Design and Analysis of Vortex Induced Vibration Suppression Device

Abstract

The purpose of this study is to investigate the effectiveness of fairing as a device to suppress vortex induced vibration of a cylindrical structure which is commonly used as riser and conductor in oil and gas industry. This phenomenon is caused by the interaction between a structure and shed vortices which can result in large amplitude vibrations of the structure that may lead to severe damage over time. Repairs to these systems are costly and time-consuming, hence significant effort has been expended to develop a means of eliminating the need of repairs from vibrations. Passive methods of altering the flow behavior around the cylindrical structure to mitigate the hydrodynamic forces that cause VIV are considered. As a result, structural enhancements to a cylinder which use fairing is attempted to accomplish this goal. This study is performed through numerical analysis by investigating the drag coefficient and lift coefficient of bare cylinder when subjected to a typical maximum fluid flow speed range from metocean data for Malaysia region, and compare it with the data produced when cylinder is applied with fairing of different chord lengths. These marine structures could sustain longer during its service life and hence could reduce the maintenance cost for the operator as the fatigue life increases due to the application of fairing. Validation of numerical model against the data from literature is also performed to ensure that the outcomes of this analysis can be used for other related future study. This numerical analysis is conducted by using commercially available computational fluid dynamics (CFD) software ANSYS Fluent version 16. Navier-Stokes equations were solved in the simulation to obtain the results of the study.