Radiation field prediction system using solutions of exterior steady-state radiation problem

We have been studying a radiation field prediction system for an acoustic source that has an arbitrary shape. First. the nearfield sound pressure distribution around the source is measured and the normal velocity distribution over the surface of the source is predicted using the equivalent phased array method (EPAM). Then, radiation characteristics of the source, such as the pressure field, are predicted using the combined Helmholtz integral equation formulation(CHIEF). First in this paper, EPAM based on solutions for the exterior steady-state acoustic radiation problem is described. This method is applicable for predicting the normal surface velocity for sources that have an arbitrary shape. Then, an experimental example using a cylindrical source is presented. The predicted result of the pressure field is shown. and then the validity of this radiation field prediction system is confirmed by comparing the predicted pressure field with the actual field. The influence of the aperture restriction for the measurement contour on the surface of normal velocity predicted by EPAM is discussed. It is found that the error between the predicted and the ideal velocity distribution becomes smaller as the measurement contour covers the cylinder,