CN113539223A

CN113539223A - Helmholtz sound absorption device

Info

Publication number: CN113539223A
Application number: CN202110781384.5A
Authority: CN
Inventors: 杜敬涛; 郭凡浩; 贾康; 刘杨
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2021-07-11
Filing date: 2021-07-11
Publication date: 2021-10-22
Anticipated expiration: 2041-07-11
Also published as: CN113539223B

Abstract

The invention provides a Helmholtz sound absorption device, which comprises a neck pipe, a resonant cavity and a sound absorption cavity, wherein the neck pipe is communicated with the resonant cavity through a resonant cavity communication hole; the inner wall of the sound absorption cavity provided with the sound absorption cavity communicating hole is a first inner wall, and a spiral structure is arranged on the first inner wall; a track in a spiral line shape is arranged on the first inner wall, and a curved surface formed by extending from the track along a direction vertical to the first inner wall is in a spiral structure; and the initial opening of the spiral line is communicated with the sound absorption cavity communication hole. The Helmholtz sound absorption device can expand the frequency range of sound absorption waves and is widely applied to the field of noise control.

Description

Helmholtz sound absorption device

Technical Field

The invention belongs to the technical field of vibration noise control, and relates to a vibration noise control device.

Background

The modern industry and the transportation industry are developed vigorously, and the noise problem of the closed space is highlighted increasingly. Noise in closed spaces such as pipelines, ship cabins and automobile interiors can cause sound fatigue of related mechanical equipment, worsen working environment and reduce working efficiency of personnel. In order to solve the problem of noise generation, techniques for controlling and eliminating noise have been developed.

Noise control techniques are mainly classified into two types, active control and passive control. Among other things, the introduction of electronics in an active control system can make the system complex, expensive, and in some cases even subject to stability and reliability issues. Passive control techniques, such as helmholtz resonators, which are simple in structure and have good noise attenuation capability in a specific frequency band, are widely used in the field of closed space noise control.

The helmholtz resonator was originally used as an acoustic "spectrum analyzer" and, with the development of theory and rapid technological progress, it gradually became a common instrument for amplifying, and absorbing sound. The traditional Helmholtz sound absorption structure consists of a closed resonant cavity and a neck pipe communicated with the resonant cavity, and has a good absorption effect on low-frequency noise. When external sound waves are received, the air inside the neck of the helmholtz sound absorbing structure vibrates, and the air in the resonance chamber generates a restoring force, i.e. the sound energy in the system is attenuated by the air movement in the resonator neck, regulated by the stiffness of the air in the resonance chamber. If the frequency of the sound wave is equal to the natural frequency of the system, the neck gas column will generate serious resonance vibration, overcome the friction resistance and consume the sound energy.

The conventional helmholtz sound absorbing structure also has a problem that it can effectively absorb sound near its resonance frequency, but the resonance frequency is determined at the beginning of the design of the helmholtz sound absorbing structure, resulting in a narrower sound absorbing band, often used as a narrow-band low-frequency sound absorber; and the sound absorption performance is limited by the size, materials and the like of the structure, and the sound absorption coefficient is lower.

Therefore, the prior Helmholtz sound absorption structure needs to be improved.

Disclosure of Invention

In order to overcome the above-mentioned problems with conventional helmholtz sound absorbing structures, the present invention provides a helmholtz sound absorbing device.

The technical scheme of the invention is as follows.

A Helmholtz sound absorption device comprises a neck pipe, a resonant cavity and a sound absorption cavity, wherein the neck pipe is communicated with the resonant cavity through a resonant cavity communication hole; the inner wall of the sound absorption cavity provided with the sound absorption cavity communicating hole is a first inner wall, and a spiral structure is arranged on the first inner wall; a track in a spiral line shape is arranged on the first inner wall, and a curved surface formed by extending from the track along a direction vertical to the first inner wall is in a spiral structure; and the initial opening of the spiral line is communicated with the sound absorption cavity communication hole.

Optionally, the helix comprises an archimedes helix.

Optionally, the sound-absorbing chamber communication hole comprises a circular hole, and the resonance chamber communication hole comprises a circular hole.

Optionally, a starting point of the archimedean spiral is arranged at an edge of the sound absorption cavity communication hole; the initial radius of the Archimedes spiral line is equal to the radius of the sound absorption cavity communication hole.

