Double-layer Helmholtz resonance sound absorption structure lined with porous material

Abstract

The invention discloses a double-layer Helmholtz resonance sound absorption structure lined with a porous material. The double-layer Helmholtz resonance sound absorption structure comprises a plurality of cells arranged in an array. Each cell comprises a double-layer honeycomb, an inner insertion pipe and a porous material thin layer which are coaxially arranged. The honeycomb is of a double-layer structure, the upper-layer honeycomb cavity is filled with a porous material thin layer, and the inner insertion pipe is embedded into small holes in the upper surface of each layer of honeycomb cavity and connected with the honeycomb cavity in a welded or glued mode. The structure has excellent broadband sound absorption performance, and especially in a low-frequency range, through the damping effect of the porous material layer and acoustic impedance matching adjustment, the sound absorption effect is remarkably improved. Meanwhile, the double-layer design enhances propagation and dissipation of sound waves. In addition, structural parameters and material parameters are adjustable and can be selected according to actual working condition requirements, and wide engineering application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of air sound-absorbing composite structures, and in particular relates to a double-layer Helmholtz resonance sound-absorbing structure lined with porous materials. Background Art

[0002] Low-frequency broadband sound absorption is of vital research significance for noise reduction technologies in fields such as aerospace, rail transportation, and large-scale industrial equipment. Due to the physical properties of low-frequency sound waves, such as large wavelength, slow loss, and strong penetration, traditional sound-absorbing materials are limited by the quarter-wavelength resonance mechanism and often require a thickness comparable to the wavelength of the sound wave to achieve effective absorption, which makes the low-frequency sound-absorbing material structure often too thick. Although resonant sound-absorbing structures can achieve sound wave attenuation in a compact size, they are usually accompanied by the defects of narrow absorption bands and low energy dissipation capabilities. In addition, the noise generated by large-scale industrial equipment is usually broadband noise containing sound waves of different frequencies. The sound absorption performance limited to a single frequency is obviously unable to meet the broadband noise reduction needs in practical applications. Although a large amount of current research focuses on improving the low-frequency sound absorption performance of sound-absorbing structures, due to the limitations of the single mechanism of resonant sound absorption, the existing sound-absorbing structures still have significant shortcomings in low-frequency broadband sound absorption. Summary of the Invention The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a double-layer Helmholtz resonant sound absorption structure lined with porous material to solve the technical problems of poor low-frequency sound absorption performance and narrow effective sound absorption bandwidth in airborne sound.

[0003] The present invention adopts the following technical solutions: A double-layer Helmholtz resonant sound absorption structure lined with porous material includes a plurality of cells arranged in an array, each cell is provided with a double-layer resonant cavity honeycomb, the double-layer resonant cavity honeycomb is embedded with an inner insert tube, and the honeycomb cavity of the double-layer resonant cavity honeycomb is filled with a thin layer of porous material, and the double-layer resonant cavity honeycomb, the inner insert tube and the thin layer of porous material are coaxially arranged.

[0004] Furthermore, the inner tube has a radius of 2 to 10 mm, a length of 5 to 30 mm, and a wall thickness of 0.5 to 3 mm.

[0005] Furthermore, the height of the porous material layer is 5 to 15 mm.

[0006] Furthermore, the height of the double-layer resonant cavity honeycomb is 10-40 mm, the diagonal length of the diamond-shaped interface of the double-layer resonant cavity honeycomb is 30-80 mm, and the wall thickness of the double-layer resonant cavity honeycomb is 0.5-2 mm.

[0007] Furthermore, the inner tube is connected to the upper surface of the cavity of the double-layer resonant cavity honeycomb.

[0008] Furthermore, the length of the inner tube is smaller than the cavity height of the double-layer resonant cavity honeycomb.

[0009] Furthermore, the thin layer of porous material is filled into the upper cavity of the double-layer resonant cavity honeycomb by gluing.

[0010] Furthermore, the double-layer resonant cavity honeycomb is made of steel, alloy, resin or composite material.

[0011] Furthermore, the height of each cell is 30 to 60 mm.

