An Investigation of Unsteady Impeller-Diffuser Interactions in a Centrifugal Compressor

An investigation of steady and unsteady flow phenomena in centrifugal compressors has been performed. The effect of vaned diffuser geometry on the compressor unsteady aerodynamics has been considered, with particular emphasis on the diffuser vane unsteady loading generated by the impeller circumferentially nonuniform flow field. A series of experiments was performed in the Purdue Research Centrifugal Compressor Facility to quantify the compressor performance, impeller blade and diffuser vane steady surface static pressure, vaneless diffuser steady and unsteady velocity field, diffuser vane unsteady surface static pressure, as well as surge and rotating stall occurrence. These measurements were made for various flow rates, number of diffuser vanes, diffuser vane leading edge-impeller exit radius ratios, diffuser vane stagger angles, and nonuniform circumferential vane spacing. Centrifugal Compressor, Unsteady Aerodynamics, Vaneless Diffuser, Laser Anemometry, Vaned Diffuser.