Experimental Study of Liquid Droplet Dynamic Behaviors Impacting on Surfaces with Different Hydrophilicity/Hydrophobicity

Impact of droplets with low velocity on surfaces with different hydrophilicity/hydrophobicity was studied experimentally with a high speed camera at 4000 fps. Experiments were performed at normal pressure and temperature. Droplets with diameter of (2.25±0.02) mm impacting on different solid surfaces at three kinds of velocity, and morphological parameters such as spreading diameter D and drop height h of impacting droplet were obtained using image processing technology under different circumstances. Results show that D and h are both greatly influenced by impacting velocity of droplet and the hydrophilicity/hydrophobicity of solid surface. At the same speed, the maximum spreading diameter D on hydrophilic quartz glass is larger than others, with smaller degree of retraction. And the spreading process requires for longer time. On the same solid surface, the maximum spreading diameter D increases with impacting droplet velocity (0.94 m/s to 1.64 m/s). Meanwhile, the cycles of drop height oscillation from lows to highs until balance decrease and the time required for balance decreases.