Fluid resistance testing device for drag reduction structure surface based on tesla valve principle

Abstract

The application provides a drag reduction structure surface fluid resistance testing device based on the principle of Tesla valve, which is used for testing and researching the drag reduction performance of the drag reduction structure. The device comprises a rack, an outer cylinder, a Tesla valve flow limiting device, a rotor, a transmission device, a motor connecting frame and a motor. The outer cylinder is fixed on the upper surface of the rack, the Tesla valve flow limiting device is fixed on the inner surface of the outer cylinder, the rotor is rotatably installed at the central position of the inner part of the outer cylinder and is connected with the motor through the transmission device, and the motor is fixed on the lower surface of the rack through the motor connecting frame. The application proposes a fluid resistance testing device based on the characteristics that the liquid flows reversely in the Tesla valve flow limiting device with high damping. The device can provide a relatively stable and stationary flow field condition for the test sample laid on the rotor, can also avoid the phenomenon that the middle area of the flow field is seriously depressed and the liquid surface of the peripheral area is raised and splashed under the action of the centrifugal force of the rotor, and further accurately evaluates the drag reduction performance of the test sample.

Description

Technical Field

[0001] This invention relates to a fluid resistance testing device, and more particularly to a surface fluid resistance testing device based on the Tesla valve principle for a drag-reducing structure. Background Technology

[0002] Drag reduction in turbulent flow has always been a hot topic of research, playing a crucial role in energy conservation and improving ship maneuverability. Currently, researchers have proposed using drag-reduction structures such as flexible coatings, grooved structures, and superhydrophobic surfaces to reduce fluid resistance, and have validated these methods through theoretical analysis, numerical simulation, and model experiments. Among these methods, building appropriate testing equipment to experiment with the proposed drag-reduction structures is the most practical research approach and an essential component of the research process.

[0003] Currently used testing devices mainly include wind tunnels, water tunnels, and towed water tanks. These devices can provide flow field conditions close to actual working conditions, but they occupy a large area, are expensive to build and test, and have high requirements for the test environment, thus causing great inconvenience to the fluid resistance testing of drag-reducing structures. Therefore, designing a small fluid resistance testing device that meets the test requirements and is inexpensive is crucial for the research of drag-reducing structures. Existing small fluid resistance testing devices test the drag-reducing performance of the structure by placing the drag-reducing structure on the surface of a disc or cylindrical rotor and using a motor to drive the rotor to rotate in the fluid. However, because the rotor inevitably generates centrifugal force during rotation, the test flow field exhibits phenomena such as central region depression and liquid splashing, and the entire flow field continues to flow with the rotation of the rotor, failing to provide a relatively stable and static flow field environment for the drag-reducing structure, thus leading to inaccurate test results. Summary of the Invention

[0004] The purpose of this invention is to provide a surface fluid resistance testing device for drag-reducing structures based on the Tesla valve principle, for experimental research on the proposed drag-reducing structure.

[0005] The present invention achieves its objective by comprising a frame, an outer cylinder, a Tesla valve flow limiting device, a rotor, a transmission device, a motor connecting frame, and a motor. The outer cylinder has a boss with a central through hole at its inner bottom surface center. The outer cylinder is fixed to the upper surface center of the frame. The Tesla valve flow limiting device is coaxially fixed to the inner surface of the outer cylinder. The rotor is coaxially and rotatably mounted to the inner center of the outer cylinder and connected to the motor via the transmission device. The motor is fixed to the lower surface of the frame via the motor connecting frame.

[0006] Preferably, the frame is made of Q235 steel and includes a square support plate with rounded corners and four legs. The Tesla valve flow limiting device is made of stainless steel and includes an annular cover plate and nine Tesla valve units. The annular cover plate is fixedly connected to the inner surface of the outer cylinder, and the nine Tesla valve units are uniformly fixed to its lower surface around the central axis of the annular cover plate. Each Tesla valve unit includes an inner flow limiting plate, an outer flow limiting plate, and a connecting plate. The upper surface of the connecting plate is fixedly connected to the lower surface of the annular cover plate, and the openings of the inner and outer flow limiting plates face the same direction and are opposite to the rotation direction of the rotor, and are coaxially fixed to the lower surface of the connecting plate.

