Influence of non-axisymmetric endwall profiling under incoming vortex on the corner separation of a diffusion cascade

To suppress corner separation, numerical simulation methods were used to investigate the effects of two passive flow control technology, non-axisymmetric endwall profiling (NAEP) and vortex generator (VG), on the aerodynamic performance of a diffusion cascade under design conditions. The results indicate that under the D1 circumferential installation position, the optimal combination of the vortex generator stagger of 15 degrees and the NAEP of the blade suction surface concave structure in the passage is optimal. Under design conditions, the VG has a significant effect on suppressing the development of laminar separation bubbles in the middle of the chord, while NAEP has a worse effect. However, the NAEP scheme has a significant effect on the corner separation and reversed flow in the corner region, reducing the Cpt by 28.433 %. The combination scheme combines the advantages of both control technologies. Under design conditions, the high dissipation region caused by laminar separation bubble migration on the suction surface of the blade is reduced, the separation in the corner region is further suppressed, the reversed region in the corner region is reduced, the diffusion capacity of the cascade is improved, and the Cpt of the combination scheme is reduced by 29.045 %.