Influence of Blade Surface Super-hydrophilic and Super-hydrophobic Property on Formation of Secondary Droplets

To reduce the erosion damage of low-pressure turbine blades by water impact, considering the formation mechanism of secondary water droplets, a suggestion was proposed to take super-hydrophilic and super-hydrophobic treatment to relevant blade surfaces, based on which a test platform was set up to simulate the process of water film fragmentation on the super-hydrophilic and super-hydrophobic surfaces, and the process of formation of secondary droplets in the steam turbine. The particle size and velocity of water droplets were measured using single frame single exposure imaging method, and subsequently the influence of surface hydrophilicity and hydrophobicity of simulation blades on formation of droplets was analyzed. Results show that, compared with ordinary and super-hydrophobic surface, small-sized droplets are easy to generate on the super-hydrophilic blade surface, which will be carried over by main steam flow, and therefore producing slight water droplet impact damage; super-hydrophilic treatment to stationary blade may help to reduce the water droplet impact damage.