Reducing Vortex-Induced Vibration of Drilling Risers...
Transcript of Reducing Vortex-Induced Vibration of Drilling Risers...
• 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
• Structural Damping
• Avoiding Resonance
• Suppression Devices [3]
• Surface Protusions
• Shrouds
• Nearwake Stabilizer
[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)
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
• 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