Acoustic analysis of elliptical muffler chamber having a perforated pipe

Evidently, a perforated pipe is an essential component in muffler systems. It has the ability to reduce the power levels of noise sources generated by flow. Muffler systems are composed of several elements joined together in series or parallel. In practical approach, each element can have one or more perforated pipe installed. This yields the ability to estimate the acoustic characteristic by the product of the individual element four-pole parameters.In this work, a method to derive the four-pole parameters of such element with consideration of higher-order mode is presented. Based on the results obtained, the parameter C was investigated systematically. Some comparisons between the experimental measurements and the predicted results are discussed. The mean flow velocity is not considered in this paper.