不同来流附面层特性下端壁射流对弯曲叶栅内流场的影响

Effects of Endwall Jet on Flow Fields in Bowed Compressor Cascades at Different Inlet Boundary Layers

关键词:  弯曲扩压叶栅  来流附面层  射流式旋涡发生器  流动分离  损失降低

Key words:  Bowed compressor cascades  Inlet boundary layers  Vortex generator jet  Flow separation  Loss reduction

摘要:

给定不同型式的来流附面层，采用数值模拟方法，旨在讨论变来流附面层特性下端壁射流式旋涡发生器对于弯曲扩压叶栅内流场的影响。结果表明，对于正弯叶栅，射流可有效减弱其吸力面上的流动分离，随着来流附面层变厚或附面层内总压亏损的增加，原型叶栅角区内的分离范围逐渐增加，因此提供给射流改善流场的空间也相应增大，损失降低程度由2.3%提高到8%。在反弯叶栅当中，射流作用之后，在零附面层来流条件下，角区内的分离范围减小且损失降低了9.1%；随着来流附面层增厚，在分离范围降低的同时，吸力面上的集中脱落涡也相应消失，因而损失降低程度增加到了12.5%。此时，随着来流附面层条件进一步恶化，射流对于流场的作用效果基本保持不变，这说明针对本文给定的射流参数，端壁射流对于反弯叶栅内流场的改善程度已达到极限。

Abstract:

A numerical calculation was carried out to study the effects of endwall jet on the flow fields in bowed compressor cascades at different inlet boundary layers. The results show that，for the positively bowed blade，the endwall VGJ can effectively suppress the flow separation on the suction side. With the increase of the inlet boundary layer thickness or the total pressure defect into the boundary layer，under the effects of VGJ，the region of separation in the baseline cascade increases accordingly，which applies the larger space to the flow field improvement caused by the VGJ，and hence the loss reduction increases from 2.3% to 9.8%. For the negatively bowed blade，with the VGJ，under the condition without inlet boundary layer，the separation is suppressed and a loss reduction of 9.1% is obtained. As the inlet boundary layer thickens，the concentrated shedding vortex disappears while the flow separation weakens. Therefore，the loss reduction increases to 12.5%. With the further aggravation of the inlet boundary layer，the loss reduction keeps unchanged，which means that the improvement to the flow filed in the cascade caused by the VGJ has reached its limit under the jet parameters shown in this paper.