Effect of Casing Treatment on the Centrifugal Compressor Shock Wave/Tip Leakage Interaction

The interaction of shock wave and tip leakage greatly affects the performance of transonic centrifugal compressor. Numerical simulation was carried out for the designed transonic centrifugal compressor and the interaction of shock wave/tip leakage was analyzed. Impacts of different casing treatment bleeding locations on shock wave/tip leakage interaction were investigated. The simulation shows that the interaction of tip leakage with shock wave near inducer contributes a lot to the compressor instability. The casing treatment bleeding slot locating near splitter blade could improve choke flow while the bleeding slot locating near main blade leading edge could improve compressor performance near surge. Recirculation flow through casing treatment could add positive pre-swirl into the impeller inflow and reduce the interaction of shock wave and tip leakage. Little flow through the casing treatment, similar effect as micro injection or bleeding, could suppress the tip leakage and delay surge of compressor.