Low-frequency sound radiation of marine object

Abstract

Object and purpose of research. This paper discusses induced noise radiation into water from spherical uniform bodies and spherical shells to estimate the acceptability of commonly used simplified approach to prediction of low-frequency acoustic signatures for marine objects. Materials and methods.The calculations were performed as per analytical expressions and numerical simulation techniques (FEM). Main results. The study has shown that increasing the density of radiating body and increasing mechanical resistance of shell at the location of exciting force reduces noise radiation. Resonant noise radiation typically occurs due to structural non-uniformities of marine objects, like local masses needed to ensure zero buoyancy, e.g. equipment or ballast. These nonuniformities create reactive forces that reach their peak values at resonant frequencies of the hull. Conclusion. The study concludes that reliable computational estimate of low-frequency acoustic signatures must take into account both mechanical resistance and non-uniform distribution of masses along hull, which can be done in numerical simulation packages.