Study on Stability Extension Using Pre-Swirl and Variable Diffuser for Centrifugal Compressor

For a centrifugal compressor with vaneless diffuser,designed inlet guide vanes and adjustable diffuser,the centrifugal compressor performances in different conditions of using pre-swirl,settled diffuser and pre-swirl,variable diffuser and pre-swirl etc.were simulated to investigate the centrifugal compressor stability extension characteristics by pre-swirl and variable diffuser.The results show that using pre-swirl can widen the surge margin by 16.7% with keeping the max.efficiency unchanged simultaneously, and using vane diffuser,the max.efficiency of the compressor increases by 1.7%.On the basis of centrifugal compressor with vaneless diffuser,using both pre-swirl and variable diffuser can widen the surge margin and improve the compressor efficiency by 1.2%.