Experimental and mechanism analysis of casing treatment with different axial angles

Experimental and numerical simulations were performed on a subsonic compressor to investigate the stabilizing mechanisms of casing treatment with different axial angles at rotation speed of 8130 r/min. Flow structures and static pressure distribution of rotor tip, flow structure in the slots (or grooves), loss distribution in rotor tip, axial momentum of the injected flow at different mass flows were studied. Results confirmed that the capability of the casing treatment of extending the compressor stall margin first increased and then decreased within the whole mass flow range, the loading of rotor tip increased and the isentropic efficiency decreased under large mass flow with the increasing axial angle of the casing treatment.