A propeller water-tunnel test device based on PIV particle tracking technique

Abstract

The utility model discloses a propeller water tunnel test device based on PIV particle tracking technique, including water tunnel shell, tracking particle emission subassembly, light curtain subassembly, imaging subassembly, propeller subassembly, drive mechanism and PLC controller, and the water tunnel shell includes water inlet section, observation section and water outlet section. The left end of water inlet section is equipped with the water inlet, and the water outlet section is equipped with the drain. Tracking particle emission subassembly is established at the top of water inlet section, and propeller subassembly is arranged in the inside of water inlet section, and drive mechanism is arranged at the top of observation section, and its output end drives the propeller subassembly to work. The light curtain subassembly includes pulse laser and laser emission unit, and the laser emission unit is connected with pulse laser through light guide arm. The imaging subassembly includes no. 1 high speed camera, no. 2 high speed camera and no. 3 high speed camera. The utility model discloses through the way of partial flow sowing to make tracking particle distribution even, realizes the multi -angle, multi -directional capture of the flow field information around propeller, makes information capture more comprehensive, accurate.

Description

Technical Field

[0001] This utility model relates to the field of flow field measurement and testing technology, specifically to a propeller water tunnel test device based on PIV particle tracing technology. Background Technology

[0002] Anchor bolts are an important component of geotechnical engineering support technology. China possesses vast sea areas, and protecting maritime rights and sea lanes is crucial for safeguarding national security and interests. The development of various new types of marine equipment is also a key focus for both national defense and civilian applications. When underwater vehicles operate under high pressure, high salinity, and other special environments for extended periods, the overall requirements for the propulsion system are extremely high. Simultaneously, the maneuverability of underwater vehicles is a crucial criterion for evaluating their operational capabilities, and the propulsion system is both the power source and the primary noise source. Therefore, the propulsion system has a vital impact on the overall performance of underwater vehicles. Flow field testing can analyze and study the vortex structure, flow field changes, and cavitation dynamics around the propulsion system, providing strong support for research on flow field structure, flow law analysis, and flow field control. Traditional flow field measurement methods mainly include the smoke line method and Doppler velocity measurement method, but these methods often cannot quantitatively study the flow field and may interfere with the original flow field due to equipment deployment issues, or may only achieve single-point measurements. As the design optimization of ships and propulsion systems in water and the study of wake effects have become increasingly in-depth, scholars are paying more and more attention to the physical characteristics of fine flow fields. Accurate acquisition of flow field information is crucial for refining flow field information, revealing the physical phenomena, flow details and mechanisms of flow field. Therefore, it is very important to obtain accurate flow field information.

[0003] Particle image velocimetry (PIV) can accurately measure transient flow information without disturbing the flow field. It calculates the surrounding velocity field through image processing, quantifying the flow information and characteristics. Its working principle involves emitting a laser in a flow field filled with uniform tracer particles. A cylindrical lens forms a laser sheet light source, illuminating the flow field containing tracer particles. An image acquisition device then captures the image, and computer image processing software analyzes the acquired image to determine the flow field conditions. PIV mainly consists of an image acquisition system and a laser illumination system. In image acquisition, CCD camera technology has developed rapidly, and the introduction of complementary metal-oxide-semiconductor (CMOS) cameras has led to a qualitative leap in particle imaging technology, achieving a frame rate of 10 frames per second. 6The scale is significant. Laser imaging technology has gradually evolved from continuous lasers to dual-pulse high-frequency lasers with high energy, high excitation frequency, and low pulse interval. PIV experiments have strict environmental requirements. In order to complete PIV experiments in different environments, various laser illumination methods, such as copper vapor lasers, helium-neon lasers, ruby ​​lasers, and semiconductor lasers, have been developed, greatly enriching the application environment of PIV.

