Power Output and Aerodynamic Loads of Scaled Wind Turbines Under Yaw Misalignment*

Wind tunnel experiments were conducted to evaluate the performance of two scaled wind turbines (G06 Turbine with 0.6 m rotor diameter). Three turbine layouts were examined with the turbines positioned at stream-wise spacing of 5 times the rotor diameter (5D). The first layout (aligned layout) was tested with no lateral offset of the turbine towers. In contrast, the second and third layouts, known as the staggered-left and staggered-right layouts, were tested with turbines staggered laterally by 0.5D to the left and right, respectively. Results indicate that adjusting the yaw angles of upstream turbines reduces wake velocity deficits at the downstream turbine's location, with this effect being more pronounced in the staggered layouts. For the aligned layout, the wind farm power output can increase by up to 2% when the first-row turbine (hereafter T1) is yawed to -20°, whereas in the staggered layouts, wake steering leads to an increase in power output up to 13% with T1 yawed to -20° for the staggered-left layout and 9% with T1 yawed to 10° for the staggered-right layout. Measurements of the aerodynamic loads revealed that the resultant average tower base bending moments under intentional yaw misalignment decrease, while the resultant main bearing average bending moments have modest increase at the optimal yaw angles.