CN112509545B

CN112509545B - Multilayer nested formula low frequency broadband sound absorbing device based on resonance sound absorption

Info

Publication number: CN112509545B
Application number: CN202011480540.6A
Authority: CN
Inventors: 朱俊喆; 瞿叶高; 孟光
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2022-07-12
Anticipated expiration: 2040-12-16
Also published as: CN112509545A

Abstract

A multilayer nested formula low frequency broadband sound absorbing device based on resonance sound absorption includes: a plurality of sequentially nested resonator elements, each resonator element comprising: bottom plate, casing, baffle and neck nozzle stub, wherein: the baffle and the bottom plate are respectively arranged at two ends of the shell, the neck short pipe penetrates through the center of the baffle, multi-stage resonance is realized through mutual coupling between the resonator units of different stages, and then the absorption frequency band is widened. The invention widens the absorption frequency band based on the multi-order resonance principle, and improves the adjustability of the sound absorption coefficient and the absorption peak frequency. Compared with the existing structure, the invention has small volume, light weight, broadband sound absorption performance in a low frequency range, and good application prospect and industrial value.

Description

Multilayer nested formula low frequency broadband sound absorbing device based on resonance sound absorption

Technical Field

The invention relates to the technology in the field of noise processing, in particular to a multilayer nested low-frequency broadband sound absorption device based on resonance sound absorption.

Background

Most of the existing porous sound absorption materials adopt melamine and asbestos, but the sound absorption effect of the materials on low-frequency-band noise is poor. In the Helmholtz resonator composed of the small holes and the cavity, the vibration amplitude of air around the small holes is maximum near the resonance frequency of the Helmholtz resonator, and the dissipation of sound energy is maximum due to the viscous effect, so that the Helmholtz resonator generates a good sound absorption effect near the resonance frequency of the Helmholtz resonator, but the application range is limited due to the narrow absorption frequency band. In the seventies of the last century, a micro-perforated resonance sound absorption structure proposed by massachusetts 29495 generates a broadband sound absorption phenomenon near the resonance frequency of the structure, but for low-frequency sound absorption, the diameter of a micropore needs to be reduced, the volume of a back cavity needs to be increased, so that the production cost is increased, the structure volume is enlarged, and the mass production is not facilitated.

The development of the acoustic metamaterial provides a new direction for the design of the low-frequency sound absorption structure. The size of the structural unit of the acoustic metamaterial is far smaller than the wavelength, and the noise in a low-frequency range is absorbed through a periodic/aperiodic geometrical structure. However, most of the acoustic metamaterials have a plurality of groups of structural units, and the sound absorption frequency band is widened by using the multi-order resonance principle, so that complex coupling effect is often generated between the units, and the loss of sound absorption efficiency is caused. Therefore, there is still a great need in engineering for a product that has a broadband sound absorption effect on low-frequency noise, and is simple in structure, small in size, light in weight, low in cost, and convenient for mass production.

Disclosure of Invention

Aiming at the defects that the prior art is difficult to absorb sound in a low frequency range in a broadband manner, a low-frequency sound absorption structure is large in size, poor in absorption effect and narrow in absorption frequency band, the invention provides the multilayer nested low-frequency broadband sound absorption device based on resonance sound absorption, the absorption frequency band is widened based on a multi-order resonance principle, and the adjustability of the sound absorption coefficient and the absorption peak frequency is improved. Compared with the existing structure, the invention has small volume, light weight, broadband sound absorption performance in a low frequency range, and good application prospect and industrial value.

The invention is realized by the following technical scheme:

the invention relates to a multilayer nested low-frequency broadband sound absorption device based on resonance sound absorption, which comprises: a plurality of sequentially nested resonator elements, each resonator element comprising: bottom plate, casing, baffle and neck nozzle stub, wherein: the baffle and the bottom plate are respectively arranged at two ends of the shell, the neck short pipe penetrates through the center of the baffle, multi-stage resonance is realized through mutual coupling between the resonator units of different stages, and then the absorption frequency band is widened.

The multilayer nested low-frequency broadband sound absorption device is preferably of a central symmetrical structure.

The number of the resonator units can be designed and increased according to the absorbed target frequency band.

The outer diameter and the height of the shell of each resonator unit are sequentially increased so as to achieve the purpose of mutual nesting.

In the multilayer nested low-frequency broadband sound absorption device, the absorption peak frequency of a single unit is as follows:

wherein: s represents the neck cross-sectional area, V represents the shell cavity volume, and l represents the neck corrected length.

The shape of the bottom plate adopts but is not limited to a circle, a square or other geometric shapes.

The cross section of the shell is in a shape of, but not limited to, a circle, a square or other geometric shapes, and the cross section of the bottom surface of the shell is matched with the shape of the bottom plate.

