Abstract: During the launch of submarine launched missile with a gas-steam ejection system, an outlet cavity is formed because of a strong interaction between water and gas. The development of cavity has an effect on the motion of missile. Dynamic mesh and MIXTURE model are used to simulate the law of development of cavity: expansion, contraction and disruption. Pressures at different locations and the transmission process of pressure are also discussed. The shape of cavity is proved to have a negative correlation with the cavity pressure. The simulation result can be used for engineering prediction.

Key words: fluid mechanics, outlet cavity, submarine launched missile, MIXTURE model