混流式水轮机转轮区叶道涡压力脉动数值研究

Numerical Investigation on Pressure Fluctuations Induced by Interblade Vortices in a Runner of Francis Turbine

混流式水轮机在偏离最优工况区运行时,不但在尾水管中有明显的旋转涡带,在转轮区也会有涡束沿着叶片流出,我们称之为叶道涡。随着大型混流式水轮机的广泛应用,叶道涡有可能对机组的稳定运行产生影响。本文利用数值模拟技术对某混流式模型水轮机转轮内压力脉动进行研究。研究表明:转轮区的压力脉动主要是由叶道涡诱发的,叶道涡的频率基本等于转动频率。

When Francis turbines operate at off design conditions, not only vortex rope in the draft tube occurs but also the vortex bunches, which are called interblade vortices, generate and flow out from the blades. As the huge Francis hydraulic turbines are widely used, the interblade vortices may affect the operation stability of the turbines. In this paper, the numerical simulation is used to investigate the pressure fluctuations in the runner. The numerical result shows that the pressure fluctuations in the runner are mainly caused by the interblade vortices at part load condition. The fluctuation frequency of the pressure is almost equal to the rotational frequency of the runner.