Prediction and experimental evaluation of the threshold velocity in water droplet erosion

Abstract

Gradual wear of materials due to repetitive high-speed impacts of water droplets is a serious reliability concern for blades of gas, steam, and wind turbines. The phenomenon is commonly referred to as water droplet erosion (WDE). Analogous to fatigue, WDE has an endurance regime, called threshold velocity, where material resists erosion damage for prolonged exposure. The ability to predict the threshold velocity from material properties is crucial for the prevention of WDE phenomenon. In the past decades, developing models to predict the threshold velocity have been attempted. This has resulted in one semi-analytical model and several empirical equations, all of which exhibited limitations in applicability and physical meaning. Drawing on previous attempts along with contemporary theoretical and experimental investigations of WDE phenomenon, we report on the prediction of threshold velocity using an analytical model. The developed model represents the WDE threshold velocity using materials properties and impact conditions. A procedure to experimentally evaluate the threshold velocity in rotating erosion test devices has also been developed. The developed model predicted threshold velocities with higher accuracy than the previous analytical model. The present work introduces an important tool to the design and selection of WDE resistant materials.

Keywords

• Water droplet erosion
• Rain erosion
• Threshold velocity
• Prediction models