[0004] Although PIV technology has been applied to propeller flow field measurement, challenges remain during testing, such as uneven distribution of tracer particles and difficulty in observing the flow field in the circumferential cross-section of the propeller. These challenges result in incomplete propeller flow field measurement information and low measurement accuracy, thus requiring improvement in the completeness and accuracy of propeller flow field visualization test results. Utility Model Content

[0005] To address the shortcomings of the existing technology, the purpose of this invention is to propose a propeller water tunnel test device based on PIV particle tracer technology. This device solves the problems of uneven distribution of tracer particles, difficulty in observing the flow field of the propeller circumferential section, incomplete propeller flow field measurement information, low measurement accuracy, and poor completeness and accuracy of flow field visualization test results during the testing process.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A propeller-driven water tunnel experimental device based on PIV particle tracing technology includes a water tunnel shell, a tracer particle emission assembly, a light curtain assembly, an imaging assembly, a propeller assembly, a drive mechanism, and a PLC controller. The water tunnel shell includes an inlet section, an observation section, and an outlet section connected end to end. The inlet section, observation section, and outlet section are all square tubes, and the right end of the outlet section is closed.

[0008] The water inlet section has a water inlet at its left end, and the water outlet section has a water outlet on its right side.

[0009] The tracer particle emission assembly is located at the top of the water inlet section of the water tunnel shell, and its outlet end is located on the upper inner side of the water inlet section.

[0010] The four side walls of the observation section are all transparent windows. The propeller assembly is located inside the water inlet section. The drive mechanism is located on the top outer side of the observation section, and its output end is connected to the propeller assembly and drives the propeller assembly to work.

[0011] The light curtain assembly includes a pulsed laser, a light guide arm, and a laser emitting unit. The laser emitting unit is located below the observation section and is connected to the pulsed laser through the light guide arm.

[0012] The imaging assembly includes a No. 1 high-speed camera, a No. 2 high-speed camera, and a No. 3 high-speed camera. The No. 1 and No. 2 high-speed cameras are arranged adjacently on the rear side of the observation section, and the No. 3 high-speed camera is located on the right side of the water outlet section. The signal terminals of each high-speed camera are connected to the PLC controller for communication.

[0013] Furthermore, a reducing pipe is fixedly connected to the right end of the water inlet section, and the reducing pipe is connected to the left end of the observation section.

[0014] The observation section has square openings of the same specifications on its left and right ends. The left end of the water outlet section is fixedly connected to the right end of the observation section. An end plate is fixed to the right end of the water outlet section, and the end plate closes the right end of the water outlet section.

[0015] The interior of the water outlet section is connected to the interior of the observation section through a square opening at the right end of the observation section, and the drain outlet is located on the lower side of the water outlet section.

[0016] Furthermore, the tracer particle emission assembly includes a particle storage unit, a transmission pipeline, and a shunt pipe. The particle storage unit is fixedly installed above the water inlet section and has a cavity inside for holding tracer particles.

[0017] The diversion pipe is fixedly embedded in the top wall of the water inlet section, and its upper end is connected to the particle storage device through the transmission pipeline, so as to quantitatively send the tracer particles inside the particle storage device into the water inlet section.

[0018] Furthermore, the diversion pipe has an S-shaped flat structure, with its upper end located outside the water inlet section and its lower end located below the top wall of the water inlet section.

[0019] The inside of the diversion pipe has multiple diversion channels arranged in parallel at equal intervals. The lower port of each diversion channel is in the same direction as the water flow inside the inlet section. The inside of the transmission pipe has a flat variable diameter cavity. The upper port of each diversion channel is connected to the variable diameter cavity inside the transmission pipe.

[0020] Furthermore, the observation section includes a cuboid frame and a highly transparent glass panel, with an observation window on each of the four circumferential side walls of the cuboid frame.

[0021] Each observation window has a glass panel on its outer wall. Each glass panel has an annular frame on the side away from the cuboid frame. The annular frame fixes the corresponding glass panel to the side of the cuboid frame, and each glass panel closes the corresponding observation window.

