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根据逆环状流膜态沸腾(IAFB)的可视化实验结果,将该流型理想化为一个两区物理模型。按双区物理模型假定,建立二维、二流体数学解析模型。它由质量、动量和能量守恒微分方程以及相应的本构方程构成完全方程组,然后用数值方法求解。用该模型分析了液相、汽相参数以及加热管的壁温,与Stewart的实验数据进行了比较,两者相当一致。可信地预示了液体过冷度、质量流率、系统压力和加热热流率对加热面温度的影响。同时选择实例分析了流动二维效应和初始汽膜厚度取值对加热面温度和膜厚变化的影响。结果表明:在讨论的范围内忽略两维效应对壁面温度影响不大;初始膜厚取值不同对加热面温度变化和膜厚变化无显著影响。
According to the experimental results of inverse cyclic flow boiling (IAFB), the flow pattern is idealized as a two-zone physical model. According to the assumption of two-zone physical model, a two-dimensional and two-fluid mathematical analytical model is established. It consists of mass, momentum and energy conservation differential equations and the corresponding constitutive equations form a complete system of equations, and then solved numerically. The model was used to analyze the liquid phase, vapor phase parameters and the wall temperature of the heating tube, which were in good agreement with Stewart’s experimental data. The effects of liquid undercooling, mass flow rate, system pressure and heating heat flux on the heating surface temperature are forecasted. At the same time, the effects of two-dimensional flow and initial vapor thickness on the heating surface temperature and film thickness were also analyzed. The results show that ignoring the two-dimensional effect has little effect on wall temperature within the scope of the discussion. Different initial film thickness has no significant effect on the temperature change and film thickness variation of the heating surface.