局部/组合抽吸对压气机叶栅分离流动控制的机理研究

Mechanism on Flow Separation Control for CompressorCascade with Local and Combined BoundaryLayer Suction

关键词:  压气机叶栅  组合抽吸  流动分离  壁面摩擦系数

Key words:  Compressor cascade  Combined boundary layer suction  Flow separation  Skin friction coefficient

摘要:

为了研究不同抽吸形式对压气机内部分离流动的控制效果和机理，基于数值模拟方法，对内部同时存在角区分离和附面层分离的直列叶栅进行抽吸计算，共设置8套不同的方案进行了详细的探究。结果表明：对于控制分离的效果和机理，不同抽吸形式之间存在着一定差异；在分离发展的不同阶段，实施抽吸对其控制效果也有所不同。近端壁吸力面抽吸方案SS3同时减小了角区分离和近端壁处的尾缘附面层分离，尾部近吸力面沿展向静压分布为正“C”型，使角区内的低能流体向叶中流动，角区流动得到改善，但导致叶展中部流场的恶化；端壁抽吸和全叶高组合抽吸则使尾部近吸力面静压沿展向分布更均匀，低能流体的迁移现象减弱。基于以上结果可得：组合抽吸可以更有效地控制叶栅内部流动分离，降低损失，提高叶栅流通能力。

Abstract:

To explore the effectiveness and mechanisms of different forms of boundary layer suction (BLS) in controlling the separations in compressors, a linear compressor cascade, with separated flows on the whole span and three-dimensional separations over end wall corner, was researched based on the numerical simulation method. A total of eight suction schemes were set up. And the results show as follows: The effectiveness and mechanisms for flow separation control are different for different suction schemes, the control effectiveness is also different for the implement of suction at different development stages of separation. The separation at the suction surface and corner are reduced simultaneously under the control of suction scheme SS3 on suction surface near end wall, and the ‘C’ shape span-wise distribution of static pressure at the trailing edge near the suction surface prompts the transport of the low-energy fluid near the end wall to the mid-span which leads to the deterioration of the flow field near the mid-span. However, the span-wise distribution of static pressure is more uniform under the control of end wall suction and full span combined suction schemes resulting in the reduction of the transport of the low-energy fluid near the end wall to the mid-span. Based on these results, it can be seen clearly that combined BLS can more effectively control the flow separation inside the cascade, reduce the cascade loss and improve the flow capacity.