2D CFD Modeling of H-Darrieus Wind Turbines Using a Transition Turbulence Model

In the present paper, the authors describe the strategy to develop a 2D CFD model of H-Darrieus Wind Turbines. The model was implemented in ANSYS Fluent solver to predict wind turbines performance and optimize its geometry. As the RANS Turbulence Modeling plays a strategic role for the prediction of the flowfield around wind turbines, different Turbulence Models were tested. The results demonstrate the good capabilities of the Transition SST turbulence model compared to the classical fully turbulent models. The SST Transition model was calibrated modifying the local correlation parameters through a series of CFD tests on aerodynamic coefficients of wind turbines airfoils. The results of the tests were implemented in the 2D model of the wind turbine. The computational domain was structured with a rotating ring mesh and the unsteady solver was used to capture the dynamic stall phenomena and unsteady rotational effects. Both grid and time step were optimized to reach independent solutions. Particularly a high quality 2D mesh was obtained using the ANSYS Meshing tool while a Sliding Mesh Model was used to simulate rotation. Spatial discretization algorithm, interpolation scheme, pressure - velocity coupling and turbulence boundary condition were optimized also. The 2D CFD model was calibrated and validated comparing the numerical results with two different type of H-Darrieus experimental data, available in scientific literature. A good agreement between numerical and experimental data was found. The present work represents the basis to develop an accurate 3D CFD unsteady model and may be used to validate the simplest 1D models and support wind tunnel experiments.