A local resonant drag-reduction, vibration-damping, and noise-reducing skin based on a stacked fork-shaped elastic component

Abstract

This invention discloses a localized resonant drag-reduction, vibration-reduction, and noise-reducing skin based on stacked fork-shaped elastic components. The localized resonant units are arranged in a lattice array between the base and the flexible skin. Each localized resonant unit is composed of stacked fork-shaped elastic components and a mass block. Each stacked fork-shaped elastic component consists of at least two layers of fork-shaped elements. Each layer of fork-shaped elements consists of a top plate, a bottom plate, a piston rod, a piston cylinder, a rod head, and a V-shaped support leg. When the skin is applied to the surface of the aircraft, the stiffness and damping of the stacked fork-shaped elastic components in the localized resonant unit can be passively adjusted according to the speed of the aircraft. This changes the vibration wave and acoustic wave propagation dispersion characteristics of the skin system, enabling the skin to produce a more adaptive dynamic response to flow field excitation. It controls the generation and development of energetic vortex structures in the boundary layer flow field, thereby reducing fluid resistance and suppressing flow noise and flow-induced vibration noise. Compared with existing flexible surface drag-reduction and noise reduction technologies, it has stronger adaptability to flow field changes.

Description

Technical Field

[0001] This invention relates to a metamaterial skin for drag reduction, vibration reduction, and noise reduction, and more particularly to a local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component. Background Technology

[0002] Based on whether energy input is required, existing fluid dynamics technologies for drag reduction, vibration reduction, and noise reduction can be divided into two categories: active and passive. Active drag reduction, vibration reduction, and noise reduction technologies work by placing sensors on the surface of the aircraft to sense changes in the flow field, and then using the response of actuators to influence and control the flow field on the surface of the aircraft, thereby achieving drag reduction, vibration reduction, and noise reduction effects. In addition to requiring additional energy consumption, this type of technology is also limited by the design and manufacturing level of sensors and actuators, as well as the influence of control strategies, so it has not yet been able to achieve large-scale practical applications. Passive drag reduction, vibration reduction, and noise reduction technologies are mostly derived from the imitation of the appearance or behavior of animals and plants in nature. For example, flexible surface technology originated from the imitation of the structure and appearance of dolphin skin. Its advantage is that it can produce good drag reduction, vibration reduction, and noise reduction effects within a certain flow velocity range without additional energy input. However, it should be noted that the drag reduction efficiency of existing flexible surface technologies is still far inferior to that of dolphin skin, and it decreases significantly with the increase of flow velocity, and may even produce drag and noise increase phenomena. This is because such passive technologies do not have the ability to adapt and adjust the mechanical properties (stiffness, damping) of their own skin to changes in the flow field like dolphins. Summary of the Invention

[0003] The technical objective of this invention is to address the shortcomings of the prior art by providing a local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component.

[0004] The technical solution adopted by this invention to solve its technical problem is: a local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component, comprising a base, a local resonant unit, and a flexible skin. The local resonant unit is arranged in a lattice array between the base and the flexible skin. The local resonant unit is composed of a stacked fork-shaped elastic component and a mass block. Stacked fork-shaped elastic components are provided on both the upper and lower surfaces of the mass block. Each stacked fork-shaped elastic component consists of at least two layers of fork-shaped elements. Each fork-shaped element consists of a top plate, a bottom plate, a piston rod, a piston cylinder, a rod head, and a V-shaped support leg. The rod head is located inside the piston cylinder, and the top surface of the rod head is fixedly connected to the piston rod. The top of the piston rod passes through the piston cylinder and is fixedly connected to the top plate. The upper end of the V-shaped support leg is fixedly connected to the top plate, and the lower end of the V-shaped support leg is fixedly connected to the bottom plate.

[0005] Further improvement: Four stacked fork-shaped elastic components are provided on the upper and lower surfaces of the mass block.

[0006] Further improvement: The number of V-shaped outriggers is four.

[0007] Further improvements: The mass block, top plate, bottom plate, piston rod, rod head, and piston cylinder are all made of non-metallic materials with sound absorption and sound transmission properties.

[0008] Further improvements: The V-shaped support leg is made of a non-metallic material that is elastic, sound-absorbing, and sound-permeable.

[0009] Further improvement: The stacked fork-shaped elastic component consists of three layers of fork-shaped elements, namely an upper fork-shaped element, a middle fork-shaped element, and a lower fork-shaped element.

