抄録
Transonic centrifugal compressor impellers for automotive turbochargers operate from near surge limit to choke limit. In order to improve operating range of compressors, it is indispensable to understand flow physics of unsteady flow phenomena at off-design condition. In this study, the unsteady flow phenomena in a transonic centrifugal compressor impeller at impeller stall condition have been investigated by DES(Detached Eddy Simulation). The numerical simulation results showed that shock-vortex interaction generated large low speed regions in the impeller and the low speed regions make unsteady flow field at the near disturbance onset point. At the disturbance onset point, due to the tip leakage spiral-type vortex breakdown, unsteadiness appeared in the vortical structures. Moreover, at the developed disturbance point, low speed regions rotated in the impeller with time.
