Numerical study of the flow passing through the rotor of a vertical axis wind turbine

Savonius type wind turbine is the subject of the present study. The Savonius wind turbine has a relatively simple design, omnidirectional wind acceptance, excellent self-starting capabilities and stable operation under turbulent wind. The operation of the Savonius wind turbine is characterized by pronounced unsteadiness, due to the continuous change of the relative velocity acting on the blades. In order to gain deeper understanding over the ongoing processes during the turbine operation a numerical modelling of the flow passing through its rotor was carried out. Due to computational hardware and time limitations a 2D URANS approach was adopted. The k-ω SST turbulence model was chosen for the calculation of the vortex structures generation, dissipation and interactions. The k-ω SST combines the advantage of the k-ε model of excellent main flow modelling and the advantage of the k-ω model of excellent near-wall (blades) flow modelling. The obtained numerical data was postprocessed and the flow passing through the rotor was visualized at different angular positions. The aerodynamic theoretical characteristics of the Savonius wind turbine are obtained.