Numerical Analysis of Separated Flow through a Centrifugal Impeller in Volute Casing by the Discrete Vortex Method

Abstract

Separated flow through a centrifugal impeller in a volute casing has been analyzed by the discrete vortex method. The results on velocity distribution at 40% of the design flow rate were in good agreement with those of Miner's experiment, which was performed under the same conditions with the same impeller and volute geometry. The flow pattern change due to interference effects between the blades and the volute tongue causes periodical change in the flow rate through one blade passage and in the torque of one blade during rotation. Head coefficients obtained from the head difference between the impeller center and the exit of the volute became smaller than the theoretical head coefficients calculated from the impeller torque because of the mixing loss.