A circulating water tunnel blade impact jet flow velocity multi-stage regulation test device

Abstract

The application is suitable for the technical field of fluid mechanics experiment, and provides a circulating water tunnel blade impact jet velocity multi-stage regulation test device, which comprises an experimental water tunnel, a velocity multi-stage regulation mechanism, a water pump, a laser generator, a pulse laser controller, a blade angle adjusting mechanism, a high-definition CCD camera, a water tank, an image acquisition computer and a signal synchronous collector; the water tank, the water pump and the experimental water tunnel are connected through pipelines to form a circulating loop; the velocity multi-stage regulation mechanism is installed on the experimental water tunnel; the blade angle adjusting mechanism is installed on the back plate of the experimental water tunnel; the laser generator is arranged above the experimental water tunnel; the optical axis of the high-definition CCD camera is perpendicular to the pulse laser sheet light provided by the laser generator; and the image acquisition computer is signal-connected with the high-definition CCD camera through the signal synchronous collector. The device can dynamically simulate the complex actual working conditions of a hydraulic torque converter with high fidelity, and realizes the visual measurement of the blade near-wall flow field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluid mechanics experiment, and particularly relates to a circulating water tunnel blade impinging jet velocity multi-stage regulation test device. BACKGROUND

[0002] Torque converter (TC) is the core transmission component of automatic transmission (AT) and continuously variable transmission (CVT), and its working performance is determined by the complex flow field characteristics inside. Therefore, accurately revealing the spatiotemporal evolution rule and control mechanism of the flow structure of the blade near-wall region inside the torque converter has important scientific significance and engineering application value for optimizing the cascade design and improving the energy transmission efficiency. Based on the impinging jet experiment of the circulating water tunnel, combined with the particle image velocimetry (PIV) technology, a feasible technical path is provided for carrying out the research. The PIV technology has the advantages of non-disturbance, instantaneousness and full-flow field measurement, and can accurately reconstruct the wall turbulent flow structure in theory, providing key data support for simulation verification and design optimization.

[0003] However, the existing technical solutions have significant limitations in engineering practice, which are difficult to meet the needs of high-precision flow field visualization research. First, the cooperative regulation ability is insufficient. The actual working condition of the torque converter is complex, and the experimental device is required to accurately and cooperatively adjust the velocity, impact angle and spatial pose of the impinging jet. However, the existing device is difficult to realize high-precision, multi-degree-of-freedom cooperative control of the jet velocity, impact angle and relative distance between the blade and the jet, which leads to the inability to accurately reproduce the real unsteady flow state, seriously affecting the fidelity of the experimental simulation. Secondly, the measurement accuracy of the flow field near the blade is limited. In terms of the reliability of the measured data, the strong reflection of the blade surface during the experiment causes serious optical boundary pollution, which makes the PIV technology's measured data in the most critical near-wall region have low signal-to-noise ratio, and even completely fail. This problem makes it difficult to extract the flow velocity information near the blade boundary, seriously affecting the accuracy of the wall turbulent flow structure analysis. In addition, the working condition simulation is single and inefficient. In terms of flexibility and efficiency of the experiment, the velocity regulation range of the existing jet device is narrow and low in precision, and the response is slow, which makes it difficult to realize the rapid and accurate switching of multiple working conditions in a wide parameter range. The lack of such regulation ability limits the systematic exploration of the flow field characteristics under different operating conditions, and greatly reduces the coverage and measurement efficiency of the experimental research. The above problems seriously restrict the in-depth study of the evolution of the blade wall turbulent flow structure and the flow control mechanism.

[0004] In summary, the prior art still lacks an experimental solution capable of integrating multi-degree-of-freedom accurate regulation, wide-range multi-stage speed control and high-efficiency optical anti-interference capability. Therefore, developing a comprehensive experimental device with multi-stage speed accurate regulation, high-degree-of-freedom spatial positioning and effective optical interference suppression has become an urgent engineering requirement for breaking through the current research bottleneck and promoting the development of the forward design theory and method of the hydrodynamic torque converter blade. SUMMARY

[0005] The embodiment of the present application aims to provide a circulating water tunnel blade impact jet velocity multi-stage regulation test device, which aims to solve the problems in the above background art.

