水轮机活动导叶关闭过程中导水机构内动态流场数值模拟研究

水力机组在暂态过程中诱发的强瞬变流是一种复杂的非定常湍流,对机组安全稳定运行具有重要影响。为了探索水轮机活动导叶动态调节动作诱发叶后强瞬变流对机组暂态特性的影响,本文应用模拟流固耦合动态效应较好的浸入边界法和大涡模拟技术来处理该类强非线性动边界流体动力学问题。首先,精细模拟槽道内两级线性排列动静叶栅动态绕流叶后压力和尾迹结构分布,由于受到固定导叶和活动导叶动静干涉的影响,其下游流场表现出复杂的非定常流动特征。随后完成了水轮机导水机构两级非线性环列叶栅动态绕流的模拟,展现了水轮机导叶调节运动的关闭过程。该方法可用于水轮机流道内多级翼型叶栅绕流的精细模拟,为研究水轮机调节振荡对机组暂态性能的影响提供有益的参考,对耦合上游管道系统水力暂态和水轮机三维暂态效应的研究也有指导意义。

Numerical simulation of dynamic flow around wicket gate in hydro turbine with guide vane closure

The strong fluid transient induced by the hydraulic transient process is an unsteady turbulent flow,which has an important influence on the stable operation of hydro unit.In order to explore the hydro-turbine dynamic regulating action induced by strong fluid transient effect on the transient characteristics of the unit,the immersed boundary method and large eddy simulation for simulating fluid-structure interaction were applied to deal with the strong nonlinear dynamic boundary problem of fluid dynamics.The distribution of pressure and wake structure was finely simulated in linear cascades in a channel.The flow field of the downstream is very complicated due to the unsteady flow characteristics of staying vanes and moving guide vanes.The dynamic flow around wicket gate in hydro-turbine with guide vane closure was simulated. The change of corresponding flow topology is more complicated.The real simulation of the closing process of guide vanes in wicket gate was performed.The method can be used for the fine simulation of flow around multi-cascade in hydro-turbine,and provides reference for studying the transient performance influenced by the oscillation in the hydro-turbine adjusted process.The research was instructive to the hydraulic transient of the upstream pressure conduit and the three dimensional hydraulic transient effect of hydro-turbine.