Mechanism Analysis and Performance of Combined Control Method for Corner Separation in Compressor Cascades

Abstract

Enhancing the aerodynamic performance of compressors requires a thorough investigation and management of high-loss flow in the corner. This study introduces a new combined control method that integrates the Blended Blade and EndWall (BBEW) profile with Vortex Generator (VG) to optimize corner separation on the endwall. To evaluate the effectiveness of the combined control method and explore the fundamental physical principles governing corner separation, numerical simulations were conducted in a linear cascade.  Based on the findings, the BBEW profile increases the angle between the blade and the endwall, allowing low-energy fluid to enter the mainstream more easily. This weakens the boundary layer interaction in the corner region, delaying the start of separation. Additionally, applying VG to the endwall creates downstream vortices that improve mixing between mainstream and low-energy fluid and push the low-energy fluid downward. As a result, viscosity and vorticity near the hub are reduced, effectively minimizing negative effects.  VG significantly reduces losses below the $16\%$ span, while BBEW counteracts the losses introduced by VG across the whole span. The combined control method results in the most significant reduction in losses to a reduction of $6.06\%$, surpassing the individual effects of VG and BBEW. It effectively eliminates the Corner Vortex and reduces the Passage Vortex, resulting in a more stable flow. Additionally, a quantitative evaluation model has been established and used to assess the influence of the combined control method on secondary flow more clearly and accurately.Overall, the combined control approach effectively mitigates corner separation by improving secondary flow and boundary layer interaction, thereby greatly enhancing compressor performance.

Keywords: Compressor, Corner separation, Secondary flow, Vortex generator, BBEW