水平管外降膜流动和膜厚分布三维数值分析

运用Fluent软件对水平管蒸发器管外降膜流动进行三维数值模拟,分析了换热管间为柱状流时水在管外流动过程及液膜分布,研究了喷淋密度和管间距对管外液膜厚度的影响。模拟结果表明,管间为柱状流时,液膜沿管外壁面分布不均匀,管外壁面局部液膜厚度与其所处轴向位置和周向角度有关。在波峰截面,增加喷淋密度或管间距,液膜厚度均明显增加;在液柱截面,改变喷淋密度或管间距仅对上半管周的液膜厚度有影响,且液膜厚度随着喷淋密度的增加而增大,随着管间距的增大而减小。

3-D Numerical Analysis of Falling Film Flow and Film Thickness Distribution outside a Horizontal Tube

3-D numerical simulations of falling film flow outside tubes in horizontal tube evaporator were simulated by Fluent, the flow process of water outside the tube and the distribution of liquid film were analyzed and the effects of spray density and tube spacing on the liquid film thickness were studied. The simulation results show that the liquid film’s uneven distribution along the outer surface of tube during flow pattern in jet model and the thickness of local liquid film is related to the axial position and the circumferential angle of tube. The thickness of liquid film increases obviously at the section of crest with the increasing of spray density or tube spacing. At the section of liquid column, the changing the spray density or tube spacing only affects the thickness of liquid film around the upper half of the tube. The thickness of liquid film increases with the increasing of spray density while decreases with the increasing of tube spacing.