M.H Shojaei fard - Prof. , Dep. of Mechanical Eng, Iran Univerdity of Science & Technology
R Talebitooti - Assist. Prof. , Dep. of Automotive Eng, Iran Univerdity of Science & Technology
A Yadollahi - MSc., Dep. of Automotive Eng, Expert at IKCO, Iran, Tehran

In this paper, boundary element analysis of perforated mufflers is discussed. The Perforated mufflers can be modeled by two different methods, the detailed holes model and the empirical formula model. In the present work the transfer impedance formulas which contains the details pertaining to the tube wall thickness and hole size, are used. Accordingly, the empirical formula is applied in order to model the perforated tube and also the recently developed tree-point method to calculate the TL utilizing commercial boundary element software. In order to demonstrate the effect of porosity and hole diameter on transmission loss three kinds of perforated tubes are considered. The BEM analysis is conducted in a frequency range of 50Hz and 3000Hz. Finally, the TL obtained from the empirical formula for each models are compared to the detailed perforate modeling and available experimental data of other researchers. A good agreement is achieved during this comparison which indicated that the empirical formula approach is the most suitable and especially simplest way of modeling in perforated surfaces

Transmission Loss, Muffler, Perforated-Tube, Empirical Formula, Boundary Element Method