Three-dimensional simulation of a complete Vertical Axis Wind Turbine using overlapping grids

Three‐dimensional simulations of the aerodynamic field around a three‐blade straight‐axis Vertical Axis Wind Turbine (VAWT) are presented for two values of the Tip Speed Ratio $\lambda$ (TSR), namely $\lambda =1.52$ and $\lambda =2.5$ . Numerical simulations were carried out using the over‐set grid solver ROSITA (ROtorcraft Software ITAly). The Reynolds‐Averaged Navier–Stokes equations are completed by the Spalart–Allmaras turbulence model. A strong interaction between the blade and the blade wakes is evidenced. Dynamic stall is observed in the case $\lambda =2.5$ . The computed flow‐field presents diverse three‐dimensional effects, including the interaction between the blades and the tip vortices and the aerodynamic disturbances from the turbine shaft and the support arms. Three‐dimensional effects are more relevant for $\lambda =2.5$ . The comparison to experimental data confirms the general features of the flow.