In order to uncover the evolutionary tendency of the tip clearance flow in a subsonic axial-flow compressor rotor as well as its associated flow mechanism

the unsteady three-dimensional multi-passage numerical simulations were carried out to investigate the flow field of the compressor rotor. The computational results show that as the compressor rotor's mass flow decreases

the axial momentum of the incoming flow reduces

and that of the tip leakage flow increases under the impact of the pressure gradient between the pressure side and suction side of the tip clearance block combined with the secondary leakage flow

thus increasing the axial momentum ratio of the tip leakage flow to the approach flow in the clearance region. The consequence is a movement of the interface between the incoming flow and the tip leakage backflow toward the leading edge of the rotor. As the strength of the axial reversed flow is increased from design status to near stall

the flow blockage zone in the rotor tip region becomes more severe and moves further upstream

which plays a role in triggering the compressor stall.