Wake analysis of a yawed wind turbine using RANS CFD simulation

Wind power is one of the most favorable renewable energy resources. In a wind farm, when a turbine extracts power from the wind, a wake evolves downstream of the turbine. The power of turbines interacting with these wakes is much less efficient, due to decreased wind speed, increased turbulence and dynamic loading. Yaw control system could change wake characteristics in a significant way. For this reason, a Reynolds-averaged Navier-Stokes solver employing the SST k-ω turbulence model is carried out for analyzing yaw angle effect on downstream wake for the full rotor wind turbine model. In this study, the NREL Combined Experiment Phase II wind turbine at a zero yaw angle is used to validate the model. In addition, the model with yaw angles of 10°, 20°, 30° and 45° are simulated and downstream wake and velocity profiles are compared with model at a zero yaw angle. The comparison indicates that yawed flow conditions can increase the dissipation rate up to approximately 35% in the worst case and decrease wind speed up to 20%, demonstrating the importance of yaw control system on flow behavior

Keywords:

CFD , RANS , wind turbine , yaw angle , wake