Mechanism of stall margin improvement in a centrifugal compressor with circumferential grooves casing treatment

To study the mechanism of stall margin improvement, a time accurate 3-dimentional numerical simulation is performed for a low speed centrifugal compressor with the circumferential grooves casing treatment. The computational results with the mass flow rate of 13 kg/s have been compared between the two different cases with the circumferential grooves and with untreated smooth wall. It is because the development of tip leakage vortex is restrained that the circumferential grooves can extend stall margin.