Movimentos induzidos por vórtices (VIM) de plataformas TLWP submetidas a correntes de alta intensidade

Abstract

Vortex Induced Motions (VIM) classified as galloping occurs frequently in TLWP Platforms, however these movements are not always correctly taken into account during design phases. This work aimed to develop a formulation that represent this kind of movement for sway and yaw degrees-of-freedom. Initially, the mathematical formulation developed to represent this phenomenon were presented, for both coupled and uncoupled cases. When dealing with the uncoupled cases, it is shown that the equations of motion can be represented as equations that gives rise to limit cycle solutions, particularly the Rayleigh and Van der Pol Equations for sway and yaw, respectively. After presenting the equations of motion, some dimensional analysis considerations are made, in order to change the problem’s variables from real scale to model scale. After this, all the results obtained for added mass, force and moment coefficient and damping ratios are presented. With all the required parameters in hand, the equations of motion are solved numerically, in order to estimate the galloping amplitude for all the proposed cases. The differences between the results of this work and experimental result from the literature are then presented and discussed.