Seal beard-imitated flow field measuring device and flow field measuring method

Abstract

The invention discloses a seal beard-imitated flow field measuring device and a seal beard-imitated flow field measuring method, and belongs to the technical field of flow field detection.The seal beard-imitated flow field measuring device comprises a base, a cross beam, a piezoresistive strain gauge, a seal beard imitated part and a guide wing, four beam bodies of the cross beam are respectively provided with the piezoresistive strain gauges, the seal beard bionic part forms a cylinder extending in the axial direction, the section of the seal beard bionic part is oval, the size of the seal beard bionic part changes periodically in the axial direction, the guide wing is installed on the seal beard bionic part, and the seal beard bionic part is connected with the guide wing. The bottom end of the seal beard bionic part is installed at the center position of the cross beam in an axial rotation mode and is perpendicular to the plane where the cross beam is located. Through the innovative design of simulating seal beards, the accuracy, the reliability and the adaptability of flow velocity measurement are remarkably improved, and the flow velocity sensor has the advantages of being outstanding in performance in low-speed water flow and complex water flow environments, small in size, light in weight, easy to integrate and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of flow field detection, and particularly relates to a seal-whisker-like flow field measurement device and a flow field measurement method. Background Art

[0002] Small and medium-sized underwater vehicles play a crucial role in China's marine industry. As a flexible and efficient underwater detection tool, they are widely used in marine exploration, scientific research, security patrol and other fields, providing strong support for the development of China's marine economy and scientific and technological progress. The accurate perception of the underwater flow field is a key factor for the safe and efficient operation of these vehicles, and the flow velocity is one of the important parameters for flow field perception. However, existing flow velocity measurement technologies, such as propeller-type current meters, acoustic Doppler profilers, laser Doppler velocimeters, etc., generally have problems such as large volume, high energy consumption, and complex structure, which limit their application on small and medium-sized unmanned underwater vehicles to a certain extent.

[0003] In recent years, studies have found that seals can identify and navigate underwater objects through their nasal whiskers. Seal whiskers have a unique geometric shape, with an elliptical cross-section, and their major and minor axes change periodically in the length direction. This structure can effectively suppress vortex-induced vibration, and this suppression effect has obvious directional sensitivity, which is closely related to the magnitude of the angle of attack. The angle of attack refers to the angle between the water flow direction and the major axis of the whisker. When the angle of attack is 0°, the whisker structure has the best suppression effect on vortex-induced vibration. As the angle of attack increases, the suppression effect gradually decreases. Existing studies have shown that 30° is a critical value. When the angle is lower than this value, the whisker structure can maintain an effective suppression effect on vortex-induced vibration.

[0004] In view of the limitations of existing flow velocity measurement technologies and the unique underwater flow field adaptability of seal whiskers, it is particularly necessary to design a flow velocity measurement device imitating seal whiskers. Summary of the Invention

[0005] Aiming at the problems of large volume, high energy consumption, and complex structure existing in the application of existing flow velocity measurement technologies in small and medium-sized underwater vehicles, the present invention provides a seal-whisker-like flow field measurement device and a flow field measurement method.

[0006] The present invention is implemented as follows. An artificial seal whisker flow field measurement device, characterized in that it includes a base, a cross beam, piezoresistive strain gauges, an artificial seal whisker part, and guide vanes. The cross beam is installed on the base, and the piezoresistive strain gauges are respectively installed on the four beam bodies of the cross beam. The artificial seal whisker part forms a cylinder extending along the axis, the cross section of the artificial seal whisker part is elliptical and its size varies periodically along the axis. The guide vanes are installed on the artificial seal whisker part, and the bottom end of the artificial seal whisker part is installed at the central position of the cross beam in a way of axial rotation and is perpendicular to the plane where the cross beam is located.

[0007] In the above technical solution, preferably, the cross section of the artificial seal whisker part includes cross section A and cross section B that are equidistantly spaced along the axis. The included angle between cross section A and the plane where the cross beam is located is α, and the included angle between cross section B and the plane where the cross beam is located is β.

