Numerical Simulation of Vapor-Liquid Interfaces During Saturated and Subcooled Film Boiling

饱和或过冷薄膜在垂直表面沸腾时的Dhir气液界面形状由开尔文-亥姆霍兹不稳定性决定，而在水平表面沸腾时，由罗利-泰勒不稳定性决定界面结构。界面的演变和诱导流场控制了界面上的传热和传质，反过来又控制了加热器表面的传热。本文提出了一种完整的气液界面演化过程的数值模拟方法，并对气液界面的流动和温度场进行了数值模拟。模拟将在不引入任何经验常数的情况下进行，并将包括界面不稳定性的线性和非线性增长。在第一阶段，工作将仅限于两个维度，并将使用谱搭配法和SIMPLE算法对控制方程进行数值积分。数值结果也会产生壁面过热，在这种情况下，连续汽膜不能支撑在加热器表面上。从而为最小热通量的预测提供了完整的理论依据。数值上的努力将得到文献中已经报道的实验数据的支持。如认为有需要，将使用现有的实验设施在垂直和/或水平板上获取所需的数据。

ABSTRACT CTS-9322481 Dhir Vapor-liquid interface shape during saturated or subcooled film boiling on a vertical surface is governed by Kelvin-Helmholtz Instability whereas it is the Raleigh-Taylor instability that governs the configuration of the interface during film boiling on horizontal surfaces. The evolution of the interface and the induced flow field govern the heat and mass transfer across the interface and in turn the heat transfer from the heater surface. In this study a complete numerical simulation of the evolution of the vapor-liquid interface and the accompanied flow and temperature field in the vapor and the liquid is proposed. The simulation will be carried out without introducing any empirical constants and will include both linear and non-linear growth of the interfacial instabilities. In the first phase, the effort will be limited to only two dimensions, and spectral collocation method along with SIMPLE algorithm will be used to numerically integrate the governing equations. The numerical results will also yield the wall superheats at which a continuous vapor film could not be supported on the heater surface. Thus the results will provide a completely theoretical basis for prediction of minimum heat fluxes. The numerical effort will be supported with experimental data already reported in the literature. If deemed necessary, existing experimental facilities will be used to obtain the required data on vertical and/or horizontal plates.