Experimental investigation of droplet oscillation and impact on hydrophilic and hydrophobic surfaces with varying wettability

A liquid repellent surface can potentially be used to reduce ice accretion on surface and improve asset integrity and safety in harsh environment. Icing on a hydrophobic surface is affected by the oscillation of water droplets impacting on the surface. This paper uses a statistical design of experiments method to investigate the effects of surface temperature (A), impact speed (B), droplet temperature (C), and surface wettability (D) on the oscillation time of a droplet. The Design Expert software was used to analyze 38 data points. It was found that the impact speed and surface wettability are significant factors. The interaction effect between surface temperature and droplet temperature, and that between surface temperature and surface wettability are also significant. The oscillation time increased significantly on a hydrophobic surface. Visualization with a high-speed camera showed that the liquid droplet started to freeze at the moment when the oscillation fully stopped.