Flow Modes and Mode Transitions for Falling Films on Flat Tubes
Flow Modes and Mode Transitions for Falling Films on Flat Tubes
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DOI：
10.1115/1.4005095
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发表时间：
2012-02
影响因子：
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通讯作者：
Xiaofei Wang;P. Hrnjak;S. Elbel;A. Jacobi;M. He
中科院分区：
文献类型：
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作者：
Xiaofei Wang;P. Hrnjak;S. Elbel;A. Jacobi;M. He
文中给出了不同流型的过渡雷诺数，并提出了一个过渡图。本文研究了扁管降膜的转变过程。水和乙二醇被用作工作流体，用于在绝热条件下进行的降膜实验，而不施加蒸汽流。使用高速数码相机在流速和管间距的范围内记录流型。流态与圆管上的流态相似，包括片状流、片状射流、射流、射流-液滴和液滴流，但乙二醇的转变不同，在片状流和射流之间的转变过程中没有片状射流。过渡阈值随管间距的增加而增加，分布器高度的影响取决于流型。文中给出了不同流型的过渡雷诺数，并提出了一个过渡图。
The transitional Reynolds numbers for different patterns are available and a proposed transitional map is also provided in this paper. The transition of falling-films on flat tubes is studied in this work. Water and ethylene glycol are used as working fluids, for falling-film experiments conducted under adiabatic conditions, without an imposed vapor flow. The flow patterns are recorded using a high-speed, digital camera over a range of flow rate and tube spacing. The flow patterns are similar to those on round tubes, including sheet, sheet-jet, jet, jet-droplet and droplet flows, but the transitions for ethylene glycol are different–there is no sheet-jet pattern during transition between the sheet and jet flow patterns. The transition threshold increases with tube spacing and the effect of distributor height depends on flow patterns. The transitional Reynolds numbers for different patterns are available and a proposed transitional map is also provided in this paper.