针对倾斜扁平管内的湍流蒸汽，考虑交界面剪切力，建立蒸汽凝结的 CFD 模型。在一根实验样管上(长宽高尺寸：2600 mm×3 mm×50 mm，倾斜角：60°)，对比管内平均凝结传热系数和蒸汽凝结率的CFD解与实验值，验证模型的有效性。计算不同蒸汽入口流速下的交界面剪切力值，发现剪切力的大小由蒸汽入口流速决定，其数值随蒸汽流动持续递减。对剪切力对蒸汽凝结影响进行CFD模拟，发现，剪切力增大管内局部凝结传热系数，减小蒸汽凝结质量；在0～0.8 m管段，剪切力明显破坏了重力对液膜的累积，削薄了液膜厚度，但从1.0 m到蒸汽出口，液膜厚度由重力控制，剪切力的影响可忽略不计；剪切力迫使液膜加速流动，其加速作用0～0.2 m管段表现突出。%Considering the interfacial shear force, a mathematical model to the condensation of turbulent vapor flowing downward in an inclined flat tube is proposed and implemented in computational fluid dynamics (CFD). The predicted results from the CFD model are compared with the experimental results from the literature for the vapor condensation in a prototype tube (2600 mm length, 3 mm width and 50 mm altitude in60°inclination to vertical). It is found that the condensate rate and mean condensation heat transfer coefficient (HTC) from CFD simulation agree very well with the experimental quantities. Using CFD model to calculate the interfacial shear stress by varying vapour velocity, the results demonstrate that the value of shear force depends on the vapor velocity at the tube inlet, and shear force decreases continuously with the vapor flow and condensation. Simulating the interfacial shear effect on the condensation, it shows that the interfacial shear increases the local condensation HTC, and meanwhile, reduces the local condensate rate. The simulation results also shows that the interfacial shear weakens the gravitational effect on the film accumulation and obviously decreases film thickness from 0 to 0.8 m in the tube axial length. However, from 1.0 m to the tube outlet, the gravitational force dominates over the shear force, and thus the shear effects can be completely neglected. It is also found that the condensate film is speeded up particularly from 0 to 0.2 m in axial length thanking for the interfacial shear.
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