Numerical investigations were conducted to study the effects of double inclined slotted casing treatment on a certain centrifugal compressor's performance.The numerical results show that appropriate inclined angle combination of casing treatment slots helps to organize the flow matching between inlet guide vane and rotor blades.The detailed analysis of the flow-filed in compressor with casing treatment indicates that configuration A has the best ability to expand stability margin.With the suction and re-organization of the tip leakage flow

high energy flow is re-injected into the adjacent flow channel which controls the development intent of leakage flow in the axial and circumferential directions and improves the blockage situation downstream of rotor passage.Thus

the compressor stability margin is substantially increased.