Reducing Vortex-Induced Vibration of Drilling Risers with Marine Fairing

Aswin Janardhanan

• Analyze the VIV suppression of drilling risers with the use of marine fairing. [1]

• A free academic license of Star CCM+ was used to complete the work.

• Pressure increase from free stream to the stagnation

• Impels the developing boundary layers around the cylinder

• Pressure at downstream end insufficient to withhold boundary layers

• The boundary layers separate from each side of the cylinder surface

[2]

• Structural Damping

• Avoiding Resonance

• Suppression Devices [3]

• Surface Protusions

• Shrouds

• Nearwake Stabilizer

[2]

• Marine Fairings [4]

[1]

• Pre-processing

– Solution Domain

• Pre-processing

– Grid Generation

Configuration 1

Configuration 2

• Pre-processing

– Fluid Properties • Fluid - Water (Density 1kg/m3 & Dynamic Viscosity 8.9X 104 N∙s/m2)

• Fluid Flow Velocity – 8.9m/s

• Turbulent Flow

• RANS equation based turbulence model (k-ω model)

• Pre-processing

– Boundary Conditions

• Re = 100

• Re = 500

• Re = 1000

• Re = 10,000

• Re = 10,000

Re Asyikin’s Results[5] Janardhanan’s Results[1]

CD CL CD CL

100 1.42 0.38 1.38 0.21

500 1.27 1.01

1000 1.40 1.22 1.48 1.35

10000 1.45 1.72

• Spring system

– m = 1.09 kg/m

– k = 13.74 N∙s/m

– b = 0.166

• Mechanical System with Zero Damping

• Mechanical System with Structural Damping

• Configuration 1 in a fluid at Rest

• Configuration 2 in a fluid at Rest

• Configuration 1 in fluid flow

• Configuration 2 in a fluid flow

Re = 10,000 CD CL Amplitude (mm)

Configuration 1 1.45 1.72 5.1

Configuration 2 1.01 0.63 2.7

• Structural properties of the cylinder inaccurate

• Both configurations assumed to have same mass system

• The Re value used for the analysis is 1.0X 104

• NO Galloping

• Partial 3D models

• No water inside the void spaces assumed

• Turbulence modeling Error

[1] A. Janardhanan. Reducing Vortex-Induced Vibration of Drilling Risers with Marine Fairing. Master’s thesis, University of New Orleans, 2014

[2] R.D. Blevins. Flow-induced vibration. Krieger Publishing Company, New York, 2nd edition, 1994.

[3] M.M. Zdravkovich. Review and classification of various aerodynamic and hydrodynamic means for suppressing vortex shedding. Journal of Wind Engineering and Industrial Aerodynamics, 7(2):145–189, 1981.

[4] Lankhorst. Lankhorst VIV fairings. http://www.lm-offshore.com/en/viv-suppression, 2014.

[5] M.T. Asyikin. CFD simulation of vortex induced vibration of a cylindrical structure. Master’s thesis, Norwegian University of Science and Technology (NTNU), 2012

Reducing Vortex-Induced Vibration of Drilling Risers with Marine Fairing

Aswin Janardhanan