Experimental study of a wind turbine wake in a convective boundary layer

Wind turbines are interacting with the flow in the lowest part of the atmospheric boundary layer, which is directly affected by the temperature of the Earth's surface. During daytime, the surface is mostly warmer than the air above, causing convection. The flows interacting with wind turbines are strongly turbulent and complex, making the prediction of wind turbine electricity production difficult. Laboratory studies allow us to study the effect of surface heating in a controlled environment. We use the Prandtl Wind Tunnel (PWT) at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany. The PWT is equipped with an active grid and heated plate, which we use to create convective, turbulent boundary layer flows. Here we present systematic measurements of surface heat flux and velocities behind a wind turbine model, over different magnitudes of surface heating, inflow velocities, and turbulence intensities. We then discuss some implications of our results on the effect of convection on the wakes of wind turbine flows.