Influence of incoming turbulent scales on the wind turbine wake: A large-eddy simulation study

Abstract

In this study, we aim to investigate the influence of inflow turbulent length scales on wind turbine wakes. For this purpose, large-eddy simulations of the wake of a wind turbine are performed under neutral atmospheric conditions with different boundary layer heights. Different inflow turbulent scales are generated by varying the boundary layer height, while a systematic approach is proposed to ensure that all the simulations have the same total turbulence intensity at the hub level. First, we study the simulations without the turbine to analyze the inflow scale variations and ensure a fairly constant rotor-averaged total turbulence intensity among the cases. Next, we investigate the influence of the inflow turbulent scales on the simulations with the turbine. We find that larger inflow scales in three flow directions lead to a faster wake recovery. For analytical wake modeling, the physics-based model that includes the effect of inflow integral scales is more accurate in capturing the wake expansion. Regarding wake dynamic characteristics, larger inflow turbulent scales tend to produce more wake meandering behind the turbine in both lateral and vertical directions. It is observed that the vertical-to-lateral wake center standard deviation ratio is fairly constant for all the cases. In addition, we study the turbulent momentum fluxes and their divergence to understand the role of inflow scales in the wake recovery mechanism.