Optionally, a center point of the resonance chamber communication hole and a center point of the sound-absorbing chamber communication hole are both provided on an extension line of an axis of the neck tube.

Alternatively, the diameter of the resonance chamber communication hole and the diameter of the sound-absorbing chamber communication hole are equal.

Optionally, the curved surface formed by the extension extends to a second inner wall of the sound absorption cavity opposite to the first inner wall.

Optionally, the material of the wall of the neck tube, the wall of the resonance chamber and the wall of the sound absorption chamber comprises a sound absorbing material.

Optionally, a sound absorbing coating is provided on the inner wall of the sound absorbing chamber and/or on the spiral structure.

The invention has the technical effects that:

the Helmholtz sound absorption device comprises a neck pipe, a resonant cavity and a sound absorption cavity which are communicated. When receiving outside sound wave, the air vibration in the neck pipe, the air in the resonant cavity produces the restoring force, and when the frequency of sound wave was unanimous with the natural frequency of vibration of the helmholtz sound absorption structure that neck pipe and resonant cavity constitute, the resonance took place for the air in the resonant cavity, and the sound wave arouses helmholtz sound absorption structure to produce vibration to make the amplitude reach the biggest. At the same time, the air in the sound absorption cavity also vibrates synchronously. Because the spiral structure is arranged in the sound absorption cavity, the spiral structure provided with the damping sound absorption coating has negative rigidity characteristic, so that sound waves are more disordered in the transmission process of a spiral channel formed along the spiral structure, the possibility of collision and friction between a propagation medium (air) and a wall surface is increased, and the energy of the sound waves is more consumed. Therefore, the technical scheme of the invention can widen the resonant frequency range of the sound absorption device, can absorb more dissipated energy, and achieves the aim of the invention.

Further effects of the above alternatives will be described below in conjunction with the detailed description.

Drawings

FIG. 1 is an elevational cross-sectional view of one embodiment of a Helmholtz sound absorbing device of the present invention.

Fig. 2 is a perspective cross-sectional view of the embodiment shown in fig. 1.

Fig. 3 is a top cross-sectional view of fig. 1.

Fig. 4 is a sound pressure distribution diagram of a conventional helmholtz sound absorbing structure after absorbing sound waves.

Fig. 5 is a sound pressure distribution diagram of the helmholtz sound absorption device of the present invention after absorbing sound waves.

The designations in the figures illustrate the following:

101. a first inner wall; 102. a helical structure; 103. a second inner wall; 104. a sound absorbing chamber; 105. the sound absorption cavity communication hole; 106. a resonant cavity; 107. the resonant cavity is communicated with the hole; 108. a neck tube.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

As shown in fig. 1, the helmholtz sound absorbing device of the present invention includes a neck 108, a resonance chamber 106, and a sound absorbing chamber 104, which are sequentially communicated, in a bottom-up direction in fig. 1. The resonant cavity 106 and the sound absorption cavity 104 are both hollow structures. The neck 108 is connected to the resonance chamber 106 to form a resonance chamber communication hole 107. The resonance chamber 106 communicates with the sound-absorbing chamber 104 through the sound-absorbing chamber communication hole 105. The resonance chamber communication hole 107 is disposed opposite to the sound-absorbing chamber communication hole 105, and the center point of the resonance chamber communication hole 107 and the center point of the sound-absorbing chamber communication hole 105 are both disposed on the extension line of the axis of the neck 108. The sound-absorbing chamber communication hole 105 and the resonance chamber communication hole 107 are both circular holes, and the hole diameters thereof are equal.

A spiral structure 102 having a negative stiffness characteristic is disposed within the sound-absorbing chamber 105. The description for the helix structure 102 is as follows: the inner wall of the sound absorption chamber 104 provided with the sound absorption chamber communication hole 105 is a first inner wall 101, a spiral-shaped track is arranged on the first inner wall 101, and a curved surface formed by extending from the spiral-shaped track to the second inner wall 103 along the direction perpendicular to the first inner wall 101 is a spiral structure 102. The second inner wall 103 is an inner wall of the sound-absorbing chamber 104 opposite the first inner wall 101. The spiral is an Archimedes spiral. As can be seen with reference to fig. 3, the starting point of the archimedean spiral (i.e., the central starting point of the archimedean spiral) is set at the edge of the sound-absorbing-chamber communication hole 105, and the initial radius of the archimedean spiral is equal to the radius of the sound-absorbing-chamber communication hole 105.

