Potential flow analysis of a centrifugal pump: Comparison of finite element calculation and laser velocimeter measurement

Potential flow and laser velocimetry were used to determine the velocity field within a laboratory centrifugal pump. Results from both techniques showed the interaction between the impeller and volute. Comparison of the potential flow and laser velocimeter results showed that potential flow accurately predicts the velocity field within the pump at design and near design flows.; The potential flow solution modelled the impeller and volute together. This allowed the interaction between the two components to develop naturally. In addition, the impeller was modelled at 10 different angular orientations within the volute to simulate the rotation of the impeller. The complete pump model results showed that even at design flow there are circumferential asymmetries in the velocity field. At off design flows the asymmetries become more pronounced. These asymmetries are a direct result of the interaction between impeller and volute. An unbounded impeller analysis cannot predict these asymmetries. The potential flow solution also correctly predicted the movement of the tongue stagnation point as a function of flow rate.; Blade to blade velocity profiles measured using laser velocimetry showed circumferential asymmetries in the velocity field. Differences in the relative velocities were up to 1.0 ft/sec for the relative radial velocity and 2.0 ft/sec for the relative tangential velocity. Detailed measurements in the tongue region showed the stagnation point moving from the outside of the tongue at flows below design, to the tongue tip at design flow, to the inside of the tongue at flows above the design. In addition, at the design flow the slip factor was calculated for five different radii in the impeller. Maximum value for the slip was 0.96.; Comparison of the computational and experimental results showed that potential flow correctly predicts the flow within the centrifugal pump. Slip calculations based on the potential flow solution were within 5% of the experimental results. Predicted locations of the tongue stagnation point coincided with the experimentally determined points. Blade to blade velocity profiles were compared for the potential flow solution and the laser velocimeter data; agreement was within 1.0 ft/sec.