Experimental analysis of the wake behind a small wind-turbine model in yaw

In this work we study the wake of a yawed wind-turbine model immersed in an atmospheric boundary layer (ABL). The ABL is replicated in the wind tunnel by means of a barrier-spires and distributed roughness configuration and is representative of a rural terrain. We quantify the properties of the wake in the horizontal plane at hub height and compare the predictions of available wake models to our data for different yaw angles. It is found that the model based on lifting-line theory performs best in predicting the velocity deficit without the need of tuning the parameters to the current setup. However, the wake deflection is slightly underestimated, most notably at the transition between near and far wake. Furthermore, a comparison with the turbine in a uniform incoming flow highlights the enhanced downward deflection of the wake which results from its interaction with the ABL.