The neck collar nozzle is in a shape of, but not limited to, a circle, a square, an ellipse or other geometric shapes.

The neck short pipes of each resonator unit are not in contact with each other, the cross-sectional area of each neck short pipe is gradually increased from inside to outside, and the centers of all the neck short pipes are positioned on the same straight line.

The mutual coupling means that: the neck short pipes of two adjacent resonator units are mutually overlapped in height, namely a part of neck short pipes are positioned in the shell below the partition plate, and a part of neck short pipes are positioned outside the shell above the partition plate, so that the space is fully utilized, and the purpose of mutual coupling is achieved.

Technical effects

The invention integrally solves the problems that the traditional sound absorption material and structure have unobvious inhibition on low-frequency noise, narrow absorption frequency band in a low-frequency range and large volume of a device for absorbing the low-frequency noise. The continuous and efficient sound absorption characteristic is shown in a low-frequency range through the multilayer nested sound absorption structure by utilizing the sound absorption mechanism of the Helmholtz resonator.

Compared with the prior art, the invention changes the sound absorption coefficient and the absorption peak frequency by changing the length of the neck short pipe, the cross section area of the neck short pipe, the depth of the neck short pipe inserted into the partition plate, the height of the shell and the cross section area of the bottom surface of the shell, thereby greatly improving the adjustability of the sound absorption coefficient and the absorption peak frequency and further being capable of designing the required absorption frequency band more conveniently. The novel multilayer nested low-frequency broadband sound absorption structure designed by the scheme can continuously increase the number of the shell and the partition plates under the condition of not changing the internal dimension so as to form more resonators coupled with each other and generate more absorption peak values, thereby further widening the sound absorption frequency band of the structure. Based on the resonance sound absorption principle, the coupling effect between the resonators is reasonably utilized, the sound absorption effect of each resonator is improved, the sound absorption frequency band is widened by utilizing the multi-stage resonance phenomenon, and the purpose of sound absorption of a low-frequency broadband is achieved.

Drawings

FIG. 1 is a half sectional view of the present invention;

FIG. 2 is a perspective view of the present invention;

FIG. 3 is a full sectional view of the present invention;

FIG. 4 is a top view of the present invention;

FIG. 5 is a schematic illustration of an embodiment and sound absorption coefficients of the various cells;

FIG. 6 is a schematic diagram of theoretical and experimental sound absorption coefficients according to one embodiment.

In the figure: the device comprises a bottom plate 1, a first shell 2, a second shell 3, a third shell 4, a fourth shell 5, a first partition plate 6, a second partition plate 7, a third partition plate 8, a fourth partition plate 9, a first neck short pipe 10, a second neck short pipe 11, a third neck short pipe 12 and a fourth neck short pipe 13.

Detailed Description

As shown in fig. 1 to fig. 6, the present embodiment relates to a multilayer nested low-frequency broadband sound absorbing structure, which adopts, but is not limited to, a four-layer nested structure, taking a four-layer structure as an example, including: four resonator units nested in turn, specifically: bottom plate 1, first casing 2, second casing 3, third casing 4, fourth casing 5, first baffle 6, second baffle 7, third baffle 8, fourth baffle 9, first neck nozzle stub 10, second neck nozzle stub 11, third neck nozzle stub 12 and fourth neck nozzle stub 13, wherein: the bottom plate is provided with a shell with the inner diameter and the height sequentially increasing from inside to outside, and the upper end of the shell is sealed by a partition plate provided with a neck short pipe.

The centers of the bottom plate, the shell, the partition plate and the neck short pipe are on the same straight line, and the structure is a symmetrical structure.

The adjacent neck short pipes are provided with overlapped parts, and the cross sections of the neck short pipes are gradually increased and are not in contact with each other.

As shown in fig. 1-4, in the embodiment, four resonators coupled with each other are coupled with each other, so that each resonator achieves the best sound absorption effect. The sound absorption coefficient and the absorption peak frequency of the multilayer nested low-frequency broadband sound absorption structure are related to the length of the neck short pipe, the cross section area of the neck short pipe, the height of the shell, the cross section area of the shell and the depth of the neck short pipe inserted into the partition plate. The method specifically comprises the following steps: the longer the neck short tube is, the lower the absorption peak frequency is; the larger the pipe diameter of the neck short pipe is, the larger the cross-sectional area of the pipe orifice is, and the higher the absorption peak frequency is; the higher the height of the shell and the larger the bottom area of the shell, the larger the volume of the cavity enclosed by the shell and the lower the absorption peak frequency. The depth of the neck stub inserted into the baffle is used to adjust the coupling effect between adjacent resonators. In practical application, a user can adjust the length of the neck short pipe, the cross section area of the neck short pipe, the depth of the neck short pipe inserted into the partition plate, the height of the shell and the cross section area of the bottom surface of the shell according to own requirements to change the sound absorption coefficient and the absorption peak frequency, and can also continue to increase the number of the shells so as to increase the absorption peak value and widen the absorption frequency band.

