Numerical analysis of flow field around NREL Phase II wind turbine by a hybrid CFD/BEM method

• The presented mixed CFD/BEM method provides a considerably fast and accurate route for simulating the flow field around wind turbines.
• Numerical accuracy of the method is highly dependent on predicting the location of transition from laminar to turbulent state.
• Applying the Du-Selig stall delay modification to BEM method, could decrease the numerical error to less than 9%.

In this study, a mixed CFD (Computational Fluid Dynamics) and BEM (Blade Element Momentum Method) analysis is implemented for simulating the flow field around a wind turbine rotor to predict the aerodynamic performance such as the Power Curve diagram and the forces and moments imposed on the rotor blades that are essential in structure and/or aeroelastic design. The present approach requires considerable less computational time and memory than three-dimensional simulation of a wind turbine rotor by merely CFD methods, while retains the desirable accuracy. This work consists of two parts: 1—calculating 2D aerodynamic coefficients of several spanwise sections of the blades by CFD methods, using Fluent commercial software. 2—Simulating 3D-flow field through the wind turbine rotor using the BEM technique. To validate the current approach, the Combined Experiment Phase II Horizontal Axis Wind Turbine known as NREL Phase II Rotor is used. The comparison indicates that the combination of CFD and BEM methods is much faster than merely CFD approaches while accurate enough to be used for engineering purposes.