[0012] Furthermore, the inner insert tube is connected to the layer resonant cavity honeycomb by welding or gluing.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a double-layer Helmholtz resonator sound-absorbing structure lined with porous material. Under the excitation of sound waves of a specific frequency, the vibration speed of the air particles in the double-layer Helmholtz resonator intensifies, causing severe friction with the porous material layer, and dissipating a large amount of sound energy. Due to the double-layer design, the coupling between the double-layer Helmholtz resonator and the porous material layer enhances the propagation and dissipation of sound waves. The introduction of the porous material layer not only adjusts the impedance matching between the structure and the air, but also, through its complex internal pore structure, utilizes the friction and viscosity effects of the porous material skeleton to dissipate sound energy during the propagation of sound waves, thereby achieving efficient sound absorption at low frequencies. Compared with traditional double-layer Helmholtz resonators, the addition of the porous material layer significantly improves the sound absorption performance, especially in the low-frequency range. By changing key material parameters, the sound absorption effect can be further improved to achieve wider-band sound wave absorption. In addition, the vibration of the porous material layer can also increase the dissipation of sound energy, thereby improving the overall sound absorption effect.

[0014] Furthermore, the cavity of the present invention is made of hard materials such as structural steel, and the wall thickness of the double-layer resonant cavity honeycomb is 0.5 to 3 mm. The structure has good pressure resistance and is a load-bearing, lightweight and multifunctional structure.

[0015] Furthermore, the height of the double-layer resonant cavity honeycomb ranges from 10 to 40 mm, and the diagonal length of the honeycomb diamond interface ranges from 30 to 80 mm. The diagonal length and height of the honeycomb alter the volume of the cavity inside the cell, thereby changing the resonance characteristics and resonant frequency of the overall structure, thereby adjusting the sound absorption performance.

[0016] Furthermore, the radius of the inner tube structure embedded in each layer of cavity is 2 to 10 mm, and the length is 5 to 30 mm. By changing the radius and length of the inner tube structure, the sound absorption coefficient and resonance frequency of the overall structure can be changed, thereby regulating the sound absorption performance.

[0017] Furthermore, the height of the porous material thin layer is 5 to 15 mm. By changing the height of the porous material thin layer, the sound absorption coefficient and resonance frequency of the overall structure can be changed, thereby regulating the sound absorption performance.

[0018] In summary, the present invention has excellent broadband sound absorption performance and good pressure bearing capacity; in terms of design, the structural parameters and material parameters are highly adjustable and can be selected according to actual working conditions, and has broad engineering application prospects.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a double-layer Helmholtz sound absorption structure lined with porous material according to the present invention; Figure 2 is the side view of the cell; Figure 3 is a cross-sectional view of the cell; Figure 4 A comparison chart of the sound absorption coefficients of the sound absorption structure of the present invention and a porous material layer without an inner lining; Among them: 1. Double-layer resonant cavity honeycomb; 2. Inner tube 3. Thin layer of porous material. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," "one side," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0024] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0025] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0027] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] The present invention provides a double-layer Helmholtz resonance sound absorption structure lined with porous material, such as Figure 1As shown, a double-layer resonant cavity honeycomb 1 and an inner tube 2 are connected by gluing or welding to form a Helmholtz resonant sound absorption structure. Both are made of metal or carbon fiber / glass fiber composite materials. A thin layer of porous material 3 is fully filled into the upper cavity, closely adhering to the wall surface. The porous material lining effectively enhances system damping and adjusts acoustic impedance matching, thereby achieving perfect sound absorption in the originally weakly resonant structure. In the resonant state, the air at the perforations vibrates violently, dissipating sound energy through the friction and viscosity effects of the porous material skeleton. This achieves perfect sound absorption at 574Hz and 1125Hz, with an absorption coefficient close to 1 and a significantly increased half-absorption bandwidth. This provides a compact and efficient solution for low-frequency noise control and can be widely used in transportation, architectural acoustics and other fields.

[0029] See also Figure 1 、 Figure 2 and Figure 3 The present invention discloses a double-layer Helmholtz resonant sound absorption structure lined with a porous material. The structure comprises a plurality of cells, each of which comprises a double-layer resonant cavity honeycomb 1, an inner tube 2, and a thin layer of porous material 3. The lower surface of the lower cavity of the double-layer resonant cavity honeycomb 1 is fixed to the surface of an object requiring acoustic treatment. The upper surface of each cavity layer is provided with a small hole, and the inner tube 2 is disposed within the small hole and connected to the cavity by gluing or welding. The upper cavity layer is filled with a porous material layer and connected to the cavity by gluing, thereby forming a double-layer Helmholtz resonant sound absorption structure lined with a porous material.

[0030] The height of each cell is 20 to 60 mm.

