Suppression of Vortex-Induced Vibration by Fairings on Marine Risers

Abstract

Vortex-induced vibration is quite common during the operation of offshore risers or umbilical cables, commonly leading to serious damage to risers and reduced service life. Vortex-induced vibration of the offshore risers could be effectively suppressed by fairing devices. In this paper, a newly developed vortex-induced vibration fairing and large eddy simulation model of the FLUENT software were used for numerical analysis, experimental research and stimulating vortex-induced vibration at 0.1–2 m s –1 . The data of the numerical model with fairing was compared and analyzed to study the vortex shedding frequency at different Reynolds numbers and changes in drag and lift coefficients. The displacement state of 12 in risers with and without fairing was experimentally tested using a five degree-of-freedom balance. The vortex-induced vibration effect of the fairing was tested at different velocities. The result shows the drag reduction effect of the fairing is more obvious when the flow velocity is 0.4–1.2 m s –1 and the maximum drag reduction reaches 55.6% when the flow velocity is 0.6 m s –1 . Additionally, the drag reduction effect was obvious when the flow velocity was greater than 1.3 m s –1 and less than 0.3. The result indicates that the developed 12 in fairing, with good potential in engineering applications, has good vortex-induced vibration-suppression effects.