Investigation of hydrodynamic forces and their reduction in wastewater pumps with single-blade impellers

At the Technical University, Lippe, in Lemgo, tests have been performed in a special pump lest system under pure water conditions on wastewater pumps with single-blade impellers in order to investigate the hydraulic forces acting on the impeller. An automatic measured data acquisition system makes it possible to determine not only the pump characteristics curves but also the axial and radial force components which act on the impeller bearing system in any position of the impeller in the housing. In addition, a special software package is used to differentiate between the static and dynamic components of these forces. The new measuring system permits, in particular, investigation of single-blade impellers for the dynamic force on the impel/er acting in the radial direction, which is also referred to as hydrodynamic imbalance. A fest aimed at reduction of radial hydrodynamic force has been conducted on this fest system for a single-blade pump impeller. lt was observed that the addition of an extra blade makes it possible to achieve reduction of this force component at all working points. This method of reducing hydrodynamic imbalance involves a greater power consumption and a reduced efficiency, however.