The Effect of Boundary Layers on Bulk Reacting Liners at Low Mach Number Flows

Abstract

Sound absorbing linings are effective noise treatments in many applications in order to meet noise emission requirements. Stricter noise requirements set harder demands on the performance of the liners, why better prediction models of their performance have to be developed. As of today, several models to predict the sound reducing properties in the presence of flow exist and are shown to give diverging absorption properties for locally reacting liners exposed to high Mach number flows. The effect of flow on absorption properties is often seen as an issue that only needs to be addressed at high Mach number flows. In this paper, the existing models are applied to bulk reacting liners exposed to low

Absorption of sound at a surface exposed to flow and temperature gradients

“…[12][13][14] among others. The acoustic properties of the boundary have been shown to be significantly altered; however, the results using the different conditions differ [8]. Recently, Gabard presented a benchmark study [15] evaluating these conditions for a locally reacting lined surface in relation to a numerical solution of the Pridmore-Brown equation [16].…”

“…In applications where a grazing mean flow and velocity gradients are present, the acoustic performance will change and consequently alter the boundary condition [8]. Extensive research has been performed on a condition including mean flow boundary layer effects.…”