[0022] Furthermore, the propeller assembly includes a flow guide shell, a bevel gearbox, a drive shaft, and a propeller. The flow guide shell is an ellipsoidal shell, and the top of the flow guide shell has an extension integrally formed therewith. The extension is fixedly connected to the top wall of the observation section.

[0023] The bevel gearbox is located inside the flow guide housing, and its input end is connected to the drive mechanism through the drive shaft. The drive shaft is vertically arranged inside the extension and rotates in a sealed fit with it.

[0024] The propeller is located on the outside of the right side of the bevel gearbox, and the left end of the propeller shaft passes through the guide housing and is fixedly connected to the output end of the bevel gearbox.

[0025] Furthermore, the driving mechanism includes a stepper motor, which is mounted above the observation section via a motor bracket. The output shaft of the stepper motor points vertically downward, and its signal terminal is connected to the PLC controller for communication.

[0026] The motor bracket is fixed to the upper surface of the glass panel at the top of the observation section. The upper part of the drive shaft is rotatably engaged with the motor bracket through a sealed bushing, and the upper end of the drive shaft is connected to the output shaft of the stepper motor through a coupling.

[0027] In operation, the stepper motor drives the propeller to rotate forward or backward through the transmission shaft and bevel gear box.

[0028] Furthermore, an observation window 2 is provided in the middle of the end plate, and a glass panel 2 is embedded in the inner side of the observation window 2, which seals the left end of the observation window 2.

[0029] The third high-speed camera is located on the right side wall of the end plate, and its lens corresponds to the second observation window.

[0030] By adopting the above technical solution, the beneficial technical effects of this utility model are as follows: This utility model can ensure that the tracer particles are evenly dispersed in the outer shell of the water tunnel by uniformly dispersing tracer particles into the water tunnel through the diversion pipe above the water tunnel. This solves the technical problem of difficult and uneven distribution of tracer particles when using PIV technology to obtain flow field information distribution in the propeller water tunnel test in the prior art. By configuring multiple imaging devices, it can realize multi-angle and multi-directional capture of flow field information around the propeller, which greatly improves the comprehensiveness and accuracy of capturing flow field information around the propeller. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the propeller-driven water tunnel experimental device based on PIV particle tracing technology of this utility model. Figure 1 .

[0032] Figure 2 This is a schematic diagram of the propeller-driven water tunnel experimental device based on PIV particle tracing technology of this utility model. Figure 2 .

[0033] Figure 3 yes Figure 1The schematic diagram of a part shows the tracer particle emission component.

[0034] Figure 4 yes Figure 1 Another part of the diagram shows a cuboid frame.

[0035] Figure 5 This is a cross-sectional view of the propeller-driven water tunnel test device based on PIV particle tracing technology of this utility model.

[0036] Figure 6 yes Figure 5 A magnified view of part A in the middle.

[0037] Figure 7 This is a schematic diagram of the combined structure of the drive mechanism and propeller assembly of this utility model.

[0038] Figure 8 yes Figure 7 A partial cross-sectional view of the combined structure of the drive mechanism and propeller assembly shown.

[0039] The diagram shows: 1. Outer shell of the water tunnel; 11. Inlet section; 111. Inlet; 12. Observation section; 121. Rectangular frame; 122. Glass panel one; 123. Annular frame; 124. Square opening; 13. Outlet section; 131. Drainage outlet; 14. End plate; 141. Observation window two; 142. Glass panel two; 15. Variable diameter pipe; 2. Tracer particle emission assembly; 21. Storage device; 22. Transmission pipeline; 23. 1. Diverter pipe; 231. Diverter channel; 3. Light curtain assembly; 4. Propeller assembly; 41. Guide housing; 42. Bevel gearbox; 43. Drive shaft; 44. Propeller; 441. Propeller shaft; 45. Sealing bushing; 46. Upper bracket; 47. Bearing sleeve; 51. Stepper motor; 52. Motor bracket; 53. Bearing seat; 54. Coupling; 61. High-speed camera No. 1; 62. High-speed camera No. 2; 63. High-speed camera No. 3. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings:

