An acoustic black hole combined noise reduction structure embedded with a micro-perforated structure
By using an acoustic black hole combined noise reduction structure with embedded micro-perforated structure, the problem of poor low-frequency and mid-frequency noise suppression in existing technologies has been solved, achieving effective noise suppression across the entire frequency band and improving sound field comfort.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU ZHENBO INTELLIGENT TECH CO LTD
- Filing Date
- 2025-07-28
- Publication Date
- 2026-07-10
AI Technical Summary
Existing acoustic black hole noise reduction structures are not effective in suppressing low-frequency and mid-frequency noise, and traditional passive sound-absorbing materials have problems such as narrow sound absorption bandwidth and poor stability.
An acoustic black hole combined noise reduction structure with embedded micro-perforated structure is adopted. By combining the acoustic black hole cavity and the micro-perforated side cavity, the system impedance is increased by utilizing the resonant cavity principle and the impedance effect of micro-perforation. Combined with sound-absorbing materials, noise reduction effect is achieved across the entire frequency band of low, mid and high frequencies.
It effectively suppresses noise across the entire frequency band above 150Hz, with a sound absorption coefficient consistently above 0.9, improving sound field comfort and making it applicable to environments such as aerospace, thermal power, and nuclear power.
Smart Images
Figure CN224480802U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of noise reduction device technology, specifically relating to an acoustic black hole combined noise reduction structure with embedded micro-perforated structure. Background Technology
[0002] Excessive indoor and outdoor noise can cause physical and mental fatigue, and even damage hearing, resulting in irreversible harm. Environmental noise can also directly affect the judgment and thinking of operators. Therefore, whether in daily office environments or in special working environments such as aerospace, thermal power, nuclear power, and deep-sea ships, there is an urgent need for a good sound field environment.
[0003] Traditional passive sound absorption and noise reduction measures include using sound-absorbing materials such as inorganic fibers, organic fibers, and inorganic foams, as well as suppressing noise by designing sound-absorbing structures such as micro-perforations, perforations, and resonant cavities. However, the above-mentioned passive noise reduction methods usually have problems such as unsatisfactory sound absorption effect, narrow effective frequency band, single sound absorption frequency band, large structural volume, and poor stability.
[0004] In recent years, the development of acoustic black hole noise reduction structures has, to some extent, addressed the problems of narrow bandwidth and low stability associated with passive sound absorption noise reduction. The acoustic black hole structure was initially proposed by the Russian scientist Morinov, referring to a structure whose thickness is designed to gradually decrease along a power function in one direction. This allows for the focusing and manipulation of curved waves propagating within the structure. Figure 1 As shown, with in-depth research, acoustic black hole noise reduction structures have been used to focus and control sound waves in flow fields, thereby achieving good broadband noise reduction effects. However, existing acoustic black hole noise reduction structures, when using a sound absorption coefficient of 0.9 as a benchmark, typically only have a certain suppression effect on high-frequency noise above 900Hz. How to further suppress low-frequency and mid-frequency noise has become a bottleneck problem for its further development. Summary of the Invention
[0005] The purpose of this invention is to address the shortcomings of existing vibration control technologies by providing an acoustic black hole combined noise reduction structure with an embedded micro-perforated structure. This structure is compact, simple, easy to use, and available in various forms. It can solve noise reduction problems across the entire frequency band, from low to high frequencies above 150Hz, improve the system's noise energy dissipation efficiency, and has broad application prospects.
[0006] This utility model provides an acoustic black hole combined noise reduction structure with embedded micro-perforated structure, including an acoustic black hole cavity, a side cavity, and micro-perforations connecting the acoustic black hole cavity and the side cavity;
[0007] The acoustic black hole cavity includes a thin plate array and an acoustic black hole cavity shell; the thin plate array consists of several thin plates with a circular hole in the center, each thin plate is fixed to the inner side of the acoustic black hole cavity shell, the thin plates are arranged at equal distances, the centers are coaxial, and the inner diameters are arranged in a monotonically decreasing or increasing pattern to form an acoustic black hole structure.
