Numerical investigation of aeroelasticity of wind turbines using a nonlinear frequency domain solution method

An extensive numerical investigation of the aeroelasticity of wind turbines is presented in the present paper. A highly efficient nonlinear frequency domain solution method is employed for this analysis. A complete wind turbine model including a tower with oscillating blades is analysed based on a relatively high amplitude of vibration. A nonlinear frequency domain solution method only requires a single blade to be modelled; however, it can capture the unsteady flow behaviour associated with blade vibration at a given inter-blade phase angle. The results revealed that the blade oscillation has an impact on the aerodynamic and aeroelastic performance of a wind turbine by producing pressure fluctuations on the pressure and suction surfaces of the blade and influencing the flow structures around the wind turbine. It is seen that the flow structures leaving from the rotor are distorted by the tower, and a combined effect of the blade oscillation and the tower leads to an unsteady and turbulent downstream wake. It is also noted that a nonlinear frequency domain solution method employed in this study is computationally efficient as it solves significantly faster than the conventional time domain methods.