Abstract This study reports an experiment to investigate the wetted wall fraction (WWF), which represents the shape of the continuous interface of the air–water stratified and wavy flow regimes, in horizontal and inclined pipes with an inner diameter of 40 mm. Using the experimental data, a semi-empirical model to predict the WWF was developed based on the energy balance for the liquid phase in separated flows. The model used a relationship between the WWF and the center of gravity of the liquid phase with a concave interface that can describe continuous changes to the flow regime from a stratified to an annular. The coefficients of the model were empirically determined based on a wide range of experimental data from the literature obtained in the air and various liquids covering a void fraction of greater than 0.79, a pipe with inner diameter in the range 24–150 mm, density differences varying from 812 to 1052 kg/m3, a range of liquid phase viscosity of 0.87–5.66 mPa s, surface tension ranging from 27.9 to 72.7 mN/m, a wide range of inclination angles from −27° for a downward flow to +3° for an upward flow, and gas and liquid Reynolds numbers based on a superficial velocity of up to 219,000 and 7500, respectively. This WWF model was tested using an extensive experimental database of the WWF and void fraction in the stratified and wavy flow regimes, and yielded the best agreement compared with existing models in the literature.

中文翻译：

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水平管和斜管分离流中湿壁分数的经验模型

摘要 本研究报告了一项研究湿壁分数 (WWF) 的实验，该分数代表内径为 40 毫米的水平和倾斜管道中空气-水分层和波浪流态的连续界面的形状。使用实验数据，基于分离流中液相的能量平衡，开发了预测 WWF 的半经验模型。该模型使用了 WWF 与具有凹界面的液相重心之间的关系，可以描述流态从分层到环形的连续变化。该模型的系数是根据在空气和各种液体中获得的文献中获得的广泛实验数据凭经验确定的，这些液体覆盖了大于 0.79 的空隙率，内径在 24-150 mm 范围内的管道，密度差从 812 到 1052 kg/m3，液相粘度范围为 0.87-5.66 mPa s，表面张力范围从 27.9 到 72.7 mN/m，范围很广倾角范围从向下流动的 -27° 到向上流动的 +3°，气体和液体雷诺数分别基于高达 219,000 和 7500 的表观速度。该 WWF 模型在分层和波浪流状态下使用 WWF 和空隙率的广泛实验数据库进行了测试，与文献中的现有模型相比，产生了最佳一致性。从向下流动的 -27° 到向上流动的 +3° 的广泛倾角范围，以及基于高达 219,000 和 7500 的表观速度的气体和液体雷诺数，分别。该 WWF 模型在分层和波浪流状态下使用 WWF 和空隙率的广泛实验数据库进行了测试，与文献中的现有模型相比，产生了最佳一致性。从向下流动的 -27° 到向上流动的 +3° 的广泛倾角范围，以及基于高达 219,000 和 7500 的表观速度的气体和液体雷诺数，分别。该 WWF 模型在分层和波浪流状态下使用 WWF 和空隙率的广泛实验数据库进行了测试，与文献中的现有模型相比，产生了最佳一致性。