Numerical study of the dynamic characteristics of an air-gun bubble generated above the solid boundary

摘要

Air gun has become a common tool in deep-sea resource explorationfor its low cost and green environmental protection. Due to the highlycompressed air inside the air-gun chamber is released for a brief time,sound wave is generated almost simultaneously. However, an undesiredair-gun bubble is generated subsequently, which causes the reduction ofthe signaloise ratio and threaten the survivability of the air gun. Thusthe study of the air gun bubble is of great significance, especially thenear field pressure caused by the air gun. This paper systematicallyinvestigated the dynamic characteristics of an air-gun bubble oscillatingabove the solid wall; the bubble shape, jet formation and upwardmigration of bubble center etc. were main focus on. As bubble’s motionhas the features of high-speed and large-deformation, boundary elementmethod was adopted to simulate the motion of the bubble. In thesimulation, the formation of the air-gun bubble is divided into twophases, i.e., gases moving into the bubble from air-gun chamber and thesubsequent bubble freely oscillating. Finally, we discussed theinfluence of time length of the bubble aeration and standoff distancefrom bubble to the solid wall.