EXPERIMENTAL INVESTIGATION ON THE MOTION FEATURE OF INCLINED WATER-ENTRY OF A SEMI-CLOSED CYLINDER

The objective of this present study is to address the cavitating flowing characteristics and kinetic features in inclined water-entry created by a semi-closed cylinder. For this purpose, based on the high speed camera technology, an experimental study of the inclined water-entry of a semi-closed cylinder are investigated. According to the results of the experiment, the special fluctuation flow pattern form of the semi-closed cylinder cavitation is found around the body and the typical kinetic motion law is gained by analyzing the cavity image data. A further insight into the influence of the initial impact velocity and attitude on the movement characteristics such as water trajectory and cavity shape is discussed. The obtained results show that the cavitation flow pattern form of fluctuation cavitation appears two cavity deep closure successively. The cavity evolution of water entry alerts the hydrodynamic distribution, and then influences the movement pattern of the semi-closed cylinder and trajectory characteristics. The internal flow of the cylinder is relatively independent of the flow filed. Interestingly, a periodic flow occurs at the open end. We also found that the surface pressure on the lower wall of the model is larger, which is related to the stability of the water entry. With the increase of water velocity, the characteristics of cavitation fluctuation are obvious, the closing time is delayed and the lateral displacement caused by asymmetric deepening is reduced, but the deflection angle is independent of the inlet velocity. As the initial attitude inclination decreases, the degree of cavitation fluctuation decreases, the closing time is delayed, both the deflection angular velocity and the lateral displacement are increasing subsequently.