Experimental and Theoretical Study of the Flow in the Volute of a Low Specific-Speed Pump

The flow in the volute of a low specific-speed pump was studied both experimentally and numerically near its design point. Measurements included time-averaged values of velocity and static pressure at a large number of locations in the volute. The numerical computations were based on the unsteady three-dimensional potential flow model for the core flow. Viscous losses were quantified using additional models that use the potential flow as input. It is shown that near the design point of this pump, the core flow behaves like a potential flow, provided that no boundary layer separation occurs. Explanations are given for the presence of local deviations due to secondary flow. These local deviations do not influence the overall potential flow characteristics significantly.