中文摘要：

为了适应当前水电朝着成本更低、输出更加灵活的趋势发展，混流式水轮机在非设计工况点下运行时各水力部件之间干涉引起的流体动力作用和动态流动现象在水力设计过程中成为非常重要的一环。本文使用CFD技术获取尾水管中压力脉动情况，通过对动态能量分布的比较，陈述了转轮能量高速旋转传播造成的螺旋涡带缩胀变化，对尾水管流动的干涉作用。

英文摘要：

The present push in hydropower generation towards lower cost and more flexible output. As a result, for Francis turbine, hydrodynamic effects from interaction within hydraulic components and dynamic flow phenomena at off-design conditions become important issues in the hydraulic design process. Pressure pulsations of draft tube were obtained by CFD. According to the dynamic energy distribution, helical vortex rope breathes due to the energy propagation of runner outflow, and flow interference between runner outflow and draft tube inflow were clarified.