Effects of Surface Wettability on Cavitation Inception and Cloud Cavitation

A small-scale water tunnel combined with high-speed imaging is utilized in this research to investigate Cavitation Inception and Cloud Cavitation on a Venturi-type test model. The formation of microbubbles on the diverging part of the Venturi is captured and analyzed using continuous back-lit illumination. To understand the surface wettability effects on inception and cloud cavitation, the model’s top surface, measuring 66.1 mm in length and 5 mm in width, is engineered into a range of wettable surfaces with contact angles from 60° to 160° via chemical etching and spray coating techniques. This research is essential to comprehend the impacts of surface wettability on the cavity length and shedding frequency of cloud cavitation, as well as the location and size of cavitation inception bubbles. To analyze the flow field visualizations around the diverging section of the Venturi model, various steps of image processing techniques are followed. The obtained results clearly state that surface wettability strongly impacts the cavitation phenomenon, by altering the size of the bubbles, changing the bubble’s growth evolution and collapse, varying the shedding frequency of the cloud cavitation bubbles, and overall affecting the flow dynamics.