Parameters and influence of gas injection on modification of cavitation stability

Cavitation occurs around high-speed underwater vehicles, which induces shedding and collapse of bubbles with noises, vibration, etc. Gas-injection is an important method to adjust the unstability of cavitating flow field. In this paper, dimensionless quantities are got though the dimensional analysis on ventilated cavitation. Among these dimensionless quantities, the ratios of mass flux and momentum flux of the gas-injection to those of the main flow are crucial in ventilated cloud cavitation. Numerical simulation is carried out on these two dimensionless quantities. The results indicate that gas-injection mass flux has greater impact on the evolution of ventilated cavitation than momentum flux. As gas-injection mass flux increases, the form of gas entrainment changes from bubbles to air-layer. Besides, increase of gas-injection mass flux can reduce the high pressure at the closure of the cavity and improve the pressure stability while it can also lead to the rise of drag of the vehicle. Gas-injection momentum flux has little effect on the evolution and pressure. Increase of gas-injection momentum flux can reduce drag of the vehicle.