Plane wave analysis of side inlet/outlet chamber mufflers with mean flow

Abstract

Integration of side inlet and/or side outlet expansion chambers into the rest of the muffler system for prediction of overall transmission loss (TL) or insertion loss requires knowledge of the four-pole parameters of these elements for propagation of plane waves in a moving medium. In this paper, transfer matrices have been derived for side inlet and side outlet elements for typically small mean flow Mach numbers. These are validated against the 3-D model existing in the literature for a stationary medium and for acoustically long chambers. The effect of mean flow on TL of the side inlet/ outlet chambers has been demonstrated. Incidentally, it has been shown that side inlets and side outlets behave more or less like extended inlets and extended outlets, respectively.