The study on performance and aerodynamics of micro counter-rotating HAWT

Compared with large HAWT, the power coefficient and economical performance of the micro HAWT are inferior. However, due to flexible deployment, rapid installation, easy-to-use and low cost, it is still necessary to carry out research on micro HAWT to improve their performance. As a structure proven to be able to increase the power coefficient of HAWT effectively, the aerodynamic characteristics of the micro counter-rotating HAWT (CRWT) is studied in detail by experiments and LBM-LES simulation in this paper. Firstly, the results show the micro CRWT can enhance the power coefficient by two schemes. One is that the equal diameter counter rotating rotors with certain pitch angle can achieve a maximum power coefficient in a wider range of speed. The other is to use the vice rotor to enhance the power output of the main rotor, whether the vice rotor is in front rotor or rear, the rotation of the vice rotor can significantly improve power coefficient of the main rotor, so as to enhance the power coefficient of the total system. Then the aerodynamic mechanism of the Vice-Main and Main-Vice rotor schemes is further discussed with LBM-LES result in detail.