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

CTS-9322481 Dhir汽液界面在垂直表面饱和或过冷汽膜沸腾过程中的界面形状主要由开尔文-亥姆霍兹不稳定性决定，而水平表面汽膜沸腾过程中的界面形状主要由罗利-泰勒不稳定性决定。界面的演化和诱导流场控制着界面上的传热和传质，进而控制着加热器表面的换热。本文对汽液界面的演化过程以及汽液两相内伴随的流动和温度场进行了完整的数值模拟。模拟将在不引入任何经验常数的情况下进行，并且将包括界面不稳定性的线性和非线性增长。在第一阶段，计算将仅限于二维，并将使用谱配置法和SIMPLE算法对控制方程进行数值积分。数值结果还将给出壁面过热度，在该过热度时加热器表面不能支撑连续的汽膜。从而为预测最小热流密度提供了完整的理论依据。这一数值工作将得到文献中已报道的实验数据的支持。如果认为有必要，将使用现有的实验设备来获取垂直和/或水平板上所需的数据。

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.