幾何形狀對圓管內長氣泡發展影響之研究

The Geometric Effect on the Evolution of a Long Bubble in a Circular Tube

郭家全(Chia-Chaun Kuo)

指導教授 ： 許政行

中原大學/工學院/機械工程研究所/博士(2010年)

https://doi.org/10.6840/cycu201000737

摘要

摘要
本研究以實驗觀測和數值模擬方法研究：長氣泡穿透充滿黏彈性流體的突縮突擴圓管內之氣泡輪廓的進展情形，並評估突縮角及流體特性對氣泡輪廓與殘留率的影響。
本文採用的實驗觀測方法為：先以高速照像機拍攝氣泡照片，再以影滿像處理得到氣泡的輪廓和殘留率。本文數值方法的流場求解程序是先將連續方程式與動量方程式轉化為流線方程式與渦度方程式，再以有限差分法將其離散化，再高斯-賽得疊代法配合鬆弛係數求解。本文採用保守型式的等位函數法描述液氣界面預測並記錄氣泡輪廓的演變。
當氣泡通過突縮突擴管時，流體在流道上的殘留率、氣泡的輪廓和速度由於填充流體的黏度、入射氣體流量和流道的突縮角等因素的影響而產生變化。正當氣泡輪廓沿著流體的流線方向擴展時，因受慣性力、表面張力、毛細力等因素交互影響而產生變化。本文以數值模擬的氣泡輪廓和流場解釋實驗觀測結果，並和早期相關的研究結果有良好的一致性。

關鍵字

殘留率 ； 氣泡輪廓 ； 界面追蹤方法

並列摘要

Abstract
In this thesis, a long bubble elongates through a contraction tube followed by an expansion tube filled with viscoplastic fluids was studied experimentally and numerically. The effects of both tube geometry and fluid characteristics on the bubble profiles and fractional converge were evaluated.
In the experimental aspect, the bubble profiles and the fractional converge were obtained by image processing the photos captured with a high-speed camera. In the numerical analysis aspect, the continuity equation and momentum equation were converted to the equations in the form of streamline and vorticity. The differential equations were discretized with the finite difference method. Gauss-Seidel Iteration method with successive over-relaxation (SOR) were applied in the computation of the viscous fluid flows. The evolution of the bubble contour predicted by a conservative Level Set Method was applied to this study.
The results showed that the fractional converge of the fluid, the bubble profile and velocity changed due to the effects of the fluid viscosity, the flow rate and the contraction/ expansion angle of the tube. The bubble profile, developing along the stream line, was changed by the effects of the inertia force, surface tension and capillary force. The bubble profiles and the flow fields generated by numerical simulation were applied to explain the experimental observations. Both experimental observation and numerical simulation results were in the same trend. A good consistency was shown between our results and the related researches.

並列關鍵字

Bubble profile ； Interface-tracking method ； Fractional converge

參考文獻

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