A TIME-DOMAIN METHOD FOR THE PREDICTION OF SOUND ATTENUATION IN LINED DUCTS

This paper describes the development and application of a time-domain acoustic liner model which is suitable for the simulation of sound propagation and attenuation in lined ducts. The fluid flow within the duct domain is represented by the non-linear, unsteady Euler equations while the liner model consists of a resistive frequency-independent part and a reactive part which is obtained by solving the one-dimensional Euler equations within the liner cavity. Specialized boundary conditions are used for matching the 1D cavity flow and the 2D duct flow. The liner model has been formulated in order to predict the sound attenuation with or without mean flow, as well as for linear or non-linear sound propagation. The model has been validated in the case of linear pure-tone and N -wave signals by checking against analytical formulations obtained via eigensolutions of the linearized inviscid flow equations. Very good agreement was obtained for both zero and subsonic mean flows.