Effect of Different Radial Inclined Angles of Self-circulation Casing Treatment on the Transonic Axial Flow Compressor Performance

Unsteady numerical simulation of single passage was carried out on NASA Rotor 35 to study the influence of the radial inclined angle of self-circulation casing treatment (SCT) on the performance and stability of a transonic compressor at 100% design speed. The radial inclined angles were set to 0°(D0), °(D30) and 60°(D60), respectively. The calculated result indicates an increase in the stall margin improvement (SMI) and the design efficiency improvement (DEI) as the radial inclined angle increases gradually. The SMI of the SCT with a 60° radial inclined angle is 12.5%, the biggest among the three SCTs, and the peak efficiency improvements (PEI) of the SCTs are almost the same. The radial inclined angle is provided with the effect of strengthening the self-circulation casing treatment effect, which further improves the stable working range of the compressor, and the efficiency loss is also lower than that of the 0° angle structure. The flow conditions inside the bleeding part can be improved by radially skewing the self-circulating structure toward the rotor rotating direction.