TY - GEN

T1 - Fully Coupled Three-Dimensional Dynamic Response of a TLP Floating Wind Turbine in Waves and Wind

A1 - Ramachandran,Gireesh Kumar V.R.

A1 - Bredmose,Henrik

A1 - Sørensen,Jens Nørkær

A1 - Jensen,Jørgen Juncher

AU - Ramachandran,Gireesh Kumar V.R.

AU - Bredmose,Henrik

AU - Sørensen,Jens Nørkær

AU - Jensen,Jørgen Juncher

PB - American Society of Mechanical Engineers

PY - 2012

Y1 - 2012

N2 - A dynamic model for a tension-leg platform (TLP) floating offshore wind turbine is proposed. The model includes threedimensional <br/>wind and wave loads and the associated structural response. The total system is formulated using 17 degrees of freedom (DOF), 6 for the platform motions and 11 for the wind turbine. Three-dimensional hydrodynamic loads have been formulated using a frequency- and direction-dependent spectrum. While wave loads are computed from the wave kinematics using Morison’s equation, aerodynamic loads are modelled by means of unsteady Blade-Element-Momentum (BEM) theory, including Glauert correction for high values of axial induction factor, dynamic stall, dynamic wake and dynamic yaw. The aerodynamic model takes into account the wind shear and turbulence effects. For a representative geographic location, platform responses are obtained for a set of wind and wave climatic conditions. The platform responses show an influence from the aerodynamic loads, most clearly through a quasi-steady mean surge <br/>and pitch response associated with the mean wind. Further, the aerodynamic loads show an influence from the platform motion <br/>through more fluctuating rotor loads, which is a consequence of the wave-induced rotor dynamics. In the absence of a controller <br/>scheme for the wind turbine, the rotor torque fluctuates considerably, which induces a growing roll response especially when the <br/>wind turbine is operated nearly at the rated wind speed. This can be eliminated either by appropriately adjusting the controller so <br/>as to regulate the torque or by optimizing the floater or tendon dimensions, thereby limiting the roll motion. Loads and coupled <br/>responses are predicted for a set of load cases with different wave headings. Based on the results, critical load cases are identified <br/>and discussed. As a next step (which is not presented here), the dynamic model for the substructure is therefore being coupled to <br/>an advanced aero-elastic code Flex5, Øye (1996), which has a higher number of DOFs and a controller module.

AB - A dynamic model for a tension-leg platform (TLP) floating offshore wind turbine is proposed. The model includes threedimensional <br/>wind and wave loads and the associated structural response. The total system is formulated using 17 degrees of freedom (DOF), 6 for the platform motions and 11 for the wind turbine. Three-dimensional hydrodynamic loads have been formulated using a frequency- and direction-dependent spectrum. While wave loads are computed from the wave kinematics using Morison’s equation, aerodynamic loads are modelled by means of unsteady Blade-Element-Momentum (BEM) theory, including Glauert correction for high values of axial induction factor, dynamic stall, dynamic wake and dynamic yaw. The aerodynamic model takes into account the wind shear and turbulence effects. For a representative geographic location, platform responses are obtained for a set of wind and wave climatic conditions. The platform responses show an influence from the aerodynamic loads, most clearly through a quasi-steady mean surge <br/>and pitch response associated with the mean wind. Further, the aerodynamic loads show an influence from the platform motion <br/>through more fluctuating rotor loads, which is a consequence of the wave-induced rotor dynamics. In the absence of a controller <br/>scheme for the wind turbine, the rotor torque fluctuates considerably, which induces a growing roll response especially when the <br/>wind turbine is operated nearly at the rated wind speed. This can be eliminated either by appropriately adjusting the controller so <br/>as to regulate the torque or by optimizing the floater or tendon dimensions, thereby limiting the roll motion. Loads and coupled <br/>responses are predicted for a set of load cases with different wave headings. Based on the results, critical load cases are identified <br/>and discussed. As a next step (which is not presented here), the dynamic model for the substructure is therefore being coupled to <br/>an advanced aero-elastic code Flex5, Øye (1996), which has a higher number of DOFs and a controller module.

BT - Proceedings of the ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering

T2 - Proceedings of the ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering

SP - Paper OMAE2012-82271

ER -