Assessing analysis of a small-scale dual rotor counter-rotation wind turbine with a unique pitch mechanism: Experimental parametric study

The increasing global energy demand and the search for sustainable solutions have brought wind energy to an important position among renewable energy sources. This study focuses on the design, manufacturing and testing of a double rotor counter-rotating wind turbine aiming to improve aerodynamic efficiency and structural integrity. The NREL S822 airfoil optimised for low wind speeds is used. In the study conducted under laboratory conditions using an open-circuit wind tunnel, an alternator with a direct drive system was used to minimize mechanical losses and maintenance requirements. The double rotor system, which operates in counter rotation, has shown high performance especially at low wind speeds. The results show that the blades do not rotate contrarily when the torque difference between the two rotors is greater than 28.46%. The maximum power output was obtained when the front blade angle was 12 degrees and the rear blade angle was 3 degrees. Compared to the single rotor wind turbine, the power output of the twin rotor wind turbine is 60% higher. With the increase in the front blade angle, the power output of the twin rotor wind turbines decreased. In addition, the experimental results were statistically analysed and a mathematical model was created to predict the power output of double rotor wind turbines.