Effect of some design parameters on the performance of a Giromill vertical axis wind turbine

The maximum power coefficient obtained in this research was 25% using turbine radius of 40 cm, chord length 15 cm, pitch angle of 10°, airfoil type NACA 0024, and four blades (which is found to be the best configuration in this study). For the effect of pitch angle, the obtained maximum power coefficient is decreasing, this decrease in performance was due to increasing in the pitch angle above 10° and also due to decreasing it below this value showing the high effect of pitch angle. It was also noticed that, when decreasing the turbine radius to 20 cm at 0° pitch angle the maximum power coefficient is much decreased. Moreover, decreasing the chord length to 12 cm at 10° pitch angle decreases the maximum power coefficient significantly, which again show the high effect of turbine radius and chord length. In order to compare the effect of airfoil type; the blades with NACA 4420 were used compared to NACA 0024 at the same above parameters of turbine radius 40 cm, chord length 15 cm, pitch angle of 10° and four blades. The maximum power coefficient obtained was 15%. Finally, the effect of the number of blades have been investigated using two, three and four blades at 0° pitch angle and the same other above parameters of turbine radius 40 cm, chord length 15 cm and airfoil type NACA 0024. The obtained maximum power coefficients were decreased significantly when decreasing the number of blades from four to two blades.