長氣泡在突縮突擴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 Sudden Contraction and Sudden Expansion Tube

沈仁堯(Jen-Yao Shen)

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/cycu200901186

摘要

本文為透明突縮突擴圓管內以氮氣驅動流體之流場流型實驗觀測研究。本文研究以注入氣體所形成之一不斷裂長氣泡來驅動圓管內之非牛頓流體，並觀測其所產生之雙流體擠壓流型。進而探討此一長氣泡通過突縮或突擴段時的其所產生之擠壓輪廓與流型以及其穿透行為。
本文藉由影像擷取系統，並搭配控制氮氣流量、被驅動流體之黏度以及突縮突擴之發展夾角等參數。進行一系列之長氣泡擠壓流型觀測，並探討長氣泡於通過突縮突擴段前後之中空率變化。實驗結果可知，當氮氣流量、流體黏度以及突縮突擴圓管角度皆增加的狀態下，長氣泡的速度將會提高以致突縮突擴段中空率變小，而入口段之中空率只會受到前兩項參數影響，即中空率與毛細係數、威森堡數的關係皆成反比的情況。

關鍵字

突縮突擴管 ； 中空率 ； 非牛頓流體 ； 長氣泡 ； 雙流體

並列摘要

The study presents the visualization of the Non-Newtonian fluid flow driven by a continuous long Nitrogen gas bubble in a circular tube with a sudden contraction and a sudden expansion. The characteristics of the flow patterns and the penetration behaviors are recorded as, categorized and studied.
The flow patterns is captured through a video capture device (DV). The controlling parameters of the experiments are the volumetric flow rate of Nitrogen, the viscosity of the expelled fluids and the sudden changed angle of the contraction and expansion portion in the circular tube. The fractional ratio is observed as the long gas bubble penetrates the fluid through the sudden contraction and the sudden expansion portion of the tube. The experiment results showed that when the volumetric flow rate of Nitrogen, the fluid viscosity or the angle of the sudden contraction and the sudden expansion protion of the circular tube increase, the velocity of the long bubble will also increase, causing a decreasing fractional ratio near the location of around the sudden contraction. The dominate parameters on the fractional ratio at the inlet are the volumetric flow rate of Nitrogen and the viscosity of the fluid. Also, the Capillary number and the Weissenberg number are inversely proportional to the fractional ratio.

並列關鍵字

Long gas bubble ； Non-Newtonian fluid ； Fractional ratio ； Contraction and Expansion tube ； Twin flow

參考文獻

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