An aerodynamic fairing can reduce the effects of the wind turbine tower wake on the blades of a downwind rotor. Previous studies on fairing design have focused on idealized conditions and time-averaged drag reductions, whereas this is the first study to obtain and analyze unsteady velocity field data in the wake of minimum drag fairings at non-zero angles of attack, specifically designed for wind turbine towers. Experiments were conducted in a water channel using flow visualization and PIV to analyze the effect of the fairing on the tower wake compared to a typical cylindrical tower. The two tested fairing geometries, a C30u and an E863 airfoil, resulted in significant reduction of the wake deficit when the airfoils were aligned with the incoming flow. At an angle of attack of 10°, the airfoils produced wake deficits comparable to the cylinder wake, although the performance of the airfoils was improved farther downstream. Due to the self-aligning nature of the fairing, it should not be misaligned with the incoming flow direction for an extended period of time. Furthermore, the flow is more likely to remain attached at the full-scale Reynolds number, which would lead to further improvement in the performance of the fairing. Both of the fairing designs that were tested could be used to significantly reduce the effects of a cylindrical tower wake on a downwind rotor if the yaw angles can be held to less than 10°.
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