A deep subwavelength multi-frequency acoustic absorber

Abstract

The present application belongs to the technical field of acoustic noise reduction, and particularly relates to a deep subwavelength multi-harmonic sound absorber. The absorber is formed by arraying a plurality of resonator units with the same structure. The double-channel Mie resonator can excite monopole and dipole modes, thereby realizing perfect absorption of deep subwavelength fundamental frequency and double frequency. The simulation and experimental absorption coefficients of the absorber at the fundamental frequency of 160 Hz are 99.7% and 97.7% respectively. The simulation and experimental absorption coefficients of the absorber at the double frequency of 320 Hz are 98.6% and 98.5% respectively. In this case, the thickness (19 mm) of the absorber is only 1 / 112.8 and 1 / 56.4 times of the corresponding working wavelength. The present application has the characteristics of deep subwavelength and multi-harmonic absorption, and provides a feasible method for low-frequency noise control.

Description

Technical Field

[0001] This invention belongs to the field of acoustic noise reduction technology, specifically relating to a deep subwavelength multi-harmonic sound absorber. Background Technology

[0002] Low-frequency noise has become one of the most serious environmental problems today, and its control is an important and challenging issue in the field of acoustics. Traditional porous sound-absorbing materials are limited by linear response theory, requiring large-area materials for low-frequency sound wave absorption, making them extremely inefficient for absorbing low-frequency noise in limited spaces. Furthermore, addressing the issue of harmonic noise in addition to fundamental frequency noise generated by large servers, vehicles, etc., the development of ultra-thin sound absorbers capable of simultaneously eliminating both fundamental and harmonic noise is also a crucial research topic.

[0003] In recent years, the emergence of acoustic metamaterials has provided a feasible solution for the absorption of low-frequency sound waves. Acoustic metamaterials localize acoustic energy in a finite space through resonators, increasing the local energy density of sound waves and thus overcoming the limitations of linear response theory. The localized energy is dissipated as heat through frictional losses between the sound wave and the structure, as well as the relaxation process of molecules. However, existing metamaterial absorbers, such as Helmholtz resonators, can only absorb sound waves at a certain fundamental frequency (…). f 0) Excites a resonant mode; while the Fabry-Perot resonator can only excite monopole resonant modes, lacking the ability to excite at even harmonics (2n). f 0, (n=1, 2, 3…) excites dipole resonance modes, thus failing to simultaneously absorb low-frequency noise from both the fundamental frequency and even harmonics.

[0004] In view of this, in order to solve the above problems, the present invention designs a deep subwavelength multi-harmonic sound absorber. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to address the shortcomings of current technology by providing a deep subwavelength multi-harmonic sound absorber that can simultaneously absorb low-frequency noise of both fundamental and even harmonic frequencies.

[0006] Technical Solution: To achieve the above objectives, this invention provides a deep subwavelength multi-harmonic sound absorber, comprising multiple sound-absorbing cells, each cell including a dual-channel Mie resonator with an embedded labyrinth channel; the dual-channel Mie resonator includes a front panel, a rear panel, side panels, a top panel, and a partition; the front and rear panels are arranged opposite to each other, with side panels connected to both sides of the front and rear panels, and a top panel connected above the front, rear, and side panels; a partition connects the rear and front panels; the height W of the front panel is less than the height H of the rear and side panels, thereby forming an external channel below the front panel; the partition forms a labyrinth channel, with identical openings at the top and bottom of the labyrinth channel for sound waves to propagate within the labyrinth channel, thereby generating monopole and dipole resonance modes.

[0007] Furthermore, the dual-channel Mie resonator adopts a ring structure or a square structure.

[0008] Furthermore, the dual-channel Mie resonator is manufactured by 3D printing or injection molding, or the dual-channel Mie resonator is manufactured from wood or metal materials.

[0009] Furthermore, the thickness of the front panel, rear panel, side panel, top panel, and partition is 1~2 mm.

[0010] Furthermore, the distance from the opening to the top plate is... w z =20~28 mm, the distance between the outermost layer of the partition and the side panel w y =20~40 mm.

[0011] Furthermore, the width of the maze passage is w =8~12 mm, the thickness of the maze passage is t p =13~22 mm.

[0012] Furthermore, the thickness of the dual-channel Mie resonator is T =15~25 mm.

