Bionic flexible sawtooth-shaped covering feather and manufacturing method thereof

Abstract

The invention discloses a bionic flexible sawtooth-shaped covering feather which is made of a flexible silica gel thin film material and is of a long-strip-shaped structure, and sawteeth are evenly distributed on one side of the long edge of the feather. The invention further provides a fixed-wing unmanned aerial vehicle which comprises a fixed wing and further comprises the bionic flexible sawtooth-shaped covering feather, and the bionic flexible sawtooth-shaped covering feather is installed on the fixed wing in a hinged mode. The long edge is vertical to the chord length of the fixed wing. Self-adaptive vibration can be achieved under the effect of incoming flow, the flowing stall and eddy current noise phenomena can be effectively controlled, and due to the flexible silica gel material, the manufacturing cost is reduced, and meanwhile the difficulty of the installation technology is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of flow stall control of unmanned aerial vehicles, and in particular to a bionic flexible sawtooth covert feather and a manufacturing method thereof. Background Art

[0002] At present, fixed-wing UAVs often use aerodynamic layouts with straight wings with large aspect ratios. When the angle of attack of the wing is too large, the airflow will separate on the upper surface of the wing, causing the wing to "stall". The main manifestations of wing stall are a sudden drop in lift and a surge in drag, accompanied by vibration and noise, which deteriorate the aerodynamic performance of the aircraft and affect the stability and safety of the flight.

[0003] The feather structure of bird wings has excellent flow control effects and suppresses eddy noise. Matloff et al. (2020) found in their experiments that whether the feathers are tight can effectively affect the noise of birds during flight. Wu Kangling et al. (2023) found through numerical simulation that when birds fly, soft feathers can adaptively deform close to the wing surface, making the birds appear streamlined when flying.

[0004] At present, the main methods to improve the flow stall and noise phenomena of aircraft include changing the shape of the wing, installing rigid vortex generators, designing flexible wings and flexible flaps, etc. Although these methods can play a certain positive role in the flow stall and eddy noise phenomena, they also have certain disadvantages, such as difficulty in design, high production cost, inflexible installation and limited application range. Summary of the invention

[0005] The invention provides a bionic flexible sawtooth covert feather and a manufacturing method thereof to solve the technical problems existing in the known technology.

[0006] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is:

[0007] A bionic flexible sawtooth covert is made of a flexible silicone film material and is a long strip structure with evenly distributed sawteeth on one side of the long side.

[0008] Furthermore, the saw teeth are helical saw teeth.

[0009] Furthermore, the sawtooth thickness is 0.1 to 1.5 mm.

[0010] Furthermore, the shape of a single sawtooth is a right triangle.

[0011] Furthermore, the ratio of the sawtooth tooth height to the tooth width is 1.5 to 2.5.

[0012] Furthermore, the number of teeth of the saw teeth per meter is 60 to 70.

[0013] The present invention also provides a fixed-wing UAV, comprising a fixed wing and the above-mentioned bionic flexible sawtooth coverts, wherein the bionic flexible sawtooth coverts are connected to the fixed wing; the long side of the bionic flexible sawtooth coverts is perpendicular to the chord length of the fixed wing.

[0014] Furthermore, the bionic flexible sawtooth coverts are evenly distributed along the chord length direction of the fixed wing.

[0015] Furthermore, the bionic flexible sawtooth coverts are connected to the upper wing surface and / or the lower wing surface of the fixed wing.

[0016] The present invention also provides a method for making the above-mentioned bionic flexible serrated coverts. First, the outer contour of the bionic flexible serrated coverts is drawn on a whole piece of flexible silicone film, and the bionic flexible serrated coverts are cut from the flexible silicone film according to the outer contour, and the length of the bionic flexible serrated coverts is made close to the span of a unilateral fixed wing.

[0017] The advantages and positive effects of the present invention are as follows: experiments show that the bionic flexible sawtooth cover feathers can generate wind-adaptive vibrations under the action of incoming flow; when the bionic flexible sawtooth cover feathers are installed at a position of 20% of the chord length of the leading edge of the wing, they are obviously affected by the incoming flow, generate large-scale flapping, and generate a low-frequency large-scale coherent structure behind the wing; when the bionic flexible sawtooth cover feathers are installed at a position of 80% of the chord length of the trailing edge of the wing, the influence of the incoming flow is reduced, and the force on the upper surface of the bionic flexible sawtooth cover feathers and the force on the lower surface are balanced, so that the bionic flexible sawtooth cover feathers present a state of slight vibration in a quasi-equilibrium position, can effectively promote the development of the low-frequency large-scale coherent structure towards the high-frequency small-scale coherent structure, promote the generation of high-frequency pulsation, and produce a positive control effect on the flow stall phenomenon. In the noise experiment, when the incoming flow is at a wind speed of 25 to 50 m / s, the use of double-piece bionic flexible serrated feathers installed on the upper wing surface can effectively reduce the eddy noise phenomenon. The bionic flexible serrated feathers are installed at the 40% and 60% chord length positions at the same time. When the wind speed is 30 m / s and 35 m / s, the sound pressure levels can be reduced by 4.19 and 2.84 respectively compared with the wing without the bionic flexible serrated feathers.

