Comparison between scale model and prototype pump

1. 10 november 2015
Comparison between scale model and
prototype pump

2. 10 november 2015
Introduction
• Scale modelling testing for large submersible pumps
• Testing performed based on the ANSI/HI 9.8-2012 standard
• No scientific background of guidelines / acceptance criteria
available
• Current guidelines are black/white
(acceptable / not acceptable) and
might therefore be in some cases too
conservative

3. Introduction
Well designed pump set-up? Why?
• Ensure pump capacity
• Limited amount of vibrations and noise
• Ensure lifetime and minimum maintenance costs
• Maintain efficiency of the pump
-> Physical scale models performed to asses approach flow
10 november 2015

4. Introduction
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5. Pre-rotation
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What is pre-rotation?
𝜃
𝜃
𝜃 Is called the swirl-angle (pre-rotation)

6. Pre-rotation
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How to measure pre-rotation?

7. Experimental set-up
• Two identical pump compartments + comparable approach flow
• Prototype pump: Flygt type PL7020
• Model: 1:1 scale model of prototype
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8. Experimental set-up
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9. Exp. Set-up prototype pump
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Measurements:
• Discharge
• Head
• Input power
• Frequency (adjustable by means of VFD)
Goal:
• For different approach flows and pump speeds
the pump operation is determined:
> Q-H curve
> Q-P curve
> Q-ɳ curve

10. Model pump results
• By implementation of flow
obstructions in the pump
compartment, different approach
flows are created
10 november 2015

11. Model pump results
• By implementation of flow
obstructions in the pump
compartment, different approach
flows are created
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12. Model pump results
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16 CW3 CW

13. Q-H
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0
1
2
3
4
5
6
7
8
9
200 220 240 260 280 300 320 340 360 380 400
H(m)
Q (l/s)
15CW
9CW
6CW
3CW
3CCW
6CCW
10CCW
16CCW
Poly. (15CW)
Poly. (9CW)
Poly. (6CW)
Poly. (3CW)
Poly. (3CCW)
Poly. (6CCW)
Poly. (10CCW)
Poly. (16CCW)

14. Q-P
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10
12
14
16
18
20
22
24
26
28
30
200 220 240 260 280 300 320 340 360 380 400
p(kW)
Q (l/s)
15CW
9CW
6CW
3CW
3CCW
6CCW
10CCW
16CCW
pecu_50
BEP
Poly. (15CW)
Poly. (9CW)
Poly. (6CW)
Poly. (3CW)
Poly. (3CCW)
Poly. (6CCW)
Poly. (10CCW)
Poly. (16CCW)

15. Preliminary conclusions
Pump performance is affected by pre-rotation in a predictable way:
• Co-swirl: Q, H, P decrease
• Counter-swirl: Q, H, P increase
• HI limit of 5 deg is safe (conservative)
> It should be used for cooling pumps, etc
> It can be exceeded for storm water pumps
• For swirl angles -10 deg < a < 10 deg deviations in Q, H, P are
about equal to allowed manufacturing tolerances
• Prolonged operation with swirl > 5 deg not recommended
• To prevent swirl:
> Control approach flow
> Install splitters
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16. Further research
Flow-conditioning sump features
• Splitters
• Corner fillets
• Bottom clearance
• Submergence
PIV (Particle Image Velocimetry)
• Detailed measurements of flow field near pumps
• Measurements of vortex strength
CFD (Computational Fluid Dynamics)
• Simulations of pump sumps
• Comparison of simulations and experiments
10 november 2015