电场作用下非牛顿流体微射流行为及非等温表面沉积调控机制的研究

Electrospray deposition (ESD) has important application potential in the fields of nano-materials, microelectronics and biomedicine,etc as the key technology of micronano additive manufacturing. ESD is the multiphase flow in coupled multifield and the physical model of heat and mass transfer ,which involves the frontier issues in engineering thermophysics and electronics. This project proposes to study the fundamental mechanisms of non-Newtonian fluid electrostatics spraying and the charged droplets deposition and phase transition on non-isothermal surface via flow measurement of LIF, high-speed microscopy photograph measurement and PIV. The active characteristics of micro-jet and the microflow of charged droplets evaporation and deposition will be investigated by visualization. The key factors affecting non-Newtonian spraying behavior, deposition of droplets and the distribution of object sediment will be analyzed to reveal the mechanism of electric adjustment of non-Newtonian droplets deposition behavior. The models of non-Newtonian fluid electrospraying and evaporation phase-transition deposition will be established to simulate electrospray evaporation and deposition process, revealing the effect of rheological characteristics coupled with thermal and electric fields on droplets motion, evaporation deposition and internal micro-flow. The adjustment of non-Newtonian fluid micro-jet behavior and deposition characteristcs in electric field can be recognized and clarified from mechanism so as to realize the target, precise and high-efficiency deposition of object sediment. This investigation will provide theoretical basis and research foundation for developing new technology of the nano-materials preparation .

静电雾化沉积（ESD）作为微纳增材制造的关键技术，在纳米材料、微纳电子及生物医疗等领域具有重大应用潜力。静电雾化沉积涉及多场耦合作用的多相流动与传热传质物理模型，是工程热物理交叉学科研究的前沿。本项目提出开展非牛顿流体静电雾化及荷电液滴在非等温表面相变沉积的基础研究。通过激光诱导荧光技术、显微高速数码摄像及PIV等现代流动测试技术，对微射流动态特性及荷电液滴沉积蒸发微流动进行可视化研究。分析多场耦合条件下影响非牛顿流体雾化行为、液滴沉积规律及目标沉积物分布特性的关键因素。揭示电场调控非牛顿流体液滴沉积行为的机制。建立非牛顿流体静电雾化及蒸发相变沉积模型，利用数值模拟探索流变学特性与温度场、电场耦合对液滴运动、蒸发沉积、内部微流动的作用。从机理层次认识并阐明电场对非牛顿流体微射流行为及沉积特性的调控机制，实现目标沉积物的靶向、精准及高效沉积。为发展纳米材料制备新技术提供研究基础和指导依据。

静电雾化液滴沉积在纳米薄膜和颗粒制备、芯片加工和制造、生物医疗检测等领域具有重要应用。本项目基于先进流场测量技术，开展了温度和电场耦合作用下液体雾化动态行为及特性的研究。获得了温度对喷雾弯液面动态行为的影响规律，提出了微滴模式下弯液面振荡频率预测模型。揭示了温度对微射流模式和形态的作用机制，实现了工质雾化质量的显著提高。建立了多场耦合下射流破碎长度与液滴粒径的预测模型。开展了非牛顿流体液滴撞击壁面的动力学行为研究。首次发现了剪切变稀流体液滴在疏水表面特殊的反弹行为。通过数值模拟揭示了非牛顿流体特性对液滴撞击动力学行为的影响机制。推导建立了剪切变稀流体液滴最大铺展因子、最大回弹高度以及回弹现象判定条件的数理模型。研究了不同电场下蒸发过程中关键参数的变化规律。实现了通过电场形式、场强大小对固着液滴蒸发速率和微观动态行为的调控。发现了一种电场作用下液滴在超疏水表面特有的极限蒸发模式。通过外加电场实现了纳米流体液滴固相组分在壁面的定向沉积。获得了形态特征可定制的石墨烯沉积物颗粒。通过理论分析揭示了电场-温度场耦合作用下非牛顿流体液相变规律，阐明了电场对目标沉积物堆积形态和沉积效率的调控机理。项目聚焦多场耦合作用下多相流动与传热传质中的基础科学问题，取得了较好的学术成果，为功能纳米材料的制造提供了技术基础与指导。