[0008] The side cavity is located outside the acoustic black hole cavity and surrounds the acoustic black hole cavity, forming a closed space.
[0009] Furthermore, the inner diameters of each thin plate are arranged sequentially according to a power function.
[0010] Furthermore, the inner diameters of the thin plates arranged sequentially according to a power function are:
[0011]
[0012] Where R is the inner diameter of the thinnest plate with the largest inner diameter. This refers to the inner diameter of the thinnest plate with the smallest inner diameter. The length of the cavity in an acoustic black hole; The axial distance from each position in the thin plate array to the outer end of the thin plate with the smallest inner diameter. Let be the power that the inner diameter of each thin plate in the thin plate array follows as a power function. .
[0013] Furthermore, the thin plate with the largest inner diameter is fixed to one end face where the acoustic black hole cavity and the side cavity coincide, and the circular hole at the center of the thin plate with the largest inner diameter serves as the noise incident end of the acoustic black hole structure.
[0014] Furthermore, the two end faces of the acoustic black hole cavity coincide with the two end faces of the side cavity, that is, the end face of the acoustic black hole cavity where the thinnest inner diameter plate is located coincides with the end face of the side cavity. The openings on the two end faces of the side cavity are equal in size to the outer edge of the two end faces of the acoustic black hole cavity and are fixed to form a closed space. Micro-perforations are provided on the surface of the acoustic black hole cavity shell between each thin plate.
[0015] Furthermore, the resonant frequency of the side cavity is estimated according to the following formula:
[0016]
[0017] Where c is the speed of sound, P is the micro-perforation rate (not exceeding 20%), t is the thickness of each thin plate, and L is the equivalent depth of the back cavity.
[0018] Furthermore, the thin plate with the largest inner diameter and the thin plate with the smallest inner diameter in the thin plate array serve as the two end faces of the acoustic black hole cavity, respectively; the thin plate with the largest inner diameter is fixed on the end face of the acoustic black hole cavity and the side cavity that coincide, and the circular hole in the center of the thin plate with the largest inner diameter serves as the noise incident end of the acoustic black hole structure; the edge dimension of the missing part of the end face of the side cavity is equal to the outer edge dimension of the end face of the acoustic black hole cavity where the thin plate with the largest inner diameter is located, and the other end face of the side cavity is located outside the thin plate with the smallest inner diameter, enclosing the acoustic black hole cavity and forming a closed space.
[0019] Furthermore, the surface of the acoustic black hole cavity shell between each of the thin plates is provided with micro-perforations.
[0020] Furthermore, the thin plate with the smallest inner diameter is provided with micro-perforations, which connect the acoustic black hole cavity and the side cavity.
[0021] Furthermore, a ring-shaped sound-absorbing material is filled between each adjacent thin plate; the material removed from the middle of each layer of sound-absorbing material is in the shape of a frustum or cylinder.
[0022] The beneficial effects of the acoustic black hole-type noise reduction structure and vibration damping device with embedded micro-perforated structure of this utility model are as follows:
[0023] The acoustic black hole combined noise reduction structure and vibration damping device with embedded micro-perforated structure of this utility model has the advantages of low cutoff frequency, wide effective frequency range, and stable and adjustable acoustic impedance characteristics compared with the prior art.
[0024] This invention relates to an acoustic black hole-integrated noise reduction structure and vibration damping device with an embedded micro-perforated structure. The structure combines an acoustic black hole with a micro-perforated side cavity. This combination, without altering the traditional acoustic black hole structure, utilizes the resonant cavity principle and the impedance effect of the micro-perforations to significantly increase the system's impedance along the sound wave propagation path, thereby improving the system's sound energy dissipation efficiency. Simultaneously, the acoustic black hole's sound wave focusing effect effectively concentrates mid- and high-frequency sound waves into the cavity between the annular thin plates, while the resonant cavity effect of the micro-perforated side cavity structure concentrates low-frequency sound waves. Through this combination, the acoustic black hole, sound-absorbing material, and the sound energy dissipation capability of the micro-perforations work together to achieve lower-frequency noise suppression and noise reduction across the entire frequency range (above 150Hz), with a sound absorption coefficient consistently above 0.9. This enhances the acoustic comfort in various environments, including aviation, thermal power, and nuclear power plants.
