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This study investigates the influence of free-stream turbulence (FST) and the thrust coefficient (CT) on wind turbine wakes. Wakes generated at CT \0. 5, 0. 7, 0. 9\ are exposed to turbulent inflows with varying FST intensities (1\, \% TI 11\, \%) and integral length scales (0. 1 Lₓ/\!D 2, D is the rotor diameter). For high- TI inflows, a flow region in the wake is observed where a mean momentum deficit persists despite the turbulence intensity having already homogenised with that of the free stream, challenging traditional wake definitions. A ‘turning point’ in the mean wake width evolution is identified, beyond which wakes spread at slower rates. Near-field (x\!/\!D 7) wake growth rate increases with higher TI and CT, while far-field (x\!/\!D 15) wake growth rate decreases with higher TI – a finding with profound implications for wind turbine wake modelling that also aligns with the entrainment behaviours observed in bluff- and porous-body wakes exposed to FST. Increasing Lₓ delays wake recovery onset and reduces the mean wake width, with minimal effect on the spreading rate. Both CT and FST influence the high- and low-frequency wake dynamics, with varying contributions in the near and far fields. For low- TI and small- Lₓ inflows, wake meandering is minimal, sensitive to CT and appears to be triggered by a shear-layer instability. Wake meandering is enhanced for high- TI and large- Lₓ inflows, with the integral length scale playing a leading role. This emphasises the complex role of FST integral length scale: while increasing Lₓ amplifies meandering, it does not necessarily translate to larger mean wake width due to the concurrent suppression of entrainment rate.
Bourhis et al. (Mon,) studied this question.