[0018] 1. The entire product is an integrated structure made of flexible silicone film material. The size of the bionic flexible serrated coverts can be freely changed according to the size of the wing, which is convenient for the serial application of the product.

[0019] 2. The soft flexible silicone film can maintain a self-balanced state well under the action of the incoming flow. The change in stiffness of the bionic flexible serrated coverts will affect its vibration effect during the working process, and then affect the control effect of flow stall and eddy noise.

[0020] 3. The serrated design of the bionic flexible serrated coverts is derived from the structure of bird coverts. The soft serrated shape can have a similar "combing" effect to the bird feathers on the airflow, effectively "combing" the wing surface flow, inhibiting flow separation and reducing aerodynamic noise.

[0021] 4. The soft bionic flexible serrated coverts can vibrate freely under the action of the incoming flow, which is equivalent to being hinged on the upper wing surface, reducing the difficulty of installation and achieving quick installation.

[0022] In summary, when the bionic flexible serrated coverts adaptively vibrate under the action of the incoming flow, they can effectively control the flow stall and eddy noise phenomena. The flexible and soft silicone material not only reduces the production cost, but also reduces the difficulty of the installation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a bionic flexible sawtooth covert structure of the present invention.

[0024] Figure 2 The present invention is a schematic diagram of a fixed-wing structure equipped with bionic flexible sawtooth coverts.

[0025] In the picture: 1. Bionic flexible serrated coverts; 2. Fixed wings.

[0026] L: length of bionic flexible zigzag coverts.

[0027] a: Width of the connecting section of the bionic flexible zigzag coverts;

[0028] b: The height of the teeth of the bionic flexible serrated coverts;

[0029] h: Width of the teeth of the bionic flexible serrated coverts;

[0030] c: chord length of the fixed wing.

[0031] s: span of a fixed wing.

[0032] The arrow direction indicates the incoming flow direction. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0034] In the description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. The terms "connected" and "connection" used in the present invention should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can also be an electrical connection or signal transmission; for those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0035] See also Figure 1 to Figure 2 A bionic flexible serrated covert 1 is made of a flexible silicone film material and is a long strip structure with uniformly distributed serrations on one side of the long side.

[0036] Preferably, the saw teeth may be helical saw teeth.

[0037] Preferably, the sawtooth thickness may be 0.1-1.5 mm.

[0038] Preferably, the single sawtooth shape may be a triangle.

[0039] Preferably, the single sawtooth shape may be a right triangle.

[0040] Preferably, the ratio of the sawtooth height to the tooth width may be 1.5 to 2.5.

[0041] Preferably, the number of teeth per meter of the sawtooth may be 60 to 70.

[0042] A bionic flexible sawtooth-shaped feather cover 1, wherein the sawtooth height is preferably 30 mm, the sawtooth width is preferably 15 mm, and the width a of the connecting section of the bionic flexible sawtooth-shaped feather cover is preferably 20 mm. The connecting section of the sawtooth-shaped feather cover is used to connect and fix with the fixed wing 2.

[0043] like Figure 1 As shown: the width a of the connecting section of the bionic flexible sawtooth cover feathers can be 20 mm, the sawtooth tooth height b of the bionic flexible sawtooth cover feathers can be 30 mm, and the sawtooth tooth width h of the bionic flexible sawtooth cover feathers can be 15 mm.

[0044] The present invention also provides a fixed-wing UAV, comprising a fixed wing 2 and the above-mentioned bionic flexible sawtooth coverts 1, wherein the bionic flexible sawtooth coverts 1 are connected to the fixed wing 2; and the long side thereof is perpendicular to the chord length of the fixed wing 2.

[0045] Preferably, the bionic flexible sawtooth coverts 1 may be evenly distributed along the chord length direction of the fixed wing 2 .

[0046] Preferably, the bionic flexible sawtooth coverts 1 can be connected to the upper wing surface and / or the lower wing surface of the fixed wing 2.

[0047] The connecting section of the sawtooth-shaped coverts and the fixed wing 2 can be connected by bonding.

[0048] The present invention also provides a method for making the above-mentioned bionic flexible serrated coverts 1, firstly drawing the outer contour of the bionic flexible serrated coverts 1 on a whole piece of flexible silicone film, cutting the bionic flexible serrated coverts 1 from the flexible silicone film according to the outer contour, and making the length of the bionic flexible serrated coverts 1 close to the span of the unilateral fixed wing 2.

[0049] For example, if the wing length of a single-sided fixed wing 2 is 1000 mm, the length of the bionic flexible sawtooth coverts 1 may be 990 mm.

[0050] like Figure 2 As shown: the chord length c of the fixed wing can be 300 mm, the span s of a section of the fixed wing can be 1000 mm, and the length L of the bionic flexible zigzag coverts can be 990 mm.

