Transient Flow Structures and Energy Loss Mechanisms of a Multistage Pump as a Turbine Under Runaway Conditions

Peng Lin, Yuting Xiong, Xiaolong Li, Yonggang Lu (), Dong Hu, Wei Lu and Jin Peng
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Peng Lin: School of Energy and Mechanical Engineering, Hunan University of Humanities, Science and Technology, Loudi 417000, China
Yuting Xiong: School of Energy and Mechanical Engineering, Hunan University of Humanities, Science and Technology, Loudi 417000, China
Xiaolong Li: National Research Center of Pumps, Jiangsu University, Zhenjiang 212013, China
Yonggang Lu: Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
Dong Hu: School of Energy and Mechanical Engineering, Hunan University of Humanities, Science and Technology, Loudi 417000, China
Wei Lu: Huaneng Lancangjiang River Hydropower Inc., Kunming 650214, China
Jin Peng: Huaneng Lancangjiang River Hydropower Inc., Kunming 650214, China

Energies, 2025, vol. 18, issue 17, 1-21

Abstract: Multistage pumps serve as the core power source for fluid transportation, and runaway conditions of multistage pumps as turbines (PATs) may lead to severe consequences. This study investigated the pressure pulsation, flow structure, and impeller transient characteristics of an 11-stage petrochemical pump under runaway conditions. Full-flow numerical simulations at varying speeds analyzed head, efficiency, and entropy production via the entropy diagnostic method. The results showed that total entropy production generally increases with rotational speed, while efficiency first rises then declines, peaking at 78.48% at 4000 r/min. Maximum/minimum pressure pulsation peaks consistently occur at identical stages, with dominant peak amplitudes overall increasing with speed. Pressure coefficient amplitudes decrease with frequency growth, with larger pulsation magnitudes observed at monitoring points closer to impeller outlets. Dominant pressure pulsation peaks exhibit upward trends with increasing rotational speed. Both the blade-passing frequency and its harmonics were detected at 5100 r/min, including the impeller inlet/outlet side and the region near the cutwater within the guide vanes. This study identified the critical threshold of 4800 r/min and pinpointed fatigue risk zones, providing a theoretical foundation for designing and manufacturing high-performing multistage PAT systems under runaway conditions.

Keywords: PAT; runaway conditions; entropy; pressure pulsation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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