[0041] Combination Figures 1 to 8 A propeller-driven water tunnel experimental device based on PIV particle tracing technology includes a water tunnel shell 1, a tracer particle emission component 2, a light curtain component 3, an imaging component, a propeller component 4, a drive mechanism, and a PLC controller. The water tunnel shell 1 includes an inlet section 11, an observation section 12, and an outlet section 13 connected end to end. The inlet section 11, the observation section 12, and the outlet section 13 are all square tubes. An end plate 14 is detachably and fixedly installed on the right end face of the outlet section 13, and the end plate 14 closes the right end of the outlet section 13.

[0042] The inlet section 11 has an inlet 111 at its left end, and the outlet section 13 has a drain outlet 131 at its bottom near its right end. A reducer 15 is fixedly connected to the right end of the inlet section 11, and is connected to the left end of the observation section 12 via the reducer 15. In operation, water entering the inlet section 11 through the inlet 111 flows into the observation section 12 through the reducer 15, flows from left to right within the observation section 12, enters the outlet section 13, and exits through the drain outlet 131. In practical applications, the inlet 111 of the inlet section 11 can be connected to the drain outlet 131 of the outlet section 13 via an external pipeline. The external pipeline is equipped with a water pump and a solenoid valve, which are connected to the outer shell 1 of the water tunnel to form a circulation loop. The solenoid valve controls the flow rate of the water.

[0043] The left and right ends of the observation section 12 are provided with square openings 124 of the same specifications. The left end of the water outlet section 13 is fixedly connected to the right end of the observation section 12. The interior of the water inlet section 11 is connected to the interior of the observation section 12 through the square opening 124 at the left end of the observation section 12. The interior of the water outlet section 13 is connected to the interior of the observation section 12 through the square opening 124 at the right end of the observation section 12.

[0044] The tracer particle emission assembly 2 is located at the top of the water inlet section 11 of the water tunnel shell 1, with its outlet end located on the upper inner side of the water inlet section 11. The tracer particle emission assembly 2 includes a particle storage unit 21, a transmission pipeline 22, and a diversion pipe 23. The particle storage unit 21 is fixedly installed above the water inlet section 11 and has an internal cavity for holding tracer particles. The diversion pipe 23 is fixedly embedded in the top wall of the water inlet section 11, and its upper end is connected to the particle storage unit 21 through the transmission pipeline 22, quantitatively delivering the tracer particles inside the particle storage unit 21 into the interior of the water inlet section 11.

[0045] The diversion pipe 23 has an S-shaped flat structure. The upper end of the diversion pipe 23 is located outside the water inlet section 11, and its lower end is located below the top wall of the water inlet section 11. The interior of the diversion pipe 23 has ten equally spaced parallel diversion channels 231. The diversion channels 231 are pipes with a circular cross-section. The lower port of each diversion channel 231 is consistent with the water flow direction inside the water inlet section 11. The interior of the transmission pipe 22 has a flat variable diameter cavity. The upper port of each diversion channel 231 is connected to the variable diameter cavity inside the transmission pipe 22. In operation, the tracer particles stored inside the particle storage unit 21 enter the ten diversion pipes 23 through the transmission pipe 22. Then, they converge from the lower port of each diversion pipe 23 into the water body of the inlet section 11. As the water flows, the tracer particles in this embodiment are added to the water body in a surface distribution after being diverted, and the direction of entry of the tracer particles is consistent with the water flow, which greatly improves the uniformity of the diffusion of tracer particles in the water body.

