Design and Analysis of Vortex Induced Vibration (VIV) Suppression Device

Riser which have a cylindrical structure is used in Oil & Gas industry to facilitate the safe transportation of material, fluids, and gases between seafloor and host platform. However, the continues interaction between the cylinder riser and shed vortices causes a several damage to the riser due to large amplitude of vibration experienced by the riser. As consequence, maintenance cost and time consuming to repair the damage increases. Hence, present study is conducted to investigate the effectiveness of fairing geometry to suppress vortex induced vibration of a cylindrical structure. Comparative analysis between bare cylinder and the proposed design is conducted to study the effect of fairing geometry on the drag coefficient and lift coefficient of proposed design. The result shows the existence of fairing geometry in proposed design has obtained the lower St number then cylinder riser and thus reduced the vortex shedding formation near to main structure. Besides that, vortex shedding formed by the proposed design is less aggressive and slower than bare cylinder. At the lower velocity (v = 0.5m/s), proposed design with the chord length of 1.5D shows the lowest CL and CD value. However, at the higher velocity (1.0m/s?v?2.0m/s), proposed design with the chord length of 1.25D shows the lowest CL value with average drag coefficient.