Formation mechanism of suction vortex and its influence on the performance of centrifugal pumps
The suction vortex is easy to be generated in the pump sump under the condition of small submerged depth,which affects the safe and stable operation of the pumping station.In order to study the formation mecha-nism of the suction vortex before the inlet of the suction pipe of the centrifugal pump and explore the influence of the suction vortex on the flow components,the visualization test was carried out to capture the dynamic development process of the suction vortex,and the numerical simulation method was carried out to analyze the cause of suction vortex and its effect on impeller performance.The results show that the accuracy of numerical simulation of the suc-tion vortex,including the inception,development,strengthening and retention stages,is verified by visualization experiment.A penetrating suction vortex appears under the calculated condition.The air enters the inlet of the suc-tion pipe in the form of'funnel shape'air core,and continues to enter other flow components in the form of a con-tinuously falling broken airbag.The development of suction vortex is a periodic process accompanied by the collec-tion,maintenance and dissipation of vortex energy,which is mainly affected by the large velocity gradient.The suction vortex carries air into the suction pipe,causing the disordered flow inside the suction pipe.The distortion inflow makes the uniformity of the velocity distribution and the weighted average angle of the velocity decrease obvi-ously,and the assumption of uniform inflow in the axial direction of the impeller fails,which affects the internal flow of the impeller.The development of the suction vortex has a significant correlation with the power and efficien-cy of the impeller.In the process of carrying gas,the accumulation of gas phase leads to a low-speed region near the suction surface of the blade,resulting in a significant decrease in the pressure difference.The load distribution is uneven and the power capacity of the impeller reduces.
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