Experimental and numerical study of oblique water exit in free surface penetration by a blunt body's supercavity

The supercavitation technique has important military applications such as underwater launched ballistic missiles, high-speed torpedo, airborne sea mine clearance system, etc. The relevant fundamental study was carried out in USSR and USA in 1960's and 1970's era respectively. Since the year of 2001, Chinese scientists have begun intensive and broad study on this subject and many innovative results have been achieved. This paper presents the research on the inclined water-exit of supercavitating vehicles through experimental, theoretical and numerical methods. It is found that when the supercavity is in touch with the free surface, a ventilated cavity is formed easily. When the underwater body jumps into air, it obtains a sudden increase in velocity. Using Ansys14.0 software and VOF multiphase flow model, the whole process from the cavity growth to its collapse in the inclined water-exit has been simulated. The computational results show that when the supercavitating body approaches the free surface, it piles up and the pressure at the lower part of the cavity is greater than that at the upper part of the cavity. However, after comparing with the experimental data, it is found that the cavitation model of Schnerr and Sauer used in the software is not suitable for the ventilation of the supercavity after its interaction with the free surface. This paper's work emphasizes the research strategy of conducting all of the experiment, theoretical analysis and numerical simulation for the problem.