Adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin

Abstract

The application discloses a self-adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin, and belongs to the technical field of fluid bionic active drag reduction. The self-adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin comprises a plurality of bionic piezoelectric fish scale rigid-flexible integrated drag reducers. The bionic piezoelectric fish scale rigid-flexible integrated drag reducer comprises a piezoelectric vibrator and a bionic fish scale rear area. One end of the piezoelectric vibrator is fixedly connected with the bionic fish scale rear area in a gluing mode. The piezoelectric vibrator comprises a flexible sheet, a piezoelectric sheet and a wire. One end of the flexible sheet is fixed between a reference surface of a micro vehicle in a flexible mode, and the fixed position is A. The other end of the flexible sheet, i.e. the end which is glued with the bionic fish scale rear area, is a free end. The self-adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin can reduce the frictional resistance of near-wall laminar or turbulent boundary layers when the micro vehicle is sailing, can improve the sailing speed of the vehicle and increase the cruising range of the vehicle.

Description

Technical Field

[0001] This invention relates to the field of fluid biomimetic active drag reduction technology, and in particular to an adaptive biomimetic piezoelectric scale rigid-flexible integrated drag reduction skin. Background Technology

[0002] When underwater micro-vehicles navigate underwater, they come into contact with fluids, and the coupling of the boundary layer generates significant viscous friction. Therefore, reducing drag on underwater micro-vehicles can effectively improve their navigation efficiency. Current research on drag reduction for underwater vehicles includes, for example, Chinese Patent Publication No. CN110282070B, which relates to an integrated piezoelectric vibration drag reducer that can be embedded in a wall. This drag reducer is embedded in a groove cut into the outer wall of the underwater vehicle. It requires an external cavity for sealing and also necessitates piezoelectric stacking for drive, making its structure and fabrication quite complex.

[0003] This application designs a rigid-flexible integrated drag reducer that can achieve flexible micro-deformation of the fish's skin, satisfying adaptive drag reduction when the characteristics of the turbulent boundary layer flow field change. By relying on the active micro-vibration of the scales to generate coupled disturbances to the boundary layer, it simulates the active control of the turbulent boundary layer caused by the fine-tuning of the fish's attitude. This will more accurately realize the biomimicry of the drag reduction method of fish scales and obtain a more ideal drag reduction effect. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin, which can reduce the frictional resistance of the near-wall laminar or turbulent boundary layer during micro-vehicle navigation, thereby increasing the vehicle's speed and range.

[0005] To achieve the above objectives, the present invention provides an adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin, comprising a plurality of biomimetic piezoelectric fish scale rigid-flexible integrated drag reducers. Each biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer includes a piezoelectric vibrator and a biomimetic fish scale rear region. One end of the piezoelectric vibrator is fixedly connected to the biomimetic fish scale rear region by adhesive bonding. The piezoelectric vibrator includes a flexible sheet, a piezoelectric sheet, and a wire. One end of the flexible sheet is flexibly fixed to the reference surface of the micro-vehicle at position A. The other end of the flexible sheet, i.e., the end bonded to the biomimetic fish scale rear region, is a free end.

[0006] Preferably, the piezoelectric sheet is attached to the middle position of the inner surface of the flexible sheet, and the wire is welded to the surface of the piezoelectric sheet and the surface of the flexible sheet.

[0007] Preferably, a sealing film is adhered to the inner surface of the flexible sheet and the inner surface of the piezoelectric sheet, and the outer surface of the flexible sheet has a smooth transition with the outer wall of the micro-vehicle.

[0008] Preferably, the micro-vehicle has a process hole, and the wire passes through the process hole and connects to the interior of the micro-vehicle.

[0009] Preferably, the material of the biomimetic fish scale rear region is polyvinyl chloride, and the biomimetic fish scale rear region is similar to that of bony fish scales.

[0010] Preferably, the flexible sheet is a copper sheet or other flexible metal material, and the piezoelectric sheet is a piezoelectric ceramic or ferroelectric material.

[0011] Preferably, the biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer is installed in a row along the incoming flow direction of the micro-vehicle, and adjacent biomimetic piezoelectric fish scale rigid-flexible integrated drag reducers are subjected to excitation signals with different phase differences to form a flowing wave drag reduction, or multiple rows can be installed as needed.

[0012] Preferably, the biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer is installed in a row along the outer wall of the micro-aircraft to form spanwise traveling wave drag reduction, or multiple rows can be installed as needed.

