camera, dx, dy represents the physical size of each pixel on the horizontal axis x and the vertical axis y, and Z c is the scale factor, u and v are the pixel coordinates of the center of the area of ​​the dust particle, W ,Y W ,Z W are the real coordinates of the dust particles, R and T are the translation and rotation matrices respectively.

Images