Metamaterial module and its pressure-resistant skin structure for suppressing underwater low-frequency flow-induced noise

Abstract

The present invention discloses a metamaterial module for suppressing underwater low-frequency flow-induced noise. The module comprises a negative Poisson's ratio unit cell structure, a tuning core, and a synergistic coupling device. The tuning core is placed within the negative Poisson's ratio unit cell structure and, in combination with the negative Poisson's ratio unit cell structure, forms a resonant functional unit. The synergistic coupling device and the resonant functional unit are combined in a predetermined manner to form a metamaterial module unit. The metamaterial module unit is then sequenced and expanded in a predetermined manner to form a metamaterial module for suppressing underwater low-frequency flow-induced noise. A metamaterial module pressure-resistant skin structure is also provided, comprising one or more metamaterial modules and a pressure-resistant layer. The metamaterial module and its pressure-resistant skin structure of the present invention combine the excellent comprehensive properties of low frequency, broadband, lightweight, and high load-bearing capacity, and have broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of vibration and noise reduction of new materials, new technologies and underwater equipment, and in particular relates to a metamaterial module for suppressing underwater low-frequency flow-induced noise and a pressure-resistant skin structure thereof. Background Art

[0002] When underwater equipment such as underwater vehicles are working underwater, the surrounding flow field will interact with its skin structure, causing the fluid at the boundary to exhibit irregular random motion, causing mutual jumps between flow layers, and generating randomly changing pulsation quantities (pulsation pressure or pulsation speed, etc.), which will in turn cause the shell of underwater equipment such as underwater vehicles to vibrate and generate noise radiation, thereby reducing the acoustic stealth and survivability of underwater equipment such as underwater vehicles.

[0003] The skin structure is an important system for underwater equipment such as submersibles to control vibration and noise. Traditional skin structures are mostly "Aiberich" skin configurations. When underwater equipment such as submersibles are working, due to factors such as hydrostatic pressure and underwater pulsating pressure, the "Aiberich" skin structure will cause obvious deformation, resulting in its weak ability to suppress flow-induced vibration and flow-induced noise generated by the flow field. It can only suppress a small amount of vibration and noise energy, and its suppressed working frequency is mainly in the medium and high frequency range, making it difficult to effectively suppress low-frequency vibration and noise.

[0004] In recent years, the rapid development of acoustic metamaterial technology has provided a new approach for suppressing low-frequency noise in underwater vehicles and other underwater equipment. To overcome the shortcomings and deficiencies of the aforementioned skin structure technology, the present invention designs a metamaterial module and its pressure-resistant skin structure for suppressing underwater low-frequency flow-induced noise. Summary of the Invention

[0005] The purpose of the present invention is to provide a metamaterial module and a pressure-resistant skin structure thereof for suppressing underwater low-frequency flow-induced noise, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides a metamaterial module for suppressing underwater low-frequency flow-induced noise and its pressure-resistant skin structure, comprising a negative Poisson's ratio unit cell structure, a tuning core, and a synergistic coupling device; the tuning core is arranged in the negative Poisson's ratio unit cell structure, the negative Poisson's ratio unit cell structure and the tuning core together constitute a resonant functional unit element, the synergistic coupling device is symmetrically arranged about the resonant functional unit element, the synergistic coupling device and the resonant functional unit together constitute a metamaterial module unit element, and a plurality of the metamaterial module units are sequentially expanded in a rectangular array to form the metamaterial module for suppressing underwater low-frequency flow-induced noise.

[0007] Preferably, the negative Poisson's ratio unit cell structure includes a first top plate, a second bottom plate, a third adjustment plate, and a fourth adjustment plate, wherein the first top plate is arranged parallel to the second bottom plate; the third adjustment plate and the fourth adjustment plate are both arranged between the first top plate and the second bottom plate, and the third adjustment plate and the fourth adjustment plate are arranged symmetrically; the first top plate and the second bottom plate are fixedly connected to the upper and lower ends of the third adjustment plate and the upper and lower ends of the fourth adjustment plate, respectively.

[0008] Preferably, the third adjustment plate and the fourth adjustment plate are both bent plates or curved plates;

[0009] If the third adjustment plate and the fourth adjustment plate are bent plates, the third adjustment plate and the fourth adjustment plate are both bent inward (i.e., the third adjustment plate is bent from left to right, and the fourth adjustment plate is bent from right to left), and the bending angle is the respective adjustment angle θ;

[0010] If the third adjustment plate and the fourth adjustment plate are curved plates, they are both curved inward (ie, the third adjustment plate curves from left to right, and the fourth adjustment plate curves from right to left), and the curvature angles are their respective adjustment angles θ.

