Numerical simulations and experiments on thermal viscous power dissipation of perforated plates

Lijun Li,Yiran Liu,Xianxu Zhang,Fan Zhang,Xianyue Gang

doi:10.1063/1.5044705

Abstract

The micro-perforated plates (MPPs) are widely used in sound absorption structures. As perforations become smaller, the energy loss caused by viscous dissipation and thermal radiation of the medium should be considered on calculation and design of the MPPs. In this paper, the energy loss of thin tube, micro tube and capillary tube are analyzed by using the finite element method (FEM). The acoustic finite element models of MPPs are created, and the power dissipation, impedance, resonant frequency, absorption coefficient and correction length of perforated plates are analyzed. The impedance experiments are carried to test the numerical results. This paper approves that the energy loss caused by thermal and viscous should be considered on MPPs, which is determined by air viscous, and affected by the diameter of perforations, porosity and frequency. The resonant frequency is affected by viscous. The theoretical formula of Helmholtz resonator cause great error for micro-perforated plates usage, and it should be calculated by numerical simulation in the field of MPPs design and application.

Highlights

Micro-perforated plates (MPPs) are plates with small perforations whose diameter is about 0.1mm and with low porosity values
The viscous dissipation and thermal radiation become significant, which induces the unsatisfied sound absorption effect of micro-perforated plates based on theoretical models
The impedance, absorption coefficient, resonant frequency of perforated plates are researched by theoretic and finite element method (FEM) two methods, and the impedance test are carried as a complement to computations

Summary

INTRODUCTION

Micro-perforated plates (MPPs) are plates with small perforations whose diameter is about 0.1mm and with low porosity values. Since the 40s of the 20th Century, research on theory and application of MPPs have attracted great interest of researchers.[1] The reason is that MPPs have the advantages of simple structure and obvious sound absorption effect. They are widely used in muffler systems, sound absorbing panels, liners, architectural acoustics, industrial noise, combustion oscillation suppression, and pipeline noise elimination, etc.[2,3]. When the sound wave frequency is relatively low or the tube is thick, sound wave propagation in the tube can be considered the ideal and the energy loss is negligible. The impedance experiments are carried to test the numerical results.[11]

THEORETICAL BACKGROUND

NUMERICAL SIMULATION BY FEM

Power dissipation of perforated plates by FEM

Resonant frequency of perforated plates by FEM

IMPEDANCE TEST

CONCLUSION