Variation of acoustic energy accross a sudden cross section area increase sustaining a subsonic mean flow

Abstract

International audienceThe variation of acoustic energy across a given geometrycan be quantified using the acoustic absorption coefficient.A quasi-steady analytical model predicting the absorptioncoefficient across an axisymmetric sudden area expansionsustaining a subsonic mean flow is derived in this study.This dimensionless parameter is shown to depend on theinlet Mach numberMu, cross section area ratioθ, and up-stream acoustic reflection coefficientRu. Numerical sim-ulations are then used to validate the analytical model fora wide range of parameters. It is found that depending on(Mu,θ,Ru), the acoustic energy can be either completelydamped, partially damped, unaffected, or even amplifiedacross the sudden area expansion