不同仰角之突縮突擴管內長氣泡穿透非牛頓流體之研究

A Study of a Long Gas Bubble Penetrates a Non-Newtonian Fluid in a Sudden Contraction and Sudden Expansion Tube with Different Inclined Angle

王軾勛(Shih-Hsun Wang)

指導教授 ： 許政行

中原大學/工學院/機械工程研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200985

摘要

本文主要是探討在不同仰角下之透明突縮突擴管內，使用氮氣驅動非牛頓流體所產生之流動特性。本研究將氮氣注入於透明突縮突擴管，使得形成之一長氣泡來驅動管內之非牛頓流體，探討非牛頓流體之穿透行為，以及相關實驗參數的比較。
本文藉由影像系統，搭配仰角、氮氣流量、實驗流體黏度的不同以及突縮突擴之角度等參數，進行一系列的實驗。並探討長氣泡通過突縮突擴管之殘留率變化。
實驗結果顯示當仰角減小、氮氣流量增加、流體黏度增加的情況下，長氣泡在圓管內的速度將會增加，導致突縮突擴段之殘留率變大，而毛細係數也呈現增加的趨勢。而突縮突擴之夾角變化對於速度並無明顯的效應。若以高流率氣體通過高黏度流體時，可以發現其殘留率最高可趨近於0.60左右，低黏度則為0.43左右。而注入氣體的流量增加，也會使得毛細係數及威森堡數皆呈現增加的趨勢，且二者呈現線性關係。

關鍵字

長氣泡 ； 傾斜角 ； 毛細係數 ； 突縮突擴管 ； 非牛頓流體 ； 二相流

並列摘要

The flow behaviors of Non-Newtonian fluids driven by a long Nitrogen gas bubble in an inclined tube with a sudden contraction and a sudden expansion are investigated. Behaviors of Non-Newtonian fluids due to gas penetration, and relationships between some related parameters are recorded and studied.
The bubble patterns are captured by a video capture device (DV). The controlling variables of experiments are the inclined angle, the volumetric flow rate of Nitrogen, the viscosity of experimental fluids and the sudden changed angles of the contraction and expansion portion in the circular tube.
The experimental results showed that when the inclined angle decreases, as well as the volumetric flow rate of Nitrogen and the fluid viscosity increase, the velocity of the long bubble increases, which in turn, causing increases of the fractional coverage and the Capillary number. The angles of the sudden contraction and the sudden expansion of the circular tube have no apparent effects on the bubble penetration velocity. With a higher volumetric gas flow rate penetrates higher viscous fluids, the results indicated that the fractional coverage approaches 0.6 while the Capillary number increases. However, for lower viscous fluids, the fractional coverage obtained in the present experiments only reaches 0.43. An increase of the penetration gas velocity also causes increases of the Capillary number and the Weissenberg number. In addition, it showed that the relationship between both parameters is nearly linear.

並列關鍵字

Non-Newtonian fluid ； Contraction and expansion tube ； Two phase

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