Droplet and Spray Deposition on Complex Surfaces

液滴对固体表面的冲击发生在许多工业应用中，例如喷漆、喷墨打印和喷雾冷却，并且已经对水或烃液滴对不可渗透表面的冲击进行了许多研究。关于液滴对受热多孔表面的影响的实验研究少得多，尽管在木材喷涂、纸张喷墨印刷、洒水系统土壤灌溉和热多孔体的喷雾冷却等许多过程中，表面都是多孔的。液体也可以是复杂的，因为油漆和涂料中使用的配方通常是非牛顿的，并且含有表面活性剂，颗粒或其他改变其性质的添加剂。本研究将研究液滴和喷雾与复杂表面的相互作用，以及复杂液体的喷雾沉积。将开展的一些项目是： 液滴对多孔材料的影响：将使用高速摄像机记录液滴对夹在中间的多孔基质切片的影响。将发展液体吸收到孔隙中的模型。 多孔表面上液滴的蒸发和沸腾：水和碳氢化合物的液滴将沉积在加热的多孔金属板上，并测量其重量变化以确定液体蒸发速率。将开发表面冷却模型。 复杂表面的喷雾冷却：将建立一个喷雾装置，其中喷水淬火加热的复杂表面，如球体或圆柱体阵列。将开发模型来预测表面内液体渗透和蒸发的速率。 复杂流体的喷射沉积：复杂流体含有颗粒，如薄片或粉末，可改变油漆和涂料的性能。实验将在含有颗粒和薄片的聚合物流体中进行，这些颗粒和薄片被喷射到表面上并固化，使得它们硬化。将测量涂层的特性（硬度、颜色变化），并将其与颗粒的浓度和取向相关联。 我们将从这项研究中获得的见解将在许多不同的领域中发挥重要作用，并补充我们与工业合作伙伴在喷雾冷却和喷涂领域所做的工作。这项研究的结果将： 提高我们对液滴-表面相互作用的理解，这一领域已经研究了世纪，但仍然是一个非常活跃的研究领域，有许多尚未回答的问题。 改进快速冷却多孔和不规则形状表面的方法。例子包括电子冷却，核电站的安全系统，以及自动喷水灭火系统。 有助于更好地配制涂料，优化有机涂层的性能，以最大限度地减少缺陷，获得良好的机械和光学性能。

Droplet impact on solid surfaces occurs in many industrial applications such as spray painting, ink-jet printing and spray cooling and many studies have been done of water or hydrocarbons droplet impact on impermeable surfaces. Far fewer experimental studies have carried out on the impact of droplets on heated porous surfaces, even though surfaces are porous in many processes such as spray coating of wood, ink-jet printing on paper, soil irrigation by sprinkler systems and spray cooling of hot, porous bodies. Liquids can also be complex since formulations used in painting and coating are frequently non-Newtonian and contain surfactants, particles, or other additives that modify their properties. This research will study both the interaction of droplets and sprays with complex surfaces, and spray deposition of complex liquids. Some of the projects to be undertaken are: Impact of droplets on porous materials: The impact of a droplet on slices of porous substrates sandwiched will be recorded using a high-speed video camera. Models will be developed of liquid absorption into pores. Evaporation and boiling of droplets on porous surfaces: Droplets of water and hydrocarbons will be deposited on heated porous metal plates and their change in weight measured to determine the rate of liquid evaporation. Models of surface cooling will be developed. Spray cooling of complex surfaces: A spray apparatus will be built in which water sprays quench heated, complex surfaces such as arrays of spheres or cylinders. Models will be developed to predict the rate of liquid percolation and evaporation within the surface. Spray deposition of complex fluids: Complex fluid contain particles such as flakes or powders that modify the properties of paints and coatings. Experiments will be done in polymeric fluids containing particles and flakes are sprayed onto a surface and cured so that they harden. Properties of coatings (hardness, colour variation) will be measured and related to the concentration and orientation of particles. The insights we will gain from this research will be important in a number of different areas and complement the work that we are doing with industrial partners in the areas of spray cooling and of spray coating. The results of this research will: Enhance our understanding of droplet-surface interactions, an area that has been studied for over a century but is still a very active area of research with many unanswered questions. Improve methods of rapidly cooling surfaces that are porous and irregular shaped. Examples include electronic cooling, safety systems in nuclear plants, and fire suppression with sprinkler systems. Help better formulate coating materials and to optimize the properties of organic coatings to minimize defects and obtain good mechanical and optical properties.