Florida

Challenges and objectives:

With the impending development of floating offshore wind farms, new questions are emerging about the wake of floating wind turbines (FWTs). The additional motion imposed by the floating platform affects the interaction of the turbine with the incident wind and therefore the generation of its wake, a phenomenon that is already very complex for land-based machines. The different types of platform have a specific damping of their motion induced by the waves and by the interaction of the turbine with the incident turbulent wind.

The result is periodic movements, the hallmarks of which can be seen in the overall wake dynamics and which can even trigger a more rapid absorption of the wake velocity deficit. In wind farm configurations, these wakes encounter other floating wind turbines and have an impact on their performance and hydrodynamic behaviour. It is therefore important to understand the wake dynamics of floating wind turbines in order to optimise the layout of the farm and reduce fatigue loads and therefore maintenance times (which are costly and time-consuming at sea). 
 

Methods / Technologies used:

Wind tunnels are essential for studying wind turbine wake dynamics. The FLORIDA project takes this further by analyzing floating wind turbines, simulating their movements in realistic turbulent flow conditions. The goal is to understand how these movements influence the wake, particularly its meandering.

Through wind tunnel and wave tank experiments, we will develop new models to better represent these effects. These models will incorporate advanced methods and be used to predict the impact of wake dynamics on downstream turbines. They will also be used to optimize coupled simulations and experimental tests under realistic conditions.
The project brings together experts in wake modeling, hydrodynamics, and turbulence to improve the understanding and design of floating wind turbines. This approach will contribute to the development of more efficient offshore wind farms, better adapted to marine environments.

Results one year into the project

• Definition of floating wind turbine configurations and environmental conditions
  The objective was to identify the situations most likely to generate two types of wake dynamics: meandering (lateral wake movements) and pulsating wake (variations in wake velocity). To this end, several float concepts, associated with wind turbines of between 5 and 15 MW, were modelled using OpenFAST software. The amplitudes and frequencies of the movements were then expressed in standardised form, as a function of rotor diameter and wind speed at hub height. This approach made it possible to identify the degrees of freedom that have the greatest influence on wake dynamics, in particular those generating instabilities that can increase with distance.
• Development of algorithms for wind tunnel wake analysis
  For the forthcoming tests in the wind tunnel at the University of Oldenburg, it is essential to pinpoint the wind turbine's wake accurately at all times. Specific algorithms have therefore been developed to ensure reliable detection of the centre of the wake, a key element in accurately characterising its meandering.

Outlook

The environmental conditions to be reproduced in the wind tunnel, as well as the characteristics of the movements of the floating wind turbines, will be defined in collaboration with the project partners. An initial series of tests is planned in the wind tunnel at the University of Oldenburg before the end of 2025. At the same time, simplified models will be used to simulate the impact of wakes on the wind. These data will be used to carry out the first simulations of the behaviour of floating wind turbines using OpenFAST software, which specialises in multiphysics simulation. These initial results will help to prepare for the large-scale trials, which will take place in the LHEEA's ocean engineering tank between now and the end of 2026.