[0008] In the above technical solution, preferably, the guide vanes are connected to the root of the artificial seal whisker part. The chord line of the airfoil of the guide vanes coincides with the major axis of the ellipse of the artificial seal whisker part, and the end point of the minor axis of the ellipse of the artificial seal whisker part coincides with the leading edge of the airfoil of the guide vanes.

[0009] In the above technical solution, preferably, the leading edge and the trailing edge of the guide vanes form an arc transition structure.

[0010] In the above technical solution, preferably, the base forms an annular structure, the cross beam is formed by the cross intersection of two rectangular beams, and the piezoresistive strain gauges are arranged on the upper surface of the rectangular beam near the base.

[0011] Compared with the prior art, the artificial seal whisker flow field measurement device of the present invention has the following remarkable advantages and effects:

[0012] By imitating the undulating structure of seal whiskers and adopting the design of the major and minor axes of the elliptical cross section with periodic changes, the artificial seal whiskers of the present invention can effectively suppress vortex-induced vibration. In water flow, the undulating artificial whisker part can control the generation of vortices better than traditional smooth whiskers and stabilize the sensor structure, thereby reducing the measurement error caused by vortex-induced vibration. This design greatly improves the accuracy and reliability of flow velocity measurement, and is especially suitable for the high-precision measurement requirements in complex water flow environments.

[0013] The present invention installs guide vanes at the bottom of the artificial seal whisker part. Through the hydrodynamic force generated by the guide vanes, the major axis of the artificial whiskers always remains parallel to the water flow direction, maximizing the inhibitory effect of the seal whisker structure on vortex-induced vibration. This design can effectively guide the whiskers to the optimal position in the water flow, further improving the accuracy of flow velocity measurement, and at the same time enhancing the automatic adaptation ability of the sensor to different water flow directions.

[0014] Through the cross-beam structure and the bearing connection method, the present invention realizes the multi-directional perception ability of the whiskers. Under the action of water flow, the whiskers can freely rotate through the bearings and adjust the angle to automatically align with the water flow direction. This design enables the sensor to automatically adjust its attitude in real time to obtain the best detection effect. Especially in low-speed water flows or complex flow fields, it can improve the perception ability of the sensor and ensure the stability and reliability of the flow velocity measurement.

[0015] The overall structural design of the present invention is light, compact, small in size and light in weight, which is convenient to be integrated into various underwater monitoring devices. Compared with traditional large flow velocity sensors, the flow velocity measurement device of the present invention has obvious advantages in terms of volume and weight, making it more suitable for medium and small-sized underwater vehicles and meeting the requirements of modern underwater detection and exploration equipment for light weight and high performance. This design not only reduces the occupation of equipment space but also reduces energy consumption, further improving the comprehensive performance of the system.

[0016] Through the above structural innovations, especially the design of the guiding wings and free rotation, the seal-whisker-like flow field measurement device of the present invention has stronger adaptability in low-speed water flows. In a low-flow velocity environment, the seal-whisker-like whiskers can automatically adjust to align with the water flow direction, better exerting the ability of the seal-whisker-like whiskers to suppress vortex-induced vibration, thereby maintaining a stable flow velocity measurement effect. This design effectively avoids the unstable response phenomenon of traditional flow velocity sensors in low-speed water flows, greatly improving the application performance of the system in complex marine environments.

[0017] The design of the present invention takes into account both the lightness of the structure and the high efficiency of the function, enabling it to be easily integrated into various underwater monitoring and detection systems. Whether it is various underwater tasks such as marine exploration, scientific research or security patrol, the present invention can provide reliable flow velocity measurement support, providing an ideal flow field perception solution for medium and small-sized underwater vehicles.

[0018] In summary, through the innovative design of the seal-whisker-like structure, the present invention significantly improves the accuracy, reliability and adaptability of flow velocity measurement, especially outstanding in low-speed water flows and complex water flow environments. At the same time, it has the advantages of small size, light weight and easy integration, making it an ideal choice for flow velocity measurement devices of medium and small-sized underwater vehicles.

