Boundary element evaluation on the performance of sound absorbing wedges for anechoic chambers

In the present study, the acoustic performance analysis for wedges used in an anechoic chamber by the boundary element method is conducted. In a wedge formed by porous material, mechanisms of dissipated processes due to viscosity and heat conduction are very complicated and are not easy to handle. For simplicity, the laws of Delany and Bazley are used to replace the porous material by an equivalent fluid. With this assumption, the agreement between numerical results and experimental measurements reported elsewhere is still good. Influences on the pressure reflection coefficient due to the dimensions of wedge, such as the length of the wedge, the thickness of base, the thickness of air gap, for fiber and foam materials with different flow resistances are studied. In addition, the hybrid wedge and the wedge with cutting head are also investigated. (C) 1997. Published by Elsevier Science Ltd.