[0046] The four side walls of the observation section 12 are all transparent windows. The observation section 12 includes a cuboid frame 121 and highly transparent glass panels 122. Each of the front, rear, upper, and lower side walls of the cuboid frame 121 has an observation window. Two square openings 124 are located at the left and right ends of the cuboid frame 121, respectively, and the two square openings 124 face each other. Each observation window has a glass panel 122 on its outer wall. Each glass panel 122 has an annular frame 123 on the side facing away from the cuboid frame 121. The annular frame fixes the corresponding glass panel 122 to the side of the cuboid frame 121, and the glass panel 122 closes the corresponding observation window.

[0047] Specifically, each glass panel 122 is provided with an annular rubber sealing strip between it and the corresponding side wall of the cuboid frame 121. Each rubber sealing strip is embedded in the side wall of the cuboid frame 121. Each annular frame 123 is equipped with a set of bolts. The annular frame 123 fixes the corresponding glass panel 122 to the corresponding side wall of the cuboid frame 121 through the bolts, so that each glass panel 122 and the cuboid frame 121 are sealed together. The movement of tracer particles in the flow field inside the observation section 12 can be observed through the glass panel 122.

[0048] The propeller assembly 4 is located inside the water inlet section 11, and the drive mechanism is located on the top outer side of the observation section 12. Its output end is connected to the propeller assembly 4 and drives the propeller assembly 4 to work.

[0049] The propeller assembly 4 includes a flow guide shell 41, a bevel gearbox 42, a drive shaft 43, and a propeller 44. The flow guide shell 41 is an ellipsoidal shell, and the top of the flow guide shell 41 has an extension 411 integral with it. The extension 411 is fixedly connected to the top wall of the observation section 12.

[0050] The bevel gearbox 42 is located inside the flow guide housing 41. Its input end is connected to the drive mechanism via the drive shaft 43. The drive shaft 43 is vertically arranged inside the extension 411 and is in rotational sealing cooperation with it. The propeller 44 is located on the outside right side of the bevel gearbox 42. The left end of the propeller shaft 441 of the propeller 44 passes through the flow guide housing 41 and is fixedly connected to the output end of the bevel gearbox 42.

[0051] The drive mechanism includes a stepper motor 51, which is mounted above the observation section 12 via a motor bracket 52. The output shaft of the stepper motor 51 points vertically downward, and its signal terminal is connected to the PLC controller. The motor bracket 52 is fixed to the upper surface of the glass panel at the top of the observation section 12. The upper part of the drive shaft 43 is rotatably engaged with the motor bracket 52 via a sealed bushing 45, and the upper end of the drive shaft 43 is connected to the output shaft of the stepper motor 51 via a coupling 54. In operation, the stepper motor 51 drives the propeller 44 to rotate forward or backward via the drive shaft 43 and the bevel gearbox 42. Adjusting the speed and direction of rotation of the propeller 44 controls the flow field.

[0052] The light curtain assembly 3 includes a pulsed laser 31, a light guide arm 32, and a laser emitting unit 33. The laser emitting unit 33 is located below the observation section 12 and is connected to the pulsed laser 31 via the light guide arm 32. The light guide arm 32 can be adjusted to regulate the position and angle of the pulsed laser 31. A two-dimensional laser curtain is projected onto the flow field around the propeller through the glass panel 122 at the bottom of the observation section 12. As the tracer particles flow in the flow field around the propeller, they move on the laser curtain of the light curtain assembly 3, forming motion trajectories. The imaging component captures the motion trajectories of the tracer particles in real time.

[0053] The imaging assembly includes a first high-speed camera 61, a second high-speed camera 62, and a third high-speed camera 63. The first and second high-speed cameras 61 and 62 are arranged adjacent to each other along the propeller axis on the rear side of the observation section 12, with their shooting angles forming a certain relative angle. In operation, the first and second high-speed cameras 61 and 62 capture images of the flow field information of the propeller 44 in the axial section to obtain the position data of the tracer particles in the x, y, and z axes, and transmit the real-time image information to a computer for processing. The third high-speed camera 63 is located outside the right end of the outlet section 13. The signal terminals of each high-speed camera are connected to a PLC controller. In operation, the third high-speed camera 63 captures images of the flow field information of the propeller 44 in the circumferential section to obtain the position data of the tracer particles in the y and z axes, and transmits the real-time image information to a computer for processing. Wherein, the x-axis is the axial direction of the propeller, the y-axis is the direction perpendicular to the propeller shaft in the horizontal plane, and the z-axis is the direction perpendicular to the propeller shaft in the vertical plane.