[0006] The embodiment of the present application is implemented as follows: a circulating water tunnel blade impact jet velocity multi-stage regulation test device, comprising an experimental water tunnel, a velocity multi-stage regulation mechanism, a water pump, a laser generator, a pulse laser controller, a blade angle adjustment mechanism, a high-definition CCD camera, a water tank, an image acquisition computer and a signal synchronous collector.

[0007] The water tank, the water pump and the experimental water tunnel are connected by pipelines to form a circulating loop.

[0008] The velocity multi-stage regulation mechanism is installed on the experimental water tunnel and is used to regulate the flow direction and value of the impact jet.

[0009] The blade angle adjustment mechanism is installed on the back plate of the experimental water tunnel and is used to fix the blade and adjust the angle thereof.

[0010] The laser generator is arranged above the experimental water tunnel and is used to provide pulse laser sheet light.

[0011] The optical axis of the high-definition CCD camera is perpendicular to the pulse laser sheet light provided by the laser generator, and the high-definition CCD camera is used to acquire the blade near-wall flow field image.

[0012] The image acquisition computer is connected with the high-definition CCD camera through the signal synchronous collector and is used to receive and process image data.

[0013] In a further technical solution, the velocity multi-stage regulation mechanism comprises, in sequence along the fluid flow direction: a flow control valve, a digital flow meter, an outer cylindrical pipe of the water tunnel, an inner cylindrical pipe of the water tunnel, a slidable pipe, a clamping device, a movable rod, a transmission device, a spherical joint bearing, a long shaft, an angle locking and measuring device, a conical pipe, an iris control device, a push rod, a linear motor, a handle, a horizontal angle measuring device and an impact jet head.

[0014] The transmission device is connected with the movable rod, the movable rod is connected with the clamping device, the slidable pipe is installed in the clamping device, and the transmission device is used to drive the slidable pipe to slide along the sliding groove above the experimental water tunnel.

[0015] The angle locking measuring device is used to lock and measure the rotation angle of the ball joint bearing;

[0016] The linear motor is connected to the iris control device via a push rod and is used to adjust the flow area;

[0017] The impact jet head is used to form a high-speed impact jet with a flat outlet.

[0018] In a further technical solution, the flow control valve includes a ball valve control switch and a rotating ball.

[0019] In a further technical solution, the transmission device includes a first base, on which a slider is slidably mounted in a horizontal direction, and the slider is connected to a movable rod. A first rotating shaft is also mounted on the first base, the rotary motor is connected to the first rotating shaft, and the rotating handle is connected to the first rotating shaft through a handle connecting rod. The first rotating shaft is connected to a connecting rod, and the connecting rod is connected to the slider through a ball connecting rod.

[0020] In a further technical solution, the spherical joint bearing includes a cylindrical tube with an indicator arrow at the bottom. A ball is installed inside the cylindrical tube, and the long axis radially penetrates the cylindrical tube and the ball, and is welded and fixed to the ball.

[0021] In a further technical solution, the angle locking measuring device includes a limiting block and an angle indicator;

[0022] The angle indicator is welded to the long axis and is used to indicate the rotation angle;

[0023] The limiting block is used to fix the position of the angle indicator.

[0024] In a further technical solution, the iris control device includes a slider, an arc-shaped rod, a rotating base, and an iris, and the push rod is connected to one of the sliders.

[0025] A further technical solution is that the impact jet head includes a pipe, a large conical pipe, a small conical pipe, and a nozzle connected in sequence;

[0026] The nozzle outlet has a flat structure.

[0027] A further technical solution is that the blade angle adjustment mechanism includes: an angle measuring device, an inner and outer connecting plate of the experimental water tunnel, an angle changing drive mechanism, a fixed connecting rod, and a movable connecting rod;

[0028] The fixed link and the movable link are respectively connected to the blade, and the angle changing drive mechanism is connected to the movable link to adjust the blade angle.

