Modélisation du transducteur BF "Janus-Helmholtz". Nouvelle interprétation du fonctionnement et application à la tomographie acoustique de l'océan

Abstract
Ocean Acoustic Tomography (measurement of the dynamic behaviour of the ocean) has needs for low frequency, high efficiency, broadband and great depth transducers, in order to reach ranges above 500 km [1]. The double-ended longitudinal "Janus-Helmholtz" projector designed by DCN INGENIERIE SUD widely answers these requirements. An attractive characteristic of such a transducer is the coupling between two resonances implying a large bandwidth. The first observed resonance is usually interpreted as a Helmholtz resonance and the second one as the driver resonance. First part of this study is about the working principles of the Janus-Helmholtz source. Two modelling tools have been used : the finite-element code ATILA and an equivalent circuit model. Thanks to them, a new interpretation of each resonance has been obtained and this transducer has then been optimized for acoustic tomography.