[0054] Specifically, an observation window 141 is provided in the middle of the end plate 14, and a glass panel 142 is embedded in the inner side of the observation window 141, which seals the left end of the observation window 141. The third high-speed camera 63 is located on the right side wall of the end plate, and the lens of the third high-speed camera 63 corresponds to the observation window 141.

[0055] Specifically, the computer receives images captured by each high-speed camera and processes them according to intervals. Calculate the velocity components of particles on a two-dimensional laser screen in the x, y, and z axes from two time-series acquired particle images. , and :

[0056] ;

[0057] ;

[0058]

[0059] in, Let be the position of the particle on the x-axis at time t. Let be the position of the particle on the y-axis at time t. Let be the position of the particle on the z-axis at time t. To capture the time between two consecutive particle images, For the time elapsed The position of the tracer particle on the x-axis. For the time elapsed The position of the tracer particle on the y-axis For the time elapsed The position of the tracer particle on the z-axis.

[0060] When the imaging component acquires images of tracer particles in the flow field region, the angle and position of the two-dimensional laser screen are adjusted via the light guide arm 32. First, when capturing the axial wake information of the propeller 44, the two-dimensional laser screen needs to be adjusted to a vertical position coinciding with the propeller shaft of the propeller 44, ensuring that the shooting direction of the first high-speed camera 61 is perpendicular to the two-dimensional laser screen, and that the shooting direction of the second high-speed camera 62 forms a certain angle with the two-dimensional laser screen, allowing for clear and complete capture of the propeller 44 and its wake region. Second, when capturing the circumferential wake information of the propeller 44 using the third high-speed camera 63, the angle of the two-dimensional laser screen needs to be rotated by 90 degrees compared to when capturing the axial wake information of the propeller 13, ensuring that the shooting direction of the third high-speed camera 633 is perpendicular to the adjusted two-dimensional laser screen.

[0061] The parts not mentioned in this utility model can be achieved by adopting or referencing existing technologies.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0064] Of course, the above description is not intended to limit the present utility model, and the present utility model is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model should also fall within the protection scope of the present utility model.

Claims

1. A propeller-driven water tunnel experimental device based on PIV particle tracing technology, characterized in that, The system includes a water tunnel shell, a tracer particle emission assembly, a light curtain assembly, an imaging assembly, a propeller assembly, a drive mechanism, and a PLC controller. The water tunnel shell includes an inlet section, an observation section, and an outlet section connected end to end. The inlet section, observation section, and outlet section are all square tubes, and the right end of the outlet section is closed. The water inlet section has a water inlet at its left end, and the water outlet section has a water outlet on its right side. The tracer particle emission assembly is located at the top of the water inlet section of the water tunnel shell, and its outlet end is located on the upper inner side of the water inlet section. The four side walls of the observation section are all transparent windows. The propeller assembly is located inside the water inlet section. The drive mechanism is located on the top outer side of the observation section. Its output end is connected to the propeller assembly and drives the propeller assembly to work. The light curtain assembly includes a pulsed laser, a light guide arm, and a laser emitting unit. The laser emitting unit is located below the observation section and is connected to the pulsed laser through the light guide arm. The imaging assembly includes a No. 1 high-speed camera, a No. 2 high-speed camera, and a No. 3 high-speed camera. The No. 1 and No. 2 high-speed cameras are arranged adjacently on the rear side of the observation section, and the No. 3 high-speed camera is located on the right side of the water outlet section. The signal terminals of each high-speed camera are connected to the PLC controller for communication.