[0029] A further technical solution is that the inner and outer connecting plates of the experimental water tunnel include a detachable plate and a threaded fixing plate, wherein the threaded fixing plate is fixed to the back plate of the experimental water tunnel by threaded connection.

[0030] In a further technical solution, the angle-changing drive mechanism includes a second base, on which a second rotating shaft is mounted, and a rotating arm is connected to the second rotating shaft. The rotating arm is connected to a movable connecting rod via a locking nut. A forward rotation motor and a reverse rotation motor are also mounted on the second base, and both the forward rotation motor and the reverse rotation motor are connected to the second rotating shaft.

[0031] The present invention provides a multi-stage control test device for the impact jet velocity of a circulating water tunnel blade, the beneficial effects of which are as follows:

[0032] (1) A crank-connecting rod mechanism is used to drive the sliding pipe, which can be freely and quantitatively adjusted in the horizontal direction of the water tunnel. A set of friction self-locking devices is used to lock the spatial position of the adjusted sliding pipe. Finally, the dynamic and precise adjustment of the distance between the impact jet head and the blade is realized during the experiment, and reliable mechanical stability is maintained. This fundamentally solves the technical problem that the existing device cannot change the impact distance in real time and achieve precise distance adjustment during the experiment.

[0033] (2) The movable rod is directly connected to the spherical joint bearing inside the impact jet head, forming a self-locking spherical joint. This design restricts the pitch freedom of the impact jet head, thus significantly suppressing measurement errors caused by angle jitter during the experiment. In order to achieve precise locking and measurement at different angles, an angle measuring device and a high-inertia limit block are set above the spherical joint bearing. When the device is in the working position, the limit block achieves mechanical locking, fixing the spherical joint bearing. At this time, the azimuth angle of the jet head and the blade pitch angle can be directly read through the angle measuring device. When the device is unloaded, the long shaft can drive the spherical joint bearing to deflect freely within a certain angle range until it is adjusted to the required angle, and then it is locked again by the limit block. By switching between the static locking state and the dynamic adjustment state, the precise and stable control of the blade impact jet angle is achieved, solving the technical problem that the existing device cannot freely adjust the impact jet angle in real time.

[0034] (3) An innovative automatic control iris mechanism is introduced as the core of flow rate regulation. This mechanism consists of dozens of linked telescopic baffles. An external linear motor drives the slider and drives the arc-shaped connecting rod, converting the linear motion into the rotational motion of the iris mechanism, and precisely controlling the opening and closing of dozens of linked telescopic baffles. The iris mechanism is stably installed downstream of the flow meter of the impact jet device. Under the condition of constant flow rate and high pressure water provided by the water tank and water pump, the flow area is quantitatively changed by controlling the extension and retraction of the iris baffles through a programmed method. According to the principles of fluid mechanics, the outlet flow rate of the impact jet head can be directly and accurately controlled. This mechatronics design scheme realizes the precise and real-time control of the outlet velocity of the impact jet head, and solves the technical problem of cumbersome flow rate control and inability to adjust online in existing impact jet devices.

[0035] (4) Precise control of the blade's spatial orientation is achieved through a blade adjustment mechanism. This mechanism is driven by forward and reverse motors outside the experimental water tunnel, causing the movable connecting rod placed in the slide to rotate the blade clockwise / counterclockwise. An angle measuring device is used to monitor the deflection angle in real time, and the mechanism can be self-locked at the target position by tightening the locking nut to ensure the absolute stability of the blade's spatial position. By coordinating the control of the blade's spatial angle and the spatial position of the impact jet head, the actual liquid flow impact conditions during the operation of the hydraulic torque converter can be accurately reproduced. Based on this integrated adjustment platform, quantitative and scientific measurement of the near-wall flow field of the blade impact jet under various operating conditions is realized, solving the technical problem of limited blade angle adjustment in existing devices. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a multi-stage control test device for the impact jet velocity of a circulating water tunnel blade provided in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the multi-stage velocity control mechanism in a test device for multi-stage velocity control of blade impact jet in a circulating water tunnel, provided in an embodiment of the present invention.

