Resonance of elliptical muffler chamber having a nonuniformly perforated pipe

Perforated pipe is an essential component in contemporary automotive mufflers, since such a pipe reduces the acoustic power of the flow noise, which is significantly influenced by its velocity. Nonuniformly perforated pipes, the orifices of which are arranged in a belt configuration, are widely used in muffler systems. The resonance of such perforated pipe when located inside the elliptic cavity is investigated experimentally in this paper. The results obtained are also compared with the predictions of our method of theoretical analysis for a uniformly perforated pipe in order to clarify the resonance mechanism. It was found that the difference between the measured and theoretical values is less than 5 Hz for a short pipe. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(7): 22–28, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1104