Sung H. Ko
Naval Undersea Warfare Ctr. Detachment, New London, CT 06320
Turbulent boundary layer pressure fluctuations can be reduced by filtering either a wave number through a finite hydrophone or a hydrophone array or by filtering the wave number through an elastomer layer. In general practice, various configurations of hydrophone arrays are embedded within a layer of elastomer, thus reducing the turbulent boundary layer pressure fluctuations. The theoretical model considered in this paper is a plane elastomer layer backed by an infinitely rigid surface; the other side of the layer is exposed to turbulent flow. This paper examines the performance of shaded, rectangular and circular hydrophones for the flow noise reduction. The rectangular hydrophone is shaded with a triangular or semicircular loading. Similarly, the circular hydrophone is shaded with a conical or hemispherical loading. Numerical calculations were made for both flush-mounted and embedded hydrophones. The results presented are comparisons of numerically calculated noise reductions between shaded and unshaded hydrophones.