Effect of turbulence length scales on wind turbine loads*

As wind turbines become larger, the temporal and spatial variations in the incoming flow field play a more important role in the structural loading of the turbine. Current design standards assume that using a single integral length scale to characterize the turbulent inflow will result in a robust design for all large turbines. However, turbines face different turbulence characteristics and atmospheric stabilities that are not reflected by a single length scale. Here, we quantify the impact of turbulent flow fields on turbine loads to identify which length scales are important. To generate turbulent flow fields of varying integral length scales and atmospheric stabilities, we use the Mann spectral tensor model and high-fidelity numerical simulations of the atmospheric boundary layer using AMR-Wind, a part of the ExaWind modeling and simulation framework. Preliminary results indicate that integral length scales have the potential to impact the standard deviation of turbine loads by a factor of up to 3.5.