The use of microperforated plates to attenuate cavity resonances

Abstract

The use of microperforated plates to introduce damping in a closed cavity is examined. By placing a microperforated plate well inside the cavity instead of near a wall as traditionally done in room acoustics, high attenuation can be obtained for specific acoustic modes, compared with the lower attenuation that can be obtained in a broad frequency range with the conventional position of the plate. An analytical method for predicting the attenuation is presented. The method involves finding complex eigenvalues and eigenfunctions for the modified cavity and makes it possible to predict Green's functions. The results, which are validated experimentally, show that a microperforated plate can provide substantial attenuation of modes in a cavity. One possible application of these findings is the treatment of boiler tones in heat-exchanger cavities.

Modeling of micro-perforated panels in a complex vibro-acoustic environment using patch transfer function approach

“…The proposed PTF approach is used to investigate the acoustic field inside a rectangular cavity used in Fenech et al 15 Results obtained from the present approach are compared with the experimental data reported in that paper. This comparison allows further validation of the proposed approach in a more complex vibro-acoustic environment.…”

“…9). In Fenech et al 15 the reverberation time of the empty cavity was found to be $0.5 s in most of the frequency range of interest. This allows the estimation of an overall damping loss factor from g ¼ 2:2=fT r , where f is the frequency and T r the reverberation time.…”

“…This was indeed shown in the past by different authors considering classical absorbing material of finite sizes. [15][16][17][18] They showed that the absorption coefficient of a patch of absorbent material depends on the size of the patch relative to the wavelength. In general, the absorption coefficient increases when the size of the patch material decreases.…”

“…Finally, the proposed model is validated through comparisons with experimental results given in the literature. 15 …”

Acoustic Metamaterials: A Potential for Cabin Noise Control in Automobiles and Armored Vehicles

“…In some works [Fenech et al, 2006;Liu and Herrin, 2010;Yang et al, 2015], the use of micro-perforated panels (MPP) are proposed, which are based on the fundamentals of HR. In this case, each perforation effectively represents a resonator with the backing air cavity representing the expansion chamber of a conventional resonator [Arenas and Crocker, 2010].…”