The Influence of Impeller Wear Ring Geometry on Suction Performance

Abstract

Wear rings are a necessary feature of an enclosed centrifugal impeller design. The purpose of the wear ring is to limit the leakage of fluid from the high pressure zone at the impeller outlet to the low pressure region at the impeller inlet. Several different wear ring geometries may be employed for this purpose. The choice of which geometry is utilized depends on which of the following goals are ranked most important: • Pump efficiency • Rotor dynamic coefficients: stiffness and damping • Preventing contact during thermal or suction transients • Resistance to wear from abrasive particles • Allow later adjustment to recover original clearances as the pump wears There have been many papers published on the effect of wear ring geometry on leakage, efficiency and rotor dynamic coefficients. However little is known about how specific wear ring geometries affect the suction performance of an impeller. This paper seeks to examine several different wear ring geometries in common use. It will then quantify how each of these geometries affects the suction performance of the impeller over the full design flow range. To facilitate this examination a test pump will be utilized with modular impeller eye side wear ring geometry. The physical testing will be accompanied by CFD simulations and the results will be compared.