[0031] The diamond diagonal of the double-layer resonant cavity honeycomb 1 is 30 to 80 mm, and the wall thickness is 0.5 to 2 mm.

[0032] The double-layer honeycomb cavity 1 is made of hard materials such as steel, alloy, resin or composite materials. The use of hard materials ensures that the structure has a certain load-bearing capacity and is connected to the inner tube 2 by gluing or welding.

[0033] The inner tube 2 has a diameter of 2 to 15 mm and a length of 5 to 30 mm.

[0034] The porous material thin layer 3 is fully filled into the upper cavity, and the friction and viscosity effects of the porous material skeleton are used to dissipate the sound energy. The height is 5 to 15 mm.

[0035] The axes of the double-layer resonant cavity honeycomb 1, the inner insert tube 2 and the porous material thin layer 3 coincide with each other.

[0036] The sound absorption performance of the double-layer Helmholtz resonant sound absorption structure lined with porous material of the present invention is mainly determined by the structural dimensions of the rhombus honeycomb and the inner insert 2 and the material parameters of the porous material, specifically including: The side lengths of the upper and lower honeycombs, the heights of the upper and lower cavities, the radius and length of the inner tube 2, the height of the porous material layer 3, the type of porous material, the porosity of the porous material, the tortuosity factor of the porous material, the viscous characteristic length of the porous material, the thermal characteristic length of the porous material, and the static flow resistivity of the porous material are all factors that determine the load-bearing capacity. The load-bearing capacity is primarily determined by the dimensions of the cavity, including the diameter and height of the upper and lower cavities, and the thickness of the honeycomb walls. Because these structural and material parameters are adjustable, the sound absorption and load-bearing performance of the structure can be precisely adjusted.

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Comparative Example 1 Metal Steel: Density 7850 kg / m 3 , Young's modulus is 201 GPa, and Poisson's ratio is 0.33.

[0039] Air: Density 1.23 kg / m 3 , the speed of sound is 343 m / s.

[0040] Comparative structural dimensions: Total height of diamond honeycomb: H =43 mm.

[0041] The diagonal length of the rhombus section is: l 1=43mm, l 2=57mm Upper and lower wall thickness: t 1=1mm.

[0042] Side wall thickness: t 2=1.5mm.

[0043] Upper and lower inner tube diameters: d 1=6mm, d 2=12mm.

[0044] Neck length: l 1=6mm,l 2=9mm.

[0045] Neck wall thickness: t 3=1mm.

[0046] Example 1 Metal Steel: Density 7850 kg / m 3 , Young's modulus is 201 GPa, and Poisson's ratio is 0.33.

[0047] Air: Density 1.23 kg / m 3 , the speed of sound is 343 m / s.

[0048] Porous material 1: Porosity: , tortuosity factor: , characteristic length of viscosity: , thermal characteristic length: , static flow resistance: .

[0049] Example structure size: Total height of diamond honeycomb: H =43 mm.

[0050] The diagonal length of the rhombus section is: l 1=43mm, l 2=57mm Upper and lower wall thickness: t 1=1mm.

[0051] Side wall thickness: t 2=1.5mm.

[0052] Upper and lower inner tube diameters: d 1=6mm, d 2=12mm.

[0053] Neck length: l 1=6mm, l 2=9mm.

[0054] Neck wall thickness: t 3=1mm.

[0055] Porous material height: h p =10mm Example 2 Metal Steel: Density 7850 kg / m 3 , Young's modulus is 201 GPa, and Poisson's ratio is 0.33.

[0056] Air: Density 1.23 kg / m 3 , the speed of sound is 343 m / s.

[0057] Porous material 2: Porosity: , tortuosity factor: , viscosity characteristic length: , thermal characteristic length: , static flow resistance: .

[0058] Example structure size: Total height of diamond honeycomb: H =43 mm.

[0059] The diagonal length of the rhombus section is: l 1=43mm, l 2=57mm Upper and lower wall thickness: t 1=1mm.

[0060] Side wall thickness: t 2=1.5mm.

[0061] Upper and lower inner tube diameters: d 1=6mm, d 2=12mm.

[0062] Neck length: l 1=6mm, l 2=9mm.

[0063] Neck wall thickness: t 3=1mm.

[0064] Porous material height: h p =10mm Both Example 1 and Example 2 use a thin layer of porous material without lining as a control group. The air parameters and total thickness are consistent with the corresponding examples. The sound absorption coefficient of the structure at 0 to 1600 Hz is calculated using numerical simulation.

