Sound Intensity Distribution and Energy Flow in the Nearfield of a Clamped Circular Plate

Abstract

Sound intensity distribution and energy flow in the nearfield of a clamped circular plate vibrating at its resonant frequencies were investigated. Theoretical calculation of the sound intensity vector was based on Rayleigh’s integral formula and the finite difference approximation of pressures to determine the particle velocity of sound in the fluid medium. The theoretically determined nearfield sound intensity distributions agreed well with the experimental measurements carried out using the two microphone method. Energy lines plotted on radial planes using the method suggested by Waterhouse et al. [3] for the axisymmetric modes of vibration showed the presence of vortex lines close to the nodal lines. The recirculating energy zones appeared to increase with the number of nodal circles, with the farfield radiation predominantly emanating from the center and outer edges of the plate. The theoretical results also revealed the existence of recirculating energy zones for the nonaxisymmetric modes of vibration.