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

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. Author