发表机构
Facultad de Ingeniería, Universidad Nacional Autónoma de México; Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México（墨西哥国立自治大学工程学院; 墨西哥国立自治大学材料研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文实验研究了20%体积分数的硅油-水乳液液滴在倾斜微结构化表面的撞击行为，识别出五种撞击模式，揭示了乳液撞击与水的差异及局部相分布对撞击的影响，为相关应用提供了新见解。
AI 中文摘要
液滴撞击极少发生在水平光滑表面上，但对于乳液而言，表面倾斜度、微结构与流体组成的综合影响仍知之甚少。本文通过实验研究了体积分数为20%的硅油-水乳液液滴在倾斜角为55°的光滑玻璃和两种柱间距（50μm和100μm）的微柱阵列上的撞击行为，还利用超疏水涂层进一步研究了表面润湿性的作用。采用高速成像技术在宽韦伯数范围（18≤We≤565）内表征撞击动力学，同时使用光学显微镜量化撞击后的残留润湿面积。研究识别出五种撞击 regimes：沉积、滑动、部分回弹、完全回弹和飞溅。表面倾斜度使铺展和反冲呈现不对称性，而微结构化基底通过减小液-固接触面积降低粘附力并促进回弹。与水相比，乳液在光滑表面上的沉积增强，在未涂层微结构上的滑动增加，且在高韦伯数下更早形成韧带并发生二次破碎。分散的油相局部改变润湿性并起到润滑作用，在光滑基底上形成液桥、产生不均匀反冲并增大残留润湿面积；然而在微结构化表面上，尽管微结构内部的液体滞留量增加，但结构内的毛细限制作用限制了投影润湿面积。这些结果表明，不能仅通过传统无量纲群预测乳液的撞击行为，因为局部相分布的变化会从根本上改变能量耗散、润湿性和破碎过程。该研究结果为与农业喷洒和涂层技术相关的倾斜结构化表面上的喷洒沉积提供了新的见解。
英文摘要
Droplet impacts rarely occur on horizontal smooth surfaces, yet the combined influence of surface inclination, microstructure, and fluid composition remains poorly understood for emulsions. Here, we experimentally investigate the impact of 20% (v/v) silicone oil-in-water emulsion droplets on smooth glass and micropillar arrays with two interpillar spacings (50 and 100 $μ$m) inclined at 55$^\circ$. The role of surface wettability is further examined using a superhydrophobic coating. High-speed imaging is employed to characterise the impact dynamics over a wide range of Weber numbers ($18 \leq We \leq 565$), while optical microscopy is used to quantify the residual wetted area after impact. Five impact regimes are identified: deposition, sliding, partial rebound, complete rebound, and splashing. Surface inclination introduces asymmetry in spreading and recoil, whereas microstructured substrates reduce adhesion and promote rebound by decreasing the liquid-solid contact area. In contrast to water, the emulsion exhibit enhanced deposition on smooth surfaces, increased sliding on uncoated microstructures, and earlier ligament formation and secondary breakup at high Weber numbers. The dispersed oil phase locally modifies wetting and lubrication, producing liquid bridges, heterogeneous recoil, and larger residual wetted areas on smooth substrates. On microstructured surfaces, however, capillary confinement within the texture limits the projected wetted area despite increased liquid retention inside the microstructure. These results demonstrate that the impact behaviour of emulsions cannot be predicted solely from conventional dimensionless groups, as local phase redistribution fundamentally alters energy dissipation, wetting, and fragmentation. The findings provide new insight into spray deposition on inclined textured surfaces relevant to agricultural spraying and coating technologies.
