Turbulent Flow-Induced Self Noise and Radiated Noise in Naval Systems—An Industry Point of View

Abstract

In naval warfare strategy, different scenarios are considered according to vessels involved and most of the time their acoustic performances determine the advantage of one over the other. To succeed, the vessel needs to be the most silent while being the most efficient in detecting the others. That is why naval reducing both the ship far field radiated noise and the self noise affecting sonar array efficiency is a permanent matter of concern for the naval industry. Several phenomena have to be considered to describe far field radiated noise and self noise. This study focuses on contributions generated by flow noise phenomena induced by Turbulent Boundary Layer (TBL) along the hull. In order to fulfil contractual commitments and design requirements, naval industry has to know how to model these phenomena to predict acoustic performances as accurately as possible. Nowadays, several models enable to describe TBL excitation from which it is possible to calculate vibro-acoustic response by different ways according to the phenomenon and the frequency range considered. In this study, flow noise phenomena induced by TBL in the hydro-acoustic studies of naval vessels and Chase model [3] are first described in general. Then, different modelling techniques of noise prediction are especially introduced for TBL excitation generating self noise on the sonar array located inside a cavity [1, 7] and far field radiated noise through external structure response. To illustrate the problems the naval industry has to deal with, some practical examples are discussed.