水泵水轮机增减负荷过程三维流动特性大涡模拟分析

摘要

This paper is concerned with large-eddy simulation of three-dimensional turbulent flow for a pump-turbine in transition process of increasing or decreasing load operation.The details of dynamical physics of the flow structures with opening variation of the moving guide vane are well captured.The vorticity distributions in the blade turbine passage are significantly distinguished.The flow characteristics in case of water pump or electricity generation in off-design conditions are obtained.This work shows the relations between flow coming angle of attack at the blade let and the vortex structures in the blade passage.Therefore,an identification method of the horseshoe vortex in the blade passage is obtained,and comparative analyses of the vortex structures in the various operation conditions are given.The results show that the flow stability of a pump-turbine is closely related to the evolution characteristics of the flow structures in different operation conditions,and in the transition process of increasing or decreasing load,the scales and distribution ranges of the vortex structures become greater with time and the flow regimes are more unstable.%采用大涡模拟(LES)对水泵水轮机增减负荷过渡过程进行三维非定常数值模拟,捕捉到了不同开度下叶道中多种涡系结构,展示了叶道涡涡量分布,分析了水轮机工况及水泵工况小流量运行区的流动结构变化特性,揭示了水流进口攻角与叶道涡涡系结构关系,对各类叶道涡不同形态进行了研究并提出了马蹄涡识别变量,并对比分析了水轮机工况及水泵工况涡结构变化特性.计算表明水泵水轮机的水力稳定性与机组运行工况改变时的流动结构特性密切相关,在增减负荷过渡过程中,叶道涡结构的尺度及分布范围均随时间发生较大变化,是影响流态发生巨变的主要因素.