EXPERIMENTAL VALIDATION OF A BOUNDARY ELEMENT SOLVER FOR EXTERIOR ACOUSTIC RADIATION PROBLEMS

The relation between harmonic structural vibrations and the corresponding acoustic radiation is given by the Helmholtz integral equation (HIE). To solve this integral equa-tion a new solver (BEMSYS) based on the boundary element method (BEM) has been implemented. This numerical tool can be used for both sound radiation and near¯eld acoustic source localization purposes. After validation of the solver with analytic solu-tions of simple test problems, a well-de¯ned experimental setup has been designed. The setup consists of a thick walled aluminum box covered with a °exible plate. Inside the box a speaker generates a sound ¯eld which is transmitted through the °exible plate into the surrounding medium. This paper describes this experimental setup and brie°y explains the properties of the boundary element solver. A comparison is made between the computed and mea-sured sound pressures and particle velocities surrounding the acoustic source. In order to obtain a boundary condition for the BEM computation, the structural vibrations of the °exible plate are measured with a laser Doppler vibrometer. The acoustic pressures are measured with a condenser microphone. The particle velocities are measured with a novel Micro°own sensor, which directly measures particle velocity. From the compari-son between numerical and measured results, it becomes evident that a good agreement is obtained and thus that the BEMSYS solver is successfully validated. 149