[0007] Preferably, the transmission device includes a flange, a connecting shaft, a coupling, and a PTFE gasket. The flange is made of 45 steel and has a through hole machined in its center. The flange is coaxially and rotatably secured to the upper surface of the outer cylinder via the PTFE gasket. The connecting shaft is also made of 45 steel, with its two ends connected to the flange and one end of the coupling, respectively. The other end of the coupling is connected to the output shaft of the motor, and all three components rotate synchronously with the output shaft of the motor.

[0008] Preferably, the rotor is made of stainless steel and has a centrally symmetrical structure, including a connecting disc, two sector-shaped connecting plates, two arc-shaped connecting plates, a connecting beam, two supporting ribs, two specimen mounting plates, and two arc-shaped guide shields. The lower surface of the connecting disc is coaxially fixed to the upper surface of the flange. One end of each of the two sector-shaped connecting plates is symmetrically fixed to the upper surface of the connecting disc, and the other end is connected to the lower end of each of the two arc-shaped connecting plates. The upper ends of each of the two arc-shaped connecting plates are fixedly connected to both ends of the connecting beam. One end of each of the two supporting ribs is fixedly connected to the connecting disc, and the other end is fixedly connected to both ends of the connecting beam. The two specimen mounting plates are curved flat plates and are fixedly connected to the two arc-shaped connecting plates. The two arc-shaped guide shields are fixed to the front end of each of the two specimen mounting plates.

[0009] Compared with the prior art, the beneficial effects of the present invention are: 1. The Tesla valve flow limiting device in the present invention can cause the fluid flowing through it to generate a backflow phenomenon, thereby effectively reducing the fluid velocity in the area behind the test sample and providing a relatively stable and static flow field environment in front of another test sample. 2. The Tesla valve flow limiting device in the present invention can significantly reduce the influence of the centrifugal force generated by the rotor during rotation on the flow field, thereby avoiding the phenomenon of severe depression in the middle area and splashing of the liquid level in the outer area under the action of centrifugal force. Attached Figure Description

[0010] Figure 1 and Figure 2This is a schematic diagram illustrating the working principle of a Tesla valve;

[0011] Figure 3 and Figure 4 This is a schematic diagram illustrating the working principle of the present invention;

[0012] Figure 5 This is a schematic diagram of the structure of the present invention;

[0013] Figure 6 yes Figure 5 A schematic diagram of the structure of the Tesla valve flow limiting device;

[0014] Figure 7 yes Figure 6 A schematic diagram of the structure of a Tesla valve unit;

[0015] Figure 8 yes Figure 5 Cross-sectional view of the central rotor;

[0016] Figure 9 yes Figure 5 Shaftside view of the intermediate rotor.

[0017] Explanation of icon numbers:

[0018] 1. Fluid 2. Tesla valve 3. Outer cylinder 4. Tesla valve flow restrictor 5. Rotor 6. Test sample 7. Fluid inside the Tesla valve flow restrictor 8. Normal fluid of the test sample 9. Fluid in the area behind the test sample 10. Rotor rotation speed 11. Fluid environment in the area in front of the test sample 12. Flow field liquid surface 13. Frame 14. Transmission device 15. Flange 16. PTFE gasket 17. Connecting shaft 18. Coupling 19. Motor connecting frame 20. Motor 21. Annular cover plate 22. Tesla valve unit 23. Outer flow restrictor plate 24. Connecting plate 25. Inner flow restrictor plate 26. Specimen mounting plate 27. Arc-shaped connecting plate 28. Connecting beam 29. Support rib 30. Connecting disc 31. Fan-shaped connecting plate 32. Arc-shaped guide shroud. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Combination Figure 1 and Figure 2 A detailed explanation of the working principle of the Tesla valve is provided: Tesla valve 2 employs a special circuit design. When fluid 1 passes through the Tesla valve in the forward direction (e.g....), Figure 1 As shown), the fluid splits into two streams at the junction of each loop, and then the two streams of fluid 1 converge at the next junction. Since the two streams of fluid 1 flow in the same direction, accelerated flow can be achieved. Conversely, when fluid 1 flows in the opposite direction through Tesla valve 2 (as shown), Figure 2As shown, the fluid will split into two streams at the junction of each loop, and then the two streams of fluid 1 will converge at the next junction. However, at this time, the flow directions of the two streams of fluid 1 are opposite, so fluid 1 will be subject to a large damping effect.