[0013] Therefore, this invention employs the aforementioned adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin. Targeting the actual working environment of underwater micro-vehicles, and considering the external structure of the micro-vehicle, piezoelectric biomimetic fish scales are adhered to the walls requiring drag reduction. These scales have flexible fixed ends, allowing for micro-changes in the scales' upstream state through attitude fine-tuning in response to different incoming flow characteristics. This achieves efficient drag reduction based on adaptive control of the turbulent boundary layer. It also offers the following advantages:

[0014] 1. Piezoelectric biomimetic fish scale drag reducers can reduce the frictional drag generated by the contact between micro-vehicles and fluids, thereby increasing the vehicle's speed and range. By relying on the active micro-vibration of the scales to generate coupled disturbances to the boundary layer, simulating the active control of the turbulent boundary layer caused by fish attitude fine-tuning, a more accurate biomimetic approach to fish scale drag reduction can be achieved, resulting in a more ideal drag reduction effect.

[0015] 2. The bonding area ensures a smooth transition between the outer wall of the drag reducer and the outer wall of the micro-vehicle, which can reduce the impact on the near-wall boundary layer; a flexible sheet is bonded under the piezoelectric material, and a sealing diaphragm is used to underwater seal the part where the piezoelectric vibrator is welded to the wire, ensuring that the drag reducer can work normally after being powered on.

[0016] 3. The flexible sheet and the piezoelectric sheet are connected by adhesive or welding. When the external excitation drives the piezoelectric sheet that can generate the inverse piezoelectric effect, the contraction, expansion or bending of the piezoelectric sheet will cause the surface of the flexible sheet to vibrate slightly, which can cause the rear fish scale area to oscillate slightly, thereby interfering with the flow of fluid near the wall of the micro-aircraft and reducing drag.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the external structure of an embodiment of the adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin of the present invention;

[0019] Figure 2 This is a cross-sectional schematic diagram of the structure of a bionic piezoelectric fish scale rigid-flexible integrated drag-reducing skin embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of a bionic piezoelectric fish scale rigid-flexible integrated drag-reducing skin embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the deformation of a bionic piezoelectric fish scale rigid-flexible integrated drag-reducing skin embodiment of the present invention.

[0022] Figure 5 This is a top view schematic diagram of a micro-aircraft according to an embodiment of the adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin of the present invention;

[0023] Figure 6 This is a schematic diagram of a bionic piezoelectric scale traveling wave drag reduction embodiment of the present invention, which is an adaptive bionic piezoelectric scale rigid-flexible integrated drag reduction skin.

[0024] Figure Labels

[0025] 1. Bionic piezoelectric fish scale rigid-flexible integrated drag reducer; 2. Micro-vehicle; 2-1. Reference surface; 2-2. Process hole; 3. Piezoelectric vibrator; 4. Bionic fish scale rear area; 5. Flexible sheet; 6. Piezoelectric sheet; 7. Wire; 8. Sealing diaphragm. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "comprising" or "including," as used in this invention, mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms "connected" or "linked," etc., are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0028] Example 1

[0029] like Figure 1-6As shown, the present invention provides an adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin, including a plurality of bionic piezoelectric fish scale rigid-flexible integrated drag reducers 1. The bionic piezoelectric fish scale rigid-flexible integrated drag reducers 1 are attached to the outer wall of the micro-aircraft 2. The bionic piezoelectric fish scale rigid-flexible integrated drag reducer 1 includes a piezoelectric vibrator 3 and a bionic fish scale rear area 4. One end of the piezoelectric vibrator 3 is fixedly connected to the bionic fish scale rear area 4 by adhesive bonding. The piezoelectric vibrator 3 includes a flexible sheet 5, a piezoelectric sheet 6 and a wire 7.

[0030] One end of the flexible sheet 5 is flexibly fixed to the reference plane 2-1 of the micro-vehicle 2 at position A. The flexible fixed end of the flexible sheet 5 can utilize other flexible methods such as coil springs to achieve adaptive drag reduction when the characteristics of the turbulent boundary layer flow field change. The other end of the flexible sheet 5, which is bonded to the biomimetic fish scale rear region 4, is a free end. The biomimetic fish scale rear region uses materials with similar mechanical properties to fish scales, such as polyvinyl chloride sheets, and is similar to bony fish scales.

[0031] A piezoelectric sheet 6 is attached to the middle of the inner surface of the flexible sheet 5. A sealing film 8 is attached to both the inner surface of the flexible sheet 5 and the inner surface of the piezoelectric sheet 6, achieving a sealing effect and preventing water from entering from the outside. The outer surface of the flexible sheet 5 has a smooth transition with the outer wall of the micro-vehicle 2, which reduces the impact on the near-wall boundary layer and reduces water flow resistance. The flexible sheet 5 is made of copper or other flexible metal material, and the piezoelectric sheet 6 is made of piezoelectric ceramic or ferroelectric material.