[0010] Advantages of this invention: This invention combines multiple fork-shaped elements to form a stacked fork-shaped elastic component. Then, the stacked fork-shaped elastic component and a mass block are combined to obtain a local resonant unit containing the stacked fork-shaped elastic component. Finally, several local resonant units are arranged into a lattice array according to a certain rule and connected to a base and a flexible skin to form a skin structure. This structure is applied to the surface of the vehicle and can passively adjust the stiffness and damping of the stacked fork-shaped elastic component in the local resonant unit according to the speed of travel. This changes the vibration wave and acoustic wave propagation dispersion characteristics of the skin system, making the skin generate a more adaptive dynamic response to the flow field excitation. It controls the generation and development of energetic vortex structures in the boundary layer flow field, thereby reducing the vibration caused by the impact of fluid fluctuations on the vehicle, making the vehicle's travel more stable. At the same time, it can also reduce fluid resistance and suppress hydrodynamic noise. Compared with existing flexible surface drag reduction and noise reduction technologies, it has stronger adaptability to flow field changes. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention.

[0012] Figure 2 This is a schematic diagram of the structure of the local resonance unit of the present invention.

[0013] Figure 3 This is a schematic diagram of the fork-shaped element of the present invention.

[0014] Figure 4 This is a schematic diagram of the drag reduction characteristics of the present invention.

[0015] Figure 5 This is a schematic diagram of the noise reduction characteristics of the present invention.

[0016] In the figure: 1. Base; 2. Local resonance unit; 3. Flexible skin; 4. Stacked fork-shaped elastic component; 5. Mass block; 6. Fork-shaped element; 61. Upper fork-shaped element; 62. Middle fork-shaped element; 63. Lower fork-shaped element; 7. Top plate; 8. Bottom plate; 9. Piston rod; 10. Piston cylinder; 11. Rod head; 12. V-shaped support leg; 13. Vehicle hull; 14. Turbulent flow field excitation; 15. Internal noise; 16. External noise. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figures 1-3 As shown, a local resonant drag-reducing, vibration-damping, and noise-reducing skin based on stacked fork-shaped elastic components includes a base 1, a local resonant unit 2, and a flexible skin 3. The local resonant unit 2 is composed of stacked fork-shaped elastic components 4 and a mass block 5. Stacked fork-shaped elastic components 4 are provided on both the upper and lower surfaces of the mass block 5. Each stacked fork-shaped elastic component 4 consists of at least two layers of fork-shaped elements 6. In this scheme, for ease of explanation of its structural principle, the stacked fork-shaped elastic component 4 is composed of three layers of fork-shaped elements 6, namely an upper fork-shaped element 61, a middle fork-shaped element 62, and a lower fork-shaped element 63. The layered fork-shaped element 6 consists of a top plate 7, a bottom plate 8, a piston rod 9, a piston cylinder 10, a rod head 11, and a V-shaped support leg 12. The rod head 11 is located inside the piston cylinder 10, and the top surface of the rod head 11 is fixedly connected to the piston rod 9. The top of the piston rod 9 passes through the piston cylinder 10 and is fixedly connected to the top plate 7. The upper end of the V-shaped support leg 12 is fixedly connected to the top plate 7, and the lower end of the V-shaped support leg 12 is fixedly connected to the bottom plate 8. Several local resonant units 2 are arranged in a lattice array between the base 1 and the flexible skin 3, thereby forming a local resonant drag-reducing, vibration-reducing, and noise-reducing metamaterial skin.

[0019] The mass block 5, top plate 7, and bottom plate 8 can be square. Four stacked fork-shaped elastic components 4 are provided on the upper and lower surfaces of the mass block 5. There are four V-shaped legs 12, with one V-shaped leg 12 corresponding to each side of the bottom plate 8 and the top plate 7.

[0020] The mass block 5, top plate 7, bottom plate 8, piston rod 9, rod head 11, and piston cylinder 10 are all made of non-metallic materials with sound absorption and sound transmission properties; the V-shaped support leg 12 is made of non-metallic materials with elasticity, sound absorption, and sound transmission properties.

[0021] Its working principle is as follows: First, the fixed connection between each component is made of cold bonding technology. The base 1 is made of flexible material. The number of layers of the fork-shaped element 6 in the stacked fork-shaped elastic component 4 can be reasonably set according to the thickness of the metamaterial skin and the speed change gear of the aircraft.

