Experimental study on supercavitating flow by injection of 773 K ventilated gas

This study presents an experimental investigation of the characteristics of a ventilated supercavitating flow using high-temperature injection gas (VSHTG). Experiments are conducted in the cavitation tunnel located at the Chungnam National University in South Korea. Ventilation gas heated up to 773 K (500 °C) is injected behind a disk-type cavitator. The geometric characteristics of the VSHTG appearing with the temperature rise are captured using a high-speed camera, and the temperature characteristics inside the ventilated supercavity are measured using two K-type thermocouple temperature sensors. A theoretical physical model hypothesis is proposed, which is used to explain the VSHTG geometry variation with the increase in temperature and predict the thermodynamic effect caused by the injection high-temperature gas. Finally, the liquid–gas interface deformation of the VSHTG is examined using a colorimetric analysis. The results show that hot gas injection may increase the length of the supercavity and also make the liquid–gas interface unstable. A theoretical model of the thermodynamic effects is proposed and gives good agreement with the measurements. However, the findings should be further verified through additional studies including numerical analysis and experiments in a larger test section with the lower blockage ratio.