钝体超空泡倾斜穿过自由面出水实验及数值模拟

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

超空泡弹体带迎角地穿过自由面时,自然空化空泡转变为充气空泡,这个过程对于评估潜射导弹的可靠性非常关键。本文对该过程进行了实验研究、理论分析和数值模拟。研究发现,当超空泡倾斜地与自由面接触后,更容易形成充气空泡。当水中物体突然进入空气中,物体速度会有一个跃增。应用数值仿真软件,采用多相流模型模拟了航行体倾斜出水时超空泡从生长到溃灭的整个过程。计算结果表明,当超空泡物体接近自由面时,自由面抬高隆起,超空泡下部的压力大于上部的压力。但是通过对比实验数据后发现,计算软件中的Schnerr and Sauer空化模型不适用于超空泡与自由面相互作用之后的充气空泡。

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 Ansys 14.0 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.