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Article

Effects of Radial Clearance Between Rotor and Casing on Flow Characteristics in a Centrifugal Pump

College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225009, China
*
Author to whom correspondence should be addressed.
Machines 2026, 14(4), 438; https://doi.org/10.3390/machines14040438
Submission received: 25 March 2026 / Revised: 10 April 2026 / Accepted: 13 April 2026 / Published: 15 April 2026

Abstract

The electrification of the automotive industry and the lightweighting of aerospace equipment demand high-efficiency centrifugal pumps for compact spaces. A novel centrifugal pump incorporates an integrated impeller-motor rotor design, achieving a more compact footprint and higher power density. However, research is scarce on the radial clearance between the rotor and casing. This study presents a comprehensive investigation of the internal flow dynamics, combining numerical simulations with experimental validation. A significant reduction in fluctuation amplitude for pump efficiency, head coefficient, and frictional loss rate occurs when the clearance ranges from 1.0 to 1.5 mm. Within clearances of 0.75 to 1.5 mm, complex vortex systems emerge in the radial clearance, inducing diverse circumferential high-speed zones. Pressure fluctuations within the radial clearance are predominantly governed by the blade passing frequency. At a clearance of 1.5 mm, the rotational harmonic amplitude at monitoring points exceeds the blade passing frequency amplitude by a factor of 1.9, while the average pressure fluctuation intensity at other points increases significantly by 36.9%. An optimal clearance of 1.25 mm achieves a balance between flow characteristics and energy consumption. This research provides practical insights for optimizing pump energy performance and operational stability.
Keywords: centrifugal pump; energy performance; flow characteristics; pressure fluctuation; entropy production centrifugal pump; energy performance; flow characteristics; pressure fluctuation; entropy production

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MDPI and ACS Style

Bian, J.; Gu, Y.; Zhu, Q.; Lu, W. Effects of Radial Clearance Between Rotor and Casing on Flow Characteristics in a Centrifugal Pump. Machines 2026, 14, 438. https://doi.org/10.3390/machines14040438

AMA Style

Bian J, Gu Y, Zhu Q, Lu W. Effects of Radial Clearance Between Rotor and Casing on Flow Characteristics in a Centrifugal Pump. Machines. 2026; 14(4):438. https://doi.org/10.3390/machines14040438

Chicago/Turabian Style

Bian, Junjie, Yandong Gu, Qiyuan Zhu, and Weigang Lu. 2026. "Effects of Radial Clearance Between Rotor and Casing on Flow Characteristics in a Centrifugal Pump" Machines 14, no. 4: 438. https://doi.org/10.3390/machines14040438

APA Style

Bian, J., Gu, Y., Zhu, Q., & Lu, W. (2026). Effects of Radial Clearance Between Rotor and Casing on Flow Characteristics in a Centrifugal Pump. Machines, 14(4), 438. https://doi.org/10.3390/machines14040438

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