Abstract:

Droplet jumping phenomena on superhydrophobic surfaces hold high application value in efficient heat dissipation, corrosion resistance, anti-icing, and other fields on chips. To investigate the influence of dual-groove channels on droplet jumping performance, various W-shaped groove superhydrophobic surfaces composed of dual V-grooves were designed and fabricated. The effects of the groove bottom spacing w and the groove depth h of the W-shaped groove on the bouncing velocity and energy conversion efficiency of the droplet were investigated experimentally. Numerical simulations were employed to study the evolution of surface energy during droplet merging and jumping on W-shaped groove superhydrophobic surfaces. The results show that the radius of droplets adapted to the W-shaped groove with a groove width of 0.9 mm is 0.5—0.9 mm, and the effect of droplet merging and jumping is more significant in this range when the groove depth h is 0.5—0.8 mm, and the groove bottom spacing w is 0.5—0.8 mm. As the radius of the droplet decreases, the depth of the channel increases, and the distance between the bottom of the channel decreases, the bouncing velocity increases. The bouncing velocity increased when the groove parameter was increased simultaneously within 0.5—0.7 mm and decreased at 0.8 mm. The results lay a theoretical foundation for surface design in the fields of condensation heat transfer and corrosion prevention.

Key words: droplets jumping, superhydrophobic surface, droplet jumping enhancement, two-phase flow, interfacial tension, numerical simulation

摘要：

超疏水表面上的液滴弹跳现象在芯片高效散热、防腐蚀、结冰等领域具有较高的应用价值。为研究双槽道对液滴弹跳性能的影响，设计并制备了由双V槽道构成的W型槽道超疏水表面，试验研究了W型槽道底部间距w、槽道深度h对液滴弹跳速度及能量转化效率的影响，采用数值模拟方式研究了W型槽道的超疏水表面液滴合并弹跳过程中表面能的演化。结果表明，槽宽为0.9 mm的W型槽道所适配的液滴半径为0.5~0.9 mm，此范围内槽道深度h为0.5~0.8 mm、槽道底部间距w为0.5~0.8 mm时对提升液滴合并弹跳的效果更显著；随着液滴半径减小、槽道深度增加、槽道底部间距减小，液滴的合并弹跳速度增加；槽道参数在0.5~0.7 mm内同时增加时，弹跳速度增加，而在0.8 mm时降低。研究结果可为冷凝换热和防腐蚀等领域的表面设计提供参考。

关键词: 液滴弹跳, 超疏水表面, 弹跳强化, 两相流, 界面张力, 数值模拟