Analysis of the Influence of Suction Chamber on the Performance of Single-Blade Centrifugal Pumps

Abstract

Abstract. Single-blade centrifugal pumps are widely used as sewage pumps. In this study, in order to comprehensively understand and improve its performance through particle image velocimetry (PIV) testing technology, a semispiral suction chamber was proposed and compared with a straight-cone suction chamber in terms of the external characteristics, entropy production, and cavitation characteristics of the pump. The characteristics of both the single-blade centrifugal pump with a straight-cone suction chamber (SCSCP) and a semispiral suction chamber (SSSCP) were simulated numerically, and the numerical results of the external characteristics were compared with the experimental data. Compared to the SCSCP, the SSSCP exhibits a lower head, with its best efficiency point (BEP) shifting to a low flow rate. The high-efficiency zone of the SSSCP becomes narrow. The total entropy production of the SSSCP can be reduced by up to 39.8%, and its fluctuating entropy production can be decreased by up to 49.1%. Additionally, these entropy productions in the SSSCP are the same as those in the SCSCP, concentrated in the impeller and volute when the flow rate is below 19.22 m3/h. When the flow rate exceeds 19.22 m3/h, entropy production in the semispiral suction chamber exceeds that in the volute, second only to the impeller, and cannot be ignored like the entropy production in the straight-cone suction chamber. The critical cavitation margin NPSH of both pumps is almost identical when the flow rate is low. As the flow rate increases, the critical NPSH of the SSSCP is considerably higher than that of the SCSCP.