Gradient Acoustic Metasurface Model

Abstract

The present invention relates to a gradient acoustic metasurface model, comprising several periodic structures, wherein a single periodic structure comprises a first uniform dielectric unit, a second uniform dielectric unit, a third uniform dielectric unit, and a fourth uniform dielectric unit arranged in sequence in a horizontal direction, and the bottoms of the second uniform dielectric unit, the third uniform dielectric unit, and the fourth uniform dielectric unit are all covered with a fifth uniform dielectric unit; the dielectric height ratios between the first uniform dielectric unit, the second uniform dielectric unit, the third uniform dielectric unit, and the fourth uniform dielectric unit are 4:3:2:1; the dielectric height ratios between the fifth uniform dielectric unit covering the bottom of the second uniform dielectric unit, the fifth uniform dielectric unit covering the bottom of the third uniform dielectric unit, and the fifth uniform dielectric unit covering the bottom of the fourth uniform dielectric unit are 1:2:3. The structure is simple, easy to implement, and can complete the reflection control of sound waves underwater, providing a new angle for ship stealth design.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic supersurfaces, in particular to a gradient acoustic supersurface model. Background Art

[0002] Acoustic metasurface is a low-dimensional acoustic metamaterial structure, which is generally composed of multiple microstructure units arranged in a special sequence to form a planar metamaterial system with subwavelength thickness. It can flexibly and effectively control the amplitude, phase, polarization and propagation mode of longitudinal waves, and has great potential and broad application prospects.

[0003] In the prior art, the research on acoustic metasurfaces is mainly in the form of simple folded space or designed resonant cavity, mainly including the following models:

[0004] (1) An acoustic metasurface model composed of a group of meta-atoms with a thickness of about 1 / 100 wavelength. Each structure contains a group of membranes and a cavity filled with air, which can achieve high-efficiency sound transmission between water and air. Based on this acoustic metasurface model, a special acoustic metasurface phase compensation method can be used to realize the design of an acoustic stealth cloak.

[0005] (2) The aeroacoustic metasurface model with a single port opening and closing has good sound absorption effect in the low frequency range;

[0006] (3) Ultra-thin labyrinth-type acoustic metamaterials based on curling theory can achieve the control of sound transmission and the amplitude and phase of the acoustic wavefront;

[0007] The above acoustic metasurface models have the advantage of being simple to manufacture. However, this type of acoustic metasurface model is extremely dependent on the parameters of the folded space structure, and the calculation and simulation process is relatively complicated, making it difficult to expand to the underwater field with water as the background medium. Moreover, the sound wave reflection control model is mostly seen in media with air as the background medium. It is urgent to propose an acoustic metasurface model that can perform underwater reflected sound wave control. Summary of the invention

[0008] In view of the shortcomings of the above-mentioned existing production technology, the applicant provides a rationally structured gradient acoustic metasurface model, which has a simple structure and is easy to implement, and can complete the reflection control of sound waves underwater, providing a new perspective for ship stealth design.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A gradient acoustic metasurface model includes several periodic structures, wherein a single periodic structure includes a first uniform dielectric unit, a second uniform dielectric unit, a third uniform dielectric unit, and a fourth uniform dielectric unit which are arranged in sequence in a horizontal direction, and the bottoms of the second uniform dielectric unit, the third uniform dielectric unit, and the fourth uniform dielectric unit are all covered with a fifth uniform dielectric unit;

[0011] The dielectric height ratio among the first uniform dielectric unit, the second uniform dielectric unit, the third uniform dielectric unit and the fourth uniform dielectric unit is 4:3:2:1;

[0012] The dielectric height ratio among the fifth uniform dielectric unit covering the bottom of the second uniform dielectric unit, the fifth uniform dielectric unit covering the bottom of the third uniform dielectric unit, and the fifth uniform dielectric unit covering the bottom of the fourth uniform dielectric unit is 1:2:3;

[0013] Two adjacent uniform dielectric units and two adjacent periodic structures are separated by a partition.

[0014] The bottom of each periodic structure is covered with a base plate.

[0015] As a further improvement of the above technical solution:

[0016] The dielectric widths w of the first uniform dielectric unit, the second uniform dielectric unit, the third uniform dielectric unit, the fourth uniform dielectric unit and the fifth uniform dielectric unit are the same.