[0038] Figure 3 A schematic diagram of the flow control valve in a multi-stage control test device for the velocity of a circulating water tunnel blade impact jet, provided in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the transmission device in a multi-stage control test device for the velocity of a circulating water tunnel blade impact jet, provided in an embodiment of the present invention.

[0040] Figure 5 A schematic diagram of the spherical joint bearing in a multi-stage control test device for the impact jet velocity of a circulating water tunnel blade provided in an embodiment of the present invention;

[0041] Figure 6This is a schematic diagram of the angle locking measuring device in a multi-stage control test device for the impact jet velocity of a circulating water tunnel blade, provided in an embodiment of the present invention.

[0042] Figure 7 A schematic diagram of the iris control device in a multi-stage control test device for the velocity of a circulating water tunnel blade impact jet, provided in an embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram of the structure of the impact jet head in a multi-stage control test device for the impact jet velocity of a circulating water tunnel blade, provided in an embodiment of the present invention.

[0044] Figure 9 This is a schematic diagram of the blade angle adjustment mechanism in a multi-stage control test device for blade impact jet velocity in a circulating water tunnel, provided in an embodiment of the present invention, within the experimental water tunnel.

[0045] Figure 10 This is a schematic diagram of the blade angle adjustment mechanism outside the experimental water tunnel in a multi-stage control test device for the velocity of a blade impact jet in a circulating water tunnel, as provided in an embodiment of the present invention.

[0046] In the attached diagram: Flow control valve 1; Ball valve control switch 1a; Rotating ball 1b; Digital flow meter 2; Outer cylindrical pipe of water tunnel 3; Inner cylindrical pipe of water tunnel 4; Sliding pipe 5; Clamping device 6; Movable rod 7; Transmission device 8; Rotating handle 8a; Rotating motor 8b; Handle connecting rod 8c; First rotating shaft 8d; Connecting rod 8e; Ball connecting rod 8f; Slider 8g; First base 8h; Spherical joint bearing 9; Indicating arrow 9a; Cylindrical tube 9b; Ball 9c; Long shaft 10; Angle locking measuring device 11; Limiting block 11a; Angle indicator 11b; Conical tube 12; Iris control device 13; Sliding plate 13a; Arc rod 13b; Rotating base 13c; Iris 13d; Push rod 14; Linear motor 15; Handle 16; Horizontal angle measurement. Device 1701; Angle measuring device 1702; Experimental water tunnel internal and external connecting plate 18; Detachable plate 18a; Threaded fixing plate 18b; Blade 19; Experimental water tunnel 20; Angle changing drive mechanism 21; Forward rotation motor 21a; Reverse rotation motor 21b; Second base 21c; Second rotating shaft 21d; Rotating arm 21e; ​​Locking nut 21f; Impact jet head 22; Pipe 22a; Large conical tube 22b; Small conical tube 22c; Nozzle 22d; Fixed connecting rod 23; Movable connecting rod 24; Image acquisition computer 25a; Signal synchronization acquisition device 25b; Laser generator 26a; Pulse laser controller 26b; High-definition CCD camera 27; Multi-level speed control mechanism 28; Blade angle adjustment mechanism 29; Water pump 30; Water tank 31. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0049] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a multi-stage control test device for the velocity of a circulating water tunnel blade impact jet, including an experimental water tunnel 20, a multi-stage velocity control mechanism 28, a water pump 30, a laser generator 26a, a pulsed laser controller 26b, a blade angle adjustment mechanism 29, a high-definition CCD camera 27, a water tank 31, an image acquisition computer 25a, and a signal synchronization acquisition device 25b;

[0050] The water tank 31, water pump 30 and experimental water tunnel 20 are connected by pipelines to form a circulation loop;

[0051] The speed multi-level control mechanism 28 is installed on the experimental water tunnel 20 and is used to control the direction and magnitude of the impact jet velocity.

[0052] The blade angle adjustment mechanism 29 is installed on the back plate of the experimental water tunnel 20 and is used to fix the blade 19 and adjust its angle.

