Combined mesh free method and mode matching approach for transmission loss predictions of expansion chamber silencers

A coupled method (abbreviated here as the MFMM method) that combines the mesh free (MF) method and mode matching (MM) approach is introduced to predict the transmission loss (TL) of expansion chamber silencers. The Hermite radial point interpolation collocation (HRPIC) method is employed to solve the 2-D eigen equation of silencer sections. Then the mode matching method is used to calculate the transmission loss. The eigenvalues predictions of circular cross section from the present method exhibit desirable precision comparison with analytical results. Additionally, the effects of size of influence domain, number of computational nodes and shape parameters of radial basis functions on the calculation accuracy are evaluated. TL calculations of four typical expansion chambers with extended inlet and outlet are presented to valid the computational accuracy and efficiency of the proposed combined method.