Liquid film thickness behaviour within a large diameter vertical 180° return bend
Liquid film thickness behaviour within a large diameter vertical 180° return bend
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DOI：
10.1016/j.ces.2013.12.009
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发表时间：
2014-04
影响因子：
4.7
通讯作者：
M. Abdulkadir;A. Azzi;D. Zhao;I. Lowndes;B. Azzopardi
中科院分区：
文献类型：
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作者：
M. Abdulkadir;A. Azzi;D. Zhao;I. Lowndes;B. Azzopardi
本文报道了空气-水混合物流过垂直180°回流弯曲时液膜厚度分布的实验结果。液膜厚度的测量实现了使用齐平安装针和平行线探针。该弯曲具有127 mm的直径和3的曲率比（R/D）。空气的表观速度为3.5至16.1 m/s，水的表观速度为0.02至0.2 m/s。在这些表观速度范围内，在这项工作中研究的流型集中在搅拌和环状流。结果表明，当气液表观速度分别为6.2 m/s和0.02 m/s时，平均液膜厚度在90°处达到峰值。在气体表观速度为16.1 m/s时，由于剪切力克服重力，它们之间呈线性关系。此外，发现夹带液滴的沉积使液膜保持在弯曲的外侧。弯曲内平均液膜厚度极坐标图的结果表明，由于重力的作用，弯管内液膜分布不对称，在弯曲内侧液膜较厚。平均液膜厚度的实验结果与文献报道的模拟数据吻合较好。
Experimental results of liquid film thickness distribution of an air–water mixture flowing through a vertical 180° return bend are reported. Measurements of liquid film thickness were achieved using flush mounted pin and parallel wire probes. The bend has a diameter of 127 mm and a curvature ratio (R/D) of 3. The superficial velocities of air ranged from 3.5 to 16.1 m/s and those for water from 0.02 to 0.2 m/s. At these superficial velocity ranges, the flow pattern investigated in this work focused on churn and annular flows. It was found that at liquid and gas superficial velocities of 0.02 m/s and 6.2 m/s, respectively, the averaged liquid film thickness peak at 90°. At gas superficial velocity of 16.1 m/s, the relationship between them is linear due to the shear forces overcoming gravity. Additionally, it was found that deposition of entrained droplets keeps the liquid film on the outside of the bend. The results of polar plots of average liquid film thickness in the bend showed that the distribution of the liquid film is not symmetrical with thicker films on the inside of the bend due to the action of gravity. Experimental results on average liquid film thickness showed good agreement with the simulation data reported in the literature.