[0053] The laser generator 26a is arranged above the experimental water tunnel 20 to provide pulsed laser sheet light;

[0054] The optical axis of the high-definition CCD camera 27 is perpendicular to the pulsed laser sheet light provided by the laser generator 26a, and is used to acquire images of the flow field near the blade wall.

[0055] The image acquisition computer 25a is connected to the high-definition CCD camera 27 via a signal synchronization acquisition unit 25b, and is used to receive and process image data.

[0056] In this embodiment of the invention, during use, the velocity and impact angle of the impact jet are first adjusted by the multi-level speed control mechanism 28, and then the angle of the blade 19 is adjusted by the blade angle adjustment mechanism 29; the laser generator 26a and the high-definition CCD camera 27 are started to acquire near-wall flow field images of the blade 19; the images are recorded and processed by the image acquisition computer 25a to obtain flow field data.

[0057] like Figure 2As shown, in a preferred embodiment of the present invention, the multi-stage speed control mechanism 28 includes the following components connected sequentially along the fluid flow direction: a flow control valve 1, a digital flow meter 2, an outer cylindrical tube of the water tunnel 3, an inner cylindrical tube of the water tunnel 4, a sliding pipe 5, a clamping device 6, a movable rod 7, a transmission device 8, a ball joint bearing 9, a long shaft 10, an angle locking measuring device 11, a tapered tube 12, an iris control device 13, a push rod 14, a linear motor 15, a handle 16, a horizontal angle measuring device 1701, and an impact jet head 22;

[0058] The transmission device 8 is connected to the movable rod 7, the movable rod 7 is connected to the clamping device 6, and the slidable pipe 5 is installed in the clamping device 6. The transmission device 8 is used to drive the slidable pipe 5 to slide along the chute above the experimental water tunnel 20.

[0059] The angle locking measuring device 11 is used to lock and measure the rotation angle of the ball joint bearing 9;

[0060] The linear motor 15 controls the iris control device 13 to work via the push rod 14, which is used to adjust the flow area.

[0061] The impact jet head 22 is used to form a high-speed impact jet with a flat outlet.

[0062] like Figure 3 As shown, in a preferred embodiment of the present invention, the flow control valve 1 includes a ball valve control switch 1a and a rotating ball 1b. The rotating ball valve control switch 1a drives the rotating ball 1b to rotate, thereby controlling the flow rate.

[0063] like Figure 4 As shown, in a preferred embodiment of the present invention, the transmission device 8 includes a first base 8h, on which a slider 8g is slidably mounted in the horizontal direction, and the slider 8g is connected to a movable rod 7. A first rotating shaft 8d is also mounted on the first base 8h. The rotary motor 8b is connected to the first rotating shaft 8d, and the rotating handle 8a is connected to the first rotating shaft 8d through a handle connecting rod 8c. The first rotating shaft 8d is connected to a connecting rod 8e, and the connecting rod 8e is connected to the slider 8g through a ball connecting rod 8f.

[0064] The relationship between the rotation angle of the rotary motor 8b and the linear movement distance of the slider 8g is as follows:

[0065] When the rotation angle is 0° or 180°, the connecting rod 8e and the ball connecting rod 8f are coplanar, which is the extreme position;

[0066] When the turning angle is arbitrary:

[0067] ;

[0068] in, The linear displacement distance of the slider, in mm; The length of link 8e is in mm; The length of the ball-connecting rod 8f is in mm. The projection angle of the line connecting the center of the connecting surface of the first rotating shaft 8d and the connecting rod 8e with the center of the ball of the ball connecting rod 8f in the direction of linear displacement of the slider, in rad.

[0069] In this embodiment of the invention, during use, the first rotating shaft 8d is rotated by the rotary motor 8b or the rotary handle 8a. The first rotating shaft 8d can drive the ball connecting rod 8f to move synchronously through the connecting rod 8e, thereby driving the slider 8g to move linearly on the first base 8h, thereby driving the slidable pipe 5 to move through the movable rod 7 and the clamping device 6.

