电场诱导下液滴撞击仿蛛丝的动力学行为及捕集机理研究

Study on the capturing mechanism of droplet in electric field is of great significance to obtain the fresh water resource in the extreme heat and humid climate zone in the South China Sea. In order to achieve the high efficiency of capturing droplet, artificial spider silk and electric field are introduced to this project. Because the droplet group is charged in the electric field and directionally moves to the collector electrode (near the artificial spider silk), in addition, the electric field force also can optimize the electric fluid dynamics characteristics of the interaction between droplets and artificial spider silk. The project will trial-produce the artificial spider silk with spindle fiber structure by coaxial electrospinning technology. Based on high speed microscope imaging system, the visualization experiment of the motion of a charged droplet and the interaction between droplet and artificial spider silk in electric field is carried out, including droplet impacting on the artificial spider silk, droplets coalescence along the artificial spider silk as well as droplet sliding on the artificial spider silk. The project will establish three-dimensional theoretical model of the motion of a charged droplet and the interaction between droplet and artificial spider silk in electric field, respectively. The couple mechanism and fluid dynamic behavior of charged droplet impacting, coalescence and sliding on the gradient surface of an artificial spider silk in electric field is revealed. Emphasis is laid on the electric field effect, scale effect and wettability effect during the droplet is captured by artificial spider silk. The project is an important supplement and improvement to the existing research on droplet dynamics theory which has the important academic value. It is of great important for development of micro devices with electric field and droplets.

电场诱导下液滴捕集机理的研究对于在南海极端热湿气候区获取淡水资源具有重要的意义。本项目将仿蛛丝引入液滴捕集，同时施加电场，一方面液滴群在电场中荷电并向捕集极（仿蛛丝附近）作定向运动，另一方面电场力可优化液滴与仿蛛丝相互作用的电流体动力学特性，以实现液滴的高效捕集。采用同轴静电纺丝技术研制具有纺锤体状纤维结构的仿蛛丝。基于高速显微成像系统，开展电场作用下的液滴荷电运动特性及液滴在仿蛛丝梯度表面撞击、聚并和滑落过程的可视化实验研究。分别建立电场作用下的液滴荷电运动及液滴与仿蛛丝相互作用的三维理论模型并进行数值模拟，揭示电场诱导下液滴在仿蛛丝梯度表面撞击、聚并、滑落的流体动力学行为及耦合机制。重点阐明液滴在仿蛛丝表面捕集过程中的电场效应、尺度效应和润湿效应。本项目是对现有液滴动力学理论的重要补充和完善，具有重要的学术价值，对研发与电场、液滴相关的微流体装置具有重要意义。

空气中的水气捕集和输运技术是解决沙漠和海岛等淡水资源匮乏地区获取淡水资源的一种优选方案。本项目针对水蒸气冷凝以及液滴在丝状、平板等润湿性表面上的高效捕集需求，结合可视化实验和数值模拟方法研究了微液滴在润湿性表面上的流型演化规律和捕集机理。揭示了液滴在润湿性表面上运动过程中的电场效应、尺度效应和润湿效应。完善了沙漠、海岛等淡水资源匮乏地区集水装置系统的设计和技术。.研究结果表明：①液滴撞击细纤维过程受重力、惯性力、表面张力、摩擦力和粘性力影响，随着We数的增大，液滴形态依次出现悬挂、合并和劈裂模式；②等直径液滴对聚结-跳跃的电场阈值随直径的增加而降低；随间距的增加而提高；随着电场强度的继续增大，在一定范围内可以促进液滴对的聚结，提高了开始聚结时的速度和跳跃速度，有利于液滴跳跃离开超疏水面；③液滴尺寸、向心力和表面张力均能影响液滴在超疏水-亲水表面导向运输过程中的偏离情况。向心力是影响液滴偏离轨道的主要因素，向心力越大，液滴越容易偏离轨道；在同一向心力作用下，液滴尺寸对液滴偏离轨道的影响较小，小于临界尺寸的液滴更容易在向心力作用下突破轨道侧壁支持力而偏离轨道；表面张力越小，液滴在重力、轨道侧壁支持力和向心力的作用下越容易形变，导向运动过程中越容易偏离轨道，当表面张力达到0.07 N/m及以上时，表面张力对液滴偏离轨道的影响越来越小。.本项目的研究不仅对完善滴液动力学理论具有重要的科学意义，也将为我国自主研发沙漠、海岛等地区的淡水捕集装置提供了重要的理论指导和技术支撑。基于本项目研究成果，共在国内外期刊发表论文8篇，其中SCI论文4篇、EI论文3篇(不含SCI、EI双收录)；申请发明专利2项（其中已授权1项）；培养已毕业研究生3名。