Why Design Load Calculations for Offshore Wind Turbine Support Structures Cannot Use Load Time Series from Moving Rotors

Muskulus, Michael (Norwegian University of Science and Technology)


It is shown how to reconstruct the total rotor loads from complex numerical wind turbine simulations of support structures, using a simplified one-dimensional equation of motion with effective parameters determined through simple numerical experiments. The reconstructed forces match the original forces very well with only a few percent differences in response and fatigue lifetime. This is in strong contrast to what happens when one naïvely uses the element forces, which leads to a resonance problem. The method opens up the possibility for detailed studies of rotor loads and aerodynamic damping by numerical simulations.