[0017] The medium width w of the first uniform medium unit, the second uniform medium unit, the third uniform medium unit, the fourth uniform medium unit and the fifth uniform medium unit is in the range of 0.1 m-0.4 m.

[0018] The medium height h1 of the first uniform medium unit is 0.2 m;

[0019] The medium height h2 of the second uniform medium unit is 0.15m;

[0020] The medium height h3 of the third uniform medium unit is 0.1 m;

[0021] The medium height h4 of the fourth uniform medium unit is 0.05 m.

[0022] The fifth uniform dielectric unit covering the bottom of the second uniform dielectric unit has a dielectric height h 5a 0.05m;

[0023] The fifth uniform dielectric unit covering the bottom of the third uniform dielectric unit has a dielectric height h 5b 0.1m;

[0024] The fifth uniform dielectric unit covering the bottom of the fourth uniform dielectric unit has a dielectric height h 5c It is 0.15m.

[0025] The impedance Z1 of the first uniform dielectric unit is 1.5×10 6 Pa·s / m;

[0026] The impedance Z2 of the second uniform dielectric unit is 1.52×10 6 Pa·s / m;

[0027] The impedance Z3 of the third uniform dielectric unit is 1.56×10 6 Pa·s / m;

[0028] The impedance Z4 of the fourth uniform dielectric unit is 1.54×10 6 Pa·s / m;

[0029] The impedance Z5 of the fifth uniform dielectric unit is 16.9×10 6 Pa·s / m.

[0030] The partition is made of steel, the width p of the partition is in the range of 0.005m-0.025m, and the height h6 of the partition is 0.2m.

[0031] The bottom plate is made of steel, and the thickness t of the bottom plate is 0.025m.

[0032] The cross-sectional shapes of the first uniform dielectric unit, the second uniform dielectric unit, the third uniform dielectric unit, the fourth uniform dielectric unit, the fifth uniform dielectric unit and the partition are all rectangular.

[0033] The beneficial effects of the present invention are as follows:

[0034] The present invention has a compact and reasonable structure and is easy to operate. By adjusting the relationship between the period width and wavelength of the gradient acoustic metasurface model, the angle of underwater sound wave reflection can be effectively controlled. The variable parameters are small and the control is simple and effective, providing a new design guidance direction for ship stealth design.

[0035] The present invention can realize the reflection control of sound waves at any incident angle, has low implementation difficulty, few implementation restrictions, and is easy to implement.

[0036] The present invention replaces part of the second uniform dielectric unit, the third uniform dielectric unit and the fourth uniform dielectric unit with the fifth uniform dielectric unit, thereby reducing the demand for specific materials and thus reducing costs and implementation difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] Figure 2 Schematic diagram of the geometric principle of the acoustic metasurface of the present invention.

[0039] Figure 3 This is the background sound pressure field of Example 1 of the present invention.

[0040] Figure 4 This is the scattered sound pressure field of Example 1 of the present invention.

[0041] Figure 5 This is the simulation result of the scattering direction of the scattered sound wave corresponding to the first embodiment of the present invention.

[0042] Figure 6 This is the background sound pressure field of the second embodiment of the present invention.

[0043] Figure 7 This is the scattered sound pressure field of Example 2 of the present invention.

[0044] Figure 8 This is the simulation result of the scattering direction of the scattered sound wave corresponding to the second embodiment of the present invention.

[0045] Among them: 1. a first uniform dielectric unit; 2. a second uniform dielectric unit; 3. a third uniform dielectric unit; 4. a fourth uniform dielectric unit; 5. a fifth uniform dielectric unit; 6. a partition; and 7. a bottom plate. DETAILED DESCRIPTION

[0046] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0047] like Figure 1-Figure 2 As shown, the gradient acoustic metasurface model of this embodiment includes several periodic structures, and a single periodic structure includes a first uniform dielectric unit 1, a second uniform dielectric unit 2, a third uniform dielectric unit 3, and a fourth uniform dielectric unit 4 which are arranged in sequence in the horizontal direction, and the bottoms of the second uniform dielectric unit 2, the third uniform dielectric unit 3, and the fourth uniform dielectric unit 4 are all covered with a fifth uniform dielectric unit 5; the dielectric height ratios among the first uniform dielectric unit 1, the second uniform dielectric unit 2, the third uniform dielectric unit 3, and the fourth uniform dielectric unit 4 are 4:3:2:1; the dielectric height ratios among the fifth uniform dielectric unit 5 covering the bottom of the second uniform dielectric unit 2, the fifth uniform dielectric unit 5 covering the bottom of the third uniform dielectric unit 3, and the fifth uniform dielectric unit 5 covering the bottom of the fourth uniform dielectric unit 4 are 1:2:3; two adjacent uniform dielectric units and two adjacent periodic structures are separated by a partition 6; and the bottom of each periodic structure is covered with a bottom plate 7.

