This thesis presents coupled model for the floating off-shore wind turbines, using a 10-MW machine as an example. The idea put forward is to employ high fidelity Navier-Stokes solvers for air and water. For this reason, the Helicopter Multi-Block solver was used for air, and the Smoothed Particles Hydrodynamic method was used for water. A multi-body solver was implemented to solve for the wind turbine dynamics. All solvers were validated before coupling, and results are presented in this thesis. The employed, loosely coupled, algorithm is described in detail, and the importance of coupling is assessed. Additional aerodynamic cases were studied to form the foundation for further model development.The study started from the aerodynamic analysis of a 10-MW wind turbine. Straight and pre-bent configurations of the blade were investigated under the assumption of uniform inflow. Next, the effects of the atmospheric boundary inflow and atmospheric turbulence were studied. For this, the power law wind speed profile was employed, and atmospheric turbulence was introduced using Mann’s model.The aero-elasticity of the 10-MW rotor was studied next. The structural model was constructed using NASTRAN, and the natural frequencies and modes were compared to published results, showing good agreement. This model was then used for steady and unsteady aero-elastic computations.The effects of employing deformable trailing and leading edge flaps on a 10-MW wind turbine were also investigated. The results showed that the trailing edge flap can be used to control flap-wise bending of the blade, whilst the leading edge flap can be used to counter additional pitching moment created by the trailing edge flap.A floating 10-MW rotor was considered next, as well as forced yaw and pitch oscillations of the machine. The results showed large variations in thrust and power as the wind turbine pitched about a point located 119m below the rotor. The vortex ring state was also encountered when the wind turbine was forced to a pitching motion with amplitude of 5° and period of 8.8s.A coupled method for the analysis of the dynamics of floating off-shore wind turbines was finally described, along with the test cases and numerical parameters. The results of decoupled and coupled computations are presented and analysed. The results showed that the employed floating turbine under studied conditions did not enter a vortex ring state. A turbulent wake state was encountered, but only at the initial pitching phase. The gyroscopic effects were also small for studied system, and did not cause significant rotations due to large inertia of the employed floater.
PDF
download
878987797
028-85220240
