抽水蓄能机组不稳定现象的流动机理与控制方法  

Study on Flow Mechanism and Control of Unstable Phenomenon for Pumped Storage Unit

作　　者：罗先武[1,2] 叶维祥 杨丹丹[1,2] 冉红娟 LUO Xianwu;YE Weixiang;YANG Danda;RAN Hongjuan(Beijing Key Laboratory of CO2 Utilization and Reduction Tech no logy,Beiji ng 100084,China;State Key Laboratory of Hydroscienee and Engineering,Tsinghua University,Beijing 100084,China;College of Mechanical and Power Engineering,Shanghai Jiaotong University,Shanghai 200240,China)

机构地区：[1]清华大学二氧化碳减排与资源化利用技术北京市重点实验室,北京市100084 [2]清华大学水沙科学与水利水电工程国家重点实验室,北京市100084 [3]上海交通大学机械与动力工程学院,上海市200240

出　　处：《水电与抽水蓄能》2020年第4期19-31,共13页Hydropower and Pumped Storage

基　　金：国家重点研发计划课题(2018YFB0606101);国家自然科学基金资助项目(91852103,51776102);北京市自然科学基金资助项目(3182014)。

摘　　要：随着电站参数水平不断提高,抽水蓄能技术对机组稳定性的要求越来越高。本文基于已有研究成果,阐述了抽水蓄能机组泵工况下不稳定现象关联的特性曲线驼峰及驼峰区域的压力脉动特征。为了深入揭示抽水蓄能机组内部不稳定流动机理,现阶段应均衡考虑预测精度与计算资源需求,开发适合于抽水蓄能机组不稳定特性分析的动态PANS方法。大量的试验与计算结果表明,抽水蓄能机组泵工况的特性曲线驼峰源自动静干涉引起的导叶流道中不稳定流动;即当机组运行在偏低流量时,较大尺度的流动分离与漩涡会堵塞相邻导叶间流道,进而导致导叶与转轮中的能量损失激增,使得机组扬程陡降、特性曲线出现驼峰;通常情况下,被称为"失速团"的不稳定流动结构只发生在部分导叶流道中,且以一定的速度进行传播;机组内部的不稳定流动可诱发强烈的压力脉动,在特定条件下甚至影响机组的安全性。最后,针对机组不稳定流动机理研究,分析了改善抽水蓄能机组不稳定特性的控制措施。With the continuous increase of the design parameters level for hydropower stations,the pumped storage technology requirement for unit operation stability is becoming increasingly high.Based on the existing research achievements,the present paper illustrates the positive slope phenomenon on the characteristic curves and the induced pressure fluctuations,which are associated with flow instability phenomenon in the pumped storage units at the pump mode.To reveal the flow instability mechanism in the pumped storage units,the dynamic PANS(Partially Averaged Navier-Stokes)model,which is suitable for analyzing unstable characteristic in pumped storage units,has been developed considering the balance between the prediction accuracy and the computing resources.A large number of experimental and simulation results indicate that the unstable flow in the guide vane induced by the rotor-stator interaction is the source of the positive slope phenomenon on the characteristic curves for pumped storage units at the pump mode.When the units operate under low flow rate conditions,large-scale flow separation and vortices may block the blade-to-blade flow passage of the guide vanes,which lead to the sudden increase of energy loss in both the guide vanes and runner,resulting in the sudden head drop.Consequently,the positive slope phenomenon appears on the characteristic curves of the units.Further,the unstable flow structure called as"stall cell"only occurs in few passages of the guide vanes and propagates at a certain speed.This kind of unstable flow in the units induces severe pressure fluctuations and even threatens the safety of the units at some conditions.Finally,based on the investigations on the flow instability mechanism of the units,several methods to suppress the unstable flows in the pumped storage units are analyzed so as to improve the operation quality of pumped storage units.

关 键 词：抽水蓄能 特性曲线 驼峰 流动机理 

分 类 号：TK73[交通运输工程—轮机工程]