【作者】 汤升才；

【导师】 金峰；

【作者基本信息】 长江科学院 ， 水力学及河流动力学， 2009， 硕士

【摘要】 水气两相流是一种复杂而重要的流动现象,许多学者耗费了的大量精力对其进行了研究。由于存在着相间质量、动量、能量及热量的交换,且具有各向异性的特点,水气两相流的动力特性比单质水动力学特性要复杂得多。本文首先对已有的水气两相流研究成果进行了综述,在此基础上深入探讨了水气两相流数值模拟的理论和方法,通过数值模拟和物理模型试验相结合的方法对台阶坝泄流和设置掺气坎的底孔泄流水力特性进行了研究,主要成果有:1.采用二维k ?ε双方程紊流模型,对台阶坝面的流态、流速、水面线以及坝面压力和水流的掺气情况进行了模拟,并由此计算了台阶坝的消能率。计算中自由表面采用VOF方法处理,边界条件的处理使用了任意网格差分法,数值求解使用了点隐式高斯—塞德尔迭代方法。物理模型试验验证表明,对台阶坝面水流的数值模拟是可行的。2.对台阶坝面水流数值模拟结果表明,水流流过一定台阶后开始掺气,与光面坝相比,坝面水深增加,流速减小,产生空化空蚀的风险降低,而消能率大大增加。3.采用三维k ?ε双方程紊流模型,对泄洪底孔的水力特性进行了数值模拟。计算分析了泄洪底孔有压短管压力、跌坎下游的掺气空腔长度、高度、通气孔的通气量、消力池流速流态和压力等水力参数。物理模型试验验证表明,对泄洪底孔泄流的数值模拟也是可行的。更多还原

【Abstract】 Water-air two-phase flow is a complicated and important phenomenon which has attracted many scholars globally spending a lot of time on mechanism study. Due to the mutual exchanges among weight, momentum, energy, and heat that exists in the flow process, the dynamic characteristics of water-air two-phase flow is a bit different from that of water flow.In this paper step energy dissipation and bottom outlet flood discharge energy dissipation with air hole had been studied by the method of the combination of numerical simulation and physical model tests. And the main results are as follows:1. The thesis used the 2D double-equation turbulence flow numerical calculation method. The whole process of the water-air two-phase flow was simulated numerically in the cases of flow pattern, velocity, water surface line on the stepped spillway as well as the step pressure and c on the surface of the spillway. Then the rate of energy-dissipation of the stepped spillway was calculated. The simulation method was called the free-surface simulation method, in which the VOF method were used. And the arbitrary mesh-finite difference method was used in the boundary condition solution. The numerical solution was made out with point Implicit Gauss - Seidel iterative method.According to the analysis of the results between numerical simulation and the physical simulation, the numerical simulation was feasible.2. The numerical simulation for the stepped spillway illustrated that the flow aeration starede to increase on the surface of the spillway, and the velocity decreased whereas the rate of energy-dissipation increased. Therefore, the risk of the cavitation decresed.3. The three-dimensional numerical simulation was used in the research of the hydraulic characteristics , which simulated the length, the height, the volume of the hole, depth distribution, velocity in the home as well as the pressure of the aeration hole in the flood hole’s aeration bottom. According to the comparative analysis with the physical experiments, the numerical simulation was feasible too.更多还原