Composite multi-cell sound absorption structure
Technical Field
The utility model relates to the technical field of sound absorption and noise reduction, in particular to a composite multi-cell sound absorption structure.
Background
The acoustic material is generally of a two-phase heterogeneous porous structure and is widely applied to the engineering fields of aerospace, ships and warships, railway traffic, construction, vehicles and the like. Plays an extremely important role in controlling noise level, adjusting reverberation time, improving listening conditions, and improving speech intelligibility. The micro-perforation plate structure consists of a plurality of thin plates with micropore diameters smaller than 1mm and a back cavity air layer with a certain depth, and is equivalent to a plurality of Helmholtz resonators connected in parallel. When the incident sound wave is transmitted to the micropores in the plate, the energy of the sound wave is attenuated through the damping and friction effects of the aperture walls, and meanwhile, the air in the micropores can resonate with the air cavity, so that the sound energy is further lost, and the purpose of noise reduction is achieved. However, the single-layer micro-perforated plate structure has the limitation that the sound absorption frequency band is mainly concentrated near the resonance sound absorption peak, so that the sound absorption and noise reduction of the full frequency band cannot be realized, and the engineering application of the actual complex noise environment is difficult to meet. Meanwhile, the sound absorption frequency band is widened by increasing the thickness, the volume weight and the air layer, and the like of the porous material, so that the sound absorption frequency band is often limited by the space volume, and the practical application difficulty is further increased. Therefore, the utility model provides the sound absorption structure which can effectively widen the sound absorption frequency band of the microperforated panel and is convenient for practical application.
Disclosure of Invention
In order to improve the sound absorption coefficient of the micro-perforated plate structure and widen the frequency range of sound absorption and noise reduction, the utility model provides a composite multi-cell sound absorption structure, wherein sound absorption units of a micro-perforated plate-air layer and sound absorption units of a porous sound absorption material-air layer are distributed in a chessboard type in parallel, and the sound absorption units are separated by rigid plates, so that the sound absorption and noise reduction effects of the sound absorption structure in different frequency sections are realized, the sound absorption frequency band of the traditional micro-perforated plate is remarkably widened, and meanwhile, the composite multi-cell sound absorption structure meets the aims of convenience in installation, light weight and high design freedom degree, and further realizes the application of the micro-perforated plate in practical engineering.
The technical scheme adopted by the utility model is as follows:
a composite multi-cell sound absorption structure comprises a micro-perforated plate, a porous sound absorption material, a rigid partition plate and a bottom square table; the micro-perforated plates and the porous sound absorbing materials are alternately arranged in a checkerboard shape, the bottom square tables are opposite to the micro-perforated plates and the porous sound absorbing materials and are respectively and correspondingly arranged, the micro-perforated plates, the porous sound absorbing materials and the bottom square tables are connected into a whole through the rigid partition plates, each micro-perforated plate, the corresponding bottom square table and the airtight air layer inner cavity formed between the micro-perforated plate and the porous sound absorbing materials form a first sound absorbing unit, and each porous sound absorbing material, the corresponding bottom square table and the airtight air layer inner cavity formed between the porous sound absorbing materials and the corresponding bottom square table form a second sound absorbing unit.
In the above-mentioned scheme, further, the structure contains an even number of sound absorbing units altogether.
Further, each sound absorption unit is uniformly distributed, and the incidence areas of sound waves are the same.
Further, the microperforated panel is coplanar with the surface of the porous sound absorbing material, and the position of the bottom square table in each sound absorbing unit determines the depth of the air layer in the sound absorbing unit.
Further, the perforated holes of the microperforated panel are straight-through round holes, the pore sizes are consistent, the perforated holes are arranged in a regular array, and the perforated holes are uniformly distributed.
Further, the porous sound absorbing material is a porous sound absorbing material plate.
Further, the perforation rates and perforation intervals of the microperforations corresponding to all the first sound absorption units are not completely consistent.
Further, the depth of the corresponding air layer in each sound absorption unit is not completely uniform.
The beneficial effects of the utility model are as follows:
according to the composite multi-cell sound absorption structure, the micro-perforated plate-air layer sound absorption units and the porous sound absorption material-air layer sound absorption units are connected in parallel, so that a multi-cavity coupling sound absorber capable of continuously absorbing sound in a wide frequency band can be obtained; the number of the sound absorption units increases with even times, so that the sound absorption frequency band of the sound absorber can be further widened, and the sound absorption performance is more excellent. The structure uses the rigid plates to separate the sound absorption units, which is helpful for enhancing the mechanical property of the sound absorption structure. In addition, the structural design has high freedom, and in the practical engineering application process, the high-efficiency noise reduction requirements can be realized for noise in different frequency bands by changing the number, the arrangement and the combination modes of the sound absorption units. The structure of the utility model can realize the light thin layer design of the sound absorption structure, and the total thickness is not more than 50mm, thereby reducing the space volume limitation in the installation and use processes.
Drawings
FIG. 1 is a schematic illustration of a 2X 1 composite multicellular sound absorbing structure of the present utility model;
FIG. 2 is a schematic illustration of a 2X 2 composite multicellular sound absorbing structure of the present utility model;
FIG. 3 is a schematic illustration of a 2X 3 composite multicellular sound absorbing structure of the utility model;
FIG. 4 is a schematic view of a "microperforated panel-air layer" in accordance with the present utility model;
FIG. 5 is a schematic view of a "porous sound absorbing material-air layer" in the present utility model;
fig. 6 is a graph showing sound absorption characteristics obtained by theoretical calculation in the present utility model.