[0070] like Figure 5 As shown, in a preferred embodiment of the present invention, the spherical joint bearing 9 includes a cylindrical tube 9b, an indicator arrow 9a is provided at the bottom of the cylindrical tube 9b, a ball 9c is installed in the cylindrical tube 9b, and the long shaft 10 radially penetrates the cylindrical tube 9b and the ball 9c, and is welded and fixed to the ball 9c.

[0071] like Figure 6 As shown, in a preferred embodiment of the present invention, the angle locking measuring device 11 includes a limiting block 11a and an angle indicator 11b;

[0072] The angle indicator 11b is welded to the long axis 10 and is used to indicate the rotation angle;

[0073] The limiting block 11a is used to fix the position of the angle indicator 11b.

[0074] like Figure 7 As shown, in a preferred embodiment of the present invention, the iris control device 13 includes a slider 13a, an arc rod 13b, a rotating base 13c, and an iris 13d; this mechanism is a mature existing mechanism, and its specific installation and matching relationship will not be described in detail here, and the push rod 14 is connected to one of the sliders 13a.

[0075] The linear motion distance of the slider 13a Rotation angle with rotating base 13c The relationship is as follows:

[0076] ;

[0077] in, The radius of the center circle of the rotating base 13c is in mm. The distance between the two hinge points of the arc-shaped rod 13b is in mm.

[0078] The rotation angle of the rotating base 13c The flow area of ​​the iris 13d The relationship is: hour, ; hour, ;in, This represents the maximum rotation angle. For maximum flow area, This represents the minimum flow area.

[0079] The flow area A of the iris 13d is represented as follows:

[0080] ;

[0081] in, The flow area of ​​the iris at 13d without the baffle is shown in mm. 2 ; The area covered by the baffle is in mm. 2 ; The diameter of the iris 13d moving wheel circulation circular channel is in mm.

[0082] In this embodiment of the invention, during use, the push rod 14 drives the slider 13a to move linearly, and the arc rod 13b drives the rotating base 13c to rotate, thereby adjusting the structure of the iris 13d and controlling the flow area.

[0083] like Figure 8 As shown, in a preferred embodiment of the present invention, the impact jet head 22 includes a pipe 22a, a large conical pipe 22b, a small conical pipe 22c and a nozzle 22d connected in sequence;

[0084] The outlet of the nozzle 22d has a flat structure.

[0085] like Figure 2 , Figure 9 and Figure 10 As shown, in a preferred embodiment of the present invention, the blade angle adjustment mechanism 29 includes: an angle measuring device 1702, an inner and outer connecting plate 18 of the experimental water tunnel, an angle changing drive mechanism 21, a fixed connecting rod 23 and a movable connecting rod 24.

[0086] The fixed link 23 and the movable link 24 are respectively connected to the blade 19, and the angle changing drive mechanism 21 is connected to the movable link 24 to adjust the blade angle.

[0087] Figure 9As shown, in a preferred embodiment of the present invention, the experimental water tunnel inner and outer connecting plate 18 includes a detachable plate 18a and a threaded fixing plate 18b, wherein the threaded fixing plate 18b is fixed to the back plate of the experimental water tunnel 20 by threaded connection.

[0088] Figure 10 As shown, in a preferred embodiment of the present invention, the angle changing drive mechanism 21 includes a second base 21c, on which a second rotating shaft 21d is mounted, and a rotating arm 21e is connected to the second rotating shaft 21d. The rotating arm 21e is connected to the movable connecting rod 24 through a locking nut 21f. A forward rotating motor 21a and a reverse rotating motor 21b are also mounted on the second base 21c, and both the forward rotating motor 21a and the reverse rotating motor 21b are connected to the second rotating shaft 21d.

