Abstract The need to understand the flow behavior and film thickness in the single screw expander is very crucial since it is known to be a complex system due to the existence of various flow patterns. The present work reports a computational fluid dynamic analysis of two-phase flow behavior and film thickness through a vertical helical rectangular channel using the volume of fluid (VOF) model. The numerical model is validated against available experimental data of annular flow in the helical rectangular channel. The numerical predictions of velocity field, pressure field and liquid phase distribution are presented as each fluid flows into the helical channel. It is found that the inlet flow inclined angle has a significant influence on the liquid film distribution at the outer side of the helical channel. The effects of curvature ratio and dimensionless pitch on the liquid film distribution, film thickness and liquid holdup are illustrated in detail. In addition, the new relationship between the average liquid film thickness and the liquid holdup is also given, and these results are necessary for the optimization design of the single screw expander prototype.

中文翻译：

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单螺杆膨胀机流动特性和膜厚的数值研究

摘要 了解单螺杆膨胀机中的流动行为和膜厚是非常重要的，因为众所周知，由于存在各种流动模式，它是一个复杂的系统。目前的工作报告了使用流体体积 (VOF) 模型对通过垂直螺旋矩形通道的两相流动行为和薄膜厚度进行的计算流体动力学分析。该数值模型根据螺旋矩形通道中环形流的可用实验数据进行了验证。当每种流体流入螺旋通道时，给出了速度场、压力场和液相分布的数值预测。发现入口流动倾斜角对螺旋通道外侧的液膜分布有显着影响。详细说明了曲率比和无量纲节距对液膜分布、膜厚和持液率的影响。此外，还给出了平均液膜厚度与持液率之间的新关系，这些结果对于单螺杆膨胀机样机的优化设计是必要的。