[0011] Preferably, the negative Poisson's ratio unit cell structure is hollow, and the tuning core is filled in the hollow area of ​​the negative Poisson's ratio unit cell structure.

[0012] Preferably, the synergistic coupling device is a weak synergistic coupling device and / or a strong synergistic coupling device.

[0013] Preferably, a cavity is provided inside the weak synergistic coupling device, and the strong synergistic coupling device is a positive Poisson's ratio unit cell structure.

[0014] Preferably, the resonant functional element may be covered with a functional constraint layer.

[0015] Preferably, the resonant functional element can be set to have a shaping angle β.

[0016] Preferably, the metamaterial module for suppressing underwater low-frequency flow-induced noise is a single-layer structure or a multi-layer structure.

[0017] The present invention also provides a metamaterial module pressure-resistant skin structure, comprising a metamaterial module for suppressing underwater low-frequency flow-induced noise and a pressure-resistant layer, wherein the pressure-resistant layer is fixedly arranged on the outside of the metamaterial module for suppressing underwater low-frequency flow-induced noise.

[0018] Preferably, the negative Poisson's ratio unit cell structure is made of a water-like material, and the impedance of the material matches the impedance of water; the tuning core is made of a high-density material, and the material density of the tuning core is at least 0.5 times higher than the material density of the negative Poisson's ratio unit cell structure.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] 1. Based on the theory of negative Poisson's ratio and the local resonance effect, the present invention proposes a new resonant functional primitive, and designs a metamaterial module primitive and metamaterial module based on it. These are then applied to the skin design of underwater equipment. The resonance effect of the designed metamaterial module and the coupling effect of the vibration wave can effectively suppress the generation of flow-induced vibration and noise of underwater equipment. While having excellent static properties (meeting high hydrostatic pressure environments), the present invention has the advantages of being lightweight and compact. It can effectively suppress the transmission of flow-induced vibration and reduce the sound radiation efficiency in a low-frequency and ultra-wideband range at a subwavelength scale, thereby effectively solving the key problems of the existing technology, such as poor pressure resistance and high hydrodynamic noise.

[0021] 2. The compression-resistant skin structure provided by the present invention has essentially the same mechanism for drag reduction and flow-induced noise suppression. The present invention can dynamically absorb the vibration energy of the skin's outer layer, thereby effectively attenuating the transmission of turbulent pulsation forces. This, to a certain extent, suppresses boundary layer transitions and reduces the generation of turbulent pulsation, ultimately reducing the flow resistance of underwater equipment.

[0022] 3. Based on the principle of multi-frequency resonance, the present invention adjusts the structural parameters such as the adjustment angle θ, the shape adjustment angle β, the thickness, and the material through topological structure, changes the combination of the synergistic coupling device and the resonant functional unit, the hierarchy and topological relationship of the metamaterial module, and other flexible adjustments to broaden the various performance indicators of the structure of the present invention. It has a large design breadth and optimization design space, can meet different engineering application environments, especially in ultra-low frequency vibration reduction applications such as underwater equipment and precision instruments, and has obvious advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 Schematic diagram of a metamaterial module for suppressing underwater low-frequency flow-induced noise according to the present invention;

[0025] Figure 2-Figure 7 Schematic diagram of different structural forms of metamaterial module primitives in the present invention;

[0026] Figures 8-18 Schematic diagram of different structural forms of the metamaterial module for suppressing underwater low-frequency flow-induced noise in the present invention;

[0027] Figure 19 Schematic diagram of the steps for constructing the compression-resistant skin structure of the metamaterial module in the present invention;

[0028] Figure 20 Comparison of the sound pressure level results between the metamaterial module pressure-resistant skin structure of the present invention and the traditional pressure-resistant skin structure;

[0029] Figure 21 This is a schematic diagram of another step of constructing the metamaterial module pressure-resistant skin structure of the present invention;

[0030] Among them, 1. Negative Poisson's ratio unit cell structure; 11. First top plate; 12. Second bottom plate; 13. Third adjustment plate; 14. Fourth adjustment plate; 2. Tuning core; 3. Synergistic coupling device; 31. Weak synergistic coupling device; 32. Strong synergistic coupling device; 4. Resonant functional element; 5. Functional constraint layer; 6. Metamaterial module element; 7. Metamaterial module for suppressing underwater low-frequency flow-induced noise; 8. Pressure-resistant layer; 9. Traditional skin structure. DETAILED DESCRIPTION

[0031] It should be noted that, unless there is a conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other. The embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0032] like Figure 1 As shown, the present invention provides a metamaterial module for suppressing underwater low-frequency flow-induced noise and its pressure-resistant skin structure, including a negative Poisson's ratio unit cell structure 1, a tuning core 2, and a synergistic coupling device 3; the tuning core 2 is arranged in the negative Poisson's ratio unit cell structure 1, the negative Poisson's ratio unit cell structure 1 and the tuning core 2 together constitute a resonant functional element 4, the synergistic coupling device 3 is symmetrically arranged about the resonant functional element 4, the synergistic coupling device 3 and the resonant functional element 4 are combined into a metamaterial module element 6 in a predetermined form, and a plurality of metamaterial module elements 6 are sequentially expanded in a predetermined manner to form a metamaterial module 7 for suppressing underwater low-frequency flow-induced noise.

