On the multi-scale turbulent structure interactions within wind farms

Abstract

The quantification of the scale-by-scale interaction of multi-wakes and background flow is required to estimate turbines behaviour within wind farms. The paper provides insight on the evolution of multi-scale turbulence of a model wind farm operating in turbulent boundary layer. The wind farm configured with aligned turbines set at streamwise spacing between units of 5 diameters by spanwise spacing of 2.5 diameters, corresponding to an array of 8x3 turbines. Howtwire anemometry was used to acquire high-resolution measurements of streamwise velocity fluctuations at various locations. Experimental results suggest that the contribution of multi-scale turbulence structures to the kinetic energy of the wake is highly dependent on the location inside the wind farm, the evolution is significantly modulated by turbine rotation, wake interactions and outer flow, large scale motions mainly dominate outer and far wakes, while small scales are popular in inner and near wakes.