Experimental study on the influence of air injection on unsteady cloud cavitating flow dynamics

The main purpose of this study was to investigate the influence of air-injection technique on unsteady cloud cavitating flow dynamics. High-speed camera and pressure measurement system are used to record ventilated cavitation images and wall-pressure fluctuation in a convergent–divergent channel, respectively. The measured ventilated cavitation evolution process and corresponding wall-pressure fluctuation are compared with those obtained under non-ventilation condition. The results show that air-injection technique can significantly suppress pressure pulses induced by cavity collapse. Furthermore, by increasing ventilation rate, the time evolution of cavitation tends to be more stable, the wall-pressure fluctuation magnitude is reduced significantly, and the cloud shedding frequency is reduced, which is believed to be related to the interaction between injected air and re-entrant flow.