[0021] Inspired by the high damping characteristics of reverse flow of fluid in a Tesla valve, this invention designs a surface fluid resistance testing device based on the Tesla valve principle and featuring a drag-reducing structure. The following is a combination of... Figure 3 and Figure 4 The working principle of this invention is explained in detail as follows: During the resistance test, a certain height of liquid is added inside the outer cylinder 3, and the test sample 6 is placed on the outer surface of the rotor 5. The rotor 5 rotates at a specific speed 10, driving the fluid around it to flow. The fluid 8 closer to the test sample 6 along the normal direction has a higher velocity (approaching the linear velocity of the test sample 6 at its maximum), and the fluid 8 further away from the test sample 6 has a lower velocity (approaching zero at its minimum). Since the velocity direction of the fluid 7 inside the Tesla valve flow limiting device 4 is contrary to the velocity direction of the fluid 9 in the area behind the test sample, it can effectively reduce the flow velocity of the fluid 9 in the area behind the test sample, thereby providing a relatively stable and static flow field environment 11 in front of another test sample. It is worth noting that the Tesla valve flow limiting device 4 is at an appropriate distance from the test sample 6, so it will not affect the fluid boundary layer on the surface of the test sample 6. In addition, since the Tesla valve flow limiting device 4 can effectively dissipate the energy of the fluid, it avoids the phenomenon of severe depression of the liquid surface in the middle area and splashing of the liquid surface in the outer area due to the centrifugal force of the rotor, keeping the liquid surface 12 of the flow field in a relatively stable state.

[0022] like Figure 5 As shown, the surface fluid resistance testing device based on the Tesla valve principle of the present invention includes a frame 13, an outer cylinder 3, a Tesla valve flow limiting device 4, a rotor 5, a transmission device 14, a motor connecting frame 19, and a motor 20. The transmission device 14 includes a flange 15, two polytetrafluoroethylene gaskets 16, a connecting shaft 17, and a coupling 18. The outer cylinder 3 has a boss with a central through hole at the center of the bottom surface inside. The outer cylinder 3 is fixed to the center of the upper surface of the frame 13. The Tesla valve flow limiting device 4 is coaxially fixed to the inner surface of the outer cylinder 3. The rotor 5 is coaxially fixed to the upper surface of the flange 15. The flange 15 is rotatably and coaxially fixed to the upper surface of the boss of the outer cylinder 3 through the polytetrafluoroethylene gasket 16. The two ends of the connecting shaft 17 are respectively connected to one end of the flange 15 and one end of the coupling 18. The other end of the coupling 18 is connected to the output shaft of the motor 20. The flange 15, the connecting shaft 17, and the coupling 18 rotate synchronously with the output shaft of the motor 20. The motor 20 is fixed to the lower surface of the frame 13 through the motor connecting bracket 19. The fluid resistance of the test sample 6 is obtained by monitoring the torque of the output shaft of the motor 20.

[0023] Combination Figure 5 , Figure 6 and Figure 7 The Tesla valve flow limiting device 4 is described in detail below: The Tesla valve flow limiting device 4 includes an annular cover plate 21 and nine Tesla valve units 22. Each Tesla valve unit 22 includes an outer flow limiting plate 23, a connecting plate 24, and an inner flow limiting plate 25. The annular cover plate 21 is fixedly connected to the inner surface of the outer cylinder 3. The nine Tesla valve units 22 are evenly fixed to the lower surface of the annular cover plate 21 around its central axis. The upper surface of the connecting plate 24 is fixedly connected to the lower surface of the annular cover plate 21. The openings of the outer flow limiting plate 23 and the inner flow limiting plate 25 face the same direction and are opposite to the rotation direction of the rotor 5, and are coaxially fixed to the lower surface of the connecting plate 24.

[0024] Combination Figure 5 , Figure 8 and Figure 9 The rotor 5 is described in detail as follows: The rotor 5 includes two specimen mounting plates 26, two arc-shaped connecting plates 27, a connecting beam 28, two supporting ribs 29, a connecting disc 30, two fan-shaped connecting plates 31, and two arc-shaped guide shields 32. The lower surface of the connecting disc 30 is coaxially fixed to the upper surface of the flange 15. One end of each of the two fan-shaped connecting plates 31 is symmetrically fixed to the upper surface of the connecting disc 30, and the other end is fixedly connected to the lower end of each of the two arc-shaped connecting plates 27. The upper ends of each of the two arc-shaped connecting plates 27 are fixedly connected to both ends of the connecting beam 28. The two specimen mounting plates 26 are fixedly connected to the two arc-shaped connecting plates 27. The two arc-shaped guide shields 32 are fixedly connected to the front end of each of the two specimen mounting plates 26. One end of each of the two supporting ribs 29 is fixedly connected to the upper surface of the connecting disc 30, and the other end is fixedly connected to both ends of the connecting beam 28.

