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Research Papers: Flows in Complex Systems

# An Experimental Investigation of the Flow Fields Within Geometrically Similar Miniature-Scale Centrifugal Pumps

[+] Author and Article Information
Daniel Kearney

Stokes Institute, University of Limerick, Limerick, Irelanddaniel.kearney@ul.ie

Ronan Grimes

CTVR, Stokes Institute, University of Limerick, Limerick, Irelandronan.grimes@ul.ie

Jeff Punch

CTVR, Stokes Institute, University of Limerick, Limerick, Irelandjeff.punch@ul.ie

J. Fluids Eng 131(10), 101101 (Sep 11, 2009) (10 pages) doi:10.1115/1.3176985 History: Received November 14, 2008; Revised June 01, 2009; Published September 11, 2009

## Abstract

Flow fields within two miniature-scale centrifugal pumps are measured and analyzed to facilitate an understanding of how scaling influences performance. A full-scale pump, of impeller diameter 34.3 mm and blade height 5 mm, and a half-scale version were fabricated from a transparent material to allow optical access. Synchronized particle-image velocimetry (PIV) was performed within the blade passage of each pump. Pressure-flow characteristics, hydrodynamic efficiencies, and high-resolution flow field measurements are reported for six rotational speeds over a Reynolds number range 706–2355. Fluidic phenomena occurring in the impeller passage at both pressure and suction surfaces are identified. Efficiencies are evaluated from direct measurement to be between 10% and 44% and compared with inner efficiencies calculated from the PIV data. Hydrodynamic losses as a percentage of overall efficiency increase from 12% to 55% for $2355≤Re≤706$. Slip factors, in the range 0.92–1.10, have been derived from velocimetry data.

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## Figures

Figure 1

Transparent centrifugal pumps

Figure 2

Pump A impeller geometry where (a) represents a plan view and (b) represents a lateral view

Figure 3

Hydrodynamic test bed (to EN ISO 5198:1998) with velocimetry

Figure 4

Pump A with impeller blades (4 and 5) in PIV measurement position 90 deg anticlockwise of the outlet

Figure 5

Nondimensional pressure-flow curves as a function of operational speed (uncertainty of Φ=±5–20% and Ψ=±0.8%)

Figure 6

Efficiency curves of test pumps as a function of operating speed (uncertainty of Φ=±5–20%; η=±5.08–20.02%)

Figure 7

Decreasing maximum hydrodynamic efficiency as a function of Reynolds number (uncertainty of η=±5.08–20.02%; Re=±5.01–20%)

Figure 8

Relative velocity flow fields normalized with respective blade speeds Vrel/Vb

Figure 9

Formation of a horseshoe vortex pair

Figure 10

Average tangential velocity normalized with blade tip speed Vθ/Vb as a function of increasing radial distance (r/R)

Figure 11

Average tangential velocity normalized with blade tip speed Vθ/Vb at each degree along a circumferential blade tip arc θ-θ at r/R=1 as a function of normalized passage angle θ/θbp

Figure 12

Radial velocity component normalized with blade tip speed Vrad/Vb at each degree along a circumferential blade tip arc θ-θ at r/R=1 as a function of normalized passage angle θ/θbp

Figure 13

Average normalized absolute tangential Vθ/Vb and radial velocity components Vrad/Vb for a circumferential blade tip arc θ-θ at the blade tip r/R=1 as a function of Reynolds number

Figure 14

Hydrodynamic efficiency and normalized boundary layer development δcl/h as a function of Reynolds number for pumps A and B

Figure 15

Euler velocity triangle illustrating velocity components

Figure 16

Velocity triangles constructed from PIV data and overall measured data illustrated in (a) for pump A and (b) for pump B

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