长短叶片混流式水轮机流动特性分析

An Analysis of Flow Characteristics of Francis Turbine with Long-short Blades

为探讨长短式叶片混流式水轮机的内部流动规律,基于CFD性能预测方法,采用SIMPLE算法和RNGk-ε模型,计算水轮机在不同工况下的速度-压力分布,探讨水轮机内部流场的速度分布、压力分布、尾水管涡带和压力脉动情况。研究结果表明:蜗壳内流体流动较为规律,当蜗壳内流体旋转至转轮进口处时,蜗壳内的流体排泄可能迟滞,流动复杂。导叶开度增加后,尾水管旋涡区向下移动,强度增大,且对扩散段流态造成影响。在部分工况下能很好地捕捉到真实最大压力脉动信息。研究可为深入了解水轮机激振的内在机理、改善水轮机的综合性能提供一定参考。

To further study the internal flow mechanism of Francis turbine with long-short blade ,this paper calculates the velocity-pressure distributions of turbine under different operating conditions based on CFD predicting theory ,k-εmodel and SIM PLEC algo‐rithm to inquire into the velocity distributions ,pressure distributions ,draft tube vortex and pressure pulsations .As the research re‐sult shows that fluid flow in volute is uniform ,the flow in volute and runner junction is complex .With guide vane opening increas‐ing ,draft tube vortex region moves downwards ,the strength increase ,and the impact on diffusion section flow .Under some condi‐tions ,the pressure pulsation information can be captured accurately .This study can provide a reference for the understanding of intrinsic vi‐brating mechanism of hydro-turbine due to excitation by the flows ,and the improvment of comprehensive hydraulic performance .