The material of the multilayer nested formula low frequency broadband sound absorbing structure of this embodiment is selected to be the steel, and the bottom plate is the cylinder, and all casings are the cylinder, and neck nozzle stub shape is circular, and first neck nozzle stub 10, second neck nozzle stub 11, third neck nozzle stub 12, fourth neck nozzle stub 13 pipe diameter are 3mm, 7mm, 11mm, 15mm in proper order, and first casing 2, second casing 3, third casing 4, the 5 internal diameters of fourth casing are 20mm in proper order, 32mm, 44mm, 58 mm. The total height of this embodiment is 74mm and the total diameter of the bottom surface is 58 mm.

As shown in fig. 5, which is the sound absorption coefficient of the multilayer nested low-frequency broadband sound absorption structure of the present embodiment, as can be seen from fig. 5, the structure has four sound absorption peaks, where four peak frequencies are the resonant frequencies under the coupling action of four resonators, and the sound absorption performance of each resonator is optimized through the coupling action of four resonators. As can be seen from fig. 5, the multi-layered nested low frequency broadband sound absorbing structure exhibits continuous broadband sound absorbing performance in the low frequency range. It should be noted that if the number of the shell, the partition, and the neck short tubes is increased, more resonators can be formed, and more absorption peaks can be realized, so that the absorption band can be further widened.

Through concrete actual experiment, carry out the acoustic absorption coefficient measurement of sample in the impedance tube, because the experimental space restriction, design total height 71mm, the nested sound absorption structure of three-layer of bottom surface diameter 60mm, the experimental data that can obtain are: as shown in FIG. 6, the experimental absorption peak value of the structure is consistent with theory, the sound absorption coefficient is more than 0.5 in the range of 260 Hz-412 Hz, and the broadband and efficient sound absorption effect is achieved.

Compared with the prior art, the device improves the sound absorption effect of each absorption unit through the mutual coupling effect, so that a higher sound absorption coefficient is kept in a wider frequency band. According to the characteristic, the number of the series units can be continuously nested, so that the absorption frequency band is further widened. Compared with the parallel arrangement of the units, the serial nesting mode saves more space, and has the excellent characteristics of compact structure and small volume in the aspect of low-frequency noise reduction.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A multilayer nested formula low frequency broadband sound absorbing device based on resonance sound absorption, its characterized in that includes: a plurality of sequentially nested resonator elements, each resonator element comprising: bottom plate, casing, baffle and neck nozzle stub, wherein: the partition plate and the bottom plate are respectively arranged at two ends of the shell, the neck short pipes penetrate through the center of the partition plate, the neck short pipes of each resonator unit are not in contact with each other, the cross sectional area of each neck short pipe is gradually increased from inside to outside, the centers of all the neck short pipes are positioned on the same straight line, multi-stage resonance is realized through mutual coupling of the resonator units at different stages, and the absorption frequency band is widened;

the mutual coupling refers to that: the neck short pipes of two adjacent resonator units are mutually overlapped in height, namely a part of neck short pipes are positioned in the shell below the partition plate, and a part of neck short pipes are positioned outside the shell above the partition plate, so that the space is fully utilized, and the purpose of mutual coupling is achieved.

2. The resonant sound absorption based multi-layer nested low frequency broadband sound absorber of claim 1 wherein the multi-layer nested low frequency broadband sound absorber is preferably a centrosymmetric structure.

3. The multilayer nested low frequency broadband sound absorbing device based on resonant sound absorption according to claim 1, wherein the outer diameter and height of the housing of each resonator unit are sequentially increased for the purpose of nesting with each other.

4. The multilayer nested low-frequency broadband sound absorption device based on resonance sound absorption as claimed in any one of claims 1 to 3, wherein the absorption peak frequency of a single unit in the multilayer nested low-frequency broadband sound absorption device is

Wherein: s represents the neck spool cross-sectional area, V represents the shell cavity volume, and l represents the neck spool corrected length.

5. The multilayer nested low-frequency broadband sound absorbing device based on resonance sound absorption as claimed in claim 1, wherein the cross-sectional shape of the shell is circular or square, and the cross-sectional shape of the bottom surface of the shell is matched with the shape of the bottom plate.

6. The multilayer nested low frequency broadband sound absorbing device based on resonant sound absorption according to claim 1 wherein the neck pipe orifice is circular, square or oval in shape.