Numerical Simulation Of The Effect Of Vortex-Induced Vibration On Jacket Platform By Vibration Damper

With world energy situation increasingly severe today, the deep exploitationof oil and gas resources has arouse great concern in the oil industry. Since theexploration of ocean oil and gas moved forward deep water, jacket platform hasdeveloped from several meters to five hundred meters water depth, accompaniedby the greatly increasing length of the rod. In the process of the jacket’sconstruction, VIV (vortex-induced vibration) phenomenon will appear when thewind of a certain velocity flows through the rod. Frequent wind-induced vibrationwill lead to fatigue damage and crack of the jacket rod, which consequentlyreduce the manufacturing quality and accuracy, and considerably affect theproduction safety and service life of jacket structure. Therefore，it is significantlyworthy in theoretical and practical application to study the control method of thejacket rod’s VIV and its practical device.First of all，the mechanism of the flow around a cylinder and vortex-inducedvibration were expounded，and the influencing factors of the vortex-inducedvibration of jacket rod was analyzed. Here, the Navier-Stokes equations werechosen as control equations of incompressible viscous fluid, and a threedimensional numerical model of the flow around jacket rod was established underlow Reynolds number. The model simulated the flow field of the flow aroundjacket rod without vibration damper. The lift and drag coefficient, the vortexshedding frequency and the the Strouhal number got from the simulation werecompared with those in literature, which verified the validity of the model andlaid the foundation of the following effectiveness assessment of vibration damper.Then, the flow field of the flow around jacket installed with vibration damper wassimulated numerically with the same Reynolds number, and was analyzed incontrast to the calculation results of the flow field without control device. Thechanges of flow field characteristics, such as velocity, pressure, streamline andvorticity, were observed of the flow around jacket before and after installingvibration damper. What’s more, the effectiveness on the reduction of vibrationand drag were calculated and their mechanism was described. The key study wason the influences to the flow field in three dimensional directions after installingvibration damper. Finally，varying the position, number and arrangement of thevibration damper, the control effect of vibration damper installation on the jacket’s VIV was compared in different number and position. Best installationplan was put forward after overall consideration, which provided a basis forpractical engineering guidance.