汽轮机调节级动叶栅大负冲角工况下的三维分离流动研究

对大功率汽轮机组提出的承担调峰任务的要求使得调节级小展弦比动叶栅非设计工况下的二次流与分离流特性受到关注。采用经试验考核的计算方法对一展弦比为0．344的动叶栅在冲角条件下的三维分离流场进行数值模拟，得到了详细的叶栅二次流与分离流的流动图谱，并给出了气流的三维分离模式。计算结果表明：在大负冲角条件下，三维分离流动显著改变了叶栅二次流结构及出口气流参数沿叶高的分布规律。叶栅出口气流在下端壁附近发生明显的欠偏转现象，同时叶栅下部的损失急剧增加，流动的总损失比设计工况增大2倍，二次流损失增大4倍。图10参5

Numerical Investigation of Three-Dimensional Separation Flow in the Rotor Cascade of a Steam Turbine Governing Stage at Large Negative Incidence

The secondary and separation flow behavior of the small aspect ratio rotor cascade of steam turbine governing stage at off-design conditions is of interest because the large power units are now working also to adjust the peak demand. In this paper the three-dimensional separation flow of a rotor cascade with aspect ratio 0.344 at negative incidence of 90( is numerically simulated by using a computational method which has been verified by experimental data. The secondary and separation flow patterns are attained and the three-dimensional separation model is presented. The computational results show that at the large negative incidence, the structure of secondary flow and the aerodynamic outlet parameter distribution along the span are significantly changed by three-dimensional separation vortices. The outlet flow under-deflects obviously at the vicinity of the bottom endwall where the loss increases dramatically. The total loss increases by three times and secondary loss increases by five times in comparison with those at design conditions. Figs10 and refs 5.