[0022] Combination Figure 4The drag reduction characteristics of the present invention are explained below. The base 1 is attached to the outer surface of the vehicle shell 13. When the vehicle travels in the fluid, the outer flexible skin 3 is subjected to the excitation 14 of the turbulent flow field, including the external tension generated by Bernoulli's principle and the pulsating disturbance generated by the coherent structure of the boundary layer flow field. The magnitude of the external tension changes with the flow velocity, and the amplitude and frequency of the pulsating disturbance also change with the flow velocity, causing the stacked fork-shaped elastic component 4 to undergo tensile deformation. When the vehicle speed is low, none of the fork-shaped elements 6 undergo large deformation, and the overall stiffness of the stacked fork-shaped elastic component 4 is k1. As the speed increases, the upper fork-shaped element 61 undergoes large tensile deformation, and its top plate 7 moves upward, pulling the piston rod 9 until the rod head 11 abuts against the upper part of the piston cylinder 10, reaching the limit position. At this time, neither the middle fork-shaped element 62 nor the lower fork-shaped element 63 has reached the limit position, and the stacked fork-shaped elastic component... 4. The stiffness under pulsating excitation is denoted as k2. When the speed increases further, the middle fork element 62 also produces large tensile deformation. The top plate 7 of the middle fork element 62 moves upward, pulling the piston rod 9 inside the middle fork element 62 until the rod head 11 inside the middle fork element 62 contacts the upper part of the piston cylinder 10. At this time, only the lower fork element 63 has not reached the limit position. The stiffness of the stacked fork elastic component under pulsating excitation is denoted as k3. Where k3 > k2 > k1. Therefore, the stiffness of the skin system is passively adjusted according to the fluid turbulence excitation 14, so as to adjust the dispersion characteristics of the skin system to the propagation of vibration waves and sound waves, thereby better controlling the boundary layer turbulence coherent structure, producing a better response to the flow field excitation, suppressing the formation and development of turbulence, and achieving the purpose of reducing fluid resistance, suppressing flow noise, and reducing flow-induced vibration and noise. Compared with the existing flexible surface drag reduction and noise reduction technology, it has stronger adaptability to flow field changes.

[0023] Combination Figure 5 The vibration reduction and noise reduction characteristics of the present invention will be explained. When the vehicle moves in the fluid, the surface of the outer flexible skin 3 is subjected to turbulent excitation 14. The metamaterial skin containing the local resonance unit 2 can effectively suppress the transmission of sound waves such as internal noise 15 and external noise 16 in the skin. In addition, since the stacked fork-shaped elastic component 4 is composed of multiple fork-shaped elements 6, and each layer of fork-shaped elements 6 corresponds to a first level of stiffness, the metamaterial skin also has adjustable stiffness, which can effectively reduce the noise generated by structural vibration caused by turbulent excitation 14, as well as reduce the vibration caused by sound waves, thereby achieving the effects of vibration reduction, noise reduction, sound insulation and noise reduction.

[0024] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A local resonant drag-reducing, vibration-damping, and noise-reducing skin based on a stacked, forked elastic component, comprising a base, a local resonant unit, and a flexible skin, characterized in that: The local resonant units are arranged in a lattice array between the base and the flexible skin. Each local resonant unit is composed of a stacked fork-shaped elastic component and a mass block. Stacked fork-shaped elastic components are provided on both the upper and lower surfaces of the mass block. Each stacked fork-shaped elastic component consists of at least two layers of fork-shaped elements. Each layer of fork-shaped elements consists of a top plate, a bottom plate, a piston rod, a piston cylinder, a rod head, and a V-shaped support leg. The rod head is located inside the piston cylinder, and the top surface of the rod head is fixedly connected to the piston rod. The top of the piston rod passes through the piston cylinder and is fixedly connected to the top plate. The upper end of the V-shaped support leg is fixedly connected to the top plate, and the lower end of the V-shaped support leg is fixedly connected to the bottom plate. The V-shaped support leg is made of a non-metallic material with elastic sound absorption or elastic sound transmission.

2. The local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component according to claim 1, characterized in that: Four stacked fork-shaped elastic components are provided on the upper and lower surfaces of the mass block.

3. The local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component according to claim 1, characterized in that: The number of V-shaped outriggers is four.

4. The local resonant drag reduction, vibration reduction, and noise reduction skin based on a stacked fork-shaped elastic component according to claim 1, characterized in that: The mass block, top plate, bottom plate, piston rod, rod head, and piston cylinder are all made of non-metallic materials that have sound absorption or sound transmission properties.

5. A local resonant drag-reducing, vibration-damping, and noise-reducing skin based on a stacked elastic component according to any one of claims 1 to 4, characterized in that: The stacked fork-shaped elastic component consists of three layers of fork-shaped elements: an upper fork-shaped element, a middle fork-shaped element, and a lower fork-shaped element.

Images