Clocking effect on the hydraulic performance and internal flow characteristics of a multistage centrifugal pump

Abstract Multistage centrifugal pumps are widely used in offshore oil production, the petrochemical and coal-chemical industries, and nuclear power fields for their advantages of large flow rate, high pressure, and excellent operation stability. The impellers in such pumps are often fixed with circumferential phase differences to avoid the synergistic excitation vibration of unbalanced mass in the same phase, which is the main cause of the clocking effect in multistage centrifugal pumps. In this study, the clocking effect on the hydraulic and internal flow characteristics of the first three stages of a 5-stage pump under the designed flow rate conditions are investigated. 9 test schemes were designed with the orthogonal design method， and internal flow characteristics measurements were done at 3 different positions of the pump. The results indicate that the clocking effect has minor impacts on the hydraulic performances, with a maximum reduction of lift coefficient of 0.275% and a maximum reduction in efficiency of 1.3%. The impeller pressure pulsation shows a maximum phase departure angle of 90 and a maximum dominant frequency departure phase of 59.17 Hz. The internal flow characteristics of a multistage pump have been improved. Comparing the results of 9 test schemes reveals adjusting the clocking positions of the impellers of the pump can obtain better internal flow characteristics of the whole pump．