Influence of cutting angle of blade trailing edge on unsteady flow in a centrifugal pump under off-design conditions

Abstract

The parameters of blade trailing edge have an important influence on the performance of centrifugal pump and internal unstable flow. In this study, the influences of cutting angles of blade trailing edge on unstable pressure pulsation and unstable flow structure are investigated using a centrifugal pump under off-design conditions through large eddy simulation. Three typical blade trailing edges, namely, original trailing edge (OTE), 15 cutting angle of blade trailing edge (OBS15) and 30 cutting angle of blade trailing edge (OBS30), are analysed. Results show that the cutting angle of blade trailing edge has a certain effect on the performance of the centrifugal pump. Under part-load conditions, the OBS30 impeller evidently contributes to the reduction in pressure pulsation intensity. By contrast, the OBS15 impeller has opposite effect because of the increase in wake vortex intensity. The OBS30 impeller can effectively improve the unstable vortex structure caused by backflow at the centrifugal pump tongue using a new method. Consequently, reduction in the unstable flow structure mainly contributes to the reduction in pressure pulsation used by the proper cutting angle of blade trailing edge.