[0048] like Figure 2As shown, the gradient acoustic metasurface model of the present invention includes at least two periodic structures, and for a single periodic structure, it includes a first uniform dielectric unit 1, a second uniform dielectric unit 2, a third uniform dielectric unit 3, a fourth uniform dielectric unit 4, a fifth uniform dielectric unit 5, a partition 6 and a bottom plate 7;

[0049] The dielectric width w of the first uniform dielectric unit 1, the second uniform dielectric unit 2, the third uniform dielectric unit 3, the fourth uniform dielectric unit 4 and the fifth uniform dielectric unit 5 is the same, ranging from 0.1m to 0.4m;

[0050] The medium height h1 of the first uniform medium unit 1 is 0.2 m;

[0051] The medium height h2 of the second uniform medium unit 2 is 0.15 m, and the medium height h2 of the fifth uniform medium unit 5 covering the bottom of the second uniform medium unit 2 is 0.15 m. 5a 0.05m;

[0052] The medium height h3 of the third uniform medium unit 3 is 0.1 m, and the medium height h4 of the fifth uniform medium unit 5 covering the bottom of the third uniform medium unit 3 is 0.1 m. 5b 0.1m;

[0053] The medium height h4 of the fourth uniform medium unit 4 is 0.05 m, and the medium height h4 of the fifth uniform medium unit 5 covering the bottom of the fourth uniform medium unit 4 is 0.05 m. 5c 0.15m;

[0054] That is, the dielectric height of the first uniform dielectric unit 1 is equal to the sum of the dielectric heights of the second uniform dielectric unit 2 and the fifth uniform dielectric unit 5 covering the bottom of the second uniform dielectric unit 2, equal to the sum of the dielectric heights of the third uniform dielectric unit 3 and the fifth uniform dielectric unit 5 covering the bottom of the third uniform dielectric unit 3, and equal to the sum of the dielectric heights of the fourth uniform dielectric unit 4 and the fifth uniform dielectric unit 5 covering the bottom of the fourth uniform dielectric unit 4;

[0055] The width p of the partition 6 ranges from 0.005m to 0.025m, and the height h6 of the partition 6 is 0.2m;

[0056] The partition 6 separates two adjacent uniform dielectric units, and the outer sides of the two outermost uniform dielectric units of the gradient acoustic metasurface model are covered with the partition 6, which can protect the uniform dielectric units;

[0057] The uniform medium unit and the corresponding partition 6 are bonded by an adhesive to form a periodic structure, and its period width d1 is 4(w+p). Each periodic structure is connected by a partition 6 and bonded by an adhesive to form a gradient acoustic metasurface model. The period width d of the gradient acoustic metasurface model is equal to the number of periodic structures*the period width d1 of a single periodic structure;

[0058] The thickness t of the bottom plate 7 is 0.025 m, and the width of the bottom plate 7 is equal to the period width d of the gradient acoustic metasurface model;

[0059] The partition 6 and the bottom plate 7 are both made of steel, and the impedance of steel is 46.8×10 6 Pa·s / m, which is about 30 times the acoustic impedance of water medium, can be used as a rigid wall to support and protect the uniform medium unit physically;

[0060] In addition, the impedance Z1 of the first uniform dielectric unit 1 is 1.5×10 6 Pa·s / m;

[0061] The impedance of the second uniform dielectric unit 2 is Z2 = 1.52 × 10 6 Pa·s / m;

[0062] The impedance of the third uniform dielectric unit 3 is Z3 = 1.56 × 10 6 Pa·s / m;

[0063] The impedance Z4 of the fourth uniform dielectric unit 4 is 1.54×10 6 Pa·s / m;

[0064] The impedance Z5 of the fifth uniform dielectric unit 5 is 16.9×10 6 Pa·s / m;

[0065] Under the above impedance, the gradient acoustic metasurface model of the present invention can realize abnormal reflection phenomenon for sound waves of any incident angle, so as to control the reflection angle of the sound waves, thereby realizing directional reflection of the sound waves and providing a new design guidance direction for ship stealth design.

