Dynamics of the interaction between explosion bubble and free surface

A strong coupling effect between the bubble and water occurs when an explosive bubble expands and contracts near the water surface, leading to the complex changes of the flow field and various shapes of water plumes. An experimental system for small equivalent of charge RDX is designed to investigate the relations between the shapes of water plumes and the changes of the flow field. Two synchronized high speed cameras are used to record the changing process of the shapes of bubbles and water plume. Three typical shapes of bubble and six typical shapes of water plumes are observed. By theoretical analysis and direct observation of flow field changes among the bubble, the water surface, and the air, the evolution rule and formation mechanism of the six shapes of water plumes are already revealed. Experimental results are also compared with that from the experiment of bubbles formed by electric spark. Through statistical analysis of bubble radius, expansion time, pulsation period, and bubble boundary movement, the dynamic process of bubble formation in near water surface explosion is clarified.