乙醇-水混合液滴撞击超疏水表面的飞溅特性

Splash characteristics of ethanol-water mixture droplets impacting on superhydrophobic surfaces

对乙醇-水混合液滴撞击微纳结构表面的动态行为进行了可视化观测,分析了单液滴撞击超疏水表面的飞溅特性,研究了乙醇质量分数以及韦伯数(We)对液滴动态演化行为的影响。实验结果表明:液滴与固体表面湿润性变化对液滴最大铺展因子以及液滴铺展时间影响较小。随着液滴中乙醇质量分数的增加,液滴与固体表面的静态接触角减小,液滴发生飞溅需要的韦伯数逐渐增加。当液滴与固体表面的本征接触角小于90.00°时,液滴撞击微纳结构表面后处于Wenzel状态,使得液滴铺展后的回缩、反弹行为消失,液滴发生破碎需要的韦伯数陡然增加。

The dynamic behavior of ethanol-water mixture droplets impacting on superhydrophobic surfaces with micro/nano structures was observed using high-speed photography.This study analyzed the splash characteristics of a single droplet impacting a superhydrophobic surface and investigated the effects of ethanol concentration and the Weber number(We)on the droplet dynamic evolution.The experimental results indicate that the surface wettability has only a minor effect on the maximum spreading factor and the spreading time.With increasing ethanol concentration,the static contact angle between the droplet and the solid surface decreases,while the minimum Weber number required for droplet splashing gradually increases.When the intrinsic contact angle is below 90°,the droplet is in the Wenzel state after impacting the micro-nano structured surface,which causes the disappearance of the retraction and rebound after the droplet spreading,and the sharp increase in the Weber number required for droplet fragmentation.