Acoustic behaviour of an aperture backed by sound-absorbing materials under grazing flow

摘要

The acoustic behaviour of an aperture backed by sound-absorbing material under grazing flow is theoretically investigated through a linearized model. Both the dissipation effect of the material and its influence on the stability of the vortex sheet over the aperture region are formally taken into account. And thus, the coupling effect between the material and the grazing flow is considered. In the situation that the size of the aperture is considerably smaller than the shear layer thickness, the model uses the particle velocity match (PVM). The predictions of the present PVM model achieve satisfactory agreement with published experimental data. On the other hand, while the relatively thin shear layer is considered, the model is based on the rigorous particle displacement match (PDM) and predicts when the acoustic energy is possibly extracted from the mean flow. (C) 2019 Elsevier Ltd. All rights reserved.