[0089] In this embodiment of the invention, when in use, the second rotating shaft 21d is driven to rotate by the forward rotating motor 21a or the reverse rotating motor 21b. The second rotating shaft 21d drives the movable connecting rod 24 to move through the rotating arm 21e, thereby adjusting the impact angle.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-stage control experimental device for the velocity of impact jet from a circulating water tunnel blade, characterized in that, It includes an experimental water tunnel, a multi-stage speed control mechanism, a water pump, a laser generator, a pulsed laser controller, a blade angle adjustment mechanism, a high-definition CCD camera, a water tank, an image acquisition computer, and a signal synchronization acquisition device; The water tank, water pump, and experimental water tunnel are connected by pipelines to form a circulation loop; The multi-level speed control mechanism is installed on the experimental water tunnel and is used to control the direction and magnitude of the impact jet velocity. The blade angle adjustment mechanism is installed on the back plate of the experimental water tunnel and is used to fix the blade and adjust its angle. The laser generator is positioned above the experimental water tunnel to provide pulsed laser sheet light; The optical axis of the high-definition CCD camera is perpendicular to the pulsed laser beam provided by the laser generator, and is used to acquire images of the flow field near the blade wall. The image acquisition computer is connected to the high-definition CCD camera signal via a signal synchronization acquisition device, and is used to receive and process image data; The speed multi-stage control mechanism includes the following components connected sequentially along the fluid flow direction: a flow control valve, a digital flow meter, an outer cylindrical tube of the water tunnel, an inner cylindrical tube of the water tunnel, a sliding pipe, a clamping device, a movable rod, a transmission device, a spherical plain bearing, a long shaft, an angle locking measuring device, a tapered tube, an iris control device, a push rod, a linear motor, a handle, a horizontal angle measuring device, and an impact jet head. The transmission device is connected to the movable rod, the movable rod is connected to the clamping device, and the slidable pipe is installed in the clamping device. The transmission device is used to drive the slidable pipe to slide along the chute above the experimental water tunnel. The angle locking measuring device is used to lock and measure the rotation angle of the ball joint bearing; The linear motor is connected to the iris control device via a push rod and is used to adjust the flow area; The impact jet head is used to form a high-speed impact jet with a flat outlet.

2. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The flow control valve includes a ball valve control switch and a rotating ball.

3. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The transmission device includes a first base, on which a slider is slidably mounted in a horizontal direction and connected to a movable rod. A first rotating shaft is also mounted on the first base, a rotary motor is connected to the first rotating shaft, and a rotating handle is connected to the first rotating shaft via a handle connecting rod. The first rotating shaft is connected to a connecting rod, and the connecting rod is connected to the slider via a ball connecting rod.

4. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The spherical plain bearing includes a cylindrical tube with an indicator arrow at the bottom. A ball is installed inside the cylindrical tube, and the long axis radially passes through the cylindrical tube and the ball, and is welded and fixed to the ball.

5. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The angle locking measuring device includes a limit block and an angle indicator; The angle indicator is welded to the long axis and is used to indicate the rotation angle; The limiting block is used to fix the position of the angle indicator.

6. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The iris control device includes a slider, an arc-shaped rod, a rotating base, and an iris, and the push rod is connected to one of the sliders.

7. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The impact jet head includes a pipe, a large conical pipe, a small conical pipe, and a nozzle connected in sequence; The nozzle outlet has a flat structure.

8. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 1, characterized in that, The blade angle adjustment mechanism includes: an angle measuring device, an inner and outer connecting plate of the experimental water tunnel, an angle changing drive mechanism, a fixed connecting rod, and a movable connecting rod; The fixed link and the movable link are respectively connected to the blade, and the angle changing drive mechanism is connected to the movable link to adjust the blade angle.

9. The experimental device for multi-stage control of the velocity of the impingement jet from the blades of a circulating water tunnel according to claim 8, characterized in that, The experimental water tunnel's inner and outer connecting plates include a detachable plate and a threaded fixing plate, with the threaded fixing plate fixed to the back plate of the experimental water tunnel via a threaded connection.

10. The experimental device for multi-stage control of the velocity of the impact jet from the blades of a circulating water tunnel according to claim 8, characterized in that, The angle-changing drive mechanism includes a second base, on which a second rotating shaft is mounted. A rotating arm is connected to the second rotating shaft. The rotating arm is connected to a movable connecting rod via a locking nut. A forward rotating motor and a reverse rotating motor are also mounted on the second base, and both the forward rotating motor and the reverse rotating motor are connected to the second rotating shaft.

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