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Proceedings of the 24th ITTC - Volume III 747
Group Discussion 2
Vortex Induced Vibrations
Session Chairman: Dr. Carl Trygve Stansberg
1. PRESENTATIONS
1.1 By Dr. Carl Trygve Stansberg, Norwegian Marine Technology Research Institute, Norway, on Recent VIV research at MARINTEK/NTNU
Marine Technology Centre in Trondheim, Norway:
Key VIV Work at MARINTEK and NTNU. Model tests in laboratory and large-scale
(fjord) testing, Analysis of experiment data (small-, large-
and full scale tests), Development of VIV prediction tools, Consultant work, Research at the Centre of Excellence on
Ship and Ocean Structures, Model tests in laboratory and large-scale
(fjord) testing, Analysis of experiment data (small-, large-
and full scale tests), Development of VIV prediction tools:
- VIVANA (Semi-empirical force model prediction tool),
- SIMVIV (Simplified response model prediction tool),
- CFD-code, Consultant work on:
- Marine risers, - Deepwater umbilicals, - Free spanning pipelines,
Research at the Centre of Excellence on Ship and Ocean Structures (CeSOS), NTNU:
- 3 PhD students on VIV on pipelines, one post doc. (CFD; PIV a.o.).
History of Projects:
1983, High Re VIV tests in cav. Tunnel for Oil company,
1993, Skarnsund project for JIP, 1996, Rotating rig VIV riser tests for
NTNU/MT, 1997, Hanøytangen project for Norsk
Hydro, 1997, Dr.ing thesis, Vikestad for NTNU, 1997, VIV test staggered buoyancy for
Shear7/JIP, 1998, Clashing criteria and VIV for NDP, 1998, VIV on Statfjord SCR for Statoil, 1999, Rotating rig VIV riser test in
directional current for Statoil/NH, 1999, Analysis full-scale drilling riser VIV
experiment for NDP,
748 Group Discussion 2
Vortex Induced Vibrations
1999, VIV in current and floater motions for NDP,
1999, Clashing energy and VIV for NDP, 2000, VIV suppression devices for Norsk
Hydro, 2000, VIV suppression of drilling riser for
NAVIS, 2000, Lift coefficients of straked risers for
NTNU, 2001, VIV of pipelines, very long free
spans for Norsk Hydro, 2001, Riser VIV tests using fibre optics for
Norsk Hydro, 2001, VIV on SCR in current at different
angles for STRIDE ph.4 / 2H Eng., 2002, 2-D riser bundle tests for US
engineering comp., 2003, VIV suppression test in rotating rig
for ExxonMobil URC, 2003, Ormen Lange free span pipe VIV
model tests, phase 3 for Norsk Hydro, 2003, Dual riser clashing tests for NDP, 2003, High mode VIV model tests for
NDP, 2004, Faired 3D riser VIV test,
effectiveness and instability for NDP, 2004, Galloping 2D tests for Statoil, 2005, Parametric 2D tests of strakes for
NDP, 2005, Ormen Lange umbilical free span
VIV tests for Norsk Hydro.
A Key Problem: Unknown Interactions for Long Risers in Shear Flow
Current Profile, URiser Strouhal Frequencyts = St U/d
Natural Frequencies:Mode # 1 2 3 4 5 6
Competing Modes
Higher Velocity: Higher modes excited and competing between modes, difficult to predict response.
Figure 1.1- NDP High Mode VIV Test in 50m x 80m Ocean Basin.
Figure 1.2- The MARINTEK Ocean Basin (50m x 80m x 10m).
riser
gondol
riser
gondol
Figure 1.3- NDP High Mode VIV Test in Ocean Basin, test set-up for uniform and sheared flow.
Figure 1.4- Straked riser and naked riser tests.
Proceedings of the 24th ITTC - Volume III 749
Uniform Sheared Flow
IL IL
C C
Figure 1.5- Example of results, modal weight vs. tow speed.
Figure 1.6- Crossflow (CF) and Inline (IL) fatigue vs. tow speed for bare riser in uniform flow.
1.00E-11
1.00E-10
1.00E-09
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
1.00E-01
1.00E+00
0.00 0.50 1.00 1.50 2.00 2.50
Velocity [m/s]
D [1
/yrs
] Bare17.5D0.25D5D0.14D
Figure 1.7- Max. fatigue damage vs. tow speed (bare and straked risers).
