中高比转速转轮内部流态与外特性的关系

为了更有效的发挥流动计算技术在转轮优化，性能预测和新产品设计方面的作用，深入探讨内部流态与外特性间的关系是十分必要的。本文选择具有实测结果的混流式转轮进行了内部流场计算。首先对不同工况下计算的能量特性与试验进行了细致的比较，结果表明，计算预测的转轮流量，效率等与试验曲线在设计工况附近时十分接近，在偏工况计算结果与实测结果虽有差别，但仍能反映转轮的主要特性；在此基础上，重点讨论了转轮内流场与外特性间的联系，分析表明：转轮的最优效率区的位置和形状与进口冲角和出口环量密切相关，即小进口冲角区与小出口环量区的交集形成了水轮机的最优效率区，尾水管的压力脉动与转轮出口环量的大小密切联系，大的转轮出口正环量区对应着强度较大的尾水管的压力脉动，较大的进口负冲角易在叶片正面形成较大旋涡，转轮进口压力脉动可能与进口处该旋涡区的不稳定性有关。

The Relationship Between the Inner Flowfield and Energy Property in Francis Turbine Runner

To take the advantage of flow field simulation more efficiently,it is very important to investigate the relationship between internal flow feature and energy property.In this paper,flow field simulation was carried out for a Francis runner.Comparison of results from calculation and experiment shows that they agree well with each other near design points;Although on off design condition there exist some differences,the mean features from simulation is still meaningful,So the simulation method is reliable.Further,Internal flow field is analyzed in detail and different flow field feature is found to connected with different runner performance:it is found that the position and shape of highest efficiency contour curve is connected with inlet attack angel and outlet circumference velocity;Intersection of small inlet attack angel and small outlet circumference velocity form the high efficiency area;large outlet circumference velocity corresponding to strong oscillation on draft tube.Great negative inlet attack angel may related with blade inlet pressure ossilation observed in experiment.