疏水性微结构表面的抗结冰特性仿真研究

目的探究不同形状微结构表面的疏水、抗结冰特性,以及两者间的关系。方法基于有限体积法对液滴滴落至微结构表面的浸润和凝结过程进行仿真探究。首先建立了具有不同形状微沟槽表面的仿真模型,然后分析了不同微结构表面的疏水特性差异,最后根据不同微结构表面的水滴滴落凝结行为及内部流场的仿真研究,获得了微结构表面疏水性和疏冰性关系,揭示疏冰性产生的原因。结果矩形微结构表面液滴的接触角为109°,表现出疏水特性。锯齿形微结构表面液滴的接触角为162°,表现出超疏水特性。液滴在锯齿形微结构表面上20 ms后凝结率低于2%,抗结冰能力最强。普通表面上的液滴凝结率为4%,低于矩形表面上的6%。对比矩形表面与普通表面上的液滴凝结过程,矩形表面上液滴内部湍流动能是普通表面上液滴的5倍,经过20 ms后,普通表面上液滴近壁面温度下降30 K,同时矩形微结构表面上液滴近壁面温度仅下降10 K。结论具有微结构的表面能表现出疏水性,这种疏水性对抗结冰特性具有双重作用,一方面降低了液滴初期的凝结速度,另一方面加快了液滴在底层形成稳定冰层后的凝结速度。

Simulation Research of the Anti-icing Micro-structured Surface

Objective To explore the hydrophobe and anti-icing character of surfaces with different micro-structures and the link between the two characters. Methods Based on FVM, simulations of the progress including water-drop falling onto the surface were done till its solidification. Firstly the model of surfaces with different micro-structures was established. Secondly, the differences between the hydrophobe of those surfaces were analyzed. Lastly, by comparing the different simulation results of the condensation progress on the surface with different micro-structures, the relationship between the hydrophobe and the anti-icing character was obtained and the reason of anti-icing character forming was disclosed. Results Contact angle of rectangle micro-structured surface was 109°, presenting hydrophobic character, while the contact angle was 162° on the zigzag micro-structured surface, presenting super-hydrophobic character. The condensation ratio of the droplets on zigzag micro-structured surface was lower than 2% after 20 ms, showing the best anti-icing character. The condensation ratio of normal surface was 4%, smaller than that of rectangle surface, which was 6%. Comparing the condensation progress of rectangle and normal surface, the turbulent force of the droplets on rectangle micro-structured surface was five times than that of normal surface. And after 20 ms, the temperature near the micro-structured wall reduced by 10 K, while it reduced by 30 K near the normal wall. Conclusion The micro-structured surface has the hydrophobic character. The hydrophobicity has both positive and negative effects on the anti-icing character. It can slow down the condensation speed on the initial stage. On the other hand, it can accelerate condensation speed after stable ice layer forms at the bottom of the droplet.