[0065] See also Figure 4 , which is a comparison chart of the simulated sound absorption coefficient curves of the two embodiments and the control group. The black solid line is the sound absorption coefficient curve of the double-layer Helmholtz resonant structure without an inner porous material, the black dashed line is the sound absorption coefficient curve of the double-layer Helmholtz resonant structure lined with porous material 1, and the black dotted line is the sound absorption coefficient curve of the double-layer Helmholtz resonant structure lined with porous material 2.

[0066] The sound absorption structure of the present invention significantly improves the sound absorption performance of an unlined porous material layer within the range of 0 to 1600 Hz. By introducing a porous material lining, the system damping can be effectively enhanced and the acoustic impedance matching can be adjusted, thereby enabling the originally weakly resonant structure to achieve perfect sound absorption and excellent broadband sound absorption. The two peak sound absorption coefficients of Example 1 are respectively increased by 207% and 127% compared to the unlined porous material layer, and the two peak sound absorption coefficients of Example 2 are respectively increased by 180% and 120% compared to the unlined porous material layer. The following technical effects are achieved: 1. Excellent broadband sound absorption performance. The structure of the present invention can achieve an average sound absorption coefficient improvement in a broadband range, and the peak sound absorption coefficient reaches above 0.99. The sound absorption performance is significantly improved compared to the structure without a porous material layer.

[0067] 2. Lining the upper cavity with a porous material effectively enhances system damping and adjusts acoustic impedance matching. Under resonance, the air at the perforations vibrates violently, boosting dissipation capacity through the friction and viscosity of the porous material skeleton.

[0068] 3. Good load-bearing capacity. The double-layer resonant cavity honeycomb 1 is made of metal steel, which gives the structure a certain load-bearing capacity. The thickness of the structure is only 20 to 60 mm, making it a multifunctional structure with load-bearing, lightweight, sound absorption and noise reduction.

[0069] 4. Adjustable structural and material parameters. Changes in the structural parameters of the double-layer resonant cavity honeycomb 1 and the inner tube 2, as well as the material parameters of the porous material layer 3, have a significant impact on the sound absorption performance of the structure and can be selected according to actual working conditions.

[0070] In summary, the present invention's double-layered Helmholtz resonant sound absorption structure, lined with a porous material, exhibits excellent broadband sound absorption performance. The structural and material parameters offer significant design flexibility, allowing for selection based on actual operating conditions. This structure has broad engineering application prospects, providing a compact and efficient solution for broadband noise control in areas such as transportation and architectural acoustics.

[0071] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A double-layer Helmholtz resonance sound absorption structure lined with porous material, characterized in that: The invention comprises a plurality of cells arranged in an array, wherein a double-layer resonant cavity honeycomb (1) is provided in each cell, an inner tube (2) is embedded in the double-layer resonant cavity honeycomb (1), a porous material thin layer (3) is filled in the honeycomb cavity of the double-layer resonant cavity honeycomb (1), and the double-layer resonant cavity honeycomb (1), the inner tube (2) and the porous material thin layer (3) are coaxially arranged.

2. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The inner tube (2) has a radius of 2 to 10 mm, a length of 5 to 30 mm, and a wall thickness of 0.5 to 3 mm.

3. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The height of the porous material thin layer (3) is 5 to 15 mm.

4. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The height of the double-layer resonant cavity honeycomb (1) is 10 to 40 mm, the diagonal length of the rhombus interface of the double-layer resonant cavity honeycomb (1) is 30 to 80 mm, and the wall thickness of the double-layer resonant cavity honeycomb (1) is 0.5 to 2 mm.

5. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The inner insert tube (2) is connected to the upper surface of the cavity of the double-layer resonant cavity honeycomb (1).

6. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The length of the inner tube (2) is less than the cavity height of the double-layer resonant cavity honeycomb (1).

7. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The porous material thin layer (3) is filled into the upper cavity of the double-layer resonant cavity honeycomb (1) by gluing.

8. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The double-layer resonant cavity honeycomb (1) is made of steel, alloy, resin or composite material.

9. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The height of each cell is 30 to 60 mm.

10. The double-layer Helmholtz resonance sound absorption structure lined with porous material according to claim 1, characterized in that: The inner insert tube (2) is connected to the layer resonant cavity honeycomb (1) by welding or gluing.

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