Interaction of clustered air gun bubbles in marine prospecting

Abstract

The study of air gun bubbles is significant to marine resource detection, and the use of clustered air guns is an effective way to reduce the undesirable bubble pulse in engineering applications. In this paper, an improved air gun bubble model is established based on the boundary element method. The mass and heat transfer of the gas from the air gun chamber to the bubble, and the heat transfer between the bubble and surrounding water, are taken into consideration. Using this model, motion of non-spherical clustered air gun bubbles is simulated. Through consideration of the bubble topology under coalescence and splitting, the multi-period pressure waves released from the clustered air guns are successfully calculated. The influence of the separation distance and the volume distribution of two bubbles on the far-field pressure wave are then investigated. A critical value for the distance between two bubbles, at which the bubble pulse is effectively suppressed, is found. Changing the bubble volume distribution not only reduces the bubble pulse but also decreases the primary pulse, provided the volumes of the two bubbles are not equal. Finally, the pressure waves generated by three bubbles and by two bubbles are compared. Although pressure waves from three bubbles have a long period, the bubble pulse attenuation effects are almost the same as those for two bubbles.