The numerical results of a CFD analysis for 5 impellers are presented and discussed to generate simple correlations for the slip factors and the aerodynamic exit blockages of centrifugal compressors. The purpose of the analysis and modeling is to supply an effective means of estimating both parameters used in the meanline performance prediction stage, only in the agile engineering sense. A finite volume time marching method was used in the analysis of three dimensional compressible turbulent flows. To generate one dimensional representative values from the three dimensional results, a mass-averaged concept was used on each impeller exit plane. The Wiesner’s slip factor was found to fail to predict accurate level of values and also the trend of variation, when the flow rate was changed, especially in case of backswept impellers. Aerodynamic blockage at the impeller exit was also found to vary with the flow rates, the blade exit angle and diffusion ratio. Some useful engineering models of both parameters were suggested to improve the current level of prediction for the impeller exit performance.
