On the characteristics of the wake of a wind turbine undergoing large motions caused by a floating structure: an insight based on experiments and multi-fidelity simulations from the OC6 project Phase III
Stefano Cioni, Francesco Papi, Leonardo Pagamonci, Alessandro Bianchini, Néstor Ramos-García, Georg Pirrung, Rémi Corniglion, Anaïs Lovera, Josean Galván, Ronan Boisard, Alessandro Fontanella, Paolo Schito, Alberto Zasso, Marco Belloli, Andrea Sanvito, Giacomo Persico, Lijun Zhang, Ye Li, Yarong Zhou, Simone Mancini, Koen Boorsma, Ricardo Amaral, Axelle Viré, Christian W. Schulz, Stefan Netzband, Rodrigo Soto-Valle, David Marten, Raquel Martín-San-Román, Pau Trubat, Climent Molins, Roger Bergua, Emmanuel Branlard, Jason Jonkman, Amy Robertson
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引用次数: 0
Abstract
Abstract. This study reports the results of the second round of analyses of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty (OC6) project Phase III. While the first round investigated rotor aerodynamic loading, here, focus is given to the wake behavior of a floating wind turbine under large motion. Wind tunnel experimental data from the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project are compared with the results of simulations provided by participants with methods and codes of different levels of fidelity. The effect of platform motion on both the near and the far wake is investigated. More specifically, the behavior of tip vortices in the near wake is evaluated through multiple metrics, such as streamwise position, core radius, convection velocity, and circulation. Additionally, the onset of velocity oscillations in the far wake is analyzed because this can have a negative effect on stability and loading of downstream rotors. Results in the near wake for unsteady cases confirm that simulations and experiments tend to diverge from the expected linearized quasi-steady behavior when the rotor reduced frequency increases over 0.5. Additionally, differences across the simulations become significant, suggesting that further efforts are required to tune the currently available methodologies in order to correctly evaluate the aerodynamic response of a floating wind turbine in unsteady conditions. Regarding the far wake, it is seen that, in some conditions, numerical methods overpredict the impact of platform motion on the velocity fluctuations. Moreover, results suggest that the effect of platform motion on the far wake, differently from original expectations about a faster wake recovery in a floating wind turbine, seems to be limited or even oriented to the generation of a wake less prone to dissipation.
摘要本研究报告了Offshore Code Comparison, Collaboration, continue with Correlation and unCertainty (OC6)项目第三阶段第二轮分析的结果。第一轮研究的是转子气动载荷,而本次研究的重点是大运动下浮式风力机的尾迹特性。本文将UNAFLOW项目的风洞实验数据与采用不同保真度方法和代码的参与者提供的模拟结果进行了比较。研究了平台运动对近尾迹和远尾迹的影响。更具体地说,叶尖涡在近尾迹中的行为是通过多个指标来评估的,如流向位置、核心半径、对流速度和环流。此外,还分析了远尾迹中速度振荡的开始,因为这可能对下游转子的稳定性和负载产生负面影响。非定常情况下近尾迹的模拟和实验结果证实,当转子降频增加超过0.5时,模拟和实验结果与预期的线性化准定常行为有所偏离。此外,模拟之间的差异变得显著,这表明需要进一步努力调整当前可用的方法,以便正确评估非定常条件下浮动风力涡轮机的空气动力学响应。对于远尾迹,可以看出,在某些情况下,数值方法高估了平台运动对速度波动的影响。此外,研究结果表明,平台运动对远端尾迹的影响似乎是有限的,甚至倾向于产生不容易耗散的尾迹,这与最初期望的浮式风力机更快的尾迹恢复不同。