[0025] The acoustic black hole combined noise reduction structure and vibration damping device with embedded micro-perforated structure of this utility model is compact, simple, easy to use, and comes in various forms. It can improve the noise and sound energy dissipation efficiency of the system and has broad application prospects. Attached Figure Description
[0026] Figure 1This is a schematic diagram of an acoustic black hole structure based on existing technology;
[0027] Figure 2 This is a schematic diagram of the overall structure of Embodiment 1 of this utility model;
[0028] Figure 3 This is a schematic diagram of the side cavity shell structure of Embodiment 1 of this utility model;
[0029] Figure 4 This is a schematic diagram of the overall structure of Embodiment 2 of this utility model;
[0030] Figure 5 This is a cross-sectional view of the acoustic black hole cavity of Embodiment 1 of this utility model;
[0031] Figure 6 This is a schematic diagram of the thin plate array structure of Embodiment 1 of this utility model;
[0032] Figure 7 This is a schematic diagram of the acoustic black hole cavity (with micro-perforations) structure of Embodiment 1 of this utility model;
[0033] Figure 8 This is a schematic diagram of the relevant parameters of the inner diameter of the thin plate array in Embodiment 1 of this utility model;
[0034] Figure 9 This is a schematic diagram of the enclosed space composed of the acoustic black hole cavity shell (with micro-perforations) and the side cavity in Embodiment 1 of this utility model;
[0035] Figure 10 This is a schematic diagram of the overall structure of Embodiment 3 of this utility model;
[0036] Figure 11 This is a schematic diagram of the overall structure of Embodiment 4 of this utility model (with micro-perforations at the bottom);
[0037] Figure 12 for Figure 11 Bottom diagram;
[0038] Figure 13 This is a schematic diagram of the overall structure after filling with sound-absorbing material according to an embodiment of the present invention;
[0039] Figure 14 This is a graph showing the sound absorption characteristics of this invention.
[0040] The diagram is labeled as follows: 1-Acoustic black hole cavity, 11-Thin plate array, 111-Thin plate, 12-Acoustic black hole cavity shell, 2-Side cavity, 21-Side cavity shell, 3-Micro-perforation, 4-Acoustic material. Detailed Implementation
[0041] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings.
[0042] One embodiment of this utility model is an acoustic black hole-based noise reduction structure embedded with micro-perforations, such as... Figure 2 and Figure 3 As shown, the structure includes an acoustic black hole cavity 1, a side cavity 2, and a micro-perforation 3 connecting the acoustic black hole cavity 1 and the side cavity 2. The side cavity 2 is located outside the acoustic black hole cavity 1 and is enclosed by a side cavity shell 21, forming a closed space. The acoustic black hole cavity 1 can be cylindrical, cuboid, or similar in shape. Figure 4 As shown. The form of the side cavity shell 21 is not limited to rectangular, polyhedral, etc.
[0043] The acoustic black hole cavity 1 includes a thin plate array 11 and an acoustic black hole cavity shell 12.
[0044] like Figure 5 and Figure 6 As shown, the thin plate array 11 consists of several thin plates 111 with a central circular hole. Each thin plate 111 is fixed to the inner side of the acoustic black hole cavity shell 12. The thin plates 111 are arranged at equal intervals, with their centers coaxial, and their inner diameters follow a monotonically decreasing or increasing pattern, forming an acoustic black hole structure. Figure 7 As shown, it has a good focusing effect on the incoming sound waves. The thin plate 111 with the largest inner diameter is fixed on the end face of the acoustic black hole cavity 1 and the side cavity 2 that coincide, and the circular hole in the center of the thin plate 111 with the largest inner diameter serves as the noise incident end of the acoustic black hole structure.