[0066] The cross-sectional shapes of the first uniform dielectric unit 1 , the second uniform dielectric unit 2 , the third uniform dielectric unit 3 , the fourth uniform dielectric unit 4 , the fifth uniform dielectric unit 5 and the partition plate 6 are all rectangular.

[0067] The following is the specific examples section.

[0068] Embodiment 1:

[0069] When the sound wave frequency f=5000 Hz, the background medium is water, and the sound wave is incident perpendicularly to the gradient acoustic metasurface model, in this embodiment, the structural parameters of the gradient acoustic metasurface model are:

[0070] The medium width w of a single uniform medium unit is 0.24 m;

[0071] The width p of a single partition 6 is 0.01 m;

[0072] The period width d of the gradient acoustic metasurface model is 1m;

[0073] According to Snell's law, the angle of reflection is equal to the angle of incidence, that is, when the angle of incidence is 0, the theoretical angle of reflection is 0°;

[0074] According to the generalized Snell's law, the angle of scattered sound waves generated by the gradient acoustic metasurface model can be theoretically calculated, that is,

[0075] The theoretical calculation formula for the scattering angle at any angle of incidence is θ r =arcsin(sinθ i +λ / d),

[0076] In the above formula, θ r Indicates the scattering angle of sound waves;

[0077] θ i represents the incident angle of the sound wave;

[0078] λ represents the wavelength of the sound wave;

[0079] d represents the period width of the gradient acoustic metasurface model, and in this embodiment, d=1m;

[0080] The theoretical calculation formula of the scattering angle can be transformed into θ r =arcsin(λ / d), according to which the theoretical scattering angle of the gradient acoustic metasurface model in this embodiment can be calculated to be 17.5°;

[0081] The simulation calculation is performed using COMSOL Multiphysics software, such as Figure 3-Figure 5 As shown, the upper boundary of the gradient acoustic metasurface model is located at x=0, and the plane acoustic wave is incident on the gradient acoustic metasurface model from the upper boundary and exits from the upper boundary;

[0082] according to Figure 3-Figure 5 It can be seen that for the vertically incident plane wave, the outgoing sound wave has an obvious deviation, which proves that the sound wave has an abnormal reflection phenomenon on the surface of the gradient acoustic metasurface model of this embodiment, and the simulated scattering angle is 17.5°;

[0083] The simulation value is in good agreement with the theoretical value. Therefore, the gradient acoustic metasurface model of this embodiment can realize arbitrary control of the angle of underwater reflected sound waves.

[0084] Embodiment 2:

[0085] When the sound wave frequency f=5000 Hz, the background medium is water, and the sound wave is incident perpendicularly to the gradient acoustic metasurface model, in this embodiment, the structural parameters of the gradient acoustic metasurface model are:

[0086] The medium width w of a single uniform medium unit is 0.1 m;

[0087] The width p of a single partition 6 is 0.05 m;

[0088] The period width d of the gradient acoustic metasurface model is 0.6 m;

[0089] According to Snell's law, the angle of reflection is equal to the angle of incidence, that is, when the angle of incidence is 0, the theoretical angle of reflection is 0°;

[0090] According to the generalized Snell's law, the angle of scattered sound waves generated by the gradient acoustic metasurface model can be theoretically calculated, that is,

[0091] The theoretical calculation formula for the scattering angle at any angle of incidence is θ r =arcsin(sinθ i +λ / d),

[0092] In the above formula, θ r Indicates the scattering angle of sound waves;

[0093] θ i represents the incident angle of the sound wave;

[0094] λ represents the wavelength of the sound wave;

[0095] d represents the period width of the gradient acoustic metasurface model, and in this embodiment, d=0.6m;

[0096] The theoretical calculation formula of the scattering angle can be transformed into θ r =arcsin(λ / d), according to which the theoretical scattering angle of the gradient acoustic metasurface model in this embodiment can be calculated to be 30°;

[0097] The simulation calculation is performed using COMSOL Multiphysics software, such as Figure 6-Figure 8 As shown, the upper boundary of the gradient acoustic metasurface model is located at x=0, and the plane acoustic wave is incident on the gradient acoustic metasurface model from the upper boundary and exits from the upper boundary;

[0098] according to Figure 6-Figure 8 It can be seen that for the vertically incident plane wave, the outgoing sound wave has an obvious deviation, which proves that the sound wave has an abnormal reflection phenomenon on the surface of the gradient acoustic metasurface model of this embodiment, and the scattering angle obtained by simulation is 30°;

[0099] The simulation value is in good agreement with the theoretical value. Therefore, the gradient acoustic metasurface model of this embodiment can realize arbitrary control of the angle of underwater reflected sound waves.