[0019] The second object of the present invention is to propose a measurement method based on the above seal-whisker-like flow field measurement device, which is characterized by including the following steps:

[0020] S1. Connect the piezoresistive strain gauges into a Wheatstone bridge and collect the voltage change information of the piezoresistive strain gauges;

[0021] S2. Establish a rectangular coordinate system adapted to the cross beam with the intersection center of the cross beam as the origin, and take the voltage increase values of two of the four piezoresistive strain gauges as Vx and Vy;

[0022] S3. Calculate the direction angle θ and the equivalent voltage V through the following formula:

[0023]

[0024]

[0025] S4. Set the 0° direction in the coordinate system, and calculate the measured oncoming flow direction as DIR according to the positional relationship between the 0° direction and the piezoresistive strain gauges; change the magnitude of the water flow velocity to obtain V values at different flow velocities, and calibrate V with the fluid velocity VEL to obtain the linear correspondence between V and VEL.

[0026] In the above technical solution, preferably, let the four piezoresistive strain gauges on the cross beam be strain gauge A, strain gauge B, strain gauge C, and strain gauge D respectively, where strain gauge A and strain gauge C are located on the X-axis of the coordinate system and strain gauge A is located in the positive direction of the X-axis, strain gauge B and strain gauge D are located on the Y-axis of the coordinate system and strain gauge B is located in the positive direction of the Y-axis, and set the water flow along the negative x-axis as 0°, and the oncoming flow direction DIR is judged according to the following:

[0027] If the data of the voltage increase value comes from strain gauge A and B, then DIR = θ;

[0028] If the data of the voltage increase value comes from strain gauge B and C, then DIR = 180° - θ;

[0029] If the data of the voltage increase value comes from strain gauge C and D, then DIR = θ + 180°;

[0030] If the data of the voltage increase value comes from strain gauge D and A, then DIR = 360° - θ. Description of the Drawings

[0031] Figure 1 is the overall structure diagram of the flow velocity measuring device of the present invention;

[0032] Figure 2 is the connection structure diagram of the beard bionic part and the guide wing of the present invention;

[0033] Figure 3 is the structure diagram of the base and the cross beam of the present invention;

[0034] Figure 4 is the parameter schematic diagram of the beard bionic part of the present invention;

[0035] Figure 5 is the schematic diagram of the flow velocity measurement principle of the flow velocity measuring device of the present invention;

[0036] Figure 6 is a schematic diagram of the Wheatstone circuit connection;

[0037] Figure 7 is a schematic diagram of the flow direction adaptation function of the flow velocity measuring device of the present invention;

[0038] Figure 8 is the simulation result of the strain distribution of the flow velocity measuring device of the present invention under the action of hydrodynamic force;

[0039] Figure 9 is the modal analysis diagram of the flow velocity measuring device of the present invention. Detailed implementation manners

[0040] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] For the problems of large volume, high energy consumption, complex structure, etc. existing in the application of existing flow velocity measurement technologies in small and medium-sized underwater vehicles, the present invention particularly provides a flow field measurement device imitating seal whiskers. In order to further illustrate the structure of the present invention, the detailed description is as follows with reference to the drawings:

[0042] Please refer to Figures 1-3 , a flow field measurement device imitating seal whiskers, including a base 1, a cross beam 2, piezoresistive strain gauges 3, a seal whisker bionic part 4 and a guide vane 5. The cross beam is installed on the base, piezoresistive strain gauges are respectively installed on the four beam bodies of the cross beam, the seal whisker bionic part forms a column extending along the axis, the cross section of the seal whisker bionic part is elliptical and the size changes periodically along the axis, the guide vane is installed on the seal whisker bionic part, and the bottom end of the seal whisker bionic part is installed at the central position of the cross beam in an axially rotatable manner and is perpendicular to the plane where the cross beam is located.

