Influence of arranged patterns on the absorption performance of parallel MPP absorbers

Abstract

Parallel connection is an effective way to improve the absorption performance of micro-perforated panel (MPP) absorbers. A parallel MPP absorber usually consists of periodically distributed MPP units with different acoustic characteristics, and the periodic distribution allows the impedance of the whole absorber to be characterized by that of a unit cell (UC). The UC can be arranged in different patterns. Thus, in this paper, the influence of arranged patterns on the normal absorption characteristics of parallel MPP absorbers are investigated based on finite element method. Firstly, different arranged UCs comprising four MPP units with variable size are numerically investigated in terms of the normal absorption properties. The numerical results show that the arranged patterns have almost no effect on the normal absorption characteristics of the UC under fully coupled condition and the numerical prediction is consistent with the analytical model, but under partially coupled condition the absorption properties are greatly affected by the arranged patterns, and the impact increases with the increase in UC size. Then, the conclusion is further verified by the numerical simulation of the UC comprising nine MPP units. Finally, the effectiveness of numerical simulation based on finite element method is validated by the experiments. The research results will provide design guidance for the practical application of parallel MPP absorbers.