To investigate the evolution process of an S-shaped air intake exit distortion as well as its influence on the downstream fan-stage performance

a series of suction control for the single air intake were carried out at first. And then the best suction solution was selected and applied to the whole structure numerical simulation. Results show that the choked mass flow and the maximum efficiency of the fan-stage increase about 0.63% and 0.57% respectively after suction. In addition

the low energy fluid gathering at cross section bottom decreases ceaselessly as it gets to the tip station of the rotor hub. Since it attaches the tip of the rotor hub

the circumferential location of this low energy fluid migrates gradually along the opposite rotation direction and finally covers about 3 flow passages at the rotor blade front edge. Under effect of the air intake flow angle increase caused by the non-uniform air admission and the adverse pressure gradient in the rear part of the flow passage

serious flow separation occurs at the stator blade suction side but mainly exists at 50% span and below and weakens after suction.