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

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.