Experimental study on structures of counter-rotating wind turbines

Based on the principle of counter-rotating wind turbine (CRWT), several experiments are done to study the wind energy extraction of the small horizontal axis CRWT with different pitch angles and space lengths between two rotors. The results show that the counter-rotating wind turbine can extract more wind energy, when the pitch angles of two rotors are both 50°. For the counter-rotating wind turbine employed in this experiment, the power output under different wind speed is higher when space length between two rotors keeps in the range of 8-12cm. Also, a counter-rotating rotor system could increase power conversion efficiency by 40% than single rotor system.