[0013] Furthermore, the front panel is a rectangular plate with a width and height of [missing information]. W =160~200 mm; the rear panel is a rectangular plate with a width of W =160~200 mm, height is H =170~230 mm.

[0014] Beneficial Effects: The absorber of this invention is formed by arraying multiple resonator units with identical structures. This dual-channel Mie resonator can excite monopole and dipole modes, thereby achieving perfect absorption of the fundamental and second harmonic frequencies at a deep subwavelength. The absorption coefficients of this absorber at the fundamental frequency of 160 Hz are 99.7% and 97.7% in simulation and experiments, respectively; and at the even harmonic frequency of 320 Hz, the absorption coefficients are 98.6% and 98.5%, respectively. Moreover, the thickness of the absorber (19 mm) is only 1 / 112.8 and 1 / 56.4 times that of the corresponding operating wavelengths. This invention possesses characteristics such as deep subwavelength and multi-harmonic absorption, providing a feasible method for low-frequency noise control. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the deep subwavelength multi-harmonic acoustic absorber of the present invention;

[0016] Figure 2(a) is a three-dimensional view of a cell of a harmonic sound absorber;

[0017] Figure 2(b) is a two-dimensional schematic diagram of the internal structure of a harmonic sound absorption cell;

[0018] Figure 3(a) shows the absorption coefficient of the multi-harmonic absorber;

[0019] Figure 3(b) shows the sound energy distribution at 160 Hz and 320 Hz.

[0020] List of reference numerals: Front panel 1, Rear panel 2, Side panel 3, Top panel 5, Partition 6, External passage 7, Maze passage 8, Opening 9. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] Example 1, according to Figure 1 Figure 3(b) provides further explanation.

[0023] This invention provides a deep subwavelength multi-harmonic sound absorber, comprising multiple sound-absorbing cells, each cell including a dual-channel Mie resonator with an embedded labyrinth channel 8; the dual-channel Mie resonator includes a front panel 1, a rear panel 2, side panels 3, a top plate 5, and a partition 6; the front panel 1 and rear panel 2 are arranged opposite to each other, the side panels 3 are connected to both sides of the front panel 1 and rear panel 2, the top plate 5 is connected above the front panel 1, rear panel 2, and side panels 3, and the partition 6 is connected between the rear panel 2 and the front panel 1; the height of the front panel 1 is... W Less than the height of rear panel 2 and side panel 3 H This results in an external channel 7 being formed below the front panel 1; the partition 6 forms a maze channel 8, with the same opening 9 at the top and bottom of the maze channel 8 for sound waves to be transmitted inside the maze channel 8, thereby generating monopole and dipole resonance modes.

[0024] The dual-channel Mie resonator adopts a ring structure or a square structure.

[0025] The dual-channel Mie resonator is manufactured by 3D printing or injection molding, or it is made of wood or metal.

[0026] The thickness of the front panel 1, rear panel 2, side panel 3, top panel 5, and partition 6 is 1~2 mm.

[0027] The distance from the opening 9 to the top plate 5 is w z =20~28 mm, the distance between the outermost layer of the partition 6 and the side panel 3 w y =20~40 mm.

[0028] The width of the maze passage 8 is w =8~12 mm, the thickness of maze passage 8 is t p =13~22 mm.

[0029] The thickness of the dual-channel Mie resonator is T =15~25 mm.

[0030] The front panel 1 is a rectangular plate with a width and height of [missing information]. W =160~200 mm; the rear panel 2 is a rectangular plate with a width of W =160~200 mm, height is H =170~230 mm.

[0031] The deep subwavelength multi-harmonic absorber is composed of an array of multiple identical absorber cells. Each absorber cell is a dual-channel Mie resonator with an embedded labyrinth channel 8. The dual-channel Mie resonator comprises a front panel 1, a rear panel 2, two side panels 3, a partition 6, and a top plate 5, all interconnected. The front panel 1 is mounted on the front of the structure, and the rear panel 2 is mounted on the back. A partition 6 is fixedly connected between the front panel 1 and the rear panel 2. The two side panels 3 are mounted on the sides of the structure and fixedly connected to the front panel 1 and the rear panel 2. The top plate 5 is mounted on the top of the structure and fixedly connected to the front panel 1, the rear panel 2, and the two side panels 3. The height of the front panel 1... W Less than the height of rear panel 2, side panel 3, and side panel 3 H This forms an external channel 7 at the front panel 1; the partition 6 can form a maze channel 8 to construct a dual-channel Mie resonator; the top and bottom of the maze channel 8 are provided with the same opening 9 for sound waves to be transmitted inside the resonator.

