Suppression of Vortex Induced vibrations in marine risers by fairings

Applications of Vortex Induced vibrations are widely used in petroleum exploration and offshore drilling and deep water engineering applications. With the increase in depth these vibrations affect the structure of pipes or vessels used in exploration of the hydrocarbons. These vibrations lead to the fatigue and constant loading of the pipes and eventually affect the structure of the pipes and vessels. In severe cases Vortex induced vibrations rupture the risers, which eventually disrupt exploration; in addition, drilling companies have to bear with the loss due to repair and maintenance cost. To eliminate or suppress these vibrations different devices are used. Suppression of the vibrations by fairing is the novice technique that introduces significant decrease in vibrations of the riser in deep water and offshore drilling applications. Fairings produce much less drag as compared to the helical strakes which are being used for suppression of VIV. Profile and geometry of the fairings are also linked with performance of fairings. For this time NACA 0070, Guide vane, Short fairing and Exxon fairings are being used by various companies in offshore drilling. This paper aims to give the comparison of bare riser and fairing by doing CFD simulations in Star CCM+. Drag Coefficient, Lift Coefficient and Translations were calculate at three different velocities 0.1 m/s, 0.5 m/s and 1.0 m/s which corresponds to Re of 1.13×10⁵, 5.63×10⁵ and 1.13×10⁶ respectively. Based on the result it is concluded that NACA fairing profile showed a minimum drag and its amplitudes of translations were smaller than riser, therefore use of fairing on marine risers could be better choice instead of helical strakes in high current or severe weather conditions.