[0045] The inner diameters of each thin plate 111 are arranged sequentially according to a power function, such as... Figure 6 and Figure 8 As shown. Taking the center of the thin plate 111 with the smallest inner diameter as the origin, and the direction from the center of the thin plate with the smallest inner diameter to the center of the thin plate with the largest inner diameter as the axial direction, the inner diameter of each thin plate 111 in the thin plate array 11 arranged according to the power function law can be expressed as:
[0046] (1)
[0047] Where R is the inner diameter of the thinnest plate with the largest inner diameter. This refers to the inner diameter of the thinnest plate with the smallest inner diameter. , that is, the length of the acoustic black hole cavity 1; The axial distance from each position in the thin plate array 11 to the outer end of the thin plate with the smallest inner diameter. The power that the inner diameter of each thin plate 111 in the thin plate array 11 varies according to a power function is given by. .
[0048] Preferably, in another embodiment, such as Figure 9As shown, the two end faces of the acoustic black hole cavity 1 coincide with the two end faces of the side cavity 2, that is, the end face of the acoustic black hole cavity 1 containing the thinnest inner diameter plate 111 coincides with the end face of the side cavity 2. The openings on the two end faces of the side cavity 2 are equal in size to the outer edges of the two end faces of the acoustic black hole cavity 1 and are fixed to form a closed side cavity. Micro-perforations 3 are provided on the surface of the acoustic black hole cavity shell 12 between each of the thin plates 111.
[0049] like Figure 1 , Figure 5 and Figure 9 As shown, micro-perforations 3 are provided on the surface of the acoustic black hole cavity shell 12 between each thin plate 111. The closed side cavity 2 is connected to the acoustic black hole cavity 1 through the micro-perforations 3, allowing the sound waves gathered by the acoustic black hole structure to enter the side cavity 2 through the micro-perforations 3. At the same time, the micro-perforations 3 dissipate the sound wave energy through friction, and the closed side cavity 2 forms acoustic resonance. The side cavity 2 and the micro-perforations 3 on the surface of the acoustic black hole cavity shell 12 work together to further intensify the friction between the sound waves and the hole wall in the micro-perforations 3, thereby ensuring the suppression effect on noise in the entire frequency band above 150Hz, as well as the noise reduction effect on environmental noise in theaters, offices, car cabs, ship working cabins, cockpits, etc.
[0050] The core function of the micro-perforations 3 is to achieve acoustic control (such as sound absorption and noise reduction), fluid filtration, and heat exchange through tiny pores. Their performance is mainly related to parameters such as pore size (diameter or equivalent size), distribution density, and thickness. The micro-perforations 3 can be created using microfabrication techniques such as laser drilling, photolithography, and etching to achieve a tiny pore structure; they can be circular or non-circular. The pore size of the micro-perforations 3 needs to be determined based on actual noise reduction requirements. Smaller pore sizes result in greater frictional resistance between air and the pore wall, a wider sound absorption band, but reduced air permeability. Preferably, the pore size of the micro-perforations 3 is 0.1 mm to 1 mm.
[0051] Preferably, on the surface of the acoustic black hole cavity shell 12 between each thin plate 111, the ratio of the sum of the areas of the micro-perforations to the surface area of the acoustic black hole cavity shell 12 is defined as the micro-perforation opening ratio, which should not exceed 20%. Too low a perforation ratio will restrict air vibration, while too high a ratio will reduce the resonance effect. In practical applications, the micro-perforation opening ratio needs to be adapted to the side cavity 2 to ensure the resonance frequency of the side cavity 2. The resonance frequency of the side cavity 2 can be estimated according to the following formula:
[0052] (2)
[0053] Where c is the velocity of sound, P is the perforation rate of the micro-perforation, t is the thickness of each thin plate 111, the magnitude of t affects the acoustic length of the neck (i.e., perforation) connecting the acoustic black hole and the side cavity, thus affecting the local acoustic impedance; L is the equivalent depth of the side cavity, approximately the total volume V of the side cavity. 侧腔 / and the area S of the perforated region开孔侧面面积 The ratio, that is:
[0054] L=V 侧腔 / S 开孔侧面面积 (3)
[0055] The inner diameter of the thinnest plate with the smallest inner diameter Not limited to Preferably, in another embodiment, the thin plate with the largest inner diameter and the thin plate with the smallest inner diameter in the thin plate array 11 serve as the two end faces of the acoustic black hole cavity 1, respectively; the thin plate with the largest inner diameter is fixed to the end face where the acoustic black hole cavity and the side cavity coincide, and the circular hole in the center of the thin plate with the largest inner diameter serves as the noise incident end of the acoustic black hole structure; the edge dimension of the missing part of the end face of the side cavity 2 is equal to the outer edge dimension of the end face of the acoustic black hole cavity 1 where the thin plate with the largest inner diameter in the thin plate array 11 is located, and the other end face of the side cavity 2 is located outside the thin plate with the smallest inner diameter in the thin plate array 11. The side cavity shell 21 encloses the acoustic black hole cavity 1, forming a closed side cavity 2, as shown. Figure 10 , Figure 11 , Figure 12 As shown, the resonant frequency of side cavity 2 can be estimated according to Equation 2. Figure 9 As shown, micro-perforations 3 are provided on the surface of the acoustic black hole cavity shell 12, connecting the acoustic black hole cavity 1 and the side cavity 2; as Figure 11 and Figure 12 As shown, a micro-perforation 3 is provided on the thin plate with the smallest inner diameter, connecting the acoustic black hole cavity 1 and the side cavity 2. The resonant frequency of the side cavity 2 can be estimated according to Equation 2.
