Abstract
This paper treats the experiment of the performance of a horizontal axis wind turbine with an extra small diameter rotor in front of the main rotor. In this experiment, the wind turbine of rotor diameter 482mm, NACA-4415 airfoil is used as a main rotor and a small rotor of diameter 276mm with the similar airfoil section to the main rotor is installed in front of the nacelle. The results show that the power output of double rotor wind turbine is greater than the normal rotor wind turbine.
