涡轮直、弯叶栅冷气掺混流场结构的分析

Flow field structure analysis in straight and bowed turbine vanes under cooling air mixture

为了解气冷涡轮叶栅内不同叶片弯角对叶栅流场的影响,对低速条件下不同射流条件及弯角的叶栅流场进行了数值模拟,分析了二次流在叶栅流道中的演变过程,用物理量swirl分析流场中的涡系及二次流分布。发现二次流集中在叶片表面、端壁、叶片尾缘和冷气孔附近;前缘道主流射流在内弧产生反向径向二次流,随弯角增加现象更加明显;多排孔喷气的弯叶栅,其叶背的极限流线呈明显的波动式流动,随弯角的增加,其波动幅度加大。

To deeply understand the effects of different blade bowed angle on flow field structure in air cooled turbine cascade, the cascade flow field was numerically simulated under different air injections and different blade bowed angles at low speed. The development of secondary flow in cascade was analyzed. The physical quantity swirl was used to analyze the vortex system and secondary flow distribution. The results show that the secondary flow gather on the blade surface, endwall and nearby trailing edge and cooling air holes; the counter radial secondary flow on pressure surface was observed with injection from leading edge, this phenomenon became more obvious as the blade bowed angle increasing; with injection from multiple rows of cooling air holes, the limiting streamlines on suction surface showed obvious fluctuant flow, the amplitude of fluctuation increased as the blade bowed angle increasing.