For the anti-icing technology of hydrophobic coating on turbine blades, the influence of the hydrophobic surface with micropatterns on the impact characteristics of water droplets is studied in present manuscript. The spreading and retraction characteristics of water droplets with diameters of 2~10 μm on micro-structured surface is numerically investigated in present research by volume of fluid (VOF) and Level-set coupling method, and the influence of surface micropattern geometry and water droplet diameter on the spreading and retraction process is analyzed in detail. It is found that the ratio of water droplet diameter D₀ to micropattern size P has a significant effect on the dynamic process and final shape of the impact on the same micropatterned wall; and the surface shows obvious hydrophobicity when the ratio of water droplet diameter D₀ to micropattern size P is 2 ≤ D₀/P ≤ 4 and the movement of water droplets on the surface is in accordance with the description of the Cassie model, although the contact angle of substrate material is 86°. However, the dynamic process and final shape of water droplets are similar to those on a smooth plane with the contact angle of 86° when D₀/P ≤ 1. In addition, when the water droplet impacts the micropatterned surface with 2 ≤ D₀/P ≤ 4, the spreading coefficient on the micropattern surface is less than 1.0 and the dimensionless spreading period gradually lengthens with the increase of D₀/P value attributed to the large pressure gradient near the three-phase line

Keywords: Spreading and retraction, Water droplets, Micropattern, Hydrophobic surface, Wind power engineering, VOF computational model.