2. The propeller-driven water tunnel experimental device based on PIV particle tracing technology according to claim 1, characterized in that, A reducing pipe is fixedly connected to the right end of the water inlet section, and the reducing pipe is connected to the left end of the observation section. The observation section has square openings of the same specifications on its left and right ends. The left end of the water outlet section is fixedly connected to the right end of the observation section. An end plate is fixed to the right end of the water outlet section, and the end plate closes the right end of the water outlet section. The interior of the water outlet section is connected to the interior of the observation section through a square opening at the right end of the observation section, and the drain outlet is located on the lower side of the water outlet section.

3. The propeller-driven water tunnel experimental device based on PIV particle tracing technology according to claim 1, characterized in that, The tracer particle emission assembly includes a particle storage unit, a transmission pipeline, and a shunt pipe. The particle storage unit is fixedly installed above the water inlet section and has a cavity inside for holding tracer particles. The diversion pipe is fixedly embedded in the top wall of the water inlet section, and its upper end is connected to the particle storage device through the transmission pipeline, so as to quantitatively send the tracer particles inside the particle storage device into the water inlet section.

4. The propeller-driven water tunnel testing device based on PIV particle tracing technology according to claim 3, characterized in that, The diversion pipe has an S-shaped flat structure, with its upper end located outside the water inlet section and its lower end located below the top wall of the water inlet section. The inside of the diversion pipe has multiple diversion channels arranged in parallel at equal intervals. The lower port of each diversion channel is in the same direction as the water flow inside the inlet section. The inside of the transmission pipe has a flat variable diameter cavity. The upper port of each diversion channel is connected to the variable diameter cavity inside the transmission pipe.

5. The propeller-driven water tunnel testing device based on PIV particle tracing technology according to claim 1, characterized in that, The observation section includes a cuboid frame and a highly transparent glass panel, with an observation window on each of the four circumferential side walls of the cuboid frame. Each observation window has a glass panel on its outer wall. Each glass panel has an annular frame on the side opposite to the cuboid frame. The annular frame fixes the corresponding glass panel to the side of the cuboid frame, and the glass panel closes the corresponding observation window.

6. The propeller-driven water tunnel experimental device based on PIV particle tracing technology according to claim 5, characterized in that, The propeller assembly includes a flow guide shell, a bevel gearbox, a drive shaft, and a propeller. The flow guide shell is an ellipsoidal shell, and the top of the flow guide shell has an extension integral with it. The extension is fixedly connected to the top wall of the observation section. The bevel gearbox is located inside the flow guide housing, and its input end is connected to the drive mechanism through the drive shaft. The drive shaft is vertically arranged inside the extension and rotates in a sealed fit with it. The propeller is located on the outside of the right side of the bevel gearbox, and the left end of the propeller shaft passes through the guide housing and is fixedly connected to the output end of the bevel gearbox.

7. The propeller-driven water tunnel testing device based on PIV particle tracing technology according to claim 6, characterized in that, The driving mechanism includes a stepper motor, which is mounted above the observation section via a motor bracket. The output shaft of the stepper motor points vertically downward, and its signal terminal is connected to the PLC controller for communication. The motor bracket is fixed to the upper surface of the glass panel at the top of the observation section. The upper part of the drive shaft is rotatably engaged with the motor bracket through a sealed bushing. The upper end of the drive shaft is connected to the output shaft of the stepper motor through a coupling. In operation, the stepper motor drives the propeller to rotate forward or backward through the transmission shaft and bevel gear box.

8. The propeller-driven water tunnel experimental device based on PIV particle tracing technology according to claim 2, characterized in that, An observation window 2 is provided in the middle of the end plate, and a glass panel 2 is embedded in the inner side of the observation window 2, which seals the left end of the observation window 2. The third high-speed camera is located on the right side wall of the end plate, and its lens corresponds to the second observation window.

Images