Numerical Analysis of Mechanical Energy Dissipation for an Axial-Flow Pump Based on Entropy Generation Theory
Simin Shen,
Zhongdong Qian and
Bin Ji
Additional contact information
Simin Shen: State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, No.8 South East Lake Road, Wuhan 430072, China
Zhongdong Qian: State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, No.8 South East Lake Road, Wuhan 430072, China
Bin Ji: State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, No.8 South East Lake Road, Wuhan 430072, China
Energies, 2019, vol. 12, issue 21, 1-22
Abstract:
Mechanical energy dissipation is a major problem affecting hydraulic machinery especially under partial-load conditions. Owing to limitations of traditional methods in evaluating mechanical energy dissipation, entropy generation theory is introduced to study mechanical energy dissipation with varying discharge and tip clearance intuitively through numerical simulations in an axial-flow pump. Results show that the impeller and diffuser are the main domains of mechanical energy dissipation, respectively accounting for 35.32%–55.51% and 32.61%–20.42% of mechanical energy dissipation throughout the flow passage. The mechanical energy dissipation of the impeller has a strong relation with the hump characteristic and becomes increasingly important with decreasing discharge. Areas of high turbulent dissipation in the impeller are mainly concentrated near the blades’ suction sides, and these regions, especially areas near the shroud, extend with decreasing discharge. When the pump enters the hump region, the distributions of turbulent dissipation near the shroud become disordered and expand towards the impeller’s inlet side. Unstable flows, like flow separation and vortices, near the blades’ suction sides lead to the high turbulent dissipation in the impeller and hump characteristic. Turbulent dissipation at the tip decreases from the blade leading edge to trailing edge, and regions of high dissipation distribute near the leading edge of the blade tip side. An increase in tip clearance for the same discharge mainly increases areas of high turbulent dissipation near the shroud and at the tip of the impeller, finally reducing pump performance.
Keywords: axial-flow pump; mechanical energy dissipation; entropy generation; tip clearance (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: 2019
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Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:12:y:2019:i:21:p:4162-:d:282078
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