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Research Papers: Fundamental Issues and Canonical Flows

Effect of Trailing-Edge Modification of a Mixed-Flow Pump

[+] Author and Article Information
Dazhuan Wu

Institute of Process Equipment,
Zhejiang University,
Hangzhou 310027, China
e-mail: wudazhuan@zju.edu.cn

Peng Yan

Institute of Process Equipment,
Zhejiang University,
Hangzhou 310027, China
e-mail: yanpeng@zju.edu.cn

Xin Chen

Institute of Process Equipment,
Zhejiang University,
Hangzhou 310027, China
e-mail: xchen@zju.edu.cn

Peng Wu

Institute of Process Equipment,
Zhejiang University,
Hangzhou 310027, China
e-mail: roc@zju.edu.cn

Shuai Yang

Institute of Process Equipment,
Zhejiang University,
Hangzhou 310027, China
e-mail: 11228024@zju.edu.cn

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received October 11, 2014; final manuscript received April 20, 2015; published online June 15, 2015. Assoc. Editor: Bart van Esch.

J. Fluids Eng 137(10), 101205 (Oct 01, 2015) (9 pages) Paper No: FE-14-1579; doi: 10.1115/1.4030488 History: Received October 11, 2014; Revised April 20, 2015; Online June 15, 2015

Modern pumps are designed to guarantee a sufficiently large operating range or to satisfy the performance requirements relative to more than one operating point. This study applies trailing-edge (TE) modification method based on TE rounding in the suction surface to widen the operating range of a mixed-flow pump. The effects of TE modification on the performance and internal flow of the mixed-flow pump are investigated through computational fluid dynamics (CFD) analysis. Local Euler head distribution is introduced to reveal the pattern of energy growth along the blade-aligned (BA) streamwise location. A pump model with TE modification is tested, and numerical results agree well with experimental data. The results show that TE modification significantly improves pump efficiency in the high flow rate region by more than 10%. The best pattern of normalized local Euler head distribution (NLEHD) is a convex curve of nearly constant growth rate. The overall heads are also improved, and the flow near the exit of the impeller exhibits better uniformity. This finding demonstrates that a small change in the TE of the impeller can influence flow structure in most areas of impeller channels and that the local Euler head distribution is closely related to pump efficiency. TE modification can effectively improve the performance of the mixed-flow pump with high flow rate.

Copyright © 2015 by ASME
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References

Figures

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Fig. 1

Mixed-flow pump model: (a) sketch of the mixed-flow pump and (b) 3D geometry of the mixed-flow pump

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Fig. 2

Schematic of the TE rounding: (a) Two-dimensional (2D) diagram of TE modification and (b) 3D geometry of modified impeller blade

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Fig. 3

Computational domain and meshes

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Fig. 4

Results of grid-independence test

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Fig. 5

Calculated and experimental head in different flow rates

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Fig. 6

Calculated hydraulic efficiency in different flow rates

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Fig. 7

Velocity triangles

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Fig. 8

Schematic of mixed-flow pump test rig

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Fig. 9

Experimental validation of hydraulic efficiency in different flow rates

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Fig. 11

Local Euler head distribution at flow rates of 3750 and 5000 m3/hr in models with various fillet radii

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Fig. 12

NLEHD in models with various fillet radii: (a) at flow rate of 3750 m3/hr, (b) at flow rate of 4250 m3/hr, and (c) at flow rate of 5000 m3/hr

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Fig. 13

NLEHD in various flow rates: (a) model without rounding and (b) model with fillet radius of 20 mm

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Fig. 14

NLEHD of the BEP in different models

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Fig. 15

Local Euler head contours at blade-to-blade surface (span = 0.5)

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Fig. 16

Relative velocity contours at blade-to-blade surface calculated by steady numerical method (span = 0.5)

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Fig. 17

Relative velocity contours at blade-to-blade surface calculated by unsteady numerical method (span = 0.5)

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Fig. 18

Partial enlarged view of relative velocity contours at blade-to-blade surface calculated by steady numerical method (span = 0.5)

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Fig. 19

Comparison of relative velocity vectors at near the TE of the blade calculated by steady numerical method (span = 0.5)

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