Vortex-induced Vibration of a Flexible Free-hanging Circular Cantilever

Authors

  • R. W. Prastianto Department of Ocean Engineering, Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia
  • K. Otsuka Department of Marine System Engineering, Osaka Prefecture University, Japan
  • Y. Ikeda Department of Marine System Engineering, Osaka Prefecture University, Japan

DOI:

https://doi.org/10.5614/itbj.eng.sci.2009.41.2.2

Abstract

The behavior of a free-hanging riser of floating offshore structures would be different from a typical at-sea-floor-terminated riser type of oil or gas platforms. For the design purpose, the present study was intended to incorporate some important factors of the riser conditions (i.e. bidirectional vibration, freeend condition, and spanwise variation of response amplitude) for investigating its dynamics characteristics. An experimental investigation on time-dependent motion of a flexible free-hanging circular cantilever subjected to uniform crossflows has been carried out. The free-end condition cantilever has a 34.4 aspect ratio and a low mass ratio of about 1.24. The cylinder freely oscillates in both inline and transverse to the flow. Reynolds number varied from 10,800 to 37,800. The "jump phenomenon" was found in the inline motion of the cylinder that agrees well with an existing comparable work. At high flow velocities, the 3rd higher harmonic frequencies of the cylinder transverse response became predominant that produce quite different motion characteristics compared to the other existing comparable works with 2-dimensional bottom-end condition. Generally, the results suggested that the flexible free-hanging cantilever generate different vortex wake mode than either, a uniform (a short-rigid flexiblymounted cylinder) or a linear amplitude variation along the span case (a pivoted cylinder)

Downloads

Download data is not yet available.

References

Bearman, P. W. & Obasaju, E. D., Transverse forces on a circular cylinder oscillating in-line with a steady current, Proc. 8th International 124 R. W. Prastianto, et al.Conference on Offshore Mechanics and Arctic Engineering, The Hague, pp. 253-258, 1989.

Moe, G. & Wu, J., The lift force on a cylinder vibrating in a current,Journal of Offshore Mechanics and Arctic Engineering (JOMAE), 112, 297-303, 1990.

Khalak, A. & Williamson, C. H. K., Dynamics of a Hydroelastic Cylinder with Very Low Mass and Damping, Journal of Fluids and Structures, 10, 455-472, 1996.

Khalak, A. & Williamson, C. H. K., Fluid Forces and Dynamics of a Hydroelastic Structure with Very Low Mass and Damping, Journal of Fluids and Structures, 11, 973-982, 1997a.

Khalak, A. & Williamson, C. H. K., Investigation of relative effects of mass and damping in vortex-induced vibration of a circular cylinder, Journal of Wind Eng. and Industrial Aerodynamics, 69-71, 341-350, 1997b.

Khalak, A. & Williamson, C. H. K., Motion, Forces and Mode Transitions Structure in Vortex-induced Vibrations at Low MassDamping, Journal of Fluids and Structures, 13, 813-851, 1999.

Sarpkaya, T., Hydrodynamic Damping, Flow-induced Oscillation, and Biharmonic Response, Journal of Offshore Mechanics and Arctic Engineering (JOMAE), 117, 232-238, 1995.

Jeon, D. & Gharib, M., On circular cylinders undergoing two-degree-offreedom forced motions, Journal of Fluids and Structures, 15, 533-541, 2001.

Jauvtis, N., & Williamson, C. H. K., The effect of two degrees of freedom on vortex-induced vibration at low mass and damping, Journal of Fluids Mechanic, 509, 23-62, 2004.

Blevin, R. D. & Coughran, C. S., Experimental Investigation of VortexInduced Vibration in Two-Dimensions, Proc. 18th International Offshore and Polar Engineering Conference (ISOPE2008), Vancouver, Canada, pp.475-480, 2008.

Sanchis, A., Salevik, J. & Grue, J., Two-degree-of-freedom vortexinduced vibrations of a spring-mounted rigid cylinder with low mass ratio, Journal of Fluids and Structures, 24, 907-919, 2008.

Kitagawa, T., Fujino, Y. & Kimura, K., Effects of Free-end Condition on End-cell-induced Vibration, Journal of Fluids and Structures, 13, 499-518, 1999.

BrankoviA, M. & Bearman, P. W., Measurements of transverse forces on circular cylinders undergoing vortex-induced vibration, Journal of Fluids and Structures, 22, 829-836, 2006.

Assi, G. R. S., et al., Experimental investigation of flow-induced vibration interference between two circular cylinders, Journal of Fluids and Structures, 22, 819-827, 2006. Vortex-induced Vibration of a Flexible Cantilever 125

Assi, G. R. S., et al., Unsteady force measurements on a responding circular cylinder in the wake of an upstream cylinder, Proc. 26th International Conference on Offshore Mechanics and Arctic Engineering, San Diego, USA, Paper no. OMAE2007-29040, 2007.

Pesce, C. P. & Fujarra, A. L. C., Vortex-induced Vibration and Jump Phenomenon: Experiments with a Clamped Flexible Cantilever in Water, International Journal of Offshore and Polar Eng., 10(1), 26-33, 2000.

Fujarra, A. L. C., et al., Vortex-induced Vibration of a Flexible Cantilever, Journal of Fluids and Structures, 15, 651-658, 2001.

Prastianto, R. W, Otsuka, K. & Ikeda, Y., Effects of Free-end Condition on Hydrodynamic Forces of a Flexible Hanging-off Circular Cylinder Undergoing Vortex-induced Vibration, Proc. JASNAOE Annual Conference, Nagasaki, Japan, pp. 259-262, 2008.

Lee, L., Allen, D. W. & Henning, D. L. Y., Motion Trajectory of Bare and Suppressed Tubulars Subjected to Vortex Shedding at High Reynolds Numbers, Proc. 14th International Offshore and Polar Engineering Conference (ISOPE2004), Toulon, France, pp. 517-523, 2004.

Wilde, J. J. D. & Huijsmans, R. H. M., Laboratory Investigation of Long Riser VIV Response, Proc. 14th International Offshore and Polar Engineering Conference (ISOPE2004), Toulon, France, pp. 511-516, 2004.

Flemming, F. & Williamson, C. H. K., Vortex-induced vibration of a pivoted cylinder, Journal of Fluid Mechanics, 522, 215-252, 2005.

Downloads

How to Cite

Prastianto, R. W., Otsuka, K., & Ikeda, Y. (2013). Vortex-induced Vibration of a Flexible Free-hanging Circular Cantilever. Journal of Engineering and Technological Sciences, 41(2), 111-125. https://doi.org/10.5614/itbj.eng.sci.2009.41.2.2

Issue

Section

Articles