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<p>The hump characteristic of large vertical centrifugal pumps (LVCP) poses a major challenge to their efficient, safe, and stable operation under low-flow conditions. In this study, numerical simulation and experimental validation are combined with entropy production theory and the <i>Q</i>-Criterion vortex identification method to systematically analyze energy loss distribution and internal flow characteristics in the hump region of a large vertical centrifugal pump with a single-layer guide vane. The aim is to uncover the underlying mechanism behind the pump's hump behavior. Results indicate that the non-monotonic head variation, which decreases first and then increases, is driven by the interaction between flow blockage in the impeller and vortex evolution in the guide vane region. Between 0.5<i>Q</i><sub>d</sub> and 0.4<i>Q</i><sub>d</sub>, intensified inlet backflow and spiral vortices at the impeller outlet, along with the formation of leading-edge vortices and vaneless-region vortices in the guide vane, lead to significant energy loss and head drop. However, between 0.4<i>Q</i><sub>d</sub> and 0.3<i>Q</i><sub>d</sub>, blockage coefficients in some impeller passages improve markedly, resulting in a more uniform outlet velocity distribution. This suppresses vortex generation in the downstream guide vane, reduces local energy losses, and leads to partial recovery of the pump head along with enhanced energy conversion under lower flow rates. By coupling entropy production analysis with vortex identification, this study quantitatively reveals the physical mechanism linking impeller blockage with the evolution of guide vane vortices. More importantly, it offers new insight into the mechanism underlying head variation in the hump region of large vertical centrifugal pumps with guide vane structures.</p>

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Investigation of flow and energy loss in the hump region of the large vertical centrifugal pump

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Shuainan Chen,
  • Luan Shi,
  • Wei Yang,
  • Zhuqing Liu,
  • Huimin Feng

摘要

The hump characteristic of large vertical centrifugal pumps (LVCP) poses a major challenge to their efficient, safe, and stable operation under low-flow conditions. In this study, numerical simulation and experimental validation are combined with entropy production theory and the Q-Criterion vortex identification method to systematically analyze energy loss distribution and internal flow characteristics in the hump region of a large vertical centrifugal pump with a single-layer guide vane. The aim is to uncover the underlying mechanism behind the pump's hump behavior. Results indicate that the non-monotonic head variation, which decreases first and then increases, is driven by the interaction between flow blockage in the impeller and vortex evolution in the guide vane region. Between 0.5Qd and 0.4Qd, intensified inlet backflow and spiral vortices at the impeller outlet, along with the formation of leading-edge vortices and vaneless-region vortices in the guide vane, lead to significant energy loss and head drop. However, between 0.4Qd and 0.3Qd, blockage coefficients in some impeller passages improve markedly, resulting in a more uniform outlet velocity distribution. This suppresses vortex generation in the downstream guide vane, reduces local energy losses, and leads to partial recovery of the pump head along with enhanced energy conversion under lower flow rates. By coupling entropy production analysis with vortex identification, this study quantitatively reveals the physical mechanism linking impeller blockage with the evolution of guide vane vortices. More importantly, it offers new insight into the mechanism underlying head variation in the hump region of large vertical centrifugal pumps with guide vane structures.