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Suppression of hump characteristics of low specific speed centrifugal pumps by the number of impeller blades based on entropy production theory and energy gradient method

Author

Listed:
  • Gao, Junhao
  • Liu, Lei
  • Luo, Jinping
  • Zhou, Chenyu
  • Mao, Jiandong
  • Liu, Lijun

Abstract

Low specific speed centrifugal pumps are extensively employed in engineering applications but frequently suffer from the hump phenomenon under low-flow conditions, which undermines operational stability. This study leverages entropy production theory and the energy gradient method to systematically evaluate the influence of impeller blade number on hump characteristics and proposes a robust hump-free improvement methodology that outperforms conventional improvement strategies. Experimental validation confirms the efficacy of the proposed approach. The results demonstrate that traditional blade-number reduction offers limited efficacy in hump suppression, whereas increasing the number of impeller blades enhances flow control, optimizes internal flow dynamics, and reduces energy loss. A hump-free configuration with 16 blades was successfully developed, exhibiting an 11.96 % reduction in total entropy production compared to the original 7-blade design in the hump region, with decreases of 15.56 % and 8.88 % in entropy production in the impeller and diffuser, respectively. Furthermore, the increased blade number improved the absolute velocity at the impeller-diffuser clearance and enhanced flow angle uniformity, yielding a 31.15 % increase in absolute fluid velocity at the impeller outlet. However, this design may elevate entropy production along the diffuser inner wall, necessitating a careful trade-off between absolute and wall entropy generation in the diffuser during blade-number optimization. Additionally, the proposed design reduces the pressure difference between the blades, augmenting impeller power output and operational stability while improving overall pump flow stability. This work provides critical insights into the hump-free design and performance enhancement of centrifugal pumps, offering a foundation for future advancements in pump stability and efficiency.

Suggested Citation

  • Gao, Junhao & Liu, Lei & Luo, Jinping & Zhou, Chenyu & Mao, Jiandong & Liu, Lijun, 2026. "Suppression of hump characteristics of low specific speed centrifugal pumps by the number of impeller blades based on entropy production theory and energy gradient method," Energy, Elsevier, vol. 342(C).
    • Handle: RePEc:eee:energy:v:342:y:2026:i:c:s0360544225052296
    DOI: 10.1016/j.energy.2025.139587
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    References listed on IDEAS

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