The current paper reports a numerical investigation of stall inception in a transonic compressor rotor, NASA Rotor-67, by using the whole flow passages in the computations. Surface roughness is added to one of the blades in order to trigger rotating stall. During stall inception, the tip clearance vortex moved away from the suction surface of the roughened blade's upper neighbour, leading to vortex breakdown. The stall cell was found to propagate opposite the direction of the blade rotation at about 30 per cent of rotational speed. The effect of air bleeding on stabilizing the compressor is also studied in this work. The mean mass flowrate removed from the bleed valves was ~1.2 per cent of the mainstream flowrate. This amount of bleeding was found to effectively suppress the stalling disturbances. [PUBLICATION ABSTRACT]
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