The Darrieus wind turbine: Proposal for a new performance prediction model based on CFD

This paper presents a CFD model for the evaluation of energy performance and aerodynamic forces acting on a straight-bladed vertical-axis Darrieus wind turbine. The basic principles which are currently applied to BE-M theory for rotor performance prediction are transferred to the CFD code, allowing the correlation between flow geometric characteristics (such as blade angles of attack) and dynamic quantities (such as rotor torque and blade tangential and normal forces). The model is proposed as a powerful design and optimization tool for the development of new rotor architectures for which test data is not available.After describing and validating the computational model against experimental data, a full campaign of simulation is proposed for a classical NACA 0021 three-bladed rotor.Flow field characteristics are investigated for several values of tip speed ratio, allowing a comparison among rotor operation at optimum and lower C_p values, so that a better understanding of vertical-axis wind turbines basic physics is obtained.