Assessing aerodynamic behavior of scaled wind turbine cluster through engineering wake modeling coupled with wind tunnel data

As of 2023, the offshore installed capacity was 73,000 MW for fixed turbines, compared to only 270 MW for floating turbines, according to the International Renewable Energy Agency (IRENA). Therefore, the offshore market for floating turbines is in its early stages. Nonetheless, the offshore sector is expected to grow since wind conditions at sea are more stable than on land, which may favor energy production. Furthermore, the floating turbine segment is also likely to expand, as beyond 60 meters of water depth, it is less costly to install a floating offshore wind farm than a fixed one, in addition to the fact that 80\% of offshore wind resources are located in regions deeper than 60 meters. This thesis aims to contribute to state-of-the-art research by proposing a methodology to assess the effect of misalignment from both yawing and tilting — typical when using floating support structures — on wind farm performance. It will model this effect using the low-fidelity tool FLORIS and implement the vertical wake deflection due to tilt to all available engineering wake models. A new validation and calibration framework has also been proposed to improve the accuracy of engineering wake models in FLORIS. The data for the calibration and validation came from an experiment in the Politecnico di Milano's wind tunnel. It was found that, for a given yaw angle of an upstream wind turbine, the farm power decreases for increasing rotor tilt and, in the scenario with zero tilt, the farm power increases when the yaw angle of an upstream wind turbine is increased to 20°. In the other tilt scenarios, the farm power decreases when the yaw angle of WT1 is increased to 20°. A yaw angle setpoint of 20° is suboptimal and has adverse effects when there is non-zero rotor tilt. The methodology proposed with a new validation and calibration framework to improve the accuracy of engineering wake models didn't show satisfactory results due to the optimization choices that were carried out. The main faults were the definition of the initial guesses for the wake model's parameters that would be optimized and their range of variability. There is a lack of knowledge on how those parameters can vary, and still, the solution foreseen by FLORIS when computing wake spatial development is physical. The optimization process made all the wake models converge to a mathematically correct set of tuned parameters, giving non-physical results when looking at the wake field. Still, the developed tools and discoveries here can lead to a wind farm layout optimization considering misalignment, not just from yaw but also from tilt: a tilt-oriented control strategy. The reason is that the proposed modification to include the vertical wake deflection in all the available models worked, and it was possible to visualize the vertical redirection of the wake in the downstream wind turbines due to tilt. Now, the work can continue focusing on improving the tuning process by developing a methodology to define better the boundaries for the range of variability of each wake parameter and its initial guess.