Abstract This work experimentally investigated vapor condensation on hydrophobic and hierarchical superhydrophobic surfaces with microgroove arrays to study the influence of groove orientation on the condensed droplet dynamics and heat transfer. This study showed that dropwise condensation on hydrophobic surfaces with microgroove arrays strongly depended on the groove orientation owing to the anisotropic wettability. The suction effect of a large droplet spanning several grooves on the liquid filaments filling the microgrooves was demonstrated on a hydrophobic surface with horizontal microgrooves with the phenomenon disappearing on a hydrophobic surface with vertical microgrooves. Furthermore, the horizontal microgrooves resulted in larger droplet departure sizes, significant deformation and retention of falling droplets, and the elimination of the liquid filaments sliding down the surface. The heat flux on the hydrophobic surface with horizontal microgrooves was 10–30% lower than on the plain hydrophobic surface. However, the groove orientation had less influence on the hierarchical superhydrophobic surface with microgroove arrays. At small surface subcooling, the hierarchical surface was rejuvenated through condensed droplet jumping and jumping-induced sweeping, the dominate droplet behavior transformed to coalesced droplet sweeping and the falling of suspended droplets with increasing surface subcooling. The dominate droplet behavior was little influenced by the groove orientation on the hierarchical superhydrophobic surface. Consequently, the heat flux was increased by 35–107% on both hierarchical superhydrophobic surfaces with microgroove arrays compared to the hydrophobic surface with vertical microgrooves.

中文翻译：

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凹槽取向对具有微凹槽阵列的疏水和分级超疏水表面上滴状冷凝的影响

摘要 这项工作通过实验研究了具有微槽阵列的疏水和分级超疏水表面上的蒸汽凝结，以研究凹槽取向对凝结液滴动力学和传热的影响。该研究表明，由于各向异性的润湿性，具有微槽阵列的疏水表面上的逐滴冷凝强烈依赖于凹槽方向。在具有水平微凹槽的疏水表面上证明了跨越多个凹槽的大液滴对填充微凹槽的液体细丝的抽吸作用，在具有垂直微凹槽的疏水表面上现象消失。此外，水平微槽导致更大的液滴离开尺寸、显着的变形和落下液滴的滞留，并消除从表面滑下的液体细丝。具有水平微槽的疏水表面的热通量比普通疏水表面低 10-30%。然而，凹槽方向对具有微凹槽阵列的分级超疏水表面的影响较小。在小表面过冷度下，分层表面通过冷凝液滴跳跃和跳跃诱导扫掠而恢复活力，主导液滴行为转变为聚结液滴扫掠和悬浮液滴随着表面过冷度的增加而下落。主要的液滴行为几乎不受分级超疏水表面上凹槽方向的影响。最后，