水泵水轮机水泵断电飞逸过程压力脉动CFD模拟

水泵断电导叶拒动导致机组飞逸是抽水蓄能电站的危险过渡过程,伴随水锤压强、水轮机流态、压力脉动、转轮受力发生剧烈波动,研究中必须综合考虑。由于常规过渡过程模拟只能考虑水锤波动,目前对后面几种特性缺乏了解。本文采用一维输水系统和三维水轮机耦合的CFD模拟方法,针对某模型抽水蓄能系统进行水泵断电飞逸过渡过程模拟。分析了流量、转速、转轮受力的宏观参数变化,发现在鞍形区及水轮机S区波动剧烈;分析了测点压强变化,发现整个过渡过程中压力脉动频率复杂,有高频低幅、高频高幅、中频中幅、低频高幅四类,在鞍形区及S区压力脉动幅值大,正常运行区附近幅值小;结合流态分析,发现高频脉动产生于动静干涉,中低频脉动来源于旋转失速和尾水管涡。

CFD simulations of pump-trip runaway process pressure pulsation of a model pump-turbine

The runaway transient process after pump-trip accompanied by invalid wicket gates is an event very dangerous to pumped-storage power stations. Violent fluctuations in water hammer, flow patterns, pressure pulsations, and runner forces are the issues that lack understanding and need further studies. In this work, A CFD method coupling the one-dimensional waterway flow and three-dimensional flow was adopted in a model pump-turbine to simulate this fast-evolving process. Analyzing the histories of discharge, rotational speed, and runner forces, it find that the fluctuations of these parameters are obvious in the hump and S regions of the characteristic curves. Examining pressure pulsations at different monitoring points, it find that the pulsating characteristics all over the four-quadrant characteristic plane are complicated and can be classified to four types: high frequency-low amplitude, high frequency-high amplitude, middle frequency-middle amplitude, and low frequency-high amplitude. In the hump and S regions, both high- and low-frequency components become stronger, while in the normal operation regions all the components calm down. The flow patterns shows that high-frequency components come from rotor-stator interaction, and middle- and low-frequency components are from the vortices in the sections of guide vanes, runner blades and draft tube.