[0032] Wires 7 are welded to the surface of the piezoelectric sheet 6 and the surface of the flexible sheet 5. A process hole 2-2 is opened on the micro-vehicle 2, and the wires 7 pass through the process hole 2-2 to connect to the inside of the micro-vehicle 2. The process hole 2-2 is used to introduce the wires 7 of the piezoelectric vibrator 3 into the micro-vehicle 2.

[0033] The piezoelectric element 6 adopts the d31 working mode. When working, it generates displacement changes in the length and width directions. When an external excitation is applied to drive the piezoelectric element 6, the piezoelectric element 6 contracts and expands under the piezoelectric effect, thereby driving the free end of the flexible sheet 5 to vibrate in the normal direction. Finally, it drives the bionic fish scale rear area 4 to reciprocate with a large vibration amplitude, thereby interfering with the flow of fluid near the wall of the micro-aircraft and achieving the purpose of reducing drag.

[0034] A row of biomimetic piezoelectric fish-scale rigid-flexible integrated drag reducers 1 is installed along the incoming flow direction of the micro-vehicle 2. Adjacent biomimetic piezoelectric fish-scale rigid-flexible integrated drag reducers 1 are connected to an excitation signal with a phase difference. As a result, the bending deformation of each piezoelectric oscillator 3 will produce a certain regular change, which can form a flow-oriented traveling wave drag reduction in the near-wall boundary layer. This regular change can effectively reduce the viscous friction of the boundary layer at the contact between the vehicle and the water flow. Similarly, installing a row of biomimetic piezoelectric fish-scale rigid-flexible integrated drag reducers 1 along the outer wall of the micro-vehicle 2 can achieve spanwise traveling wave drag reduction, thereby achieving a better drag reduction effect over a larger area.

[0035] Therefore, the present invention employs the above-mentioned adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin, which can reduce the frictional resistance of the near-wall laminar or turbulent boundary layer during the micro-vehicle's navigation, thereby increasing the vehicle's speed and range.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin, characterized in that: The device includes several biomimetic piezoelectric fish scale rigid-flexible integrated drag reducers. Each biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer includes a piezoelectric vibrator and a biomimetic fish scale rear area. One end of the piezoelectric vibrator is fixedly connected to the biomimetic fish scale rear area by adhesive bonding. The piezoelectric vibrator includes a flexible sheet, a piezoelectric sheet, and a wire. One end of the flexible sheet is flexibly fixed to the reference surface of the micro-vehicle. The flexible fixed end of the flexible sheet is a coil spring. The other end of the flexible sheet, that is, the end that is adhesively bonded to the biomimetic fish scale rear area, is a free end. The piezoelectric sheet is attached to the middle of the inner surface of the flexible sheet, and the wire is welded to the surface of the piezoelectric sheet and the surface of the flexible sheet; a sealing film is attached to the inner surface of the flexible sheet and the inner surface of the piezoelectric sheet, and the outer surface of the flexible sheet smoothly transitions to the outer wall of the micro-vehicle.

2. The adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin according to claim 1, characterized in that: The micro-vehicle has a process hole, and the wire passes through the process hole to connect to the interior of the micro-vehicle.

3. The adaptive bionic piezoelectric scale rigid-flexible integrated drag-reducing skin according to claim 1, characterized in that: The material of the rear region of the biomimetic fish scale is polyvinyl chloride, and the rear region of the biomimetic fish scale has the same structure as the bone-like fish scale.

4. The adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin according to claim 1, characterized in that: The flexible sheet is a copper sheet, and the piezoelectric sheet is a piezoelectric ceramic.

5. The adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin according to claim 1, characterized in that: The biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer is installed in a row along the incoming flow direction of the micro-vehicle. Adjacent biomimetic piezoelectric fish scale rigid-flexible integrated drag reducers are subjected to excitation signals with different phase differences to form a flowing traveling wave drag reduction, or multiple rows can be installed as needed.

6. The adaptive biomimetic piezoelectric scale rigid-flexible integrated drag-reducing skin according to claim 1, characterized in that: The biomimetic piezoelectric fish scale rigid-flexible integrated drag reducer is installed in a row along the outer wall of the micro-aircraft to form spanwise traveling wave drag reduction, or multiple rows can be installed as needed.

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