蒸汽-冷流体接触冷凝流动的数值模拟

介绍了关于蒸汽-冷流体直接接触冷凝流动与传热的数值计算模型与部分研究结果。用Level Set方法确定蒸汽-冷流体接触界面的位置和形状,建立了对蒸汽和冷流体普遍适用的动量、能量和质量守恒方程,在能量和质量寺恒方程中增加了部分项用于计算蒸汽冷凝所产生的影响。用有限差分法在交错网格上离散控制方程,用Runge-Kutta法-五阶WENO组合格式求解Level Set输运方程,用压力修正的迭代Projection方法求解动量方程,而用SIMPLE方法求解温度控制方程。对算例的计算结果表明,本文所建立的数值计算模型能反映物理现象的宏观特性。根据计算结果,分析了本文模型的优缺点,并指出了今后改进的方向。

NUMERICAL SIMULATION OF LOWING CONDENSATION OF THE STEAM DIRECTLY CONTACTED WITH SUBCOOLED WATER

This paper reports a model developed for numerical study of the flowing condensation of steam directly contacted with subcooled water. With the help of a level set method that is employed to determine the position and morphology of the interface between the steam and water, equations that are globally suitable for the governing of momentum, energy and mass conservation of both the steam and water in the whole computation region are established. Special terms are formulated to take into account the effects of the steam condensation on the two-phase flow and heat transfer, and are respectively included in the momentum and energy equations. The governing equations are discretized using the finite difference method on a staggered Cartesian grid system. A 5-order WENO (Weighted Essentially Non-Oscillatory) scheme, in combination with a 3-order Runge-Kutta scheme, is adopted to solve the advection equation of the Level Set function, and a pressure-correction projection method is employed to find solutions to the momentum equations of the two-phase flow, while a SIMPLE method is utilized to get temperature fields from the energy equation. Results of numerical tests show that the physical mechanism of the condensation phenomena can be reasonably revealed with the present model and method. Based on the numerical results obtained in the paper, both the merits and shortcomings of the present model are analyzed, and directions for future studies to improve the model are pointed out.