The Performance of a 6.5 Pressure Ratio Centrifugal Compressor having a Radially-Vaned Impeller

SUMMARY The aerodynamic design and experimental performance of a centrifugal compressor designed for a pressure ratio of 6.5 and a specific speed of 68 are described, The compressor consisted of a radially-vaned impeller and a transonic, vaned radial diffuser. At design speed a peak overall total-to-total isentropic efficiency of 0.746 was achieved at the maximum pressure ratio of 5.9, rising to 0.79 at a pressure ratio of 3.5 at 80 per cent speed. A theoretical analysis of the impeller channel flow suggests that high vane-to-vane aerodynamic loading was partly responsible for the shortfall in performance. The impeller was also tested with a vaneless diffuser and a detailed analysis is made of static pressure measurements on the impeller shroud and vaneless and vaned diffuser walls. Several recommendations are made regarding the design and testing of centrifugal compressors.