[0033] Furthermore, the negative Poisson's ratio unit cell structure 1 includes a first top plate 11, a second bottom plate 12, a third adjustment plate 13, and a fourth adjustment plate 14. The first top plate 11 and the second bottom plate 12 are arranged parallel to each other on a horizontal plane; the third adjustment plate 13 and the fourth adjustment plate 14 are both arranged between the first top plate 11 and the second bottom plate 12, and the third adjustment plate 13 and the fourth adjustment plate 14 are arranged symmetrically; the first top plate 11 and the second bottom plate 12 are fixedly connected to the upper and lower ends of the third adjustment plate 13 and the upper and lower ends of the fourth adjustment plate 14, respectively.

[0034] Furthermore, the third adjustment plate 13 and the fourth adjustment plate 14 are both bent plates or curved plates;

[0035] If the third adjustment plate 13 and the fourth adjustment plate 14 are bent plates, the third adjustment plate 13 and the fourth adjustment plate 14 are both bent inward, that is, the third adjustment plate 13 is bent from left to right, and the fourth adjustment plate 14 is bent from right to left; and the bending angle is the respective adjustment angle θ;

[0036] If the third adjustment plate 13 and the fourth adjustment plate 14 are curved plates, they are both bent inward, that is, the third adjustment plate 13 bends from left to right and the fourth adjustment plate 14 bends from right to left; and the bending arc angles are their respective adjustment angles θ.

[0037] Furthermore, the negative Poisson's ratio unit cell structure 1 is hollow, and the tuning core 2 is filled in the hollow region of the negative Poisson's ratio unit cell structure 1 .

[0038] Furthermore, the synergistic coupling device 3 is a weak synergistic coupling device 31 and / or a strong synergistic coupling device 32 .

[0039] Furthermore, a cavity is provided inside the weak synergistic coupling device 31 , which can be filled with water, air, or water-like materials (such as rubber, metal water), and the strong synergistic coupling device 32 is a positive Poisson's ratio unit cell structure.

[0040] Furthermore, the resonant functional element 4 may be covered with a functional constraint layer 5 .

[0041] Furthermore, the resonant functional element 4 can be set to have a shaping angle β.

[0042] Furthermore, the synergistic coupling device 3 and the resonant functional unit 4 are combined into a metamaterial module unit 6 in a predetermined form, and the combination forms include the following:

[0043] 1. From left to right, the combination of weak synergistic coupling device 31 - resonant functional element 4 - weak synergistic coupling device 31;

[0044] 2. A combination of a strong synergistic coupling device 32, a weak synergistic coupling device 31, a resonant functional element 4, and a weak synergistic coupling device 31;

[0045] 3. A combination of a strong synergistic coupling device 32-resonant functional element 4-weak synergistic coupling device 31-resonant functional element 4;

[0046] 4. From the center to the top, bottom, left and right, around the strong synergistic coupling device 32 in the middle, the resonant functional elements 4 are arranged symmetrically up and down, the strong synergistic coupling devices 32 are arranged symmetrically left and right, and the weak synergistic coupling devices 31 are arranged on the periphery.

[0047] Furthermore, the metamaterial module 7 for suppressing underwater low-frequency flow-induced noise is a single-layer structure or a multi-layer structure; if it is a multi-layer structure, the structural form and parameters of the metamaterial module primitives 6 in each layer can be the same or different; for example, the parameters of the metamaterial module primitives 6 in each layer are periodically set or gradient-varied.

[0048] The present invention also provides a metamaterial module pressure-resistant skin structure, including a metamaterial module 7 for suppressing underwater low-frequency flow-induced noise and a pressure-resistant layer 8, wherein the pressure-resistant layer 8 is fixedly arranged on the outer side of the metamaterial module 7 for suppressing underwater low-frequency flow-induced noise.

[0049] Furthermore, the negative Poisson's ratio unit cell structure 1 is made of a water-like material whose impedance matches the impedance of water, such as silicone rubber; the tuning core 2 is made of a high-density material whose material density is at least 0.5 times higher than that of the negative Poisson's ratio unit cell structure 1, such as titanium alloy; the pressure-resistant layer 8 is made of a high-rigidity material, such as steel, iron, composite material, or fiberglass.

