Study of hydraulic forces in sewage pumps
Using a special test bench for pumps at the Technical College of Lippe/Lemgo, experlments were carried out with clean water on sswage pumps with single-blade lmpellers to test the hydraulic forces produced at the impeller. With the aid of automatic data reglstration equipment, not only the pump's characteristic but also the axial and radial components of the hydraulic torce acting on the mountings of the impeller in all positions Inside the pump housing were determined. In addition to this, specia/ software enabled the static and dynamic components of the hydraulic force to be distinguished. In particular, the new measuring technique permits the radial dynamic force at the impeller, also known as hydrodynamic imbalance, to be examined. The results of an inquiry into the effect of the tongue of the housing on the forces acting on the impeller are also discussed. lt is demonstrated that decreasing the clearance of the tongue increases the radial forces without affecting the pump's hydraulic operating data. lt is also shown that measuring pressure at the circumference of the spiral housing of the pump permits a conclusion to be drawn as to the size of the static radial force.