竖直圆管内液氮过冷流动沸腾数值模拟研究

Numerical simulation for subcooled boiling process of liquid nitrogen in vertical tube

在现有数学模型的基础上,从沸腾换热的机理入手,对过冷流动沸腾模型中的气泡参量模型进行了修正,分析确定了壁面热流密度的拆分方法,构建出适应于液氮的过冷沸腾计算模型。将新模型应用于CFX4.4中,对液氮在三维竖直圆管内的过冷流动沸腾进行了数值模拟。研究发现,在过冷流动沸腾形成之后,蒸发热流成为壁面换热的主要部分,沸腾换热占据换热的主导地位。数值模拟结果与已有的实验数据吻合较好,证明了新建模型的正确性。

Based on the current subcooled boiling phase transformation model, the important bubble model parameters about boiling process were amended according to the mechanism of boiling heat transfer. The partition of wall heat flux was studied and the new model applicable to subcooled boiling process of liquid nitrogen was reestablished. The subcooled boiling phase transformation of liquid nitrogen in a three-dimensional vertical tube was simulated through the application of the new model in commercial CFD code CFX4.4. The results shows that the evaporation heat flux is the main part of wall heat transfer and boiling heat transfer plays a leading role in the heat transfer process. The simulated results are in good agreement with the experimental data, which demonstrates the accuracy of the new model.