Low frequency sound propagation in a coaxial cylindrical duct:: Application to sudden area expansions and to dissipative silencers

A. method based on the approximation of the radial pressure profile is developed to analyze the acoustic performance of a sudden expansion and of an expansion chamber at low frequencies. This model is able to predict very accurately the added length of an expansion which includes neither porous material nor a perforated tube. It can also be applied when a bulk-reacting lining and perforated tube are included. This model of a dissipative silencer gives results which compare very favourably with experimental data. (C) 2001 Academic Press.