Flow Field in the Secondary, Seal-Containing Passages of Centrifugal Pumps

This paper illustrates the impact of seal configuration on the through-flow leakage in centrifugal pumps with shrouded impellers. The flow model is based on the Petrov-Galerkin finite element method, and the computational domain permits the primary/secondary flow interaction at both ends of the clearance gap. The model is applied to a hydraulic pump with two different seal configurations for the purpose of comparison. The computed results show a strong dependency of the leakage flow percentage and swirl-velocity retention on the overall shape of the shroud-to-housing passage including, in particular, the seal geometry. The results are generally consistent with documented observations and measurements in similar pump stages. From a rotordynamic standpoint, the current computational model conceptually provides the centered-rotor “zeroth-order” flow field for existing perturbation models of fluid/rotor interaction. The flow model is applied to two different secondary passage configurations of a centrifugal pump, and the results used in interpreting existing rotordynamic data concerning the same passage configurations.