A CFD-based non-linear model for the prediction of tone noise in lined ducts

Bréard, C., Sayma, A., Imregun, M., Wilson, A.G. and Tester, B.J. (2001) A CFD-based non-linear model for the prediction of tone noise in lined ducts. 7th AIAA/CEAS Aeroacoustics Conference, Maastricht, The Netherlands. 27 - 29 May 2001.

Abstract

This paper describes the development and application of a time-domain acoustic liner model which is designed for the simulation of sound propagation and attenuation in conjunction with time-accurate unsteady flow computations using large-scale numerical models. The main duct domain is represented by the 3D Euler or Navier-Stokes equations while the resistive part of the liner model consists of a time-independent part and a non-linear time-dependent part. Its reactive part is obtained by solving the ID Euler equations within the liner cavity. A-3D-benchmark test geometry, including a lined intake, was modelled using an advanced aeroelasticity code. First, the liner model was validated for steady-state intake duct flows using a number of numerical benchmarks, with particular emphasis on the stability of the duct/liner boundary condition for a range of cases. The pressure perturbation due to the fan was investigated next via a full unsteady flow calculation. Both continuous and discontinuous liner models were considered. It was found that liner scattering had nonlinear effects on noise attenuation. It was concluded that the liner model could be used for both steady-state and unsteady flows.

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