Decoupling Turbulence Intensity and Integral Length Scale Effects on Wind Turbine Wake Meandering

Wake meandering is a key unsteady feature of wind turbine wakes that strongly affects downstream power variability and structural loading, yet its dependence on inflow turbulence characteristics remains incompletely understood. In this study, wind tunnel experiments are performed to systematically isolate and quantify the respective influences of turbulence intensity and integral length scale on wake meandering. Nine inflow conditions are generated by independently varying the boundary-layer height and floor roughness, enabling controlled combinations of three inflow turbulence intensities and three integral length scales. Wake meandering strength is quantified from time-resolved particle image velocimetry measurements at x = 5 D , while high-frequency laser Doppler velocimetry provides detailed cross-stream distributions of turbulence intensity and integral length scale at the same downstream location. The results demonstrate that wake meandering strength increases monotonically with both turbulence intensity and integral length scale, exhibiting a markedly stronger sensitivity to the integral length scale. However, the sensitivity to integral length scale decreases at high turbulence intensity, and the sensitivity to turbulence intensity decreases for large integral length scales, highlighting the interaction between the two inflow parameters. Inside the wake at the centerline, the integral length scale remains below the rotor diameter for all cases, while larger coherent structures are maintained in the outer wake through enhanced lateral mixing. These findings highlight the dominant role of inflow turbulence length scales in governing wake meandering and emphasize the need to explicitly account for turbulence structure, in addition to turbulence intensity, in wake modeling and wind farm design.