Observations on the Performance of Centrifugal Pumps at Low Reynolds Numbers

From the results presented herein it is clear that the viscous flow in the centrifugal pump impeller is very complicated, but we see that the internal flow itself is not necessarily too inefficient and further that the hydraulic torque does not necessarily increase with lower Reynolds numbers. These results mean that the effect of external disc friction and its interaction in the volute are as important as the impeller design itself for such viscous flows. The present tests suggest that a pump which works well at high Reynolds numbers, as for water application, will not necessarily be the best pump for the low Reynolds number application. These internal flows are certainly very complicated and the authors hope that some of the techniques and suggestions made herein will be used for such work by others in the future.