流體黏性對雙液滴碰撞彈開結合之研究

Abstract

本研究使用多種流體的液滴進行雙液滴碰撞實驗，以同步閃頻儀確定液滴所在位置後開啟高速攝影機拍攝液滴撞擊之現象，使用癸烷、十六烷、奈米粒子溶液來探討不同液滴尺寸如何影響雙液滴碰撞結果。 鑒於前人研究多為考慮歐式數差異明顯的液滴碰撞型態分界圖變化，較少比較相似歐式數的液滴碰撞變化，因此我們首先做出十二烷、十六烷和矽油的碰撞型態分界圖，分別調配相似歐式數之不同重量百分濃度甘油水溶液的液滴碰撞型態分界圖進行比較，觀察相似歐式數時液滴碰撞型態分界圖之間的變化，探討不同流體材料性質是否影響碰撞結果，討論歐式數是否為主要影響不同現象間的無因次參數。 我們使用七組不同重量百分濃度和液滴尺寸的甘油水溶液觀察黏性對碰撞彈開和顯著變形後結合間的邊界影響，發現若黏性越大則碰撞彈開區域將增加，以液滴尺寸為450 μm的甘油水溶液為例，在重量百分濃度為30%時尚未出現完全發展彈開型態，而當重量百分濃度為59.1%時則出現完全發展彈開型態，甘油水溶液黏度越大則碰撞彈開區域越大，另外液滴尺寸若越大則此趨勢越明顯。

The study aimed at investigating binary droplet collision experiments using various fluids at ambient conditions. The droplet image and collision video were recorded by using a strobe light and high-speed camera. The fluid, decane, hexadecane, and nanoparticle solution were used as working fluids to discuss how different droplet sizes influence droplet collisions. View of the fact that most of the previous studies considered the changes in the droplet collision map with obvious differences in Ohnesorge number, and seldom compared the changes in droplet collisions with similar Ohnesorge number. We compared regime diagrams of dodecane, hexadecane, and silicon oil with corresponding similar Ohnesorge number glycerol aqueous solutions, and observed changes in their regime diagrams. We investigated whether the properties of different fluid materials would affect the collision result, and discussed if the Ohnesorge number was the main dimensionless parameter that influenced the boundary between different phenomenons. Seven groups of glycerol aqueous solutions with different weight percent concentrations and droplet sizes were used to observe the effect of viscosity on the boundary between bouncing and coalescence after substantial deformation. Take the glycerol aqueous solution with a droplet size of 450 μm, for example. The fully developed bouncing regime was not observable when the concentration was 30% by weight. But when the concentration was 59.1% by weight, then the fully developed bouncing regime occurred. If the glycerol aqueous solutions concentration increased, subsequently the viscosity increased, then the bouncing area expanded. If the droplet size of the working fluid was larger, then this trend was more obvious.