飞机表面超疏水涂层防冰技术及理论研究

Ice on the surface of aircraft shall be prevented in order to ensure aviation safety. Superhydrophobic coatings may be used for aircraft anti-icing due to its special micro-nano structure and low surface energy with excellent anti-icing function. This project intends to introduce environmentally friendly fluorescent carbon quantum dots (CDs) into thermoplastic elastomers, and construct superhydrophobic coatings with excellent anti-icing performance. The inherent link of micro-nano structures, anti-icing time, ice coverage and icing adhesion will be investigated. Furthermore, the anti-icing abilities are influenced by freezing conditions such as temperature, humidity, wind velocity, water droplet size. On this basis, the effects of flight service environments such as low temperature, salt spray, ultraviolet and rain on the anti-icing performance of superhydrophobic coatings will be studied. By sheering action of flow field, the influence of water droplets on the surface of superhydrophobic coatings motion, spreading, freezing and ice growth with different micro-nano structures will be investigated systematically. Based on the theory of kinematics and microfluidics, combined with the experimental results, the mechanism of the effect of solid-liquid interface on the anti-icing effect of superhydrophobic coatings will also be revealed. Multi-scale theoretical numerical analysis and simulation will be performed, and the anti-icing mechanism of aircraft surface superhydrophobic will be established from the microscopic nature theoretically. The corresponding theory and technology of superhydrophobic coatings will be achieved and used for aviation through this project.

为确保航空安全，必须防止飞机表面结冰。超疏水涂层特殊的微纳结构和较低的表面能，使其具有优异的防冰性能，可将其用于飞机表面防冰。本项目拟将环境友好的荧光碳量子点（碳点，CDs）引入热塑性弹性体，构建具有优良防冰性能的超疏水涂层，并考察其微纳结构与防冰时间、覆冰量和结冰附着力等防冰性能的内在联系。进一步研究温度、湿度、风速、水滴直径等结冰条件对超疏水涂层防冰性能的影响，在此基础上，研究低温、盐雾、紫外、雨水等飞行服役环境对超疏水涂层防冰性能的影响。系统考察气流场剪切作用下，水滴在不同微纳结构超疏水涂层表面撞击、运动、铺展、冻结和结冰生长行为。基于运动学及微流体力学理论，结合实验研究结果，揭示固液界面作用对超疏水涂层防冰的影响机制，建立多尺度理论数值分析与模拟，从微观本质及理论上明确飞机表面超疏水涂层的防冰机理。本项目的研究将为超疏水涂层在航空领域的应用提供理论依据和技术支持。

飞机表面结冰会严重威胁飞行安全。为保障飞行安全，必须对飞机表面进行防冰处理。传统防冰方法存在效率低、污染环境的问题，而以超疏水材料为代表的新型防冰技术又存在制备过程复杂、性能不稳定等不足。本项目通过多种途径在材料表面构建微纳结构，制备了一系列防冰性能优异的超疏水涂层。同时引入疏水碳点，实现涂层表面的微区破损可视化监测，并开发了破损微区快速修复技术。重点研究了温度、湿度、风速、水滴尺寸对涂层防冰性能的影响。结果表明：风速是影响超疏水涂层防冰性能的关键因素。系统研究了温度、紫外辐射、盐雾、雨水等服役环境对超疏水涂层微纳结构以及防冰性能的影响。结果表明：温度、紫外、pH对涂层的润湿性影响较小；湿度能破坏“空气垫”结构，是导致超疏水表面性能衰退的关键因素。通过实验结合数值仿真，研究了水滴撞击超疏水表面的运动形态以及气流驱动液滴运动过程中润湿长度、动态接触角等参数的变化规律。结果表明：相比亲水表面，液滴在超疏水表面所受粘附力较小，液滴尺寸对润湿长度的影响程度也较小；当风速为15 m/s时，液滴在超疏水表面“翻滚”，基本不与表面接触。基于以上研究，进一步建立了基于减少润湿长度的防冰理论模型：当气流速度达到一定值时，液滴几乎与表面不接触、传热效率下降、界面处均相成核，成核势垒增加导致结冰困难，即使结冰也会被吹走，从而实现从源头抑制结冰。此外，考察了液滴尺寸、润湿性、过冷度等因素对液滴冻结延迟时间的影响。结果表明：接触角越大，冻结过程中体积随时间的变化率越小；冻结前沿移动速率在冻结过程中基本保持不变，其值受接触角和过冷度的影响；冻结延迟时间与过冷度呈现一次函数关系。结合液滴的运动以及冻结参数，开展了耦合表面粗糙度特征的液滴结冰数值计算。项目研究成果对深入理解超疏水表面防冰机理、推动设计防冰性能更为优异的超疏水表面、发展新型的飞机防冰技术具有重要意义。