Secondary Flow, Separation and Losses in the NACA 48-Inch Centrifugal Impeller at Design and Off-Design Conditions

An elliptic flow calculation procedure has been used to model 3-D flow in the NACA 48–inch centrifugal impeller. The results demonstrate that fully elliptic steady flow calculations can be performed at design and off-design conditions. The calculations reproduce the measured overall performance and most of the features of the loss distributions observed in the NACA flow study. They give further insight into the complex 3-D flow with leading-edge separation and tip leakage. The calculated secondary flow patterns are presented and used to explain the convection of vortices in a more recent laser anemometry study of a centrifugal compressor impeller.