Upload
delftsoftwaredays
View
74
Download
1
Tags:
Embed Size (px)
Citation preview
7 augustus 2015
Discussion on the acceptance criteria for physical
model testing of intake pumping stations
Physical model testing
7 augustus 2015
Physical model testing of pumping stations is
performed to ensure suppling hydraulically proper
feed flow towards the pumps to:
• Increase of lifetime and reduction of maintainance cost
• Maintain the efficiency of the pump
• Ensure pump capacity
Physical model testing
7 augustus 2015
Physical model testing of pumping stations is
performed to ensure suppling hydraulically proper
feed flow towards the pumps to:
• Increase of lifetime and reduction of maintainance cost
• Maintain the efficiency of the pump
• Ensure pump capacity
Acceptance criteria
7 augustus 2015
Vortices Pre-rotation Velocity variations
Acceptance criteria - Vortices
7 augustus 2015
Acceptance criteria – Pre-rotation
7 augustus 2015
“Preswirl alters the inlet velocity vector at the impeller vanes, resulting in undesired changes
in pump performance characteristics, including potential vibration” - ANSI/HI
“Except for some special cases, …, pump performance near the highest efficiency point is
influenced only slightly by rotating flow” - TSJ-S002
ANSI/HI
• long term average (600 s)
- 100% < 5
• short term (10-30 s)
˗ 90% < 5
˗ 100% < 7
IIHR
• long term average (300 s)
- 100% < 5
Recent research – Pre-rotation
7 augustus 2015
10 s 10-40% higher
than 30 s
accuracy 0.3°
accuracy 0.35°
ANSI/HI
• short term (10-30 s)
˗ 90% < 5
˗ 100% < 7
IIHR
• long term average (300 s)
- 100% < 5
ANSI/HI
• long term average (600 s)
- 100% < 5
Acceptance criteria - Velocity variations
7 augustus 2015
not required - TSJ-S002
required - ANSI/HI & IIHR
ANSI/HI
• Temporal variation < 10%
• Spatial variation < 10%
Local velocity compared to cross
sectional average:
vlocal – vaverage < + 10% vaverage
IIHR
• Spatial variation <5%
Local velocity compared to
average on concentric circle:
vlocal – vcircle < + 5% vcircle
vlocal
vaverage
vlocal
vcircle
Velocity
measurements
Measurement
location Impeller level
Bell mouth throat - ANSI/HI & IIHR
Acceptance criteria- Velocity variations
7 augustus 2015
impeller
throat
Recent research - Velocity variations
7 augustus 2015
throat impeller
throat impeller
Measurement
location Impeller level
Bell mouth throat - ANSI/HI & IIHR
Optimisation of the feed flow
7 augustus 2015
7 augustus 2015
Reference Backwall splitter
Recent research - Optimisation of the feed flow
Modifications have (sometimes) a local effect
Example: Backwall splitter decreases the velocity at the back
No other effects observed
Summary
7 augustus 2015
Vortices
Examination of a pumping station with respect to vortices is consistent
Pre-rotation
The acceptability of the feed flow with respect to pre-rotation depends on
• the used standard
• the interpretation of the acceptance criterion
Velocity variations
The acceptability of the feed flow with respect to velocity variations depends on
• the used standard
• the interpretation of the acceptance criterion
Modifications to the pump compartment have a limited effect on the velocity variations