Improvement of Muffler Transmission Loss Using Micro-Perforated Panel

In this paper, Improve of transmission loss (TL) for simple geometry mufflers using micro-perforated panels (MPP) is studied. The TLs given by numerical method using SYSNOISE are compared with experimental and analytical results of other researchers. Different configurations have been used so as to detect the real effect of resonator absorbers based on micro-perforated panels in the expansion chambers. It is shown that applying these absorbers can effectively enhance the TL in desired frequencies if their parameters are well chosen. In addition, the reactive effects of the geometry are of high importance in compare with dissipative ones. However, their dissipative effects are negligible when they act at a reactive effect resonance. Finally, numerical modeling of micro-perforated panel in numerical software that it was impossible, in this paper a suitable solution using the equivalent impedance method for modeling in boundary element software, SYSNOISE, is presented.