الفهرس 
Principals of Wind Power
Rotating domain-independent testOnly 14 pages are availabe for public view
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Abstract
This study investigates the aerodynamic performance of a special modification on the horizontal axis wind turbines aiming to maximize the power extracted from the wind. The study focuses on the effect of introducing a second rotor to the main rotor of the wind turbine in what is called a dual-rotor wind-turbine (DRWT). The numerical study was investigated on the performance of small-scale model of a wind turbine of 0.9 m diameter using S826 airfoil.
Both the Co-rotating and Counter-rotating configurations were investigated at different tip speed-ratios (TSR) and compared with the performance of the single rotor wind turbine (SRWT). Many parameters were studied in the dual-rotor turbines. These include the spacing between the two rotors, the pitch angle of the rear rotor, changing the rotation speed ratio between the rear and front rotor and the effect of the diameter ratio (D_ratio) between the front and rear rotor. Three-dimensional simulations were performed using Multi-Reference Frame (MRF) technique.
The Co-Rotating Wind Turbine (CWT) and Counter-Rotating Wind Turbine (CRWT) were found to have better performance compared to that of the SRWT with an increase of 12 to 14% in peak power coefficients. Moreover, the effect of changing the pitch angle of the rear rotor on the overall performance was found to be of a negligible effect between angles 0⁰ and 2⁰ tilting toward the front rotor. On the other hand, the ratio of rotational speed of the rear rotor to the front rotor was found to cause a further increase to the peak performance of the CWT and CRWT of about 3 to 5%. The study ends up with investigating the effect of changing the diameter ratio between the two rotors, separating distance, and the rotation speed ratio as well as study the effect on the overall performance compared to the SRWT.