抄録
In the mechanical engineering field, a noise is often generated within the cabinet and propagates through the orifice and radiated to outer space. In that case, the sound propagates through both closed and open spaces. The finite difference method in time domain(FDTD) can be applied to closed space. In order to improve the accuracy of spatial differentiation, the compact finite differences were utilized in this report. As configurations of equipments can be well represeted by non-uniform grid, the compact finite difference on that grid was applied In the outer space, the sound field can be evaluated by the boundary integral calculation. The boundary values of the sound pressure and particle velocities in frequency domain were applied by the Fourier transformation of the results by FDTD. As an example. the sound pressure distributions around the equipment were evaluated The influences of the temperature change in the cabinet on the sound pressure were examined. Due to the discontinuity of the sound velocity and density at the opening, the reflection and refraction of sound wave at the orifice was predicted.