[0056] Preferably, in another embodiment, such as Figure 13 As shown, sound-absorbing material 4, such as sound-absorbing cotton, is filled between each thin plate 111. The sound-absorbing material 4 embedded between adjacent thin plates is in a ring shape. The material removed from the middle of each layer of sound-absorbing material 4 is either frustum-shaped (the inner diameter of the two end faces of the sound-absorbing material 4 after filling between adjacent thin plates 111 is consistent with the inner diameter of the contacting thin plate 111) or cylindrical. That is, the sound-absorbing material 4 fills the cavity formed by adjacent thin plates 111 in the acoustic black hole structure to improve the dissipation effect of this invention on the sound waves gathered by the acoustic black hole. The sound-absorbing material 4 includes, but is not limited to, inorganic fibers, organic fibers, inorganic foam, and other materials.
[0057] Each thin plate 111, the acoustic black hole cavity shell 12, the micro-perforation 3 and the side cavity shell 21 in the thin plate array 11 can be integrally formed by 3D printing.
[0058] like Figure 14As shown, in simulation tests, this invention significantly improves sound absorption performance compared to traditional acoustic black holes. Simulation results show that, using an absorption coefficient of 0.9 as a benchmark, the initial effective frequency of this invention is around 150Hz, while the initial effective frequency of traditional acoustic black hole structures is around 900Hz, representing an improvement of nearly 750Hz. Furthermore, the numerical simulation results also demonstrate that this invention can suppress noise across the entire frequency band above 150Hz, and maintains absorption coefficients above 0.9 for low-frequency, mid-frequency, and high-frequency noise, far surpassing the sound absorption and noise reduction effects of traditional acoustic black hole structures.
[0059] The acoustic black hole combined noise reduction structure and vibration damping device with embedded micro-perforated structure of this utility model has the advantages of low cutoff frequency, wide effective frequency range, and stable and adjustable acoustic impedance characteristics compared with the prior art.
[0060] This invention relates to an acoustic black hole-integrated noise reduction structure and vibration damping device with an embedded micro-perforated structure. The structure combines an acoustic black hole with a micro-perforated side cavity. This combination, without altering the traditional acoustic black hole structure, utilizes the resonant cavity principle and the impedance effect of the micro-perforations to significantly increase the system's impedance along the sound wave propagation path, thereby improving the system's sound energy dissipation efficiency. Simultaneously, the acoustic black hole's sound wave focusing effect effectively concentrates mid- and high-frequency sound waves into the cavity between the annular thin plates, while the resonant cavity effect of the micro-perforated side cavity structure concentrates low-frequency sound waves. Through this combination, the acoustic black hole, sound-absorbing material, and the sound energy dissipation capability of the micro-perforations work together to achieve lower-frequency noise suppression and noise reduction across the entire frequency range (above 150Hz), with a sound absorption coefficient consistently above 0.9. This enhances the acoustic comfort in various environments, including aviation, thermal power, and nuclear power plants.
