Investigation of the Effect of Relative Circumferential Position on a Tandem Conformal Diffuser in a Mixed-Flow Compressor

Abstract

Tandem diffusers are widely employed to broaden the operating range and mitigate aerodynamic losses in compressors. However, they often suffer from significant accumulation of low-momentum fluid near the end walls, resulting in flow non-uniformity at the diffuser outlet. To address this issue, this study proposes a scheme to vary the relative circumferential positions of the fore and aft blades to optimize the aerodynamic performance of the compressor. Computational results indicate that the compressor achieves its peak stage efficiency at a circumferential position of 25%, where the total pressure loss coefficient is reduced by 4.4%. This configuration minimizes the accumulation of the boundary layer on the suction surface to the greatest extent, thereby delaying or suppressing flow separation on the aft blade. Consequently, this reduces losses and enhances the diffusion capability of the tandem conformal diffuser as well as the overall performance of the mixed-flow compressor.