The impact of turbulence model selection on the accuracy of CFD simulations of VAWTs is highly considered. In this 
paper 2D CFD simulations were carried out on a three-bladed H-Darrieus VAWT with NACA 0021 airfoil. Two turbulence models, two equations k-ε Realizable and four equations Transition-SST, were selected to validate the power coefficient calculated from simulations with numerical and experimental data from the literature. The power coefficient calculated from the simulations performed by the k-ε Realizable turbulence model was slightly underestimated, while Transition-SST turbulence model results were slightly overestimated. However, in terms of root mean square error of the power coefficient calculated from the simulations performed by the k-ε Realizable turbulence model gives a value of 0.0503, while the Transition-SST model gives a value of 0.0655. Moreover, in terms of mean average percentage error of the power coefficient calculated from the simulations performed by the k-ε Realizable turbulence model gives a value of 35.15%, while the Transition-SST model gives a value of 42.34%. Another validation with a two straight bladed numerical model with NACA 0018 airfoil was performed using 2D CFD simulations. Two equations k-ε Realizable, two equations kω SST and four equations Transition-SST were selected to conduct these simulations, the results showed that the k-ε Realizable turbulence model was the best candidate among the other ones.