The wake-wake interactions are quite substantial in an offshore wind turbines (WT) compared to onshore WT due to additional loading that arises due to sea current and wave-induced forcing. The effect of wave forcing on the wakes has been one of the important bottlenecks in the design of offshore WT. Though wind energy has matured to a technology, still offshore WT has not been realized in United States yet. To address this concern, there is a strong impetus to advance fundamental understanding of key external factors limiting the wind farms performance. Towards this direction, this project will address the challenges involved in the wake-current-air interactions by using large eddy simulation (LES) as a tool to systematically understand the effect of wave/current amplitude forcing and wind speed on the wake-wake interactions. The objectives of the current study are to determine the hydrodynamic forces due to the wave-current interaction on wind turbines. The PI will develop scaling laws of the mean and turbulence flow in the wake region in terms of dynamic forcing parameters. The scaling laws developed will be compared with the existing wakemodels.
The intellectual merit of this study is that it is fundamental in nature as by understanding the interplay of key hydrodynamic and aerodynamic processes affecting the WT, we will be able to lay down the scaling laws of the loss of wind velocity and enhancement of turbulence intensity in terms of the dynamic parameters of wave/current/wind in the wake region. The research is transformative as these scaling laws in the near-wake region of offshore WT will provide, for the first time, accurate parameterization for the existing wake models. The present study will advance the fundamental understanding of the following 3 fundamental aspects in the wake region of offshore WT: (1) Scaling of modified surface roughness, mean velocity deficit and turbulence in the wake region (2) Understanding resonance due to the nonlinear response of the wave energy (3) Isolating the wave-generated turbulence, WT-generated turbulence and turbulence due to wind.
The broader impacts of this project are its direct relevance to energy crisis in United States, where there is an urgent need to make wind energy more accessible, and a major source of sustainable form of energy. The results of this study will provide more realistic predictive tools, which will serve as important guidelines for future of offshore wind-farm installations. Specific efforts are being targeted as a part of this proposal to encourage more women to pursue education and careers in engineering.