Detailed Description
The technical scheme of the utility model is further described in detail below with reference to the attached drawings and specific examples;
the utility model relates to a composite multi-cell sound absorption structure which comprises a micro-perforated plate 1, a porous sound absorption material 2, a rigid partition plate 3 and a bottom square table 7; the micro-perforated plates 1 and the porous sound absorbing materials 2 are alternately arranged in a checkerboard shape, bottom square tables 7 are arranged opposite to the micro-perforated plates 1 and the porous sound absorbing materials 2 respectively and correspondingly, and the micro-perforated plates 1, the porous sound absorbing materials 2 and the bottom square tables 7 are connected into a whole through the rigid partition plates 3.
Each microperforated panel 1, the corresponding bottom square table 7 and the inner cavity of the airtight air layer 4 formed between the two form a first sound absorption unit 5, namely a microperforated panel-air layer sound absorption unit; each porous sound-absorbing material 2, its corresponding bottom square table 7 and the closed air layer 4 formed between them constitute a second sound-absorbing unit 6, namely a "porous sound-absorbing material-air layer" sound-absorbing unit. The two sound absorption units are alternately arranged in parallel in a checkerboard shape, and the number of the parallel sound absorption units can be designed according to noise of different frequency bands. But the sound absorption units are uniformly distributed, and the incidence areas of sound waves are the same.
As shown in fig. 1,2 and 3, for several embodiments of the present utility model, the internal rigid partition plate separates the sound absorbing structure into square sound absorbing structure units with identical sizes of 2×1,2×2 and 2×3, and the corresponding square sound absorbing structure units are respectively embedded with the micro-perforated plate and the porous sound absorbing material, so that different air layer depths are adjusted by the positions of the bottom square table for noise in different frequency bands. And then the rigid partition board is connected with the microperforated panel, the porous sound absorbing material and the bottom square table through colloid to form the sound absorbing structure formed by the sound absorbing units.
According to one embodiment of the utility model, the micropores on the panel of the microperforated panel are uniformly arranged in a square shape, the diameter of the micropores is less than 1mm, the pore spacing of each microperforated panel is inconsistent, the penetration rate is 1% -10%, and the thickness of the panel is 1mm.
According to one embodiment of the utility model, the porous sound absorbing material is a felt type material, wherein the flow resistance is 23099 N.s/m 4 The thickness is 10mm and the thickness is uniform. The porous sound absorbing material may be any porous acoustic material, such as fiber cotton, rubber-plastic cotton, sound absorbing cotton, foam, etc.
According to one embodiment of the utility model, the rigid partition plates are formed by splicing square plates, and the thickness of each rigid partition plate is 1mm.
According to one embodiment of the utility model, the microperforated panel, the internal rigid barrier may be a wooden panel, an aluminum panel or obtained by a viable process such as additive manufacturing techniques, i.e., 3D printing techniques.
According to one embodiment of the present utility model, the air layer depth of each sound absorption unit (resonant cavity) is not exactly the same, and the depth is 10mm to 30mm. The micro-perforated plates of the sound absorption units are coplanar with the outer surface of the porous sound absorption material, and the depth of the air layer depends on the cooperation of the bottom square table, so that the heights of the bottom square tables in the cavities are not completely consistent.
The sound absorption performance of the structure can be predicted through theoretical calculation and numerical simulation software, firstly, the acoustic impedance of the microperforated panel and the acoustic impedance of the porous sound absorption material are calculated respectively by utilizing the Maa's theory and the Delay-Bazley D-B model, then, the acoustic impedance of each sound absorption unit is calculated by utilizing a transmission matrix method, and finally, the acoustic impedance of the whole composite multicellular sound absorption structure and the sound absorption coefficients corresponding to the acoustic impedance at different frequencies are calculated by utilizing an equivalent circuit diagram method. In the sound absorption structure of the above-listed 2×1,2×2,2×3 sound absorption units connected in parallel, the "microperforated panel-air layer" sound absorption unit includes a microperforated panel and an air cavity at the back, as shown in fig. 4, the micropores of the microperforated panel are circular through holes, the diameters of the holes are 0.6mm, the thickness of the panel is 1mm, the perforation rate and the depth of the air layer are not completely consistent, and in the sound absorption unit listed in the present design, the perforation rate and the depth parameters of the air layer of the microperforated panel are shown in table 1, table 2 and table 3:
TABLE 1
TABLE 2
TABLE 3 Table 3
The "porous sound absorbing material-air layer" sound absorbing unit contains a porous sound absorbing material having a thickness of 10mm and an air layer having a depth of 10mm as shown in fig. 5. The rigid partition plate is formed by splicing square plates, and the plate thickness is 1mm.
Each sound absorption unit is provided with a bottom square table so as to freely adjust the depth of an air layer. The height of the bottom square table changes along with the depth change of the air layer, and the height is 0mm-20mm.
Referring to fig. 6, the sound absorption effect curve of the structure is remarkably widened compared with the traditional microperforated panel structure and the single-layer porous sound absorption material, wherein the sound absorption coefficient obviously shifts to the middle-low frequency section along with the increase of the number of unit sound absorption cavities along with the even multiple.
The structure of the utility model can aim at the noise in different frequency sections in practical application, and can obtain high-efficiency continuous noise absorption and control in a target frequency section by adjusting various parameters of the sound absorption unit, such as the thickness, the perforation rate and the perforation gap of the micro-perforated plate, the type of porous sound absorption material, the depth of an air layer and the number of the sound absorption units.
The description of the embodiments of the present utility model is merely an enumeration of possible forms of implementation for the inventive concept, and the scope of protection of the present utility model should not be construed as limited to the implementation of the specific forms set forth, as well as equivalent technical means conceivable by a person skilled in the art according to the inventive concept.