Non-linear simulation of single pass perforated tube silencers based on the method of characteristics

A quasi-one-dimensional characteristic based non-linear model for unsteady compressible flow is used to simulate the flow in single-pass perforated tube silencers. The flow in both short and long concentric tube resonators is simulated for both low and high-pressure excitation. The temporal solution is first transferred into the frequency domain using FFT, and then processed by the two-microphone technique in order to evaluate the transmission loss. Derivations of required equations, which are used to implement the method of characteristics along with the mathematical formulation of length corrections and different boundary conditions, are presented. The results obtained are compared with previously published experimental and numerical work, showing, in most cases, better agreement with the experimental data.