Abstract
This paper reports the results of a numerical study on the performance of several zero-curvature blade impeller configurations for centrifugal pumps. A “standard” zero-curvature blade impeller has been modified by introducing in the centre of the blade passage split-blades of different lengths and locations. The “standard” impeller configuration is a seven-blade impeller with inlet and exit flow angles of 22° and 66° respectively, rotating at 400 r.p.m..
The flow field in the impeller passage has been numerically investigated using a standard version of a finite element code (FEDAP of FDI Inc.); turbulence has been modelled with a two-equation, k-ε model which requires Van Driest’s wall functions to represent the law-of-the-wall profiles.
The flow is computed on a 2-D, blade-to-blade (S1) mean stream surface in the rotating reference frame. The numerical simulation has been carried out at nominal flow rate and at two off-design flow rates in order to obtain a portion of the pump characteristic.
A slight increase in e dynamic head is caused by the split-blade; a higher increase in pump head is obtainable by doubling the number of blades with respect to the standard configuration.
The velocity distributions at four radial sections of the impeller passage, the streamline contours and the hydraulic efficiency distribution for the different impeller configurations are compared and discussed.
