Droplet and Spray Deposition on Complex Surfaces

液滴对固体表面的撞击发生在许多工业应用中，如喷漆、喷墨印刷和喷雾冷却，许多研究都是关于水或碳氢化合物液滴对不渗透表面的撞击。很少有实验研究进行液滴对加热多孔表面的影响，即使表面在许多过程中都是多孔的，例如木材的喷涂，纸张上的喷墨印刷，洒水系统的土壤灌溉以及热多孔体的喷雾冷却。液体也可以是复杂的，因为用于油漆和涂层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能的添加剂。本研究将研究复杂表面的液滴与喷雾的相互作用，以及复杂液体的喷雾沉积。将进行的项目包括：

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.