Formation and steady flow characteristics of ventilated supercavity with gas jet cavitator

Substantial discrepancies in the formation and attainment conditions for different ventilated cavities are the characteristics of the cavitator and ventilation condition. In this study, a systematic experimental investigation on the concept of using a gas nozzle at the tip of the object as both the cavitator and the ventilation hole to form a supercavity was performed in a gravity water tunnel. The formation, elimination process and steady shape of the gas jet ventilated supercavity, were observed and measured. The dependence relationship of the dimensionless parameters of gas jet length, maximum cavity diameter, cavitation number, Froude number and ventilation coefficient were provided based on the experimental data. With the velocity increases in the test section, the irregular cloud cavitation, evolving with a gas jet wake, appears, and the gas jet wake flows to the back upper location. After that, an ellipsoidal bubble located in front of the gas jet cavitator within a certain distance is observed. Eventually, the ellipsoidal bubble gradually grows to a large bubble and cavity, then develops to a supercavity with increasing of the incoming flow velocity in the test section.