The riser is attached to the rotating
test rig
Current profile
The riser is attached to the rotating
test rig
Current profile
Figure 1.8- Set-up Rotating Rig experiment in towing tank.
Rotating rig riser model and instrumentation:
Type: rubber hose with intersection of
aluminium for housing accelerometers, Length: 9.6 – 13.1 m, Outer diameter: 0.023 m, Weight in air: 5.327 N/m, Pretension (at lower end): about 690 N, Instrumentation: 10 pair of accelerometers,
3 component force transducers in both ends, set-down, velocity.
Examples of results, 2D uniform current test:
Acc Rms IL &CF, Test # 1109; V=0.904 m/s
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 5 10 15 20 25 30 35
Rms of Acc. (m/s^2)
Rel
. ris
er le
ngth
from
bot
tom
Acc-ILAcc-CF
750 Group Discussion 2
Vortex Induced Vibrations
Displ Rms IL &CF, Test # 1109; V=0.904 m/s
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008
Rms of Displ. (m)
Rel
. ris
er le
ngth
from
bot
tom
Pos-ILPos-CF
w speed Flow speed
UpstreamRiser
DownstreamRiser
Reduced drag
Figure 1.9- NDP Riser Clashing Tests - principles. Towing of “vertical” risers, constant current profile and equal velocity scaling.
Figure 1.10- Test results, snapshots of risers.
Ormen Lange VIV on Free Spans:
Model testing of single and multispan pipe, Analysis of results,
VIVANA extensions (CF) and studies.
Ormen Lange Free Spanning Pipe Project: Combining VIV Model Tests and VIVANA Calculations.
Multi-span VIV behaviour, interaction between two spans
Effect from shoulders
Visualization of flow around circular cylinders using Particle Imaging Velocimetry (PIV):
Measurementarea, WxH is 471x335mm
Water surface: test object submergence 700mmInflow U
Laser sheet
Measurementarea, WxH is 471x335mm
Water surface: test object submergence 700mm Measurement
area, WxH is 471x335mm
Water surface: test object submergence 700mmWater surface: test object submergence 700mmInflow U
Laser sheetTest object:
circular cylinder
Figure 1.11- Side view of test setup.
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 pix
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
1050
1100
1150
pix
Image size: 1600×1186 (0,0), 8-bits (frame 2)Burst#; rec#: 1; 41 (6), Date: 09.02.2005, Time: 02:43:59:185Analog inputs : 10 000; 10 000; 10 000; 10 000
U
Figure 1.12- Typical picture of seeding parti-cles in the fluid.
Proceedings of the 24th ITTC - Volume III 751
Figure 1.13- Probe following the object during towing.
U
-240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2mm-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
mm
-0.250 -0.217 -0.183 -0.150 -0.117 -0.083 -0.050 -0.017 0.017 0.050 0.083 0.117 0.150 0.183 0.217 0.250
Vector map: 3D vectors, 124×96 vectors (11904)Burst#; rec#: 1; 41 (6), Date: 09.02.2005, Time: 02:43:59:185
U
Figure 1.14- 3D velocity vector plot.
-240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2mm-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
mm
-0.761 -0.691 -0.622 -0.552 -0.482 -0.413 -0.343 -0.274 -0.204 -0.135 -0.065 0.004 0.074 0.144 0.213 0.283
U
Figure 1.15- Velocity component inline with towing, U.
-240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2mm-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
mm
-0.457 -0.399 -0.342 -0.285 -0.227 -0.170 -0.113 -0.055 0.002 0.059 0.117 0.174 0.231 0.289 0.346 0.404
U
Figure 1.16- Crossflow velocity component, V.
-240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2mm-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
mm
-0.250 -0.217 -0.183 -0.150 -0.117 -0.083 -0.050 -0.017 0.017 0.050 0.083 0.117 0.150 0.183 0.217 0.250
U
Figure 1.17- Velocity component along the cylinder, W.
-240 -230 -220 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2mm-180
-160
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
mm
-15.0 -13.0 -11.0 -9.0 -7.0 -5.0 -3.0 -1.0 1.0 3.0 5.0 7.0 9.0 11.0 13.0 15.0
U
Figure 1.18- Vorticity.
Summary. High-mode VIV experiments, Riser interaction, Free spans, Particle Imaging Velocimetry experiments.
