SUPERSONIC ACOUSTIC INTENSITY ON PLANAR SOURCES

The concept of supersonic acoustic intensity was developed in 1995 out of a need to locate the sources of radiation on an internally excited , submerged cylindrical shell. Supersonic intensity is obtained throug h signal processing of near-field holographic data to remove the subso nic part of the helical or plane wave spectrum, leaving only the radia ting components. This eliminates the out-of-plane circulation of the a coustic intensity vector which results from evanescent waves. The resu lting supersonic intensity on the surface is generally only positive, representing outgoing power flow from the surface. Since negative inte nsity regions of a vibrator are removed, sources of radiation are read ily located on the surface of the vibrator. Since the earlier work con centrated on a cylindrical geometry, the theory is presented here for a planar geometry. In many ways the theory for the planar case is simp ler and more straightforward. Numerical examples are given for simply supported, baffled plates. It is shown how the supersonic intensity re constructions, and resulting location of radiating source regions are consistent with the popular theories of corner and edge mode radiation from plates. [S0001-4966(98)05810-X]