A Broadband Small-Volume Acoustic Structure Based on Acoustic Metamaterials

Abstract

The invention discloses a broadband small-volume silencing structure based on an acoustic metamaterial. The structure comprises a shell with a hollow cavity, a through pipe positioned in the hollow cavity for penetrating through two opposite end parts of the shell, a film sleeve for coating the through pipe, film materials fixed on the film sleeve and with elasticity, and mass blocks fixed on the film materials; an inner cavity of the through pipe forms a first cavity; a second cavity is formed between the outer wall of the through pipe and the inner wall of the film sleeve; the through pipe is provided with multiple through holes for communicating the first cavity with the second cavity; a sound sucking cotton is filled in the second cavity; multiple film materials and mass blocks are provided, and are corresponding one to one; and spring-mass units are formed between the film materials and the mass blocks. The silencing structure eliminates medium / low-frequency noise in air currents through the film acoustic metamaterial, uses a resistance material for eliminating high-frequency noise in the air currents, and achieves ideal silencing effect when largely reducing the silencing volume of a silencer.

Description

technical field [0001] The invention specifically relates to the technical field of sound-absorbing acoustics, in particular to a broadband small-volume noise-absorbing structure based on acoustic metamaterials. Background technique [0002] The muffler is a device that can not only make the air flow pass smoothly but also effectively reduce the noise. It is an effective tool for controlling aerodynamic noise. Generally, the muffler can be divided into passive muffler (passive muffler), active muffler (active muffler) and semi-active muffler (dual-mode muffler) according to the principle of muffler. In the passive muffler, the sound energy will be reflected by the structure or absorbed by the sound-absorbing material; the active muffler has an electronic control system to generate an infrasonic wave that is equal in amplitude to the sound wave of the sound source but opposite in phase, and achieves the sound attenuation effect through sound wave interference; The passive co...

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Problems solved by technology

[0004] Engine intake and exhaust noise is usually composed of low-to-medium frequency order noise and high-frequency explosion noise, so the mufflers used for its development are mostly broadband mufflers. In the prior art, Helmholtz resonant cavities are generally used to eliminate For low-frequency noise, use perforated components and expansion chambers to eliminate mid-frequency noise, and use resistive materials to eliminate mid- and high-frequency noise. The volume of this muffler is usually 15-18 times the engine displacement, especially for low-frequency noise. The sound volume can be eliminated, which is also the difficulty of optimizing low-frequency noise under the limited anechoic volume in the prior art

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