Analysis of Internal Flow Characteristics of the Bearingless Direct-Drive Centrifugal Pump System during Transient Start-Up

Abstract

Traditional shaft-sealed centrifugal pumps exhibit problems, such as liquid leakage and reduced efficiency, due to mechanical seal failures. To address the issue, the bearingless direct-drive centrifugal pump system (BDDCPS) has been designed with bearingless motor technology. This may cause a new issue of rotor eccentricity displacement, which can lead to a reduction in pump performance. Compared to a stable state, the changes in characteristics, such as flow rate, head, and pressure, during the transient start-up process are more severe, increasing the likelihood of system failure and requiring greater attention. In order to ensure safety and reliable operation during the transient start-up process, this paper investigates the working principle of the BDDCPS and analyzes transient start-up characteristics with three different start-up methods. The external characteristics, pressure field distribution, velocity field distribution, and hydraulic losses analysis of the pump are determined for comparative analysis. Finally, it is found that the linear acceleration start-up method is the most suitable and efficient for the BDDCPS.