[0043] The seal whisker bionic part, the cross beam and the guide vane are manufactured by 3D printing technology and made of high-toughness resin materials to improve their stability in water flow.

[0044] The seal whisker bionic part adopts RESIONE M58 high-toughness resin material, with an elastic modulus of 2.5 - 3.0 GPa and a density of 1.15 - 1.18 g / cm 3 , and the tensile strength is approximately between 50 - 70 MPa. Specifically, as Figure 4, the seal whisker has a wavy outline and an elliptical cross-section. The seal whisker bionic part includes seven control parameters: a, b, k, l, M, α, and β. The cross-section of the seal whisker bionic part includes cross-section A and cross-section B that are equally spaced along the axis. The angle between cross-section A and the plane where the cross beam is located is α, and the angle between cross-section B and the plane where the cross beam is located is β. a and b are the major and minor semi-axes of the relatively flat and long elliptical cross-section, k and l are the major and minor semi-axes of the relatively round elliptical cross-section, M is the distance between two adjacent cross-sections, and α and β are the angles between the two cross-sections and the horizontal plane respectively. In this embodiment, M is 1.82 mm, a and b are 0.595 mm and 0.24 mm respectively, k and l are 0.475 mm and 0.29 mm respectively, and the tilt angles of the control ellipses α and β are 15.27° and 17.60° respectively.

[0045] The guiding wing is in the shape of a NACA 0012 airfoil and is connected to the root of the seal whisker bionic part. The chord line of the airfoil of the guiding wing coincides with the major axis of the ellipse of the seal whisker bionic part, and the end point of the minor axis of the ellipse of the seal whisker bionic part coincides with the front end of the airfoil of the guiding wing. Moreover, the leading edge and the trailing edge of the guiding wing form an arc transition structure.

[0046] The base forms an annular structure. The cross beam is formed by the cross intersection of two rectangular beams. The piezoresistive strain gauges are arranged on the upper surface of the rectangular beam near the base. At the intersection center of the cross beam, a bearing installation hole is designed, and a bearing 6 is installed in this installation hole. The bottom end of the seal whisker bionic part is installed at the intersection center of the cross beam through the bearing, realizing the axial rotation installation of the seal whisker bionic part. In order to improve the detection sensitivity, the piezoresistive strain gauges are arranged at the positions with relatively large stress concentration on the cross beam. Therefore, the piezoresistive strain gauges are arranged on the upper surface of each beam and near the annular base. The piezoresistive strain gauges are divided into a strain gauge base and a semiconductor silicon strain gauge. The piezoresistive strain gauges are connected to the detection circuit, and the strain gauge base is pasted to the surface of the cross beam using a high-strength adhesive (such as epoxy resin, instant glue, etc.).

[0047] Embodiment 2, the measurement method of the seal whisker bionic flow field measurement device, includes the following steps:

[0048] S1. The piezoresistive strain gauges are connected into a Wheatstone bridge and the voltage change information of the piezoresistive strain gauges is collected.

[0049] Figure 5 is a schematic diagram of the measurement principle of the seal whisker bionic flow field measurement device. The piezoresistive strain gauges are connected in the form of a Wheatstone bridge, and the connection form of the bridge is as Figure 6 shown. The initial resistance values of the four resistance strain gauges are the same, all being R0. The voltage values on the four resistors are measured through a voltmeter. When not affected by the water flow impact, the voltage values are the same, all being V0. Define the fluid velocity magnitude as VEL and the oncoming flow direction as DIR. When the flow field force acts on the seal whisker bionic in a specific direction, the whisker is subjected to the water flow drag force C D is the drag coefficient, ρ is the fluid density, U is the water flow velocity, d is the equivalent diameter of the whisker, and L is the length of the whisker. The magnitude of the drag force on the whisker depends on the magnitude of the water flow velocity. The drag force causes the whisker to deform in the flow direction, and then generates a downward pressure acting on the cross cantilever beam structure, causing the cantilever beam to deform. At this time, two strain gauges bend upward, the resistance increases, and the induced voltage value increases; the two symmetric strain gauges bend downward, the resistance decreases, and the induced voltage value decreases. By measuring the changed voltage values V A , V B , V C , V D , the voltage change values ΔV of the four strain gauges are further calculated A =V A -V0, ΔV B =V B -V0, ΔV C =V C -V0, ΔV D =V D -V0.

