Liner Impedance Eduction Under Shear Grazing Flow at a High Sound Pressure Level

Abstract

This paper investigates the combined effects of high sound pressure level and grazing flow on impedance eduction for acoustical liners. Experiments are conducted in the grazing flow duct at ONERA (B2A). The impedance is then educed with an inverse method adapted to a shear flow. To take into account the effects of incident sound pressure level, a strategy for impedance eduction using a space-dependent impedance is considered. This strategy is applied to different experimental cases, and the results are compared with those obtained with a reference method in which the impedance is assumed constant.