添加界面活性劑對突縮微流道內氣泡傳動之研究

Surfactant Effect on Bubble Transport in a Small Channel with Sudden Contraction

陳星岳(Hsing-Yueh 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(2011年)

https://doi.org/10.6342/NTU.2011.03308

摘要

本研究主要在觀察界面活性劑的添加對於二相流管流中的氣泡傳動之影響。觀察的重點有三：(一)因添加界面活性劑對管流中氣泡的改變以及氣泡通過突縮障礙物的速度變化、(二)因添加界面活性劑造成液體於固體表面接觸角之改變所造成的角落流之影響、(三)因添加界面活性劑造成的馬倫哥尼效應(Marangoni effect)對於氣泡通過突縮障礙物在形變和速率上的變化。其中第三點之馬倫哥尼效應在本研究中被視為對氣泡通過突縮障礙物時的速率有最大的關連。在許多前人的研究中，對於添加界面活性劑所帶來的馬倫哥尼效應有很深入的研究，但多半是在液滴碰撞方面。本研究將焦點置於微小管流中的氣泡，並由於添加了界面活性劑使得在氣/液之間的界面上因突縮結構的擾動造成界面活性劑的濃度分佈不均，而可能形成表面張力梯度，使馬倫哥尼效應顯得重要，令氣泡在通過突縮障礙物時較為順暢。

關鍵字

界面活性劑 ； 二相流 ； 氣泡 ； 突縮微流道 ； 馬倫哥尼效應(Marangoni effect)

並列摘要

The observation of the effect of surfactant on bubble transport in a gas/liquid two-phase channel flow with a sudden contraction is done. There are three important points: (i) the effect of surfactant on the bubble shape and bubble transport velocity when it is passing the block, and (ii) the change of liquid contact angle on a solid surface, which is due to the surfactant and the variation of surface tension, results in a corner flow effect, and (iii) the Marangoni effect induced by surfactant cause the change of bubble shape and the variation of bubble transport velocity as the bubble passes the block. The Marangoni effect is seen as the most important factor affecting the bubble transport. In many researches, the Marangoni effect plays an important role in droplet collision with surfactant added. In our research, we focus on the bubble transport in a small channel. When surfactant is added, the surfactant concentration at the gas/liquid interface perturbed by the sudden contraction structure, resulting in an inhomogeneous surfactant concentration on the interface. The inhomogeneous surfactant concentration may cause a surface tension gradient on the interface, enhancing Marangoni effect and benefitting the bubble transport through the block.

並列關鍵字

surfactant ； two-phase flow ； bubble ； sudden contraction small channel ； Marangoni effect

參考文獻

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