Numerical investigation of shroud casing boundary layer suction on a counter-rotating compressor

Based on the flow field of a counter-rotating compressor, numerical investigation was conducted on the shroud casing boundary layer suction of the rear rotor in the stage environment. Research results show that as the suction flow rate increases, the compressor efficiency increases firstly and then decreases, and the efficiency of compressor improves by 0.85% for the best suction scheme. Suction makes R1 inlet flow deviate towards the axial direction and its tip leakage flow be slightly weaker accordingly with better tip region flow field. For R2, suction weakens the intensity of R2 tip leakage flow significantly and increases the flow capacity in the tip region; on the other hand, suction enlarges the flow separation range at the suction surface trailing edge of R2, resulting in larger flow loss; on the whole, suction improves the R2 tip region flow field obviously. The stall of original compressor is induced by R2 tip leakage flow, as suction can effectively control R2 tip leakage flow, suction widens the stable working range of compressor and the surge margin improvement is 7.44% after suction; meanwhile suction changes the flow instability mechanism and after suction the aerodynamic stall results from large flow separation of blade suction surface.