A Parametric Evaluation of the Effect of Inlet Swirl on the Rotordynamic Forces Generated by Discharge-to-Suction Leakage Flows in Shrouded Centrifugal Pumps

Unsteady forces generated by the fluid flow through the impeller leakage path of a centrifugal pump were investigated. The effect of leakage path inlet (pump discharge) swirl on the rotordynamic forces was examined for various ratios of fluid tangential velocity to impeller tip speed. It was observed that changing the inlet swirl velocity does not appear to significantly affect the measured forces for a given leakage flow coefficient. A bulk flow numerical model was found to predict the same general result. The model agreed with experimental data for small values of the leakage flow coefficient.