Analytical Prediction of Transmission Loss in Distorted Circular Chamber Mufflers With Extended Inlet/Outlet Ports by Using a Regular Perturbation Method

The sound attenuation performance in elliptic chamber mufflers with extended inlet and outlet ports is investigated in the present work. Unlike cylindrical geometries, the ellipticity of the chamber prevents development of analytical solutions in terms of the elliptic eigenfunctions. In order to overcome this geometric limitation, a perturbation-based approach is adopted through this work. For moderate chamber eccentricities, transmission loss (TL) curves derived through the perturbed eigensolutions are observed to compare well with numerical simulations. The effects of higher-order propagating modes on the TL curves, which otherwise are nonpropagating for the corresponding cylindrical chamber extended muffler are discussed. Parametric studies on different tuned duct extensions are presented to show broadband sound attenuation.