Multiple acoustic sources localization in a water tunnel using the modal theory

Abstract

The underwater radiated noise of a ship is of particular interest since several decades. This is due to the concern of acoustic stealth in military applications but not only: its influence on marine life has seen an increasing preoccupation recently. It exists two main ways to estimate the future radiated noise of a boat: performing experimental tests at a model-scale (the preferred approach still now) and computing the radiated noise by numerical methods. These latter are still suffering of low accuracy even if important recent progresses are encouraging for the future. The experimental approach consists of performing measurements in a hydro-acoustic tunnel with a faithful model and scaling the results obtained to the full-scale. Among many details that could generate in-accuracy of the prediction, we focus on the localization of the sources at the model-scale step. We propose to use the modal approach to determine the position of the sources, their magnitudes and phase. Results of computations are then presented. The method appears efficient especially at low frequencies for which the modal approach is designed for. This novel approach allows the determination of the number of sources present in a section of a cavitation tunnel. The acoustic fields computed thanks to the results provided by the method is very accurate.