Estimation of effective parameters for microperforated panel absorbers and applications

Liu, J.; Hua, Xin; Herrin, D. W.

doi:10.1016/j.apacoust.2013.07.009

Cited by 31 publications

(6 citation statements)

References 26 publications

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“…3e , which increases the overall porosity of the MSP/MSDEBA panel. As the open ratio ( V ) is increased, like any MPP or combination of MPPs 66 – 68 , it reduces the acoustic reactance of the system following Eqs. 5 and 7 .…”

Section: Resultsmentioning

confidence: 99%

A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

Shrestha,

Lau,

Chin

et al. 2024

Commun Eng

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Dielectric elastomer actuator (DEA)-based unimorphs that actively bend in one direction, can mimic the blooming motion of flower petals. Here we explore an application of such reconfigurable DEA to create tunable acoustic absorber capable of adapting to fluctuations in dominant noise frequency. The DEA-unimorphs consist of alternate layers of dielectric elastomers and compliant electrodes bonded to a Mylar sheet and were micro-slotted to form triangular petal-like structures that bend upon voltage activation. When arranged in an array, the micro-slotted dielectric elastomer bending actuators (MSDEBA) can open like flower petals, actively reconfiguring their open-ratio. Integrated with a base resonator comprising a micro-slotted panel (MSP) and a parallelly arranged varying-depth (VD) back-cavity, the MSDEBA forms a tunable acoustic absorber effective in the low-mid acoustic frequency range at inactive state. Meanwhile, upon voltage activation, it increased the absorber’s open-ratio and tuned the absorber to target a higher frequency. A 5 kV activation reconfigured the MSDEBA to shift its transmission loss peak by 72.74% (i.e., from 697 Hz to 1204 Hz). This acoustic spectrum tuning capability doubled the 15 dB absorption bandwidth of these absorbers from a bandwidth of ~435 Hz to 820 Hz. Such absorbers have the potential to tune the absorption spectrum to match the noise frequency in real-time to ensure optimal acoustic attenuation.

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Section: Resultsmentioning

confidence: 99%

A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

Shrestha,

Lau,

Chin

et al. 2024

Commun Eng

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“…A two-load-method-based impedance tube with an inner diameter of 34.8 mm and a frequency range of 500–3000 Hz was utilised to measure transmission loss. 47 In Figure 4, four flush-mounted pressure microphones (GRAS 46AD) were used to measure the sound pressure inside the tube. LMS SCADAS system and LMS Test Lab software were utilised for signal acquisition.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of acoustic performance of cascaded cylindrical micro-perforated panel

Alisah

Ooi

Ripin

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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A cylindrical micro-perforated panel (MPP) can be used to absorb the sound of a flow system in a circular duct of a vacuum cleaner. A cascaded cylindrical MPP is a special class type where two cylindrical MPPs are arranged in a series to improve sound attenuation. The manufacturing of MPP primarily involves the machining of micro-perforations, because small holes are not readily made using injection moulding due to the complexity of the die, flow control of the molten polymer through the small orifices and dimensional stability, making it unsuitable for mass production. This limitation can be overcome with the use of additive manufacturing (AM) technology, where the micro-perforations can be designed and manufactured, with relatively larger tolerances. Experimental validation ensures that the manufactured prototype in this study is performed according to design. Results show that the transmission loss of the model and the experimental outcomes agree. The cascaded arrangement of the cylindrical MPP results in a wider effective frequency range and an increased transmission loss. Parametric studies of the combined effects of the perforation diameter, perforation ratio and the depth of air cavity on the diameter of the duct and length ratio are conducted using a transfer matrix method. A case study is demonstrated here in the design. Moreover, an AM of cascaded cylindrical MPP is performed to attenuate peak noise at 1650 Hz, where the optimum parameters of the cascaded cylindrical MPP are obtained using a genetic algorithm. The manufactured cascaded cylindrical MPP is installed on a vacuum cleaner duct, and the measurement of sound power level shows a reduction of 4 dB(A).

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“…Fig. 2b, continuous red line) [29]. The calculations were made with (4) and ( 5), where the effective surface impedance Z eff of MPP (index 1) plus air cavity (index 0) in Figure 2a is represented by the scattering matrix T eff .…”

Section: Modeling and Parameter Fittingmentioning

confidence: 99%

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

2021

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The reduction of fan noise in ducts is a challenging task for acoustic engineers. Usually, the confined space where an absorber can be integrated is small. In addition, one has to consider the influence of the absorber on the flow field and the attenuation of noise should be as great as possible. In this contribution, we investigate the application of a micro-perforated absorber (MPA) in the direct vicinity of a low-pressure axial fan operating at low Mach number conditions. The micro-perforated plates (MPP) are modeled using the Johnson–Champoux–Allard–Lafarge (JCAL) model for porous materials. The entire geometrical setup of duct, fan and MPA is then simulated with the Finite Element (FE) method; the pre-processing effort is reduced by using non-conforming grids to discretize the different regions. The influence of the cavity length and the positioning of the fan are analyzed. The results are then applied to the construction of a full-sized MPA duct component that takes the limited space into consideration. Simulation results and overall functionality are compared to experimental results obtained in an axial-fan test rig. The Finite Element framework proved to be robust in predicting overall sound pressure level reduction in the higher volume flow rates. It is also shown that the MPP increases sound reduction in the low-frequency regime and at two resonant frequencies of the MPA setup. However, its main benefit lies in maintaining the efficiency of the fan. The location of the fan downstream or within the MPA has a significant effect on both the simulated and measured sound reduction.

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Estimation of effective parameters for microperforated panel absorbers and applications

Cited by 31 publications

References 26 publications

A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

Evaluation of acoustic performance of cascaded cylindrical micro-perforated panel

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

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