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Sound absorption of a micro-perforated panel backed by an irregular-shaped cavity.

Sound absorption of a micro-perforated panel backed by an irregular-shaped cavity. In the pursuit of more effective noise control devices, the cavity backed micro-perforated panel absorber (CBMPPA) is developed in this study. A CBMPPA differs from the conventional micro-perforated panel (MPP) absorber in that the MPP is backed by a trapezoidal cavity, which allows more effective vibroacoustic coupling between the MPP and the cavity. A two-dimensional theoretical model is established and tested both numerically and experimentally. Based on the verified theoretical model, sound absorption performance of a trapezoidal CBMPPA is investigated numerically. Results show that the shape of the backing cavity can significantly alter the sound absorption mechanisms and frequency distribution of overall sound absorption coefficient of the absorber. Further analyses show that acoustic modes that are initially decoupled from the MPP in the rectangular configuration are coupled with the air motion in the MPP, which accounts for the change in absorption pattern of the trapezoidal CBMPPA. By the same token, it also provides the flexibility for tuning the effective absorption range of the absorber. Due to the varying impedance matching conditions, the absorption performance of the trapezoidal CBMPPA exhibits obvious local characteristics over the MPP surface, which contrasts with the spatially uniform absorption in the conventional MPP absorber. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of the Acoustical Society of America Pubmed

Sound absorption of a micro-perforated panel backed by an irregular-shaped cavity.

The Journal of the Acoustical Society of America , Volume 127 (1): 9 – Mar 1, 2010

Sound absorption of a micro-perforated panel backed by an irregular-shaped cavity.


Abstract

In the pursuit of more effective noise control devices, the cavity backed micro-perforated panel absorber (CBMPPA) is developed in this study. A CBMPPA differs from the conventional micro-perforated panel (MPP) absorber in that the MPP is backed by a trapezoidal cavity, which allows more effective vibroacoustic coupling between the MPP and the cavity. A two-dimensional theoretical model is established and tested both numerically and experimentally. Based on the verified theoretical model, sound absorption performance of a trapezoidal CBMPPA is investigated numerically. Results show that the shape of the backing cavity can significantly alter the sound absorption mechanisms and frequency distribution of overall sound absorption coefficient of the absorber. Further analyses show that acoustic modes that are initially decoupled from the MPP in the rectangular configuration are coupled with the air motion in the MPP, which accounts for the change in absorption pattern of the trapezoidal CBMPPA. By the same token, it also provides the flexibility for tuning the effective absorption range of the absorber. Due to the varying impedance matching conditions, the absorption performance of the trapezoidal CBMPPA exhibits obvious local characteristics over the MPP surface, which contrasts with the spatially uniform absorption in the conventional MPP absorber.

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ISSN
0001-4966
DOI
10.1121/1.3257590
pmid
20058969

Abstract

In the pursuit of more effective noise control devices, the cavity backed micro-perforated panel absorber (CBMPPA) is developed in this study. A CBMPPA differs from the conventional micro-perforated panel (MPP) absorber in that the MPP is backed by a trapezoidal cavity, which allows more effective vibroacoustic coupling between the MPP and the cavity. A two-dimensional theoretical model is established and tested both numerically and experimentally. Based on the verified theoretical model, sound absorption performance of a trapezoidal CBMPPA is investigated numerically. Results show that the shape of the backing cavity can significantly alter the sound absorption mechanisms and frequency distribution of overall sound absorption coefficient of the absorber. Further analyses show that acoustic modes that are initially decoupled from the MPP in the rectangular configuration are coupled with the air motion in the MPP, which accounts for the change in absorption pattern of the trapezoidal CBMPPA. By the same token, it also provides the flexibility for tuning the effective absorption range of the absorber. Due to the varying impedance matching conditions, the absorption performance of the trapezoidal CBMPPA exhibits obvious local characteristics over the MPP surface, which contrasts with the spatially uniform absorption in the conventional MPP absorber.

Journal

The Journal of the Acoustical Society of AmericaPubmed

Published: Mar 1, 2010

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