Investigating Interactions Between Wind Turbines and the Atmosphere

With wind energy gaining in popularity and wind farms being developed faster than ever, it is important to quantify any effect these farms have on the atmosphere. Knowing these effects will assist in site selection as well as in optimizing array efficiency. Previous studies have looked at atmosphere-wind farm interaction using models at coarse resolutions. This study goes down to resolutions as fine as 15 m in order to resolve the turbine blades themselves. A simple wind turbine model based on the Blade Element Momentum method is used to determine the forces exerted by the turbine blades onto the incoming air flow. The turbine model results are validated against three different wind turbines - the NREL/NASA Ames UAE turbine, an LM Glasfiber turbine, and a Tjaereborg turbine. Once validated, parameters from the model are used to estimate the wind velocity in the wake of a turbine. The energy lost in a single wake is extrapolated to get a rough estimate of how much energy is lost from the atmosphere from large wind farms. The next step will be to apply the forces from the turbine model into a 3D atmospheric model which will couple the blade forces into the atmospheric flow field. The coupled model will be used to examine turbine wake development and how this feeds back into atmospheric processes.