An Experimental Study of a Multi-Size Microperforated Panel Absorber

Abstract

A new type of microperforated panel absorber (MPA) that has holes of multiple sizes instead of uniform size is experimentally investigated. The objective of this research is to obtain a wide band sound absorber that is thin, durable, clean, and healthy. The first step of this research is to investigate the performance of MPA having two different sizes and the same numbers of holes. The investigation is then extended to a combination of three and four different sizes of holes with various spatial arrangements and various densities or percentages of each size of holes on panels. The hole diameters vary between 0.4 mm and 1 mm and the cavity depths vary between 10 mm and 15 mm. The results show that a multi-size MPA enhances the absorption rate and widens the effective frequency band. This study also proves that a multi-size MPA when compared with a uniform size MPA has better sound absorption characteristics with respect to the absorber thickness and absorption bandwidth. These results make it possible to build thin, single layer sound absorbers that are effective in wide frequency bands and have the advantage of being tunable.

A finite element model of perforated panel absorbers including viscothermal effects

“…For scalars and tensors, the dot product is replaced by the scalar and the double dot product, respectively. The weak form results in the system matrix (13) where v , Some details regarding these aspects are given in the next section.…”

“…Nevertheless, in some cases this effect is linked to the porosity effect and is difficult to estimate its contribution isolated. For example, Miasa et al [13] investigated experimentally the use of multiple sizes of holes in perforated panels. They observed that the sound absorption characteristics were enhanced and attributed this fact to the interaction effect, but did not compare the results with any theoretical model.…”

Experimental and numerical investigation of Helmholtz resonators and perforated liners as attenuation devices in industrial gas turbine combustors

“…for Plate#4 and Plate#5 were obtained from [25,26] Figure 4 presents the absorption coefficients results comparison between CFD, experimental and analytical methods. While all three methods yield similar change trends of absorption coefficient as a function of frequency, there are also some remarkable differences.…”

Optimization of Multi-size Micro-perforated Panel Absorbers with Different Cavity Depths using Adaptive Genetic Algorithm

“…And many researchers keep studying and finding more new and better ways to introduce more resonance frequencies without significant increase in thickness of the absorbing structure. One is to use holes of multiple sizes for MPP absorbers instead of a uniform holes size [11,12]. Another is to use partitioned cavity of varying depths for MPP absorbers instead of a constant cavity depth [13].…”