冷气流剪切作用下超疏水表面的过冷水滴撞击结冰及抑冰特性

Whether Super-hydrophobic surface can be used for anti-icing has drawn researchers’ great attention in recent years, which may also provide new thought and method for aircraft anti-icing. Most of the reported researches focus on the static, natural convection, non supercooled , regular size droplets (mm), horizontal cold wall, which is far from aircraft icing conditions: high speed cold air flow, shear force, supercooled droplets (μm), certain incident angle impact. This project takes supercooled droplets impact-icing super-hydrophobic surface of non-equilibrium phase transition under shear of cool air as the research subject. The research contents are: (1) Analysis of dynamic behaviors of supercooled droplets impacting and moving on super-hydrophobic surface to obtain initial form of freezing process; (2) Establishment of mathematical model of supercooled droplets non-equilibrium phase transition icing on super-hydrophobic surface of under shearing effect of cooled airflow, which concerned super-cooled droplet nucleation and growth. To determine the anti-icing features of super-hydrophobic surface, nucleation and freezing time have to be calculated; (3) Revelation of influence rule of surface properties and condition parameters by using numerical simulation and experiment. Research results will be promote multi-disciplinary cross which involves the fluid dynamics and non-equilibrium thermodynamics, heat and mass transfer and surface science, provides a theoretical basis for next anti-icing research based on super-hydrophobic surface. The investigation also has important academic significance and practical application value.

超疏水表面能否用于防除冰是近年来相关领域研究人员关注的热点问题，为飞机防除冰提供了新思路和可能的新方法。目前研究多针对自然对流、静态、毫米级非过冷态水滴及水平冷壁面展开，与飞机结冰的高速冷气流剪切作用、微米级过冷水滴、以一定入射角撞击结冰的条件相去甚远。本项目以亚稳态过冷水滴为对象，研究冷气流剪切作用下超疏水表面的过冷水滴非平衡相变结冰及抑冰特性。研究内容包括：①水滴高速撞击超疏水表面的动力学行为，以获得超疏水表面相变结冰的初始状态；②剪切力作用下超疏水表面过冷水滴的形核与生长，建立过冷水滴非平衡相变结冰数学模型，由形核率和冻结时间确定超疏水表面抑制或延缓结冰的特性；③通过仿真和实验，揭示表面特性和条件参数等多重复杂因素对结冰过程的影响及规律。项目研究成果对促进流体力学、非平衡热力学、传热传质和表面科学的多学科交叉，进一步开展基于超疏水表面的防除冰研究，具有重要的学术意义和工程应用价值。

超疏水表面能否用于防除冰是近年来相关领域研究人员关注的热点问题，为飞机防除冰提供了新思路和可能的新方法。本项目以亚稳态过冷水滴为对象，研究冷气流剪切作用下超疏水表面的过冷水滴非平衡相变结冰及抑冰特性。.针对水滴高速撞击超疏水表面的动力学行为研究，建立水滴撞击表面的受力模型，将水滴撞击过程分为液滴撞击表面瞬间、液滴铺展、液滴回缩、液滴振荡及反弹、液滴稳定五个阶段，探究水滴撞击速度、水滴尺寸、表面温度等对水滴形态变化的影响规律。结果表明：水滴撞击超疏水表面过程中，表面温度相同时，撞击速度越大，水滴铺展因子越大，而撞击速度相同时，随着表面温度的降低，水滴铺展因子则无明显变化。.针对冷气流剪切作用下水滴动力学行为及过冷水滴形核生长研究，建立剪切力作用下液滴的受力模型及过冷水滴在超疏水表面上的非平衡相变模型，探究气流速度、表面浸润性、液滴尺寸等对液滴运动的影响，测试了冷气流剪切作用下不同浸润性表面上的结冰量。结果表明：气流剪切作用下，表面接触角越大，气流-水滴-固体表面三者之间的接触线开始运动时刻对应的气流速度越小，水滴从表面脱除需要的气流速度越小。超疏水表面的结冰量较亲水表面少，结冰需要的时间较亲水表面长。.针对表面特征和外界条件对超疏水表面的结冰影响规律的研究，分析了表面温度、水滴过冷度、水滴撞击速度等对超疏水表面上水滴冻结特性的影响规律，通过形核率和冻结时间确定超疏水表面抑制或延缓结冰特性。结果表明：随着表面接触角的增加，水滴冻结过程的时间随之增大。水滴尺寸越小、表面温度越低、撞击速度越大，都会使得水滴核化冻结过程所用时间越短。.项目研究成果对促进流体力学、非平衡热力学、传热传质和表面科学的多学科交叉，进一步开展基于超疏水表面的防除冰研究，具有重要的学术意义和工程应用价值。