界面活性劑對雙液滴碰撞效應之研究

Surfactant Effect on Binary Droplet Collision

陳任鈞(Jen-Chun Chen)

指導教授 ： 潘國隆

國立臺灣大學/工學院/機械工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.03488

摘要

本實驗以雙液滴碰撞為主軸，藉由高速攝影機及適當的量測與分析方法，將其碰撞結果依韋伯數 (Weber number) 及撞擊參數 (impact parameter) 分為五大區域：(一)液滴輕微變型後結合、 (二)彈開、 (三)液滴顯著變型後結合、 (四)液滴反彈分離、 (五)液滴拉伸分離。研究結果顯示這些區域將會隨著不同的液體黏度、界面活性劑種類及濃度而有所差異，特別是對彈開區域的顯著擴張與增加分離區域的臨界韋伯數。其中，界面活性劑梯度的存在將驅動馬倫哥尼效應 (Marangoni effect) 的發生，進而改變液滴表面的物理機制，導致液滴更容易相互彈開亦或延遲其分離現象的發生。這特性在微觀過程中將造成不同程度的影響力，但其效應將會隨著巨觀行為的推移而逐漸消失。

關鍵字

液滴碰撞 ； 彈開 ； 界面活性劑 ； 馬倫哥尼效應

並列摘要

The droplets collision dynamics with different surfactant and viscous fluids are investigated. The high speed camera and reliable measuring methods facilitate the experimental procedures. Depending on the two independent factors of Weber number and impact parameter, the consequences of droplets collision can be categorized into five distinct regimes: (Ⅰ) coalescence after minor deformation, (Ⅱ) bouncing, (Ⅲ) coalescence after substantial deformation, (Ⅳ) reflective separation and (Ⅴ) stretching separation, and it reveals that the viscosity, surfactant types and concentrations all have great influences on regime diagrams, especially the finding of the extensive bouncing regime and the retardant occurrence of separation regime.
It is because the Marangoni effect which is motivated by the surfactant gradient could manifestly affect droplet interfacial behaviors. However, these induced transformations will dominate over the microscopic situations such as droplet bouncing but become trivial in the macroscopic conditions such as droplet separation phenomena.

並列關鍵字

droplet collision ； surfactant ； bouncing ； Marangoni effect

參考文獻

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