Wind energy is the fastest growing energy in the world today. Vertical axis wind turbine (VAWT) is
an effective way to benefit from this energy. So that, the present work aims to improve the
performance of Darrieus straight bladed rotor. For improving the performance Darrieus straight
bladed rotor, six aspect ratios and four chord lengths of Darrieus rotor are experimentally selected in
an attempt to improve the performance of Darrieus wind turbine. The experimental results in the
present work are obtained using three blades of a new airfoil shape design which is designated as
EN0005 at different wind speeds. The comparison between six aspect ratios at the same wind speed
and chord length showed that, the rotor with aspect ratio 0.833 and chord length 18 cm produces the
maximum power coefficient.