下倾管内气-液两相流单气泡界面特征研究

Shape of Isolated Bubble in Downwardly Inclined Gas-Liquid Two-Phase Flows

本文对下倾管内气-液两相流单气泡的界面特征进行了实验和理论研究。实验采用双平行探针技术和摄像方法。结果发现,当弗劳德数Fr较小时存在单气泡的首尾倒置现象,气泡移动速度与这种倒置现象密切相关,单气泡的界面特征与气泡的长度无关而与流体的Fr数密切相关。基于双流体模型推导得到描述气泡尾部特征的计算模型,该模型对下倾管内气泡尾部界面特征的预测与实验结果吻合良好。进一步的理论分析表明,下倾管内气泡首尾倒置的临界Fr数随着管道下倾角和管道内径的增大而增大。

Experimental and theoretical studies on the shape of a single bubble in downwardly inclined gas-liquid two-phase flows are carried out. Measurements of the shape are made using conductance probes and visual observation in this paper. The experimental results show that bubble turning phenomenon of bubble shape happens at low Froude number, which is defined by gas/liquid mixture velocity. The turning phenomenon significantly affects the bubble velocity.. It is also found that the shape of bubble is mainly determined by the Froude number rather than the bubble length. A hydrodynamics model for the shape of bubble tail is de- rived based on a one-dimension two-fluid model. The model well predicts the characteristics of the bubble tailwhen compared with the experimental results. The theoretical analysis shows that the critical Froude number, at which the turning phenomenon happens, increases as the downward inclination and pipe diameter increase.