[0051] The bionic flexible serrated cover feathers 1 can be an integrated structure and made of flexible silicone film material. First, the outer contour of the bionic flexible serrated cover feathers 1 is drawn on the entire silicone plate flexible silicone film, and the bionic flexible serrated cover feathers 1 are accurately cut out according to the outer contour. Moreover, the size of the bionic flexible serrated cover feathers 1 can be freely changed according to the size of the wing, which is convenient for the serial application of the product.

[0052] The density and thickness of the flexible silicone film are selected according to the airflow and flight speed. The thickness of the flexible silicone film is preferably 1 mm.

[0053] Experiments show that the bionic flexible sawtooth cover feathers 1 can generate wind-adaptive vibrations under the action of the incoming flow. When the bionic flexible sawtooth cover feathers 1 are installed at the 20% chord length position on the leading edge of the wing, they are significantly affected by the incoming flow, resulting in large-scale flapping, causing a low-frequency large-scale coherent structure to form behind the wing. When the bionic flexible sawtooth cover feathers 1 are installed at the 80% chord length position on the trailing edge of the wing, the influence of the incoming flow is reduced, and the forces on the upper surface and the lower surface of the bionic flexible sawtooth cover feathers 1 are balanced, so that the bionic flexible sawtooth cover feathers 1 present a state of slight vibration in a quasi-equilibrium position, which can effectively promote the development of low-frequency large-scale coherent structures towards high-frequency small-scale coherent structures, promote the generation of high-frequency pulsations, and have a positive control effect on the flow stall phenomenon. In the noise experiment, when the incoming flow is at a wind speed of 25 to 50 m / s, the use of a double-piece bionic flexible serrated feather cover 1 installed on the upper wing surface can effectively reduce the eddy current noise phenomenon. The bionic flexible serrated feather cover 1 is installed at the 40% and 60% chord length positions at the same time. When the wind speed is 30 m / s and 35 m / s, the sound pressure level can be reduced by 4.19 and 2.84 respectively compared to the wing without the bionic flexible serrated feather cover 1.

[0054] The working principle of the present invention is as follows: the entire product is an integrated structure, and the connecting section is used to connect with the wing of the aircraft. Since the bionic flexible serrated coverts 1 themselves are made of flexible materials, they can adaptively vibrate with the wind and produce adaptive deformation when they are working, so they are equivalent to being hinged on the wing.

[0055] The soft flexible silicone film can maintain a self-balanced state well under the action of the incoming flow. The change in stiffness of the bionic flexible serrated covert feathers 1 will affect its vibration effect during the working process, and further affect the control effect of flow stall and eddy current noise.

[0056] The serrated design of the bionic flexible serrated cover feathers 1 is derived from the cover feather structure of birds. The soft serrated shape can be similar to the "combing" effect of bird feathers on the airflow, effectively "combing" the wing surface flow, inhibiting flow separation and reducing aerodynamic noise.

[0057] The soft bionic flexible serrated coverts 1 can vibrate freely under the action of the incoming flow, which is equivalent to being hinged on the upper wing surface of the wing, thereby reducing the difficulty of installation and achieving rapid installation.

[0058] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A bionic flexible sawtooth feather cover, characterized in that: It is made of flexible silicone film material and has a long strip structure with evenly distributed serrations on one side of the long side.

2. The bionic flexible zigzag feather cover according to claim 1, characterized in that: The saw teeth are helical saw teeth.

3. The bionic flexible sawtooth covert according to claim 1, characterized in that: The thickness of the saw teeth is 0.1 to 1.5 mm.

4. The bionic flexible sawtooth covert according to claim 1, characterized in that: The shape of a single sawtooth is a right triangle.

5. The bionic flexible sawtooth covert according to claim 1, characterized in that: The ratio of sawtooth height to tooth width is 1.5 to 2.

5.

6. The bionic flexible sawtooth covert according to claim 1, characterized in that: The number of teeth per meter is 60 to 70.

7. A fixed-wing UAV, comprising a fixed wing, characterized in that: It also includes the bionic flexible sawtooth-shaped coverts as described in any one of claims 1 to 6, wherein the bionic flexible sawtooth-shaped coverts are connected to the fixed wing; Its long side is perpendicular to the chord length of the fixed wing.

8. The fixed-wing UAV according to claim 7, characterized in that: The bionic flexible zigzag coverts are evenly distributed along the chord length of the fixed wing.

9. The fixed-wing UAV according to claim 7, characterized in that: The bionic flexible sawtooth coverts are connected to the upper wing surface and / or the lower wing surface of the fixed wing.

10. A method for making the bionic flexible zigzag feather cover according to any one of claims 1 to 6, characterized in that: Firstly, the outer contour of the bionic flexible zigzag cover feathers is drawn on a whole piece of flexible silicone film, and the bionic flexible zigzag cover feathers are cut from the flexible silicone film according to the outer contour, and the length of the bionic flexible zigzag cover feathers is made close to the span of a single-sided fixed wing.

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