Experimental and numerical analysis of a three-stage axial compressor with 3D blade design under design and off-design conditions

The corner stall is a detrimental flow feature within the axial flow compressor stator, significantly compromising its efficiency and stability. Many previous studies on simplified linear cascades have demonstrated the potential of three-dimensional blade designs in suppressing corner stall. However, the conclusions derived from linear cascades have inevitable limitations due to the disregard of multi-stage effects and the lack of experimental validation in multi-stage compressors. This paper presents the experimental and numerical investigation on improving a three-stage high-load compressor. The high-load compressor, designed based on a datum compressor, incorporates a three-dimensional blade design in each stator to control the corner stall. Experiments are conducted on both the datum and high-load compressors to verify the effectiveness of the improved design. Based on numerical results, the flow characteristics of the rear two stators of both compressors are compared under design and off-design conditions. The control mechanism and applicability of three-dimensional blade design for corner stall in multi-stage environments are revealed. The results indicate that the twisterlike vortex is the dominant feature of the corner stall. The transverse pressure gradient at the connection end wall and suction surface is enhanced by the three-dimensional blade design, thereby suppressing the twisterlike vortex. This promotes flow structure in the end region to evolve from corner stall to corner separation. The inlet boundary layer thickness significantly affects the potential of three-dimensional blade design improvements. The high-load compressor demonstrates improvements of 33.7% in total pressure ratio and 0.7% in isentropic efficiency at the near stall point. Furthermore, the stall margin improves by 4.0%.