Acoustical analysts, testing, and design of flow-reversing muffler chambers

Abstract

The transmission loss characteristics of flow-reversing muffler chambers were predicted by a numerical approach based on the finite-element method. The theoretical model developed is described in this paper; its validity is established experimentally with a number of different chambers. The standing-wave method was used to measure transmission loss and measurements were conducted with and without steady air flow. Depending on the inlet and outlet configurations, the flow-reversing chambers have two completely different transmission loss characteristics: one is similar to that for two simple expansion chambers in series and the other is similar to that for a side-branch resonator. Using the theoretical model developed, transmission loss curves were calculated for a large number of different flow-reversing chamber dimensions. A summary of the transmission loss characteristics of flow-reversing chambers is given for the assistance of muffler designers. [This work is a continuation of that reported by Young and Crocker in J. Acoust. Soc. Am. 54, 331(A) (1973)].