Investigation on passive suppression method of hump characteristics in a large vertical volute centrifugal pump: Using combined diffuser vane structure

Gang Yang, Xi Shen, Qiang Pan, Linlin Geng, Lei Shi, Bin Xu and Desheng Zhang

Energy, 2024, vol. 304, issue C

Abstract: The hump characteristic is one of the unique hydraulic instability of the large vertical volute centrifugal pump (LVVCP) under part-load conditions, which is extremely detrimental to the safe and stable unit operation. To suppress the hump characteristic of LVVCP, a passive suppression method with a combined diffuser vane structure is proposed in this paper. This diffuser vane structure consists of a combination of large and small hydrofoil vanes, with the special 6 small hydrofoil vane B are arranged within 150° range of the small volute section side. To investigate the key reasons for suppression, detached eddy simulations are performed for LVVCP with original diffuser vane (Diffuser A) and combined diffuser vane (Diffuser B), and the energy loss and flow patterns are analyzed. The hump region of LVVCP with Diffuser B is narrower, the positive slope of Q-H curve is decreased and the hump margin is increased. The reduced conversion of kinetic energy to turbulent kinetic energy and the decreased Reynolds stress diffusion loss in the Diffuser B and volute are main reasons for the hump characteristic suppression. The energy loss in the volute small section side region and its corresponding diffuser region increases significantly under hump conditions, and Diffuser B can obviously reduce the energy loss in these regions. The flow pattern analysis in the diffuser shows that the weakened rotating stall in Diffuser B leads to a more regular Qm variation with time in D1∼D6. The reduced chord length and thickness of vane B results in a significant decrease of pressure surface separation vortex (PSV) and suction surface separation vortex (SSV) scales and a weakened vortex merging phenomenon, which causes a considerable drop of ΔSPRO in the Diffuser B. The Diffuser B provides a more uniform α distribution to the volute inlet, and decreases the vortex scale and vortex-induced energy loss on the volute small section side.

Keywords: Large vertical volute centrifugal pump; Hump characteristic; Combined diffuser vane structure; Energy loss; Flow pattern (search for similar items in EconPapers)
Date: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:304:y:2024:i:c:s0360544224018413

DOI: 10.1016/j.energy.2024.132067

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