Abstract The wind condition around floating offshore wind turbines (FOWTs) can be largely different from that developed around bottom-mounted wind turbines due to the platform motions. The existing literature identifies four working state of FOWTs, one of them being the vortex ring state (VRS) which may occur as the rotor moves in its own wake. It is potentially a problem that influences the aerodynamic performance and lifetime of FOWTs. It is still unclear when, and to what extent, does the VRS happen to floating offshore wind turbines. The aim of this paper is to quantitatively predict the occurrence of VRS during the operation of FOWTs. Three different criteria are used and compared: the axial induction factor, Wolkovitch’s criterion and Peters’ criterion. The results show that the VRS phenomena may occur for a large range of operating conditions and can be correlated with the minima in the relative wind speed normal to the rotor plane. Also, the probability of occurrence of VRS is smaller for the floating platforms that exhibit the least motions such as the TLP. Finally, Wolkovitch’s criterion seems to be the most suitable one for the VRS prediction, while Peters criterion indicates the initial aerodynamic change and is thus suitable for early warning of VRS.

中文翻译：

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浮动式海上风力发电机涡环状态预测不同判据的对比分析

摘要 由于平台运动，浮动式海上风力涡轮机（FOWT）周围的风况可能与底部安装式风力涡轮机周围的风力条件有很大不同。现有文献确定了 FOWT 的四种工作状态，其中一种是涡环状态 (VRS)，当转子在其自身尾流中移动时可能会发生涡环状态 (VRS)。这可能是一个影响 FOWT 空气动力学性能和寿命的问题。目前尚不清楚 VRS 何时以及在多大程度上发生在浮动海上风力涡轮机上。本文的目的是定量预测 FOWT 运行过程中 VRS 的发生。使用并比较了三个不同的标准：轴向感应系数、Wolkovitch 标准和 Peters 标准。结果表明，VRS 现象可能在大范围的运行条件下发生，并且可以与垂直于转子平面的相对风速的最小值相关联。此外，对于像 TLP 这样的运动最少的浮动平台，VRS 发生的概率较小。最后，Wolkovitch 准则似乎是最适合 VRS 预测的准则，而 Peters 准则表示初始空气动力变化，因此适用于 VRS 预警。