Spatially-varying impedance model for locally reacting acoustic liners at a high sound intensity

Abstract

This paper is concerned with spatially-varying acoustic liner impedance in aeroacoustic ducts, in the presence of a high sound pressure level. It is shown that impedance discontinuity is a leading order parameter in the definition of the impedance variation. A large impedance discontinuity yields a high normal velocity variation, leading to significant nonlinear effects. An iterative numerical strategy is proposed to predict the spatially-varying acoustic impedance over a liner. A Bayesian inference process is coupled with a surrogate model to validate the model with measurements of the acoustic velocity fields above a liner at a high sound intensity, obtained using laser Doppler velocimetry.