In this study, the effect of stacki

In this study, the effect of stacking condition of centrifugal pump impeller was investigated by Computational fluid dynamics (CFD). The performance curves of impellers with three different stacking conditions were compared. The Local Euler head distributions (LEH distribution) at blade Leading edge (LE) and Trailing edge (TE) were obtained to evaluate the contribution of different spanwise location to the total work. The positive stacking characterised by the hub leading the shroud was considered inappropriate in centrifugal pump impellers as it deteriorated the performance of the pump in whole flow rate range. The negative stacking characterised by the shroud leading the hub could improve flow stability and efficiency in low flow rates, it was manufactured and tested. The test results showed good agreement with CFD calculations. A hump zone was observed in zero stacking impeller between 0.9Qd and Qd. It was closely related to the drastic change in pattern of LEH distribution at the two flow rates. The internal flow was analyzed to reveal the reasons responsible for the hump in head curve. It is found that the tremendous extension of low streamwise velocity region and its instant movement from the corner of shroud and blade suction surface to the midspan near blade suction surface when the flow rate decreases from Q(d) to 0.9Q(d) is the main reason for flow instability in zero stacking impeller.