Wind Turbine Wake Vertical Distributions Considering Different Inflow Shear Indices

Wind shear inflow conditions with different indices lead to different wind speed distributions in wind turbine wakes, which further affects the power output of downstream turbines. In this study we focus on wind turbine wake considering different inflow shear indices. The three-dimensional numerical simulation, based on the full NREL 5 MW wind turbine model, was implemented with the RNG k-epsilon turbulence model and solved by pressure-based implicit solver. Distributions of wind speed in the wake regions under uniform inflow and different wind shear inflow conditions were calculated. The results show that wind speed in the wake region increases with the height, especially in the cases with larger wind shear indices, which is different from the result of the simulation under uniform inflow condition. In addition, a part of the rotor of downstream turbine would be outside the wake region when the wind shear index is large enough. The calculated velocity deficit around the upper boundary of wake region would be larger than the actual value, if we ignores the influence of wind shear.