Experimental investigations on the oblique water entry of hollow cylinders

Abstract

The oblique water entry of hollow cylinders with four different apertures is investigated experimentally at low velocities. The evolution characteristics of cavities, jets and splashes with different initial conditions and apertures are disclosed and discussed. The results show that the transition of cavity closure patterns with increasing water-entry velocities is postponed due to the existing water-entry angle. A curved through-hole jet is discovered and its upward ejecting direction can be altered from right to left by different guidance of the inner wall. The cylinder velocities usually increase first, decrease second and recover gradually again. But the final recovery degrees are different with various apertures, water-entry angles and velocities. Under the clockwise moments in the early cavity evolution, hollow cylinders rotate clockwise continuously underwater.