水平横管外降膜液体流动型式数值研究 邱庆刚.docVIP

中国工程热物理学会 学科类别：多相流 学术会议论文 编号：143445 水平横管外降膜液体流动型式数值研究 邱庆刚，蒋维国，贾丹丹，沈胜强 （大连理工大学 能源与动力学院 辽宁 大连 116024） 摘要：针对流体在水平管间的降膜流动特性，建立了水平管外降膜流动物理模型，采用数值模拟方法，分析了管间流体流动型式及液滴下落随时间的变化特性。同时研究了质量流量对管间流型转换的影响。结果表明：质量流量对管间流型的转换具有重要影响；随着质量流量的增加，管间流体由滴状流动逐渐过渡为柱状乃至膜状流动；管间流体呈滴状流动时，历经液滴形成、液滴长大、液滴下落及液桥形成、液桥断裂、卫星液滴生成等过程；重力与表面张力共同控制着液滴的下落行为。 关键词：水平横管；两相流；管间流型；液滴下落 Numerical Investigation of Liquid Flow Patterns between Horizontal Tubes (Qinggang Qiu, Weiguo Jiang, Dandan Jia, Shengqiang Shen) (School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China) Abstract：A numerical investigation relating to flow-patterns of liquid falling film between horizontal tubes was presented based on the newly devepoed physical model for falling liquid film outside surface of a horizontal tubes. The effect of liquid flow rate on flow transitions and the characteristics of droplets during their formation, detachment, fall and impact had been investigated. The results show that the flow rate has an important impact on flow patterns. The droplet dripping usually appears at a low flow rate. This flow pattern changes first to a column mode, and then to a liquid sheet when the flow rate increases. It also shows that the liquid flow over a bank of tubes exhibits some interesting patterns such as droplet formation, growth, detachment, fall and impact and the resulting satellite droplets, which are governed by force of gravity and surface tension. Keywords: horizontal tube; two-phase flow; flow patterns; droplets behavior 0引言 水平管降膜技术能在较小的传热温差、较大的操作温度下进行，换热管两侧均为相变换热，还可以减少气流的流动阻力，从而提高了换热器的换热性能，减小了换热器体积，显著增大了换热系数。此外，水平管降膜换热器还具有耗材省、结构紧凑等优点。水平管降膜技术已广泛应用于空调制冷、海水淡化、化工、石油冶炼等工业中[1-3]。在水平管降膜过程中，液体的流动与传热传质过程同时进行，流体的流动是换热过程和质量传递过程的基础和载体。其中，管间液体的流动型式对整个传热传质过程至关重要[4]。 国内外学者对水平管间的液体流动型式进行了广泛的研究。Yung等[5]基于液滴生成速率等于界面波振荡频率的原则，针对静止蒸汽条件下的单管单个液滴脱离点，给出了单侧单位水平管长度上流动型式从滴状向膜状转变与液体质量流量关系的关联式。Maron-Moal