Transient Internal Flow Characteristics of Centrifugal Pump During Rapid Start-Up

Abstract

The start-up process of centrifugal pump will produce large transient effect, which can be reduced by selecting the appropriate rotational speed change rule. In this paper, a three-dimensional model of the full flow path of a single-stage single-suction clean water centrifugal pump is established, and SST turbulence model is used. The internal flow characteristics of the centrifugal pump with two linear start-up schemes of 0.1 s and 0.3 s were studied, respectively. The numerical simulation results show that, in the process of starting the centrifugal pump, when the 0.3 s start-up scheme is started, the centrifugal pump head and flow have been reduced to varying degrees. The radial force amplitude of 0.1 s start-up scheme is 2.4 times that of 0.3 s start-up scheme, and the axial force of 0.1 s start-up scheme fluctuates about 5% of axial force amplitude when the impeller reaches the design rotational speed. The vorticity distribution in the starting process shows that the vorticity distribution in the 0.3 s start-up scheme is more regular, and the slender high vorticity area is only distributed near the blade side. During the start-up process, the wall entropy production and turbulent dissipation entropy production is the largest. The impeller region of high entropy production rate are mainly at the outlet of impeller channel during the starting process of centrifugal pump. In the starting process of 0.3 s start-up scheme, the region of high entropy production rate is smaller and reaches the stable state faster. The research shows that 0.3 s start-up scheme can reduce the transient effect caused by centrifugal pump start-up process compared with 0.1 s start-up scheme.