Investigation of energy loss mechanism of shroud region in A mixed-flow pump under stall conditions

The energy consumption of various pumps accounts for almost 20% of the world’s electricity production, and the improvement of pump efficiency could save enormous energy consumption globally. In a mixed-flow pump, the hydraulic loss within the shroud region accounts for almost 30% of the whole loss in the impeller, which is an inevitable factor. Therefore, in this study, the loss near the end wall of impeller caused by the tip leakage flow (TLF), secondary flow and disorder flow, etc., is quantitatively investigated by the entropy production loss theory. The purpose is to find out the serious region of energy loss and conduct the structure optimization in the future. The research shows that the tip leakage vortex (TLV) and the TLF “jet effect” are responsible for the hydraulic loss within the shroud region in the designed flow fields. In the stall flow fields, some unsteady flow components are the additional loss source, such as the secondary flow vortex, separation flow vortex, secondary TLV, and wake vortex. In the deep stall flow fields, the coupling effect between reverse flow near shroud and inlet swirling flow would be the source of periodicity stall characteristic with high possibility.