Numerical Investigation of a TLP Wind Turbine Under Wind and Wave Loads

Research on offshore wind technology has increased in the last two decades following progress and cost reduction in turbine design and operation, and the increased demand for renewable energy production. Coupled dynamic response of a floating offshore wind turbine under simultaneous wind and wave loading can be investigated by experimental and computational methods. In the scope of this paper, a numerical study is conducted on a floating offshore wind turbine. A standard baseline wind turbine supported by a Tension Leg Platform is investigated under simultaneous wind and wave loading. For comparison, cases with only wind loading and only wave loading were also simulated to identify the dominating contributions in different design situations. Larger platform surge response is observed due to the resonance triggered by the turbulent wind at the platform surge natural frequency. Pitch motions are large at the wave frequencies and at the resonant frequency, mainly due to first-order wave loads. Aerodynamic damping associated with the rotation of the rotor resulted in decreased platform fluctuating pitch response. Results of this study are the basis of a sensitivity study aiming at improving the MIT/NREL TLP wind turbine design.