[0061] This utility model presents an acoustic black hole combined noise reduction structure and vibration damping device with embedded micro-perforated structure. It is compact, simple, easy to use, and available in various forms. It can improve the noise energy dissipation efficiency of the system, and has significant sound absorption and noise reduction effects. It has outstanding low-frequency noise reduction and wide-band noise reduction performance and has broad application prospects.
[0062] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An acoustic black hole-based noise reduction structure with embedded micro-perforated structure, characterized in that, It includes an acoustic black hole cavity, a side cavity, and a micro-perforation connecting the acoustic black hole cavity and the side cavity; The acoustic black hole cavity includes a thin plate array and an acoustic black hole cavity shell; the thin plate array consists of several thin plates with a circular hole in the center, each thin plate is fixed to the inner side of the acoustic black hole cavity shell, the thin plates are arranged at equal distances, the centers are coaxial, and the inner diameters are arranged in a monotonically decreasing or increasing pattern to form an acoustic black hole structure. The side cavity is located outside the acoustic black hole cavity and surrounds the acoustic black hole cavity, forming a closed space.
2. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 1, characterized in that, The inner diameters of the thin plates are arranged sequentially according to a power function.
3. The acoustic black hole combined noise reduction structure with embedded microperforated structure according to claim 2, characterized in that, The inner diameters of the thin plates arranged in a power function pattern are: Where R is the inner diameter of the thinnest plate with the largest inner diameter. This refers to the inner diameter of the thinnest plate with the smallest inner diameter. The length of the cavity in an acoustic black hole; The axial distance from each position in the thin plate array to the outer end of the thin plate with the smallest inner diameter. Let be the power that the inner diameter of each thin plate in the thin plate array follows as a power function. .
4. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 1, characterized in that, The thin plate with the largest inner diameter is fixed to one end face where the acoustic black hole cavity and the side cavity coincide, and the circular hole in the center of the thin plate with the largest inner diameter serves as the noise incident end of the acoustic black hole structure.
5. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 1, characterized in that, The two end faces of the acoustic black hole cavity coincide with the two end faces of the side cavity, that is, the end face of the acoustic black hole cavity where the thinnest inner diameter plate is located coincides with the end face of the side cavity. The openings on the two end faces of the side cavity are equal in size to the outer edge of the two end faces of the acoustic black hole cavity and are fixed to form a closed space. Micro-perforations are provided on the surface of the acoustic black hole cavity shell between each thin plate.
6. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 1, characterized in that, The resonant frequency of the side cavity is estimated according to the following formula: Where c is the speed of sound, P is the micro-perforation rate (not exceeding 20%), t is the thickness of each thin plate, and L is the equivalent depth of the back cavity.
7. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 1, characterized in that, The thin plate with the largest inner diameter and the thin plate with the smallest inner diameter in the thin plate array serve as the two end faces of the acoustic black hole cavity, respectively. The thin plate with the largest inner diameter is fixed on the end face of the acoustic black hole cavity and the side cavity that coincide. The circular hole in the center of the thin plate with the largest inner diameter serves as the noise incident end of the acoustic black hole structure. The edge dimension of the missing part of the end face of the side cavity is equal to the outer edge dimension of the end face of the acoustic black hole cavity where the thin plate with the largest inner diameter is located. The other end face of the side cavity is located outside the thin plate with the smallest inner diameter, enclosing the acoustic black hole cavity and forming a closed space.
8. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 7, characterized in that, The surface of the acoustic black hole cavity shell between each of the thin plates is provided with micro-perforations.
9. The acoustic black hole combined noise reduction structure with embedded micro-perforated structure according to claim 8, characterized in that, The thinnest plate with the smallest inner diameter is provided with micro-perforations, which connect the acoustic black hole cavity and the side cavity.
10. The acoustic black hole combined noise reduction structure with embedded microperforated structure according to any one of claims 1-9, characterized in that, The space between adjacent thin plates is filled with ring-shaped sound-absorbing material; the material removed between each layer of sound-absorbing material is in the shape of a frustum or cylinder.