Characteristics of a secondary wake steering from two tandem wind turbines under yaw misalignment

The wake structure of a yawed wind turbine undergoes deflection and deformation, resulting in an additional wake steering effect from the downstream wind turbine, known as the "secondary steering". Previous studies reported a substantial influence of the counter-rotating vortex pair generated by the yawed upstream turbine on the downstream turbine wake. However, further studies on the impact of the upstream turbines on the wake deflection and deformation incurred by the downstream turbines still remain largely unexplored. In the present study, a numerical investigation was performed to characterize the flow dominated by the secondary steering effect. Large-eddy simulation coupled with an actuator disk model with rotation was used to simulate the wind turbine pair submerged in an atmospheric boundary layer. In the downstream turbine, the velocity deficit revealed a deflected wake centerline, evincing the occurrence of the secondary steering effect. Moreover, the deformed wake of the downstream turbine, influenced by the yawed upstream turbine wake, was further examined to investigate the primary driver of the secondary steering mechanism.