Water, Vol. 18, Pages 437: Influence of Blade Tip Clearance on External Characteristics and Internal Flow Pattern of Axial Flow Pumps

Water doi: 10.3390/w18030437

Authors:
Ling Bai
Jie Zhang
Lei Jiang
Hong Xu
Ling Zhou

Axial flow pumps, widely utilized in critical fields such as agricultural irrigation, urban water diversion and flood control, play an indispensable role in large-scale water transport and drainage projects due to their high-flow and low-head characteristics. This study systematically investigates the influence of tip clearance on the external characteristics and internal flow field of a large-scale axial flow pump (model 1800GZX-125). By combining numerical simulations with experimental validation, a comparative analysis was conducted under four tip clearance sizes (3 mm, 12 mm, 17.5 mm, 24 mm) and various flow conditions. The results indicate that increasing the tip clearance generally reduces the pump head and peak efficiency. It also alters the blade pressure distribution, expands the low-pressure region, and intensifies tip leakage flow. While vorticity overall increases, it weakens locally under certain conditions due to changes in leakage flow patterns. Entropy generation analysis further reveals that larger clearances lead to significantly increased energy losses, thereby degrading external performance. These findings provide a theoretical basis for improving the performance and operational stability of axial flow pumps.

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