Experimental Investigation of Splashes from Hypervelocity Water Entries

The results of an experimental investigation of the impact of steel spheres through a water surface with a range of velocities from 1740--2314 m/s are presented. Particular attention is given to characterizing the splash development and the influence of velocity and entry interface material on the splash dynamics. The splash is observed to be divided into four phases: a fast-moving cloud of atomized spray, a pause, a slower bulk liquid ejection, followed by a faster liquid flow. With increasing impact velocity, the pause phase is shorter in duration, while the slow ejection phase is longer. The effect of adding a thin plastic film over the entry region lengthened the duration of the bulk ejection phase by 28% for an entry velocity of 2000 m/s, but had no effect on the spray phase duration. For all velocity and entry material conditions, the spray phase duration remained nearly constant.