[0050] S2. Establish a right-angle coordinate system adapted to the cross beam with the intersection center of the cross beam as the origin, and take two voltage increase values among the four piezoresistive strain gauges as Vx and Vy.

[0051] S3. Calculate the direction angle θ and the equivalent voltage V through the following formula:

[0052]

[0053]

[0054] S4. Set the 0° direction in the coordinate system, and calculate the measured oncoming flow direction DIR according to the position relationship between the 0° direction and the piezoresistive strain gauge; specifically, assume that the four piezoresistive strain gauges on the cross beam are strain gauge A, strain gauge B, strain gauge C, and strain gauge D respectively, where strain gauge A and strain gauge C are located on the X-axis of the coordinate system and strain gauge A is located in the positive direction of the X-axis, strain gauge B and strain gauge D are located on the Y-axis of the coordinate system and strain gauge B is located in the positive direction of the Y-axis, set the water flow along the negative x-axis as 0°, and the oncoming flow direction is DIR, and make the following judgments according to:

[0055] If the data of the voltage increase value comes from strain gauges A and B, then DIR = θ;

[0056] If the data of the voltage increase value comes from strain gauges B and C, then DIR = 180° - θ;

[0057] If the data of the voltage increase value comes from strain gauges C and D, then DIR = θ + 180°;

[0058] If the data of the voltage increase value is from strain gauges D and A, then DIR = 360° - θ.

[0059] Change the magnitude of the water flow velocity to obtain the V values at different flow velocities. By calibrating V with the fluid velocity VEL, the linear correspondence between V and VEL is obtained.

[0060] Conduct a water tunnel experiment. Change the magnitude of the water flow velocity to obtain the V values at different flow velocities. By calibrating V with the fluid velocity VEL, the linear correspondence between V and VEL is obtained.

[0061] The cylindrical base of the cross beam base is fixed. After the guiding wing is impacted by the water flow, it drives the whisker to rotate in the bearing and adjust the direction. Finally, the water flow direction is parallel to the major axis direction of the elliptical cross-section of the seal-whisker-like structure column, and the angle of attack is 0. The seal-whisker-like structure column drives the cross beam assembly to deform under the action of the fluid force underwater.

[0062] The flow velocity measuring device detects the change in the resistance of the strain gauge through the circuit system. When the water flow is applied to the artificial whisker, it causes the strain gauge in the corresponding direction to generate a resistance change. The resistance value change is converted into a voltage signal through a Wheatstone bridge and then input into the signal processing unit for analysis. The signal processing unit filters the voltage signal to ensure the accuracy of the signal and uses a microprocessor to calculate the flow velocity.

[0063] As Figure 7 shown is the schematic diagram of the flow direction adaptation function of the flow velocity measuring device, where the arrow indicates the flow direction of the water flow. Figure 7 In (a), the guiding wing is at 90° to the water flow direction, that is, the angle of attack is 90°. At this time, the impact force of the water flow on the guiding wing generates a torque, which in turn drives the rotation of the whisker. Figure 7 As shown in (b), during the rotation process, the angle of attack of the guiding wing is gradually decreasing. By Figure 7 (c), the guiding wing has been aligned with the water flow direction and reached a parallel state. At this time, the device enters a relatively balanced state, the whisker stops rotating, and the angle of attack also drops to 0°. The effect of the whisker structure in suppressing vortex-induced vibration reaches the best.

