On underwater sound radiation in a towing tank induced by continuous machine vibration in a steel circular cylinder

Abstract

An understanding of the characteristics and mechanisms of structural vibrations produced by underwater vehicles is required to reduce sound radiation in submarine environments. In this study, experiments were performed using a continuously running machine to produce low-frequency vibrations in a submerged, watertight, steel circular cylinder in the centre of a 176 × 8 × 4 m³ towing tank, and the underwater radiation sound field was measured. Finite element method simulations of the system were also performed and showed good agreement with the experimental results. The wall effects of the towing tank were simulated in detail by changing the alternative impedances of the wall. The reflection and acoustic impedance of the towing tank walls were found to significantly affect the underwater sound field in both the experiments and simulations. An analytical solution was used to verify the frequency range applied in the simulation analysis. The results of this study provide a measurement procedure and a simulation method, which can be used to evaluate the underwater radiation sound field from the vehicle machine running in the water at wall boundary environment.