Bulles Navire

Bubble generation by wave breaking and body-wave interaction is a source of diverse interest. For naval ships, this kind of bubbles generates underwater sound and a wake visible far behind the ship. In the particular case of research vessels, bubble generation must be avoided to reduce the degradation of acoustic equipment performances. Indeed, in bad weather conditions, the ship bow wave generates a significant aeration carried out by the flow under sonar locations. This phenomenon of bubble sweep-down must be prevented as much as possible in order to ensure high
quality acoustic surveys, even if today there are no experimental and numerical tools allowing the exact reproduction of bubble generation by a ship's bow under waves and motions. Ifremer have launched a research program, based on PhD works [1 ; 2], for the better knowledge of this specific diphasic phenomenon. The obtained results have been valorized through several scientific papers :

  • an in-situ study for the characterization of the sub-surface bubbles occurrence conditions from acoustic data analysis acquired during surveys in relatively shallow water with the IFREMER research vessels Thalassa and Pourquoi Pas?
    Bubble sweep-down occurrence characterization on Research Vessels ; S. Delacroix, G. Germain, L. Berger, JY. Billard, Ocean Engineering 2016.

An upcoming paper will complete this work by the comparison of three kinds of bow shape on the bubble clouds occurrence. Even if this work does not allow to answer to the entire problematic, the experimental setup developped here forms a reliable tool that simplifies the design research vessels.

[1] Sylvain Delacroix, Caractérisation de la génération et de la propagation de bulles autour de la carène des navires scientifiques, PhD Thesis 2015, Université de Bretagne Occidentale (DGA/Ifremer).
[2] Bachar MALLAT, Étude du phénomène d'aération sur les carènes des navires océanographiques, PhD Thesis (in progress), Université Lille Nord de France (Région Haut de France/Ifremer).