A Study of Intensified Wake Deflection by Multiple Yawed Turbines based on Large Eddy Simulations

Yawed turbines are known to cause wake deflection, which has been considered in wake controlling concepts for the purpose of reducing wake loss. However, an isolated yawed turbine can only produce a small amount of wake shifting for downstream turbines, resulting in an overall loss of power output. For this reason, yawing as a wake controlling method is often found to be ineffective. Based on our Large Eddy simulation (LES) results, it is discovered that wake deflection can be intensified by multiple yawed turbines in a line. While each turbine is yawed by a relatively small angle, collectively they can deflect the wake significantly to reduce wake loss of other turbines, so that the overall power output can be increased. An analysis on skew angle is carried out based on existing skew model and the challenges of combined wake skew prediction is identified.