[0025] In summary, this invention provides a fluid resistance testing device based on the Tesla valve principle, used for experimental research on the drag reduction performance of drag-reducing structures (flexible coatings, grooved structures, superhydrophobic surfaces, etc.). The invention consists of a frame, an outer cylinder, a Tesla valve flow-limiting device, a rotor, a transmission device, a motor connection frame, and a motor. The outer cylinder is fixed to the upper surface of the frame, the Tesla valve flow-limiting device is fixed to the inner surface of the outer cylinder, the rotor is rotatably mounted at the center of the outer cylinder and connected to the motor via the transmission device, and the motor is fixed to the lower surface of the frame via the motor connection frame. This invention proposes a fluid resistance testing device based on the high damping characteristic of countercurrent flow of liquid within the Tesla valve flow-limiting device. It provides a relatively stable and static flow field condition for the test sample laid on the rotor, while also avoiding the phenomenon of severe central depression and splashing liquid level rise in the peripheral area caused by the centrifugal force of the rotor, thus enabling accurate evaluation of the drag reduction performance of the test sample.

Claims

1. A surface fluid resistance testing device based on the Tesla valve principle for drag-reducing structures, characterized in that: The device includes a frame, an outer cylinder, a Tesla valve flow limiting device, a rotor, a transmission device, a motor connecting frame, and a motor. The outer cylinder has a boss with a central through hole at the center of its inner bottom surface. The outer cylinder is fixed to the center of the upper surface of the frame. The Tesla valve flow limiting device is coaxially fixed to the inner surface of the outer cylinder. The rotor is rotatably mounted at the center of the inner surface of the outer cylinder and is connected to the motor through the transmission device. The motor is fixed to the lower surface of the frame through the motor connecting frame. The Tesla valve flow limiting device includes an annular cover plate and multiple Tesla valve units. The annular cover plate is fixedly connected to the inner surface of the outer cylinder. The multiple Tesla valve units are uniformly fixed to the lower surface of the annular cover plate around its central axis. Each Tesla valve unit includes an inner flow limiting plate, an outer flow limiting plate, and a connecting plate. The upper surface of the connecting plate is fixedly connected to the lower surface of the annular cover plate. The openings of the inner and outer flow limiting plates face the same direction and are opposite to the rotation direction of the rotor, and are coaxially fixed to the lower surface of the connecting plate.

2. The surface fluid resistance testing device based on the Tesla valve principle for drag reduction structures according to claim 1, characterized in that: The transmission device includes a flange, a connecting shaft, a coupling, and a polytetrafluoroethylene (PTFE) gasket. The flange is rotatably and coaxially fixed to the upper surface of the outer cylinder via the PTFE gasket. The two ends of the connecting shaft are respectively connected to the flange and one end of the coupling. The other end of the coupling is connected to the output shaft of the motor, and all three rotate synchronously with the output shaft of the motor.

3. The surface fluid resistance testing device based on the Tesla valve principle for drag reduction structures according to claim 2, characterized in that: The rotor has a centrally symmetrical structure, including a connecting disc, two sector-shaped connecting plates, two arc-shaped connecting plates, a connecting beam, two supporting ribs, two specimen mounting plates, and two arc-shaped guide shields. The lower surface of the connecting disc is coaxially fixed to the upper surface of the flange. One end of each of the two sector-shaped connecting plates is symmetrically fixed to the upper surface of the connecting disc, and the other end is connected to the lower end of each of the two arc-shaped connecting plates. The upper ends of each of the two arc-shaped connecting plates are fixedly connected to both ends of the connecting beam. One end of each of the two supporting ribs is fixedly connected to the connecting disc, and the other end is fixedly connected to both ends of the connecting beam. The two specimen mounting plates are fixedly connected to the two arc-shaped connecting plates, and the two arc-shaped guide shields are fixed to the front end of each of the two specimen mounting plates.

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