Investigation of effect of free-wind velocity on the performance of small-scale vertical axis wind turbine

In the present study, effects of various parameters on the simulation of flow around an H-type vertical axis wind turbine with NACA0018 airfoils is studied. All computations are carried out by computational fluid dynamics method using finite volume approach. Free-wind velocities of 5, 10 and 15 m/s and tip speed ratios of 3 and 5 are considered. All obtained results are compared with experimental data and show good agreement. Examination of obtained results reveal that by increasing free-wind velocity, maximum momentum coefficient occurs at higher azimuth angles. Also, by reducing tip speed ratio, fluctuations in the rotor due to the penetration of more volume of air into the rotor increase, thus lifecycle and performance of wind turbine reduce. Furthermore, the effect of tip speed ratio on the performance of wind turbine is more significant than free-wind velocity so that by increasing tip speed ratio from 3 to 5 at a constant velocity of 10 m/s, power coefficient increases by 81/87% and by increasing free-wind velocity from 5 to 10 at a constant tip speed ratio of 3 power coefficient increases by 58.2%.