摘要
尾水管中的偏心回转涡带是引起机组振动的重要原因之一。为了降低尾水管内的压力脉动,对一混流式水轮机进行三维非定常数值模拟,分析水轮机在部分负荷工况下压力脉动的幅值及频率特性。同时对加长泄水锥、0.03Q水力干扰、加长泄水锥与水力干扰共同作用的3种改进方案进行数值模拟,对比分析改进后尾水管的压力脉动特性。研究结果表明:3种改善措施均能有效改善尾水管内的压力脉动。加长泄水锥对降低尾水管直锥管段的压力脉动比较明显,相对于仅添加水力干扰,水力干扰与加长泄水锥方法联合能更有效的改变尾水管内的压力脉动的幅值和频率。3种改进措施均会降低水轮机效率,其中加长泄水锥与水力干扰结合方案的水轮机效率下降最大。
Vortex rope in the draft tube of a Francis turbine is a key factor causing vibrations of the turbine unit. To reduce the vibrations, unsteady 3D flows in a Francis turbine were numerically simulated in this work to investigate amplitude and frequency characteristics of the pressure fluctuations in the draft tube. Three improving measures were examined： extending the runner cone, adding a hydraulic disturbance of 0.03Q to the flow rate, and combining these two modifications. Simulations of all these different cases were analyzed and compared, focusing on their effects on the vortex rope-generated pressure fluctuations. The results show that all the three measures can effectively reduce the fluctuations. A longer runner cone has an obvious effect on pressure fluctuations in the conical tube. Compared to disturbing the flow rate, a longer cone or the combination measure is more effective in frequency modification and amplitude reduction of the draft tube fluctuations, but their influences on turbine efficiency are greater.
出处
《水力发电学报》
EI
CSCD
北大核心
2017年第6期79-85,共7页
Journal of Hydroelectric Engineering
基金
国家自然科学基金(51379179)
西华大学研究生创新基金(ycjj2016096)
四川省科技计划项目(2017GZ0053)
关键词
混流式水轮机
涡带
压力脉动
改进措施
Francis turbine
vortex
pressure fluctuation
improvement measure
