Combined flow control for corner separation in compressor cascades: A mechanistic and performance evaluation

Improving compressor performance requires precise control of high-loss flows in corner regions. This study proposes a combined passive control strategy that integrates a Blended Blade and EndWall (BBEW) profile with Vortex Generators (VGs) to address corner separation near the endwall. Numerical simulations conducted in a linear compressor cascade reveal the underlying mechanisms and effectiveness of this approach. The BBEW profile increases the blade-endwall dihedral angle, guiding low-energy fluid into the mainstream and weakening boundary layer interactions in the corner region, which helps delay the onset of separation. Concurrently, VGs generate streamwise vortices that enhance mixing between the mainstream and low-momentum fluid, reducing local vorticity and viscosity near the hub and further suppressing corner-related losses. VGs reduce losses below the 15% span, while BBEW counteracts losses introduced by VGs across the entire span. The combined control method achieves the most significant reduction in losses, decreasing them by 6.06%, surpassing the individual contributions of either VG or BBEW. This integrated approach effectively eliminates the Corner Vortex and reduces the Passage Vortex, resulting in a more stable flow. A quantitative evaluation model has also been developed to assess the influence of the combined control method on secondary flow suppression and boundary layer regulation. While the results are based on linear cascade simulations, the revealed mechanisms provide valuable guidance for future applications in real compressor stages.