Experimental investigation of dissolved gas effects on the inception and desinence of tip vortex cavitation

The present study demonstrates that dissolved gas content affects cavitation behaviour on an elliptical NACA 16-020 hydrofoil, where intermittent tip vortex cavitation (iTVC) is primarily sensitive to inception conditions; in contrast, attached tip vortex cavitation (ATVC) is more strongly governed by cavity persistence and hysteresis characteristics. Experiments were conducted using high-speed visualisation in the Chungnam National University Cavitation Tunnel. Dissolved oxygen (DO) was controlled as a water-conditioning parameter representing the dissolved gas state of the test water (4–10 ppm). The experiments covered cavitation numbers (σ) from 0.91 to 4.35 and Reynolds numbers (Re) from 4.1 × 105 to 6.9 × 105. The results show that as DO increases from 4 to 10 ppm, iTVC inception increases by approximately 35%, whereas ATVC inception shows a weaker increase of about 10%. This behaviour suggests that the pressure in the attached tip vortex core approaches or falls below vapour pressure, thereby reducing the relative influence of water conditioning. Notably, ATVC desinence increases by approximately 20%, exceeding the sensitivity observed at inception. These findings highlight the influence of water conditioning on vortex-dominated cavitating flows within the investigated parameter space, with implications for cavitation prediction, repeatability, and marine hydrodynamic model testing.