752 Group Discussion 2
Vortex Induced Vibrations
1.2 By Dr. Jaap de Wilde, Maritime Research Institute Netherlands, The Netherlands, on Vortex Induced Vibrations
VIV has received much attention by the industry in the last decade. A large number of research and test campaigns has been carried out.
What have we learned from this and what is
the next step? What are the industry needs? How can we address the issues with model
tests or other methods?
FLUIDFORCES
FLUID DYNAMICS STRUCTURAL DYNAMICS
FLUID/STRUCTUREMOTIONS
VIV RESPONSE
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
-1.500 -0.500 0.500 1.500
FLUIDFORCES
FLUID DYNAMICS STRUCTURAL DYNAMICS
FLUID/STRUCTUREMOTIONS
VIV RESPONSE
-1.500
-1.000
-0.500
0.000
0.500
1.000
1.500
-1.500 -0.500 0.500 1.500
Figure 1.19- VIV is complex problem.
MARIN VIV Work. Older work in eighties (Jaap van der Vegt), Renewed interest in late nineties by
deepwater developments, VIVARRAY JIP (Triantafyllou, MIT), High Reynolds VIV apparatus (Jaap de
Wilde), SPAR VIM (Radboud van Dijk).
Test pipe
Oscillator
Figure 1.20- High Re test apparatus.
Free vibration
Flow
Forced oscillation
Figure 1.21- Free vibration and forced oscillation.
Figure 1.22- Oscillator.
Figure 1.23- Divers.
Proceedings of the 24th ITTC - Volume III 753
Figure 1.24- Bare pipe and pipe with strakes.
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-1.75
-1.75
-1.75
-1.7
5-1
.75
-1.75
-1.75
-1.75
-1.75
-1.75
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.5
-1.25
-1.25
-1.25
-1.2
5
-1.25
-1.25
-1.25
-1.25
-1.25
-1.25
-1
-1
-1
-1-1
-1
-1
-1
-1
-1
-1
-0.7
5
-0.75
-0.75
-0.75
-0.7
5-0
.75
-0.75
-0.75
-0.75
-0.75
-0.75
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.25
-0.25
-0.25
-0.25
-0.25
-0.2
5
-0.25
-0.2
5
-0.25-0.25
-0.25
-0.2
5-0
.25
0
0
0
00
0
0
0
0
0
0
00
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.250.25
0 .2 5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0 .5
0 .5 0
.75
0.75 0.75
0.75
0.75
0.75
0.75
0.75
0.75
0 .7 5 1
1
1
1
1
1
1
1
1
1
1
1.25
1.25
1.25
1.2 5
1 .2 51.251.25
1.25
1.5
1.5
1.5
1.5
1.5
1.5
1.51.5
1.75
1.75
1.75
1.75
1.75
1.75
1.75
1.75
2
2
22
2
2
2
A/D
Ur
Rough cylinder: Added Mass contour plot (Cm), Re=40829, forward
2 3 4 5 6 7
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Figure 1.25- Added mass (Cm).
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-1.8
-1.8
-1.8
-1.8
-1.8
-1.8
-1.8
-1.8
-1.8
-1.6-1.6
-1.6
-1.6
-1.6
-1.6
-1.6
-1.6
-1.6
-1.4
-1.4
-1.4
-1.4
-1 .4
-1.4
-1.4
-1.4
-1.4
-1.2-1.2
-1.2
-1.2
-1.2
-1.2
-1.2
-1.2
-1-1
-1
-1
-1
-1
-1
-1
-0.8
-0.8
-0.8
-0.8-0.8
-0.8
-0.8
-0.8
-0.8
-0.6-0.6
-0.6
-0.6
-0.6
-0.6
-0.6
-0.6
-0.6
-0.6
-0.4
-0.4
-0.4
-0.4
-0.4
-0.4
-0.4
-0.4
-0.4
-0.4
-0.2-0.2
-0.2
-0.2
-0.2
-0.2
-0.2 -0.2
-0.2
00
0
0
0
0
0
0
0.2
0.2
0.2
0.2
0.2
0.2
0.20.4
0.4
0.4
0.4
0.4
0.4
0.6
0.6
0.4
0.6
0.8
A/D
Ur
Rough cylinder: Lift in phase with velocity contour plot (Clv), Re=40829, forward
2 3 4 5 6 7
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Figure 1.26- Dynamic lift (Clv).
