相邻液柱在横管外成膜规律的三维数值模拟

3D Simulation on Flow Behavior of Two Adjacent Columns Outside Horizontal Tube

柱状流作为横管降膜流动的主要流型之一,因其流态稳定、润湿管壁效果好,传热系数较高等优点而常见于多种蒸发器的流型中。为了研究相邻液柱在管外铺展成膜的流动叠加过程和液膜在管外的分布规律,建立了相邻液柱的降膜流动三维物理模型。结果表明:相邻液柱在在下落至管壁后各自沿着横管轴向铺展润湿管壁,两侧液膜在轴向中间位置发生交汇叠加;中间位置处的液膜厚度值能达到平稳区域的2-3倍且越靠近轴向中间位置处液膜厚度值越大。

The column flow was a common flow pattern and had attracted many attention in evaporation systems because of obvious advantages. A 3 D model was applied in this paper to simulate the flow behavior and film thickness of two adjacent columns outside horizontal tube. Results show that the liquid film spread both in axial direction and circumferential direction. The collision and overlap of liquid film were observed and the flow behavior of two adjacent columns was analyzed in detail. In addition, the film thickness reached a maximum between two adjacent columns. The crest value of film thickness was more than three times as much as the minimum and the flowing region that was closer to the crests would have larger film thickness.