摘要
本文结合SST k-ω湍流模型,建立水轮机全流道三维数值模拟方法,探究巨型混流式水轮机在低水头不同负荷工况下尾水管内部涡带形成机理及压力脉动变化规律。研究结果表明:在低负荷工况下,尾水管进口主流在转轮出口正向速度环量的作用下,易形成偏心螺旋状涡带,其旋转方向与转轮一致,此时尾水管内部可监测到主频为0.17倍转频(1.85 Hz)的低频压力脉动。而随着机组过流量增加,尾水管直锥段出现与转轮运动方向相反的涡带分布,并伴随着以2.16倍转频为主的高频压力脉动现象。通过比较不同泄水锥结构的计算结果,延长泄水锥结构可以抑制部分工况下螺旋状涡带的产生,使得尾水管内部主频压力脉动幅值减弱近45.9%。
This paper develops a three-dimensional numerical simulation method for the entire flow passage of a huge Francis turbine using the SST k-ωturbulence model.The formation mechanism of vortex ropes and the variations in pressure fluctuations in the draft tube of the Francis turbine have been explored under different load conditions at the low water head.The results showed that under low-load conditions,the mainstream at the draft tube inlet tended to form an eccentric spiral vortex rope with the action of a positive velocity circulation at the runner outlet,which would rotate in the same direction of the runner,with the detection of low-frequency pressure pulsation of dominant frequency 0.17 times the runner rotation frequency(1.85 Hz)inside the draft tube.However,as the flow rate of the unit increased,a vortex zone rotating opposite to the runner emerged in the straight cone section of the draft tube,accompanied by high-frequency pressure pulsation dominated by the frequency of 2.16 times the runner rotational frequency.By comparison of predicted results among various discharge cones,we found out that the extension of discharge cone structure could suppress the generation of spiral vortices under certain working conditions,so as to cut down the amplitude of the dominant frequency of pressure pulsation in the draft tube by nearly 45.9%.
作者
周玉国
王浩博
董钟明
李秘
王彦龙
邹双喜
邹顺
周大庆
于安
郭俊勋
ZHOU Yuguo;WANG Haobo;DONG Zhongming;LI Mi;WANG Yanlong;ZOU Shuangxi;ZOU Shun;ZHOU Daqing;YU An;GUO Junxun(China Yangtze Power Co.,Ltd.,Yichang 443000,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China;College of Energy and Electrical Engineering,Hohai University,Nanjing 211100,China)
出处
《水力发电学报》
CSCD
北大核心
2023年第12期87-95,共9页
Journal of Hydroelectric Engineering
基金
国家自然科学基金(51979086,51839008)
中国长江电力股份有限公司科技项目(5322020006)。
关键词
数值模拟
混流式水轮机
尾水管
涡带
压力脉动
numerical simulation
Francis turbine
draft tube
vortex rope
pressure fluctuation