[0032] The absorber's interior is formed by multiple interconnected labyrinthine channels 8 through internal partitions 6, creating a labyrinth structure. Openings 9 at its top and bottom form a dual-channel acoustic Mie resonator, used to excite acoustic resonance modes and increase sound energy density. Therefore, an ultra-thin structure can absorb large-wavelength sound waves.

[0033] The multi-harmonic sound absorber with deep subwavelength is fabricated using 3D printing technology; the thickness of the front panel 1, rear panel 2, side panel 3, top panel 5, and partition 6 is [missing information]. t =1 mm; Width of the dual-channel Mie resonator W =176 mm, height H =190 mm; the width of the external channel 7 is ( W -2 t =174 mm, height is h =12 mm; the width of the internal maze passage 8 is w =10 mm, the wall thickness of maze passage 8 is t p =17 mm; the distance from the internal top opening 9 to the top plate 5 is w z =24 mm, the distance between the outer septum 6 and the outer panel 3 of the internal dual-channel Mie resonator. w y =28 mm; Total thickness of the absorber T =19 mm.

[0034] The monopole resonance frequency of the dual-channel Mie resonator is 160 Hz, and the dipole resonance frequency is 320 Hz. The absorption curves obtained by this absorber are shown in Figure 3(a). The simulated (experimental) absorption coefficients of the absorber at 160 Hz and 320 Hz are 99.7% and 98.6% (97.7% and 98.5%), respectively. The thickness of the absorber (19 mm) is only 1 / 112.8 and 1 / 56.4 times that of the corresponding operating wavelengths. Figure 3(b) shows the absolute sound pressure distribution of the absorption peaks at 160 Hz and 320 Hz. It can be seen that the absorption peak at 160 Hz is generated by the monopole resonance of the dual-channel Mie resonator, while the absorption peak at its second harmonic of 320 Hz is generated by the dipole resonance of the dual-channel Mie resonator. By exciting the monopole and dipole resonance modes of the dual-channel Mie resonator, near-perfect absorption of the fundamental frequency and second harmonic can be achieved using a single structure.

[0035] Table 1. Geometric parameters of deep subwavelength multi-harmonic acoustic absorbers

[0036]

[0037] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A deep subwavelength multi-harmonic acoustic absorber, characterized in that: The device includes multiple sound-absorbing cells, each of which includes a dual-channel Mie resonator with an embedded labyrinth channel (8). The dual-channel Mie resonator includes a front panel (1), a rear panel (2), a side panel (3), a top plate (5), and a partition (6). The front panel (1) and the rear panel (2) are arranged opposite to each other. The side panels (3) are connected to both sides of the front panel (1) and the rear panel (2). The top plate (5) is connected above the front panel (1), the rear panel (2), and the side panels (3). The partition (6) is connected between the rear panel (2) and the front panel (1). The height W of the front panel (1) is less than the height H of the rear panel (2) and the side panels (3), thereby forming an external channel (7) below the front panel (1). The partition (6) forms a labyrinth channel (8). The top and bottom of the labyrinth channel (8) are provided with the same opening (9) for sound waves to be transmitted inside the labyrinth channel (8), thereby generating monopole and dipole resonance modes.

2. The deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The dual-channel Mie resonator adopts a ring structure or a square structure.

3. The deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The dual-channel Mie resonator is manufactured by 3D printing or injection molding, or it is made of wood or metal.

4. The deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The thickness of the front panel (1), rear panel (2), side panel (3), top panel (5) and partition (6) is 1~2 mm.

5. A deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The distance from the opening (9) to the top plate (5) is w z =20~28 mm, the distance between the outermost layer of the partition (6) and the side panel (3) w y =20~40mm.

6. The deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The width of the maze passage (8) is w =8~12 mm, the thickness of the maze passage (8) is t p =13~22 mm.

7. The deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The thickness of the dual-channel Mie resonator is T =15~25 mm.

8. A deep subwavelength multi-harmonic acoustic absorber according to claim 1, characterized in that: The front panel (1) is a rectangular plate with a width and height of [missing information]. W =160~200 mm; the rear panel (2) is a rectangular plate with a width of W =160~200 mm, height is H =170~230 mm.

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