| dc.description.abstract | Nowadays the main approach to the aerodynamic loading calculation for wind turbines is BEM (Blade Element Momentum) method. However, it heavily relies on the experimental data of the lift and drag coefficients which need further modification to match the actual three-dimensional flow around a wind turbine. This paper presents a computational fluid dynamics simulation for the rotational effects on the wind turbine blade. Therefore, there is no need to collect the lift and drag data by experiments. A commercial software, ANSYS Fluent, with MRF (Moving Reference Frame) method is used to simulate the aerodynamic load under uniform wind conditions as to combine the advantages of CFD flow field visualization to further understand the three-dimensional flow phenomena. The analysis conditions refer to the NREL Phase VI wind tunnel experiments, considering the pitch angle 3o, upwind speeds from 7 m/s to 25 m/s with no yaw angle. Six wind speeds are compared with the experimental results and the aerodynamic loads of the blade are discussed. The analysis items include thrust, torque, streamline, pressure coefficient, thrust force coefficient, torque force coefficient, lift coefficient, and drag coefficient. The results show that there is a stall delay phenomenon at the inboard of the wing and a tip loss phenomenon at the wing tip. These phenomena are consistent with the theory. The simulated torque is less than the experimental value by about 20% on average because the simulated lift coefficient is lower while the drag coefficient is higher than their experimental counterpart. When the wind speed is between from 10 m/s to 15 m/s, the flow field is unstable, the relative error from calculated torque is up to 28%. Compared with the result from MRF method, the relative error of torque is reduced to 7% by using the sliding mesh method. It is concluded that the CFD method can simulate the 3-D effects on the blade, but it requires further research effort to reduce the errors for the separation and reverse flow near the blade surface. | en_US |