膜态沸腾阶段球体入水空泡及流体动力特性

The cavitation evolutions in water entry processes of sphere during film boiling and the hydrophilic and superhydrophobic room temperature spheres were recorded using a high-speed video camera. The curve of water entry depth is obtained by image processing. Based on computational fluid dynamics method, the volume of fluid (VOF) multiphase flow model and evaporation-condensation model are used to simulate the water entry process of sphere. The numerical results are in good agreement with the experimental results. The results show that the film boiling sphere can produce the same smooth cavitation as the superhydrophobic sphere does. The line of contact between the superhydrophobic sphere surface and the cavity wall is slightly above the center of the sphere. A vapor layer exists between the bottom of film boiling sphere and the water, the cavity wall does not contact with the surface of sphere, and the cavity diameter near the sphere is relatively large. When the water is shallow, the drag coefficient of hydrophilic sphere is relatively large; and when the water is deep, the drag coefficients of superhydrophobic and film boiling spheres are relatively large.