TransducerTensioner
Riser
Carriage
1.15 m
15.8 m
TransducerTensioner
Riser
Carriage
1.15 m
15.8 m
TransducerTensioner
Riser
Carriage
1.15 m
15.8 m
Shallow Water Basin: 220 m long
40 optical strain gauges4 accelerometers6 load cells
1.5 m1.5 mflowflow
Under water camera
Above watercamera
PipeCamera
Figure 1.27- Experiment with 12.6 m long pipe
754 Group Discussion 2
Vortex Induced Vibrations
Test 102014 - displacements at location 4
-2.4E-02
-1.6E-02
-8.0E-03
0.0E+00
8.0E-03
1.6E-02
2.4E-02
-2.4E-02 -1.6E-02 -8.0E-03 0.0E+00 8.0E-03 1.6E-02 2.4E-02
x [m]
y [m
]
Test 102014 - displacements at location 9
-2.E-02
-2.E-02
-8.E-03
0.E+00
8.E-03
2.E-02
2.E-02
-2.E-02 -2.E-02 -8.E-03 0.E+00 8.E-03 2.E-02 2.E-02
x [m]
y [m
]
Figure 1.28- Motions test 102014 from FBGs.
Figure 1.29- PIV 50 mm cylinder (experiments 2000).
Spar VIV Test Set-up.
Figure 1.30- 4 line mooring with linear springs.
Figure 1.31- Spar Tests.
Location 4
Location 9
Proceedings of the 24th ITTC - Volume III 755
Figure 1.32- VIM tests with bare hull.
A/D
Ur
w/o strakes
with strakes
Figure 1.33- Truss spar, with and without strakes.
Flow angle
Red
uced
vel
ocity
Flow angle
Amplitude
Figure 1.34- Truss Spar in waves and current.
Hurricane profile
Loop current profile
Hurricane profile
Loop current profile
Figure 1.35- Measured current profile.
Outstanding VIV Research Topics. Scale effects, Surface roughness and turbulence, High mode response of long risers, Riser-riser VIV interaction, Implementation of knowledge in codes,
software and test procedures, Miscellaneous VIV (galloping, bundles,
jumpers, Calm buoys, semi’s, TLPs, etc.).
MARIN plans:
Further development High Reynolds apparatus,
Further development SPAR VIM model tests,
PIV (MARIN-Sirenha, 2005), CFD (University Twente), Fully instrumented long catenary model
riser (PhD thesis), Development VIV prediction tool together
with Delft University (PhD thesis).
756 Group Discussion 2
Vortex Induced Vibrations
1.3 By Dr. John Shanks, RiserTec Ltd, United Kingdom, on Power Balance Methods for VIV Assessments
Basic Power Balance Approach.
X-flow velocity:
Lift force:
Power-in:
Lift curve:
Figure 1.36- Self limiting process.
Figure 1.37- Power in region.
Multi-mode response:
Basic Shear7 flow chart:
NDP High Mode Tests.
Proceedings of the 24th ITTC - Volume III 757
Figure 1.38- Small-scale VIV strakes.
Figure 1.39- VIV strakes fitted to test riser.
NDP high mode test program:
38m long x 27mm OD fibre glass pipe, 5 kN nominal tensions, Uniform and triangular current profiles, Current speeds 0.3, 0.4 to 2.4 m/s (22
cases), Plain pipe plus short and long pitch strakes, 50, 75, 90 and 100% strake cover, Over 300 cases.
Shear7 calibration flow chart:
Shear7 calibration results:
Figure 1.40- Shear7 calibration results.
758 Group Discussion 2
Vortex Induced Vibrations
Maximum power method:
Basic RTVIV flow chart:
VIV of Pipeline Spools.
Figure 1.41- Vertical Configuration.
3D ABAQUS model gives displacements and stresses for unit amplitude displacement.
Analysis Procedure:
Figure 1.42- Mode shapes - datum position.
Figure 1.43- Mode shapes - trimmed conf.
Proceedings of the 24th ITTC - Volume III 759
Vertical method:
Radial method:
Vertical v radial methods:
Summary Fatigue Results.
Conclusions. Power Balance Methods provide useful
design tool, Ongoing development needed to improve
continuity, Max power and radial methods look
promising for complex spool geometries, Further high quality high mode tests
needed, Calibration against CFD also potentially
useful;
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