Abstract The experiments on the air-water two-phase flow patterns in a 24 mm diameter vertical circular pipe under both static and rolling conditions were conducted. The superficial velocities were in the range of 0.05–4.07 m/s and 0.02–20.55 m/s for water and air, respectively. Five typical flow pattern morphologies resulting from a rolling motion were observed: dispersed bubbles; bubbles; slug; churn; and annular flow. Flow pattern transitions were identified by analysis of visual images and a bubble chord-length probability distribution function (PDF). The static experimental data was used to validate existing flow pattern transition models that were then modified to fit rolling conditions by considering the additional forces caused by rolling motion. These models also agreed well with the experimental data. Investigation of the influence of the rolling motion on flow pattern transition showed that, as the rolling amplitude increases, the formation of dispersed bubble flow requires a higher superficial liquid velocity. It was also found that, the greater the rolling amplitude, the larger region of churn. The rolling period, however, has little impact on flow pattern transitions.

中文翻译：

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轧制条件下垂直圆管向上两相流型

摘要 对直径为24 mm的立式圆管在静压和轧制条件下的气水两相流型进行了实验研究。水和空气的表观速度分别在 0.05-4.07 m/s 和 0.02-20.55 m/s 的范围内。观察到由滚动运动产生的五种典型流型形态：分散的气泡；气泡；蛞蝓; 搅拌; 和环形流。通过对视觉图像和气泡弦长概率分布函数 (PDF) 的分析来识别流型转变。静态实验数据用于验证现有的流型转换模型，然后通过考虑由滚动运动引起的附加力来修改这些模型以适应滚动条件。这些模型也与实验数据吻合得很好。滚动运动对流型转变影响的研究表明，随着滚动幅度的增加，分散气泡流的形成需要更高的表观液体速度。还发现，滚动幅度越大，搅动区域越大。然而，滚动期对流型转换几乎没有影响。