[0064] Figure 8 is the strain distribution nephogram of this flow velocity measuring device under the action of the fluid force. The device needs to avoid structural resonance during the flow velocity measurement to ensure the measurement accuracy. Figure 9As shown, the modal analysis of the overall structure of the flow velocity measuring device shows the first four natural frequencies of the measuring device. The first characteristic frequency is 180.89 Hz, the second characteristic frequency is 346.37 Hz, the third characteristic frequency is 781.11 Hz, and the fourth characteristic frequency is 1045.4 Hz, which is sufficient to support stable measurement under a low-speed flow field and avoid resonance under the action of water flow. This design ensures the dynamic stability and durability of the device under low-speed water flow.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A seal beard-like flow field measurement device, characterized in that: It includes a base, a cross beam, a piezoresistive strain gauge, a seal beard bionic part and a guide wing, the cross beam is installed on the base, the piezoresistive strain gauges are installed on the four beam bodies of the cross beam respectively, the seal beard bionic part forms a column extending along the axial direction, the cross section of the seal beard bionic part is elliptical and the size varies periodically along the axial direction, the guide wing is installed on the seal beard bionic part, and the bottom end of the seal beard bionic part is installed at the center position of the cross beam in an axially rotating manner and is perpendicular to the plane where the cross beam is located.

2. The seal whisker-like flow field measuring device according to claim 1, characterized in that: The cross section of the seal beard bionic part includes a cross section A and a cross section B which are equidistantly spaced along the axial direction. The angle between the cross section A and the plane where the cross beam is located is α, and the angle between the cross section B and the plane where the cross beam is located is β.

3. The seal whisker-like flow field measuring device according to claim 2, characterized in that: The guide wing is connected to the root of the seal beard bionic part, the airfoil chord of the guide wing coincides with the elliptical major axis of the seal beard bionic part, and the elliptical minor axis endpoint of the seal beard bionic part coincides with the airfoil front end of the guide wing.

4. The seal whisker-like flow field measuring device according to claim 3 is characterized in that: The leading edge and the trailing edge of the guide wing form an arc transition structure.

5. The seal whisker-like flow field measuring device according to claim 1, characterized in that: The base forms a circular ring structure, the cross beam is formed by the cross-intersection of two rectangular beams, and the piezoresistive strain gauge is arranged on the upper surface of the rectangular beam close to the base.

6. A flow field measurement method based on the seal whisker-like flow field measurement device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The piezoresistive strain gauge is connected to form a Wheatstone bridge and the voltage change information of the piezoresistive strain gauge is collected; S2. Establish a rectangular coordinate system adapted to the cross beam with the intersection center of the cross beam as the origin, and take the voltage increase values ​​of two of the four piezoresistive strain gauges as Vx and Vy; S3. Calculate the direction angle θ and equivalent voltage V using the following formula: S4. Set the 0° direction in the coordinate system, and calculate the incoming flow direction as DIR based on the positional relationship between the 0° direction and the piezoresistive strain gauge; change the water flow velocity to obtain the V value at different flow rates, and obtain the linear correspondence between V and VEL by calibrating V and the fluid velocity VEL.

7. The flow field measurement method according to claim 6, characterized in that: Assume that the four piezoresistive strain gauges on the cross beam are strain gauge A, strain gauge B, strain gauge C, and strain gauge D, respectively. Strain gauge A and strain gauge C are located on the X-axis of the coordinate system, and strain gauge A is located in the positive direction of the X-axis. Strain gauge B and strain gauge D are located on the Y-axis of the coordinate system, and strain gauge B is located in the positive direction of the Y-axis. Set the water flow along the negative direction of the x-axis to 0°, and the incoming flow direction to DIR. The judgment is based on the following: If the voltage increase value data comes from strain gauges A and B, then DIR = θ; If the voltage increase value data comes from strain gauges B and C, then DIR = 180°-θ; If the data of the voltage increase value comes from strain gauges C and D, then DIR = θ + 180°; If the data of the voltage increase value comes from strain gauges D and A, then DIR = 360°-θ.

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