This study investigates the yawed wind turbine wakes of a floating multi-turbine platform using a new wake model. The wake model is a trigonometry-based model which has an acceptable accuracy in the prediction of wake deflections. The wake trajectory and power output of platforms are analysed with different yaw angles in an aligned scenario and a misaligned scenario, respectively. Yaw misalignment and spanwise offset can effectively improve the downwind turbine performance. This study provides useful insights for optimizing the design and control of floating offshore wind farms.
There needs to be a 50% reduction in greenhouse gas emissions by 2030 to deliver on the undertakings of the Paris Agreement (Hutchinson and Zhao, 2023). Supporting the advancement of renewables like wind is vital in the energy field. In a wind farm, wind turbines extract energy from the wind and produce a wake region downstream with a decreased momentum. Due to the deficit of velocity, power losses of downstream turbines in the wake reduce the wind farm efficiency. There is an over 20% loss of efficiency in a dense offshore wind farm (Burton et al., 2021). Adopting multiple approaches to enhance efficiency and reduce costs of wind farm is significant for the development of renewable energy and reduction of emissions.
A practicable method is wake steering control to deflect wake of upstream turbines away from downstream turbines. By evaluating several control approaches, Fleming et al. (2014) proved that yaw misalignment is effective to redirect wind turbine wake. Compared with complicated experiments and expensive numerical simulations, analytical wake models show huge advantages of application in wind farm power optimization due to the simplicity and efficiency. Based on the mass and momentum conservation, Jiménez et al. (2010) proposed a simple model for yawed turbine wakes to predict the wake skew angle with an assumption of the wake velocity deficit in a top-hat shape. Later, many analytical wake models were developed for yawed turbine wakes based on the Gaussian wake velocity model (Bastankhah and Porté-Agel, 2016, Qian and Ishihara, 2018, Wei et al., 2021, Shen et al., 2023). These models had better performance compared to the earlier model. The main differences between these models focus on the assumption of the skew angle and determination of the wake boundary. Divergences still exist in determining wake boundaries when using Gaussian models.