The walls of the neck 108, the resonant cavity 106 and the sound-absorbing cavity 104 are made of sound-absorbing material. The sound-absorbing material may be a known sound-absorbing material such as polymethyl methacrylate (plexiglass, acrylic sheet). The inner walls of the sound-absorbing chamber 104 and the spiral 102 are provided with a sound-absorbing coating. The sound-absorbing coating material also employs known coating materials, such as porous polyurethane sound-absorbing materials.

The operation of the helmholtz sound absorption device of the present invention will be described below to further clarify the technical solution of the present invention.

The sound waves enter the resonance chamber 106 from the neck 108, and excite vibration in the resonance chamber 106, which induces synchronous vibration of the air in the sound-absorbing chamber 104 through the sound-absorbing chamber communication holes 105. Since the sound-absorbing chamber communication hole 105 and the resonance chamber communication hole 107 are coaxially provided and have the same aperture, no sound pressure loss occurs when sound waves are transmitted to the sound-absorbing chamber 104, and the energy of vibration can be smoothly transmitted to the sound-absorbing chamber 104. If there is a loss of acoustic pressure, the lost vibrational energy will reside in the resonant cavity 106 and some of the vibrational energy will not be absorbed by the acoustic cavity 014.

When the sound wave vibrating in the sound absorption chamber 104 is transmitted in the spiral direction of the spiral structure 102 having the negative stiffness characteristic, the sound wave collides with the wall surface of the spiral structure 102 and is consumed by friction, and thus the energy of the sound wave can be effectively absorbed. Fig. 4 and 5 show comparative test results of a conventional helmholtz sound absorbing structure and the helmholtz sound absorbing device of the present invention under the same test conditions. Comparing the results of fig. 4 and 5, it can be seen that the helmholtz sound absorber of the present invention can expand the frequency range of absorbing the sound waves.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and do not limit the scope of the present invention, and the present invention may be replaced by other equivalent techniques. Therefore, all equivalent changes, direct or indirect applications, made by using the description and the drawings of the present invention, or other related technical fields are included in the scope of the present invention.

Claims

1. A Helmholtz sound absorption device, comprising a neck tube and a resonance chamber, wherein the neck tube and the resonance chamber are communicated through a resonance chamber communication hole, characterized in that: the wall of the resonant cavity opposite to the resonant cavity communication hole is provided with a sound absorption cavity communication hole communicated with the sound absorption cavity; the inner wall of the sound absorption cavity provided with the sound absorption cavity communicating hole is a first inner wall, and a spiral structure is arranged on the first inner wall; a track in a spiral line shape is arranged on the first inner wall, and a curved surface formed by extending from the track along a direction vertical to the first inner wall is in a spiral structure; and the initial opening of the spiral line is communicated with the sound absorption cavity communication hole.

2. A helmholtz sound absorbing device according to claim 1 wherein: the helix comprises an archimedes helix.

3. A helmholtz sound absorbing device according to claim 2 wherein: the sound absorption cavity communication hole comprises a circular hole, and the resonance cavity communication hole comprises a circular hole.

4. A helmholtz sound absorbing device according to claim 3 wherein: the starting point of the Archimedes spiral is arranged at the edge of the sound absorption cavity communication hole; the initial radius of the Archimedes spiral line is equal to the radius of the sound absorption cavity communication hole.

5. A Helmholtz sound absorbing device as recited in claim 4, wherein: the center point of the resonant cavity communicating hole and the center point of the sound-absorbing cavity communicating hole are both arranged on the extension line of the axis of the neck pipe.

6. A Helmholtz sound absorbing device as recited in claim 6, wherein: the diameter of the resonant cavity communicating hole is equal to that of the sound absorption cavity communicating hole.

7. A helmholtz sound absorbing device according to claim 1 wherein: the curved surface formed by the extension extends to a second inner wall of the sound absorption cavity opposite to the first inner wall.

8. A helmholtz sound absorbing device according to claim 1 wherein: the wall of the neck pipe, the wall of the resonant cavity and the wall of the sound absorption cavity are made of sound absorption materials.

9. A helmholtz sound absorbing device according to claim 1 wherein: and a sound absorption coating is arranged on the inner wall of the sound absorption cavity and/or the spiral structure.