Recently, a growing interest has been seen in vortex induced motions of offshore units. These induced motions are significantly relevant for the design of mooring systems and risers of offshore platforms. This work analyzes the vortex induced motions (VIM) of a Tension Leg Platform (TLP) when submitted to currents. The model tests were carried out in the fKN@LOC/COPPE-UFRJ laboratory facilities. Furthermore, a novel arrangement to represent the TLP tendons in shallow current channels is presented and discussed. This experimental set-up is innovative since, to avoid the set down, a tower has been implemented. TLP vertical motions are restrained and necessary stiffness for horizontal modes is provided by springs. The ultra-reduced model with four square columns and four pontoons in closed configuration was built using a scale of 1:200. The range of current velocities was from 0.33 to 2.59 m/s. and five angles of attack were considered: 0, 11.25, 22.50, 33.75, 45 degrees. The reduced velocity reached a very high value of 32 for 45 degrees of heading. Results have shown that the induced motions are dependent on the angle of attack and the current speed. For zero degrees of heading a typical bell curve of VIM was observed. On the other hand, for 45 degrees, motions increase steadily with current speed.
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机译：近来，人们对近海单元的涡流引起的运动越来越感兴趣。这些引起的运动与海上平台的系泊系统和立管的设计非常相关。这项工作分析了张力腿平台（TLP）的涡流感应运动（VIM）施加电流时的情况。模型测试是在fKN @ LOC / COPPE-UFRJ实验室中进行的。此外，提出并讨论了一种在浅电流通道中代表TLP肌腱的新颖装置。该实验装置具有创新性，因为为了避免落下，已经安装了塔架。 TLP的垂直运动受到限制，弹簧为水平模式提供了必要的刚度。采用比例为1：200的超缩小模型，其中包括四方形柱和四个浮桥处于闭合配置。流速范围为0.33至2.59 m / s。并考虑了五个迎角：0度，11.25度，22.50度，33.75度和45度。对于航向45度，降低的速度达到了非常高的32值。结果表明，感应运动取决于迎角和当前速度。航向为零时，观察到典型的VIM钟形曲线。另一方面，对于45度，运动会随着当前速度稳定增加。
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