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本文采用端壁带扩张角(50°)的平面叶栅,模拟汽轮机小容积流量工况外环壁附面层是否出现大尺度分离。实验结果表明,大扩张角的端壁附近叶盆上有分离团,端壁上只有马蹄涡及其与通道涡的相互作用,并未出现大尺度的分离团,说明采用取特征截面的方法预测叶片颤振仍然有效,但需进一步考虑二次流的影响。汽轮机内环失速区的存在改变了叶片上气动功的分布,为了消除预测颤振时取特征截面的任意性,对失速颤振计算模型提出了改进意见。
In this paper, a plane cascade with an expansion angle (50 °) on the end wall is used to simulate whether there is a large-scale separation of the outer wall of the outer ring wall of the turbine with small volume flow. The experimental results show that there is a detached mass on the leaf pot near the end wall with a large expansion angle, only the horseshoe vortex and its interaction with the passage vortex do not appear on the end wall, and no large-scale isolated mass is observed. Leaf chattering is still valid, but the effect of secondary flow needs to be further considered. The existence of the inner stall zone of the steam turbine changes the distribution of aerodynamic work on the blade. In order to eliminate the arbitrariness of the characteristic cross-section when predicting the flutter, some suggestions for improving the calculation model of stall flutter are proposed.