Abstract: In order to study the flow performance of the low-pressure turbine with large meridional expansion under variable conditions， the aerodynamic performance experiments of two sets of different large meridional expansion annular sector cascades are carried out. Under the condition of designed inlet flow angle， the experimental study on variable conditions of different high subsonic Mach number at the outlet is carried out. Under the condition of constant outlet Mach number， the variable inlet flow angle experiments are completed. The characteristics of flow loss and the influence rule of secondary flow are analyzed. The results show that there are two obvious passage vortexes in the outlet. The upper passage vortex is located in 1/3 position， away from the shroud， and the intensity is significantly greater than that of the lower passage vortex. With the increase of Mach number， the flow loss of cascade outlet increased by 15%. The curvature of the endwall affects the pressure distribution of the proximal blade and the sensitivity of the variable conditions. The optimization of the curvature of the endwall will help the flow condition.

Key words: Large meridional expansion turbine；Annular sector cascade；High subsonic Mach number；Variable working conditions；Aerodynamic performance experiment

摘要： 为了研究大子午扩张低压涡轮变工况下的流动性能，分别对大子午扩张低压涡轮的两套不同的扇形叶栅进行气动实验研究。在设计进口气流角条件下，分别进行不同高亚声速马赫数出口变工况实验研究；在出口马赫数不变的条件下，完成变攻角实验。分析了大子午叶栅流动损失特点和二次流的影响规律。结果表明:大子午扩张实验叶栅出口存在两个明显的高损失通道涡，上通道涡位于展向1/3位置，远离上端壁，且强度明显大于下通道涡。随着马赫数增加，叶栅出口流动损失增加了15%。大子午扩张涡轮端壁曲率影响近端壁叶片的压强分布和变工况敏感性，优化端壁曲率将有助于流动状态的改善。

关键词: 大子午扩张涡轮；扇形叶栅；高亚声速；变工况；气动性能实验