Group Discussion 2 Vortex Induced Vibrations - ITTC · Analysis of experiment data ... Group Discussion 2 Vortex Induced Vibrations ... Figure 1.21- Free vibration and forced

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


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.


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



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.


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.



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.


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



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


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).



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.


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.



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.


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;

Documents

Group Discussion 2 Vortex Induced Vibrations - ITTC · Analysis of experiment data ... Group Discussion 2 Vortex Induced Vibrations ... Figure 1.21- Free vibration and forced