Modelling of Microperforated Panel Absorbers with Circular and Slit Hole Geometries

Pedro Cobo

doi:10.3390/acoustics3040042

Abstract

Although the original proposal of microperforated panels by Maa consisted of an array of minute circular holes evenly distributed in a thin plate, other hole geometries have been recently suggested that provide similar absorption curves to those of circular holes. With the arrival of modern machining technologies, such as 3D printing, panels microperforated with slit-shaped holes are being specially considered. Therefore, models able to predict the absorption performance of microperforated panels with variable hole geometry are needed. The aim of this article is to analyze three models for such absorbing systems, namely, the Maa model for circular holes, the Randeberg–Vigran model for slit-shaped holes, and the Equivalent Fluid model for both geometries. The absorption curves predicted for these three models are compared with the measured curves of three panels microperforated with spirally shaped slits.

Highlights

Abstract: the original proposal of microperforated panels by Maa consisted of an array of minute circular holes evenly distributed in a thin plate, other hole geometries have been recently suggested that provide similar absorption curves to those of circular holes
The main advantages of microperforated panels (MPP) as light, clean and easy-todesign sound absorbers were already established in the previous century [1,2,3]
Three models were analyzed to predict the absorption curves of microperforated plates with circular (MPPs) and slit-shaped (MSPs) holes. Two of these models were originally conceived for circles (Maa model) and slits (Randeberg–Vigran model), while the other (EF model) contains two parameters that allow for its use in both pore geometries

Summary

Introduction

The main advantages of microperforated panels (MPP) as light, clean and easy-todesign sound absorbers were already established in the previous century [1,2,3]. In order that such an MPP provides enough absorption, other complex impedance is needed to compensate for the reactive part of Z1 This can be carried out by adding an air cavity of thickness D in front of the perforated panel. An MPP appropriate for absorbing in the frequency band of interest in noise-control applications requires hundreds of thousands of sub-millimetric perforations per square meter. Such large numbers of minute perforations would be carried out by laser technology, resulting in an expensive absorber. The main objective of this article is to revisit the modelling of MPPs and MSPs and compare them with updated measured absorption data

Single-Layer Microperforated or Microslit Panels

Conclusions