Acoustical behavior of single inlet and multiple outlet elliptical cylindrical chamber muffler

Transmission loss (TL) of an elliptical cylindrical chamber muffler having a single side/end inlet and multiple side/end outlet is analyzed by means of the 3-D semi-analytical formulation based upon the modal expansion (in terms of the angular and radial Mathieu functions) and the Green’s function. The acoustic pressure response obtained in terms of Green’s function is inte¬grated over surface area of the side/end ports (modeled as rigid pistons) and upon subsequent division by the port area, yields the acoustic pressure re¬sponse or impedance [Z] matrix parameters due to the uniform piston-driven model. The 3-D semi-analytical results are found to be in excellent agreement with the results obtained by means of 3-D FEA (SYSNOISE) simulations, thereby validating the semi-analytical procedure suggested in this work. Para¬metric studies such as the effect of chamber length (L), angular and axial locations of the ports, interchanging the locations of inlet and outlet ports as well as the addition of an outlet port for double outlet mufflers on the TL performance are reported, thereby leading to the formulation of design guide¬lines for obtaining muffler configurations exhibiting a broad-band TL spec¬trum. One such configuration is an axially long chamber having side-inlet and side-outlet ports such that one of the side ports is located at half the axial length on the major/minor axis and the other side port is located at three-quarters (or one-quarter) of the axial length on the minor/major axis.