孔式抽吸对带间隙高负荷压气机性能的影响

Effects of Holes-Type Suction on Performance in a High-Load Compressor with a Clearance

关键词:  高负荷压气机  孔式附面层吸除  间隙  端壁  流动特性  气动性能

Key words:  Highly-loaded compressor  Holes-type boundary layer suction  Clearance  Endwall  Flow characteristic  Aerodynamic performance

摘要:

实验研究了端壁孔式附面层抽吸对带间隙的高负荷直列叶栅流动特性和气动性能的影响，通过三种附面层抽吸方案与原型方案的对比分析，探讨了附面层抽吸抑制间隙流动、减小损失的机理。对叶片表面和下端壁进行了墨迹流动显示，并利用五孔探针对叶栅出口气动参数进行了测量，对比分析了叶栅流道内的流场特征和损失分布。结果表明，在间隙内布置抽吸孔能有效降低间隙流动动能，削弱间隙流与主流之间的相互掺混作用，减小因间隙流动引起的端壁区域流动分离，从而达到对三维流动分离的抑制，有效降低损失，且最大降幅达16.7%；间隙流动引起的流动分离和损失在流道中占主导地位，尽管在端壁沿周向合理布置抽吸孔能在一定程度上抑制近端壁的附面层或二次流发展，但这种局部效应仍不能显著改善叶栅的整体性能；端壁上不合理的抽吸控制策略反而可能影响主流的正常流动，导致损失增加，其中方案4损失增加了约3%。

Abstract:

The effects of endwall-hole-type boundary layer suction on the airfoil flow characteristic and aerodynamic performance in a highly loaded compressor linear cascade with a clearance was studied experimentally. Through a comparative analysis of three different suction schemes and the prototype scheme，the mechanism of boundary layer suction inhibiting the clearance flow，reducing the loss was discussed. The ink-trace flow visualization on the airfoil surface and the lower end-wall was carried out and the parameters at outlet were measured by a five-hole probe to comparatively analyze a distribution of the loss and the flow characteristics. The results show that the suction can effectively reduce the kinetic energy of the clearance flow so as to reduce the blending effect between the clearance flow and the main stream and weaken the flow separation induced by clearance on end-wall when suction holes are arranged in the clearance. Thus，three-dimensional flow separation can be controlled effectively and the loss decreases a lot with a maximum reduction of 16.7%. The flow separation and the loss induced by clearance flow are dominated in the flow path. Although the suction could effectively suppress the development of boundary layer and secondary flow on end-wall when suction holes are arranged along pitch-wise，the local effect may not significantly affect the overall performance of the cascade. To some extent，the unreasonable layout of suction holes may have a negative influence on the mainstream，leading to a rising total loss. It is worth noting that the loss in scheme 4 increases by 3% approximately.