Wake Meandering in Wind Farms from the American Wake Experiment

Wake meandering, defined as the slow, large-scale lateral or vertical displacement of turbine wakes, plays a key role in determining unsteady loading and power variability in wind farms. While existing field measurement studies have primarily examined wake meandering for isolated turbines and often related its strength to turbulence intensity alone, its behavior under realistic multi-wake inflow conditions remains insufficiently understood. In this study, wake-scanning Doppler lidar measurements from the American WAKE experimeNt (AWAKEN) campaign are used to investigate wake meandering for turbines being subject to zero, one, and two upstream wakes. A unique dataset spanning an exceptionally wide range of turbulence intensities and integral length scales enables a systematic investigation of the relative roles of turbulence energy and turbulence structure. For isolated turbines, the results show that wake meandering strength cannot be explained by either turbulence kinetic energy or integral length scale alone, but instead emerges from their combined influence. Strong wake displacements are observed for flows characterized by large coherent turbulence structures, high turbulence energy, or both. For turbines operating inside the wind farm, limited multi-wake cases indicate that upstream wakes substantially enhance wake meandering by increasing inflow turbulence and unsteadiness, with cumulative effects observed for multiple upstream wakes. The findings highlight the importance of jointly accounting for turbulence intensity, turbulence length scales, and wake–wake interactions when modeling wake meandering and predicting its impact on wind farm performance.