Passive flow control of the corner separation in an annular compressor cascade with a micro

Corner separation contributes greatly to the loss and the passage blockage in a compressor stage. In order to mitigate the corner separation and improve the aerodynamic performance of compressors, a novel passive flow control method, an off-surface micro-blade installed upstream of the separation onset location, was proposed. A numerical investigation has was performed in an annular compressor cascade to assess the control effectiveness of the micro-blade. The results show that the location of the micro-blade affects the control effect significantly. The application of the well-designed micro-blade enhances the diffusion capacity considerably under the inflow incidence from ？2° to +10°, accompanied by a slight loss reduction at some particular incidences. Detailed analysis of the predicted flow field was carried out to understand the underlying mechanism. It indicates that a “jet” forms upstream of the separation onset location with the application of the micro-blade. The formation of the jet reduces the thickness of boundary layer on the suction surface and builds a “jet barrier” near the endwall to hinder the accumulation of the low momentum fluid. The influence of the incidence was also investigated. It is concluded that the incidence increase has both positive and negative influences on the control effect of the micro-blade. As a result, the performance of the micro-blade is sensitive to the variation of inlet incidence