某大型抽水蓄能电站水泵水轮机转轮强度及模态分析

Strength and Modal Analysis of Pump Turbine Runner in A Large Pumped Storage Power Station

抽水蓄能电站中由于机组工况转换频繁、正反转运行,因此对于水泵水轮机转轮结构强度及性能具有较常规机组更高的要求。本文以国内某大型抽水蓄能电站转轮为研究对象,建立了水轮机全流道三维模型,并基于ANSYS Workbench平台对不同工况下的水泵水轮机转轮进行了单向流固耦合计算,得到水轮机工况及水泵工况下转轮的静应力分布及分布情况,并展开两种运行工况下转轮的模态分析。计算结果表明:机组在相同水头的水轮机工况下运行时,随着导叶开度的增大,转轮的最大静应力及位移均呈现减小趋势;但水轮机工况与水泵工况下,叶片的最大静应力普遍发生于叶片外缘,可采取适当加厚、检查圆滑过渡等措施予以预防和避免应力集中。通过模态分析,发现转轮流固耦合第一阶振动固有频率与导叶出口的不均匀流脉动频率接近,需调整转轮固有频率以避免共振现象的发生。

In pumped storage power station,the structural strength and performance of pump turbine runner are required to be higher than that of conventional units due to the frequent conversion of unit conditions and positive and negative operation.In this paper,the runner of a large domestic pumped storage power station is taken as the research object,and a three-dimensional model of the full flow channel of the turbine is established.Based on the ANSYS Workbench platform,the unidirectional fluid-solid coupling calculation of the pump turbine runner under different working conditions is carried out,and the static stress distribution and distribution of the runner under the turbine and pump working conditions are obtained.The modal analysis of the runner under two operating conditions is carried out.The calculation results show that the maximum static stress and displacement of the runner decrease with the increase of the opening of the guide vane when the unit is operating under the same hydraulic turbine condition with the same head.However,under turbine and pump conditions,the maximum static stress of the blade generally occurs at the outer edge of the blade,which can be prevented and avoided by proper thickening,checking the smooth transition and other measures.Through modal analysis,it is found that the natural frequency of the first order vibration of rotating solid coupling is close to the frequency of the non-uniform flow pulsation at the outlet of the guide vane,and the natural frequency of the runner should be adjusted to avoid the occurrence of resonance.