Study Of Three-Dimensional Rotational Effect Of Horizontal Axis Wind Turbine Based On CFD Method

Although three-dimensional rotational effect was initially observed in propeller,it occurs more generally on wind turbine.This phenomenon has been deeply and extensively investigated in the past twenty years.In the present study,numerical simulations are performed for S809 airfoil,Phase VI and New Blade by CFD method.Great efforts are made to investigate the three-dimensional rotational effect in the following aspects:Numerical simulations of flow field around Phase VI in non-yawed condition are performed in present work.The turbulence is modeled by the k-? SST eddy viscosity model with transition correction.The results show a good agreement with experimental data.The three-dimensional rotational effect on sectional loads and flow structure are analyzed in detail,proposing the criterion of separate flow in blade and providing a deep understanding of the three-dimensional rotational stall-delay effect in physical mechanism.The unsteady inverse BEM method is applied to experimental data in yawed condition to obtain local angles of attack and sectional inflow velocities.The sectional unsteady inflow expressions in yawed condition are established.The numerical simulation of dynamic inflow is performed and three-dimensional rotational behaviors in different yaws are discussed.The results show that both dynamic stall and three-dimensional rotational effect are manifested in the blade inboard vicinity and couples with each other.To investigate the role that local twist plays in the stall-delay phenomenon,a new blade with constant chord length and no twist based on S809 airfoil was created and its aerodynamic performance is then calculated.The results show that local twist plays a significant role in the sectional load coefficients and the central pressure location,especially in deep stall delay conditions.Comparison between the experimental results and Chaviaropoulos & Hansen stall-delay model is made.The results show that stall delay model including the factor of local twist behaves better in terms of conformity with the CFD results.Therefore,the influence of local twist shall be incorporated when trying to build stall delay model.