Do Wind Turbines Pose Roll Hazards to Light Aircraft?

Wind energy development has increased rapidly to now account for 4.7% of all electricity generation in the United States. Much of this development has occurred in rural locations, where open spaces are also home to numerous local or “general aviation” airports. Almost 40% of all wind turbines in the US exist within 10 km of a small airport. Wind turbines generate electricity by extracting momentum from the atmosphere, thereby creating wakes characterized by a wind-speed deficit and increased turbulence downwind. Recently, the concern that wind turbine wakes pose hazards for small aircraft has been used to limit wind farm development; however, conflicting estimates on the extent of the wake’s hazardous influence still exist. As such, we use large-eddy simulations to examine the wake of a single turbine to assess hazards to small aircraft. Atmospheric measures of rotation (e.g. vorticity) were first examined, followed by wind-generated lift forces and subsequent rolling moments on hypothetical aircraft transecting the wake. Stable, unstable, and neutral cases are explored, with preliminary findings of the neutral case showing that discernible wake characteristics diminish by 10 rotor diameters downstream, and over 99.99% of rolling moments experienced by hypothetical planes during through-wake transects are classified as a “low” roll hazard.