Numerical investigation of unsteady IGV-impeller-diffuser interaction in a centrifugal compressor

The present understanding of the unsteady interaction mechanism between inlet guide vane (IGV) wake with centrifugal compressor impeller and its vaned diffuser is quite rough. We carry out investigation on the motion and distortion mechanism of the IGV wake and large size vortice in the centrifugal compressor impeller and its vaned diffuser for the improvement of the reliability and aerodynamic performance of the centrifugal compressor. Numerical simulation of the unsteady IGV-impeller-diffuser interaction in a centrifugal compressor is performed. The mechanism of the unsteady IGV-impeller-diffuser interaction is explored. Results show that the minimum unsteadiness in impeller occurs to the middle part of the blade, it is due to the dual unsteady influence of the IGV wake, large size vortice behind IGV and the potential repercussion of the diffuser on the impeller; and the maximum unsteadiness appears at the hub of the interface between the impeller and vaned diffuser. When the IGV prewhirl occurs, the unsteady distribution of variation is uniform along the diffuser vane due to the simultaneous influence of IGV and impeller blade wake.