[0100] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A gradient acoustic metasurface model, characterized in that: It comprises a plurality of periodic structures, wherein a single periodic structure comprises a first uniform dielectric unit (1), a second uniform dielectric unit (2), a third uniform dielectric unit (3), and a fourth uniform dielectric unit (4) which are arranged in sequence and spaced apart in a horizontal direction, and the bottoms of the second uniform dielectric unit (2), the third uniform dielectric unit (3), and the fourth uniform dielectric unit (4) are all covered with a fifth uniform dielectric unit (5); The medium height ratio among the first uniform medium unit (1), the second uniform medium unit (2), the third uniform medium unit (3) and the fourth uniform medium unit (4) is 4:3:2:1; The dielectric height ratio among the fifth uniform dielectric unit (5) covering the bottom of the second uniform dielectric unit (2), the fifth uniform dielectric unit (5) covering the bottom of the third uniform dielectric unit (3), and the fifth uniform dielectric unit (5) covering the bottom of the fourth uniform dielectric unit (4) is 1:2:3; Two adjacent uniform dielectric units and two adjacent periodic structures are separated by a partition (6); The bottom of each periodic structure is covered with a bottom plate (7); The impedance Z1 of the first uniform dielectric unit (1) is 1.5×106 Pa·s / m, the impedance Z2 of the second uniform dielectric unit (2) is 1.52×106 Pa·s / m, the impedance Z3 of the third uniform dielectric unit (3) is 1.56×106 Pa·s / m, the impedance Z4 of the fourth uniform dielectric unit (4) is 1.54×106 Pa·s / m, and the impedance Z5 of the fifth uniform dielectric unit (5) is 16.9×106 Pa·s / m, thereby achieving an abnormal reflection phenomenon for sound waves at any incident angle, thereby controlling the reflection angle of the sound waves and achieving directional reflection of the sound waves.

2. The gradient acoustic metasurface model according to claim 1, characterized in that: The medium width w of the first uniform medium unit (1), the second uniform medium unit (2), the third uniform medium unit (3), the fourth uniform medium unit (4) and the fifth uniform medium unit (5) is the same.

3. The gradient acoustic metasurface model as claimed in claim 2, characterized in that: The medium width w of the first uniform medium unit (1), the second uniform medium unit (2), the third uniform medium unit (3), the fourth uniform medium unit (4) and the fifth uniform medium unit (5) is in the range of 0.1 m to 0.4 m.

4. The gradient acoustic metasurface model according to claim 1, characterized in that: The medium height h1 of the first uniform medium unit (1) is 0.2 m; The medium height h2 of the second uniform medium unit (2) is 0.15 m; The medium height h3 of the third uniform medium unit (3) is 0.1 m; The medium height h4 of the fourth uniform medium unit (4) is 0.05 m.

5. The gradient acoustic metasurface model according to claim 1, characterized in that: The fifth uniform dielectric unit (5) covering the bottom of the second uniform dielectric unit (2) has a dielectric height h 5a The fifth uniform dielectric unit (5) covering the bottom of the third uniform dielectric unit (3) has a dielectric height h 5b 0.1m; The fifth uniform dielectric unit (5) covering the bottom of the fourth uniform dielectric unit (4) has a dielectric height h 5c It is 0.15m.

6. The gradient acoustic metasurface model according to claim 1, characterized in that: The partition (6) is made of steel, the width p of the partition (6) is in the range of 0.005m-0.025m, and the height h6 of the partition (6) is 0.2m.

7. The gradient acoustic metasurface model according to claim 1, characterized in that: The bottom plate (7) is made of steel, and the thickness t of the bottom plate (7) is 0.025 m.

8. The gradient acoustic metasurface model according to claim 1, characterized in that: The cross-sectional shapes of the first uniform dielectric unit (1), the second uniform dielectric unit (2), the third uniform dielectric unit (3), the fourth uniform dielectric unit (4), the fifth uniform dielectric unit (5) and the partition plate (6) are all rectangular.

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