偏工况下混流式水轮机压力脉动数值仿真及其改善措施研究  

Numerical simulation of pressure fluctuation in a Francis turbine at part load conditions with improved measures

作　　者：冯建军[1] 武桦[1] 吴广宽[1] 郭鹏程[1] 罗兴锜[1] 

机构地区：[1]西安理工大学水利水电学院,陕西西安710048

出　　处：《水利学报》2014年第9期1099-1105,共7页Journal of Hydraulic Engineering

基　　金：国家自然科学基金资助项目(51339005;50979091);陕西省百人计划资助项目(2012)

摘　　要：某电站混流式水轮机组在部分负荷时机组出力大幅摆动,真机试验结果显示尾水管涡带频率与发电机低频振荡频率接近,二者产生共振导致功率波动。本文采用CFD方法对该电站混流式水轮机进行了三维非定常数值模拟,对包括电站现用泄水锥、加长型泄水锥、在尾水管内安装阻尼栅、在尾水管内安装导流板等4种方案下水轮机内部非定常流动进行了仿真,对比分析了各种方案对尾水管内涡带形状和压力脉动的影响。计算结果表明:加长泄水锥能降低压力脉动的幅值,但不能改变压力脉动频率;相比于阻尼栅,在尾水管中安装导流板能更有效地改变尾水管水压力脉动的主频并减小压力脉动的幅值,且对水轮机效率的影响较小。The fluctuation of the turbine output power is very strong at part load conditions for a Francis turbine in a power plant. The test for the prototype at site shows that the main reason is the resonance between the draft tube vortex frequency and the generator natural frequency. CFD methods are adopted in this paper to simulate three-dimensional unsteady flow in the turbine of the power plant. Four kinds of draft tubes are modeled,including the origin draft,extending the runner cone,adding damping gates in the draft and adding flow deflectors in the draft. The results for the above cases are analyzed and compared,focusing on the effects on the draft tube vortex and pressure fluctuations generated by the vortex. The computational results show that the extended runner cone can reduce the pressure fluctuation amplitude,while it does not change the pressure fluctuation frequencies effectively. Compared to adding damping gate,adding flow deflector in the draft tube can be more effective to change the frequency and reduce the amplitude of the draft tube pressure fluctuations,and the influence on turbine efficiency is smaller.

关 键 词：混流式水轮机 尾水管涡带 泄水锥 阻尼栅 导流板 

分 类 号：TK733[交通运输工程—轮机工程]