長氣泡在彎管內穿透非牛頓流體之雙流體擠壓流型觀測

Flow Visualization of a Long Gas Bubble Penetrate a Non-Newtonian Fluid in a Curved Tube.

謝承偉(Cheng-Wei Xie)

指導教授 ： 許政行

中原大學/工學院/機械工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200901191

摘要

本研究為觀測在具有圓弧彎道之透明圓管內，以氮氣驅動非牛頓流體之流場流型實驗。實驗藉由氮氣的注入形成一連續延伸之長氣泡來驅動圓管內之非牛頓流體，並觀測其於圓管內前進所產生之雙流體擠壓流型。進而探討此一長氣泡通過圓弧彎道時的其所產生之擠壓輪廓與流型以及其穿透行為。
本實驗藉由改變圓弧彎道角度、非牛頓流體黏度、氣體流量並配合影像擷取進行擠壓流之觀測與分析。本研究所採用之圓弧彎道分別為90度、135度與180度，圓管直徑為8 mm，曲率為0.005 ，氮氣流量分別為200、600與1000 ml/min。
由實驗結果可歸納出，在距氣泡尖端約6倍管直徑時，氣泡寬度將趨於定值。並在此基礎下，導入偏心率來解析氣泡在圓弧彎道內之偏移情形，本研究發現在流體黏度、彎管角度相同時，流量越高偏心率也會越大，反之越小。於探討毛細係數及威森堡數兩者與偏心率間之關係發現，氣泡在彎管前端之偏心率隨著毛細係數及威森堡數的增加而增加，為正比之關係。

關鍵字

偏心率 ； 彎管 ； 非牛頓流體 ； 長氣泡

並列摘要

The experiment performed the flow visualization by using nitrogen gas to drive the non-Newtonian fluids in a curved circular tube. A continuous long gas bubble was formed to expel the non-Newtonian fluids in the curved tube. Observation of the flow patterns in the curved region, the penetration behavior and leading edge contour of the long bubble were studied.
The controlling variables of the experiments are the curving angle of the circular tube, the viscosity of the fluids and the volumetric flow rate of the injected gas. The images of the twin flow were taken and analyzed. The curving angles of the tubes are 90ﾟ, 135ﾟand 180ﾟ. The diameter and the curvature of the tube are 8.0 mm and 0.005 , respectively. The flow rates of the Nitrogen gas are 200, 600 and 1000 ml/min.
The results of the experiments showed that the bubble width approaches constant value at the location six-diameter upstream from the bubble front. A difference variable is introduced at the six-diameter location to show the shifting deviation of the bubble in the curved tube. It is shown that, with the same fluid viscosity and the curving angle, the difference is higher when the gas flow rate is higher. Also, the difference increases proportionally when the Capillary number and the Weissenberg number increase.

並列關鍵字

difference. ； Curved circular tube ； non-Newtonian fluid ； Long bubble

參考文獻

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