[0050] Example 1

[0051] like Figure 10 Figure 1 shows a metamaterial module pressure-resistant skin structure. The negative Poisson's ratio unit cell structure 1 comprises a first top plate 11, a second bottom plate 12, a third adjustment plate 13, and a fourth adjustment plate 14. The first and second bottom plates 11 and 12 are arranged parallel to each other with an 18mm spacing. The thickness of the first and second top plates 11 and 1mm is 1mm. The third and fourth adjustment plates 13 and 14 are bent plates, each bent inward with an adjustment angle θ of 120°. The metamaterial module for suppressing underwater low-frequency flow-induced noise is expanded using an 8x5 periodic structure, with the pressure-resistant layer positioned on the outer layer. Simulation calculations were performed on the far-field radiated sound pressure level of the metamaterial skin structure induced by water flow, as well as the far-field radiated sound pressure level of a conventional skin structure of the same thickness.

[0052] The results of the embodiment show that the metamaterial module pressure-resistant skin structure of the present invention has a far-field radiation sound pressure level of 200Hz-10000Hz that is much lower than that of the traditional pressure-resistant skin structure while being both lightweight and pressure-resistant. It has low-frequency and broadband noise reduction performance and is of great value in suppressing flow-induced noise of underwater equipment.

[0053] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A metamaterial module for suppressing underwater low-frequency flow-induced noise, characterized in that: The invention comprises a negative Poisson's ratio unit cell structure (1), a tuning core (2), and a synergistic coupling device (3); the tuning core (2) is arranged in the negative Poisson's ratio unit cell structure (1); the negative Poisson's ratio unit cell structure (1) and the tuning core (2) together constitute a resonant functional unit cell (4); the synergistic coupling device (3) is symmetrically arranged with respect to the resonant functional unit cell (4); the synergistic coupling device (3) and the resonant functional unit cell (4) together constitute a metamaterial module unit cell (6); and a plurality of the metamaterial module units (6) are sequentially expanded in a rectangular array to form the metamaterial module (7) for suppressing underwater low-frequency flow-induced noise.

2. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 1, characterized in that: The negative Poisson's ratio unit cell structure (1) comprises a first top plate (11), a second bottom plate (12), a third adjustment plate (13), and a fourth adjustment plate (14); the first top plate (11) and the second bottom plate (12) are arranged in parallel; the third adjustment plate (13) and the fourth adjustment plate (14) are both arranged between the first top plate (11) and the second bottom plate (12), and the third adjustment plate (13) and the fourth adjustment plate (14) are arranged symmetrically; the first top plate (11) and the second bottom plate (12) are fixedly connected to the upper and lower ends of the third adjustment plate (13) and the upper and lower ends of the fourth adjustment plate (14), respectively.

3. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 2, characterized in that: The third adjustment plate (13) and the fourth adjustment plate (14) are both bent plates or curved plates.

4. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 1, characterized in that: The negative Poisson's ratio unit cell structure (1) is hollow, and the tuning core (2) is filled in the hollow region of the negative Poisson's ratio unit cell structure (1).

5. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 1, characterized in that: The synergistic coupling device (3) is a weak synergistic coupling device (31) and / or a strong synergistic coupling device (32).

6. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 5, characterized in that: A cavity is provided inside the weak synergistic coupling device (31), and the strong synergistic coupling device (32) is a positive Poisson's ratio unit cell structure.

7. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 1, characterized in that: The resonant functional element (4) may be covered with a functional constraint layer (5).

8. The metamaterial module for suppressing underwater low-frequency flow-induced noise according to claim 1, characterized in that: The metamaterial module (7) for suppressing underwater low-frequency flow-induced noise is a single-layer structure or a multi-layer structure.

9. A metamaterial module pressure-resistant skin structure, characterized in that: The invention comprises a metamaterial module (7) for suppressing underwater low-frequency flow-induced noise according to any one of claims 1 to 8, and a pressure-resistant layer (8), wherein the pressure-resistant layer (8) is fixedly arranged on the outside of the metamaterial module (7) for suppressing underwater low-frequency flow-induced noise.

10. The metamaterial module pressure-resistant skin structure according to claim 9, characterized in that: The negative Poisson's ratio unit cell structure (1) is made of a water-like material, and the impedance of the material matches the impedance of water; the tuning core (2) is made of a high-density material, and the material density of the tuning core (2) is at least 0.5 times higher than the material density of the negative Poisson's ratio unit cell structure (1).

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