Abstract
Multistage pumps with blade-type guide vanes are widely used in offshore oil production, the petrochemical and coal-chemical industries, and nuclear power fields for its advantages of large flow rate, high pressure, and excellent operation stability. However, the internal flow of this kind of pump is complex; in particular, the hydraulic, flow, and pressure pulsation characteristics of the different stages are quite different, which has a great impact on the design and performance predictions of this kind of pump. Thus, in this paper, the hydraulic performance, unsteady flow characteristics, evolution of vortex structures and pressure pulsation characteristics in a 10 stage centrifugal pump are investigated numerically. The results show that inverse flow, jet-wake flow, and rotor-stator interaction flow are the key factors causing energy loss and efficiency decline at every stage and in the whole pump. The vortex evolution at the rotor–stator interaction regions is actually the process that the vortex structures fall off and impact on the pressure surface at the leading edge of the guide vane blade at a frequency that equals to the impeller blade passing frequency. Furthermore, under the actions of the guide vane with confluence cavity, the pressure pulsation within the final-stage guide vane contains low-frequency components with large bandwidths, which mainly results from the confluence flow disturbance at the outlet of the cylindrical guide passage.
Highlights
Multistage centrifugal pumps are widely used in the aerospace, petrochemical, and other fields due to their advantages of high head and strong reliability
Researchers have carried out much work on the relationships between the unstable flow structures and the characteristics of multistage centrifugal pumps
Wuibaut [5] compared the velocity distribution and pressure field pulsation characteristics within the impeller passage through a PIV test and concluded that the jet wake phenomenon occurred in the dynamic-static gap between the impeller outlet and the guide blade inlet, which verified that the unsteady flow within the guide blade was closely related to the jet wake phenomenon
Summary
Multistage centrifugal pumps are widely used in the aerospace, petrochemical, and other fields due to their advantages of high head and strong reliability. Kimura et al [1] investigated the relationship between the geometric parameters of the inlet pipe and the upstream flow structure of the inducer through experiments and numerical simulations. Fukao et al [2] conducted a simulation work of a model inducer using the LES (Large Eddy Simultion) method and found that the backflow gradually extends upstream to the impeller inlet with the decreasing flow rate. Wuibaut [5] compared the velocity distribution and pressure field pulsation characteristics within the impeller passage through a PIV test and concluded that the jet wake phenomenon occurred in the dynamic-static gap between the impeller outlet and the guide blade inlet, which verified that the unsteady flow within the guide blade was closely related to the jet wake phenomenon. Gao et al [7] experimentally measured the dynamic pressure pulsation at the impeller outlet, and found that the pressure pulsation amplitude near the wake vortex was large by combining their measurements with numerical simulation results
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