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

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. (C) 1997 Elsevier Science Ltd.