Enhancing micro-perforated panel attenuation by partitioning the adjoining cavity

Liu, J.; Herrin, D. W.

doi:10.1016/j.apacoust.2009.07.016

Cited by 103 publications

(40 citation statements)

References 10 publications

(16 reference statements)

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“…First resonance frequencies showed an obvious movement towards low frequencies, and their corresponding sound absorption coefficients greatly climbed. Because of the unchanged positions together with the increased thickness, sound reactance was largely changed, equivalent to a deepening air space, which lead to the occurrence of first resonance frequency at lower frequencies (Liu & Herrin, 2010). Also, in the above two figures, two composite structures with the same thickness 15.6 mm of activated carbon fiber felts, sound absorption coefficients showed a significant increase.…”

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confidence: 93%

Sound absorption properties of composite structure with activated carbon fiber felts

Shen

Jiang

2014

The Journal of The Textile Institute

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This paper is intended to study the influence of different factors on the sound absorption properties of composite structure with activated carbon fiber felts. Activated carbon fiber felts made from viscose fiber mats were prepared and later combined with perforated panels to form four different composite sound absorption structures. Based on the transfer function method, the impedance tube was used to test the sound absorption coefficients of composite structure in an acoustic range of 80-6300 Hz frequencies. Analysis was made to discuss the influence of such factors on the sound absorption properties as the position of activated carbon fiber felts, thickness, and air space. The results demonstrated that the composite structure displayed different sound absorption properties at different frequencies.Perforated panels played the dominant role in sound absorption by the occurrence of resonance at 80-3500 Hz frequencies, while porous materials contributed the most at 3500-6300 Hz frequencies. At 80-3500 Hz frequencies, the best performance could be observed in the third type of composite structure with changes in the position of activated carbon fiber; the first resonance frequency of the first type of composite structure and perforated panel structure was basically the same, and that of the remaining three types significantly shifted towards the low frequencies with the same scale. In smaller thickness range, with the increase in the thickness of activated carbon fiber felts, sound absorption coefficients of the first and second types of composite structure increased, the first resonance frequency of the first type showing no apparent shift towards the low frequencies compared with what was shown in the second type; but when the thickness arrived at 15.6 mm, sound absorption properties of the composite structure had similar traits to that performed by porous materials in an acoustic range of 80-6300 Hz frequencies. With the increase in the distance of air space, sound absorption properties were improving at 80-650 Hz frequencies but decreasing at 650-3500 Hz frequencies, the first resonance frequency moving towards the low frequencies. At 3500-6300 Hz frequencies, as the position of activated carbon fiber felts and the distance of air space varied, sound absorption coefficients were basically unchanged; while as thickness increased, sound absorption coefficients improved.

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confidence: 93%

Sound absorption properties of composite structure with activated carbon fiber felts

Shen

Jiang

2014

The Journal of The Textile Institute

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“…Because of its appealing features such as cleanable, fiber-free and noncombustible, MPPs have found their use in a wide range of practical applications. [13][14][15][16][17][18][19][20] For example, Kang and Brocklesby 13 investigated the feasibility of applying MPP absorbers in ventilated window system. Allam and Å bom 14 proposed a new type of silencer based on MPP with slit holes.…”

Section: Introductionmentioning

confidence: 99%

Modeling vibroacoustic systems involving cascade open cavities and micro-perforated panels

Guyader

2014

The Journal of the Acoustical Society of America

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While the structural-acoustic coupling between flexible structures and closed acoustic cavities has been extensively studied in the literature, the modeling of structures coupled through open cavities, especially connected in cascade, is still a challenging task for most of the existing methods. The possible presence of micro-perforated panels (MPPs) in such systems adds additional difficulties in terms of both modeling and physical understanding. In this study, a sub-structuring methodology based on the Patch Transfer Function (PTF) approach with a Compound Interface treatment technique, referred to as CI-PTF method, is proposed, for dealing with complex systems involving cascade open/closed acoustic cavities and MPPs. The co-existence of apertures and solid/flexible/micro-perforated panels over a mixed separation interface is characterized using a compound panel subsystem, which enhances the systematic coupling feature of the PTF framework. Using several typical configurations, the versatility and efficiency of the proposed method is illustrated. Numerical studies highlight the physical understanding on the behavior of MPP inside a complex vibroacoustic environment, thus providing guidance for the practical design of such systems.

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“…7-9. Recently, there has also been interest in using microperforated lining materials in flow-duct noise control applications. [10][11][12][13][14][15][16] Further, microperforated materials may be incorporated into multi-layer systems to enhance particular aspects of the system performance. 17,18 The theory of microperforated panels has also been extended to allow for the effect of panel flexibility.…”

Section: Introductionmentioning

confidence: 99%

Transfer impedance of microperforated materials with tapered holes

Herdtle

Bolton²,

Kim³

et al. 2013

The Journal of the Acoustical Society of America

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It has been previously shown that relatively simple computational fluid dynamics (CFD) models can be used to calculate the transfer impedances, including the associated end corrections, of microperforated panels. The impedance is estimated by first calculating the pressure difference across a single hole when a transient input velocity is imposed, and then Fourier transforming the result to obtain the impedance as a function of frequency. Since the size of the hole and the dimensions of the inlet and outlet channels are very small compared to a wavelength, the flow through the hole can be modeled as incompressible. By using those procedures, Bolton and Kim extended Maa's classical theory to include a resistive end correction for sharp-edged cylindrical holes which differs from those previously proposed by the inclusion of a static component. Here it is shown that CFD models can also be used to compute end corrections for tapered holes. Since practical experimental characterization of perforated materials often involves measurement of the static flow resistance, a closed form empirical equation for that quantity has been developed. Finally, it is shown that configurations having equivalent static flow resistances can yield different acoustic absorptions.

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Enhancing micro-perforated panel attenuation by partitioning the adjoining cavity

Cited by 103 publications

References 10 publications

Sound absorption properties of composite structure with activated carbon fiber felts

Sound absorption properties of composite structure with activated carbon fiber felts

Modeling vibroacoustic systems involving cascade open cavities and micro-perforated panels

Transfer impedance of microperforated materials with tapered holes

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