Sound produced by an aerodynamic source adjacent to a partly coated, finite elastic plate

Results of an analysis of the scattering of bending waves at the edge of an unbaffled thin elastic plate in the presence of arbitrary fluid loading are presented. Detailed predictions are made of the sound scattered from free and clamped edges, and empirical formulas are given for the radiation loss factor over a range of frequencies and fluid loadings. Application is made to the generation of sound by an aerodynamic dipole source adjacent to a finite plate, a finite length of which was treated with damping material. When the edges can vibrate freely, it is shown that a relatively modest amount of damping is sufficient to reduce the edge-generated sound to levels below those of the direct radiation. The efficiency with which bending wave energy is converted into sound is much larger for clamped edges, and larger values of coating loss factor and length are necessary to achieve significant reductions in the structural component of the radiated sound.