Numerical predictions and stability analysis of cavitating draft tube vortices at high head in a model Francis turbine

作     者：ZUO ZhiGang LIU ShuHong LIU DeMin QIN DaQing 

作者机构：State Key Laboratory of Hydro Science and Engineering Department of Thermal Engineering Tsinghua University Research & Test CenterDongfang Electric Machinery Co. Ltd State Key Laboratory of Hydro-Power Equipment 

出 版 物：《Science China(Technological Sciences)》 (中国科学（技术科学英文版）)

年 卷 期：2014年第57卷第11期

页      面：2106-2114页

核心收录：

学科分类：080703[工学-动力机械及工程] 080704[工学-流体机械及工程] 08[工学] 0807[工学-动力工程及工程热物理] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.51076077) National Key Technology R&D Program of China(Grant No.2008BAC48B02) 

主　　题：draft tube vortices pressure fluctuations Francis turbine cavitation Batchelor instability 

摘      要：Draft tube vortex is one of the main causes of hydraulic instability in hydraulic reaction turbines,in particular Francis turbines.A method of cavitation calculations was proposed to predict the pressure fluctuations induced by draft tube vortices in a model Francis turbine,by solving RANS equations with RNG k-turbulence model and ZGB cavitation model,with modified turbulence *** cases with different flow rates at high head were *** the study case of part load,two modes of revolutions with the same rotating direction,revolution around the axis of the draft tube cone,and revolution around the core of the vortex rope,can be *** elliptical shaped vortex rope causes anisotropic characteristics of pressure fluctuations around the centerline of the draft tube *** analyzing the phase angles of the pressure fluctuations,the role of the vortex rope as an exciter in the oscillating case can be *** analysis of Batchelor instability,*** in q-vortex like flow structure,has been carried out on the draft tube vortices in these three *** can be concluded that the trajectory for study case with part load lies in the region of absolute instability(AI),and it lies in the region of convective instability(CI)for study case with design flow *** for study case with over load lies in the AI region at the inlet of the draft tube,and enters CI region near the end of the elbow.