BOUNDARY-ELEMENT EVALUATION ON THE PERFORMANCE OF SOUND ABSORBING WEDGES FOR ANECHOIC CHAMBERS

In the present study, the acoustic performance analysis for wedges use d in an anechoic chamber by the boundary element method is conducted. In a wedge formed by porous material, mechanisms of dissipated process es due to viscosity and heat conduction are very complicated and are n ot easy to handle. For simplicity, the laws of Delany and Bazley are u sed to replace the porous material by an equivalent fluid. With this a ssumption, the agreement between numerical results and experimental me asurements reported elsewhere is still good. Influences on the pressur e reflection coefficient due to the dimensions of wedge, such as the l ength of the wedge, the thickness of base, the thickness of air gap, f or fiber and foam materials with different flow resistances are studie d. In addition, the hybrid wedge and the wedge with cutting head are a lso investigated. (C) 1997. Published by Elsevier Science Ltd.