不同间距下过冷水滴连续撞击超疏水表面的数值研究

Numerical study of supercooled water droplets continuously impacting a superhydrophobic surface with different spacings

  • 摘要: 过冷水滴撞击飞机表面后形成的积冰严重威胁着飞行安全,积冰通常是由多个液滴共同作用形成的,明晰多过冷水滴间的相互作用对撞击-结冰过程的影响具有重要意义。本文基于流体体积法,结合凝固/融化模型,数值模拟了双过冷水滴连续撞击冷超疏水表面的动力学行为,研究了液滴间距对双液滴动态行为和传热特性的影响。结果表明:随着液滴间距的增加,双液滴依次出现了“内部铺展”“表面铺展”和“包裹式铺展”3种混合模式,最大铺展系数由不变过渡到增大,双液滴的聚集行为逐渐加剧,液滴与冷壁面的传热效果随之增强,其中,液滴与冷表面的接触面积是影响传热的首要因素;此外,双液滴相互作用过程中液滴内部形成的旋涡会阻碍液滴的水平铺展,从而避免铺展面积的增大。

     

    Abstract: Ice accretion from supercooled water droplets impacting aircraft surfaces poses significant flight safety risks. As ice formation typically results from collective droplet interactions, understanding multi-droplet dynamics during impact-freezing processes is crucial. This study numerically investigated consecutive impacts of dual supercooled droplets on a cold superhydrophobic surface using the volume of fluid method coupled with a solidification/melting model. We examined the effects of droplet spacing and the Weber number on spreading behavior and heat transfer characteristics. Three distinct mixing modes emerged at low Weber numbers: internal spreading, surface spreading, and encapsulated spreading. Increasing droplet spacing sequentially triggered these modes while transforming maximum spreading behavior from constant to increasing values. Enhanced droplet aggregation accompanied larger spacing. In the internal spreading mode, vortices developing within dual droplets impeded horizontal spreading, thereby limiting spread area progression. Moreover, increasing droplet spacing enhanced the heat transfer between the droplets and the cold surface, where the droplet-surface contact area emerged as the dominant thermal factor, outweighing local heat transfer coefficient effects. This investigation advances understanding of consecutive dual-droplet dynamics and thermal transport on superhydrophobic surfaces, contributing to improved anti-/de-icing strategies.

     

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