共轴双旋翼气动特性数值仿真研究

The aerodynamic performance of coaxial twin-rotors in either hover or level flight is simulated. The numerical method using multiple reference frame method is firstly applied in a benchmark rotor and wind tunnel model in hover and level flight, respectively. The simulated thrust coefficients agree with the results from experiment. Then the CFD (computational fluid dynamics) model is established for coaxial twin-rotors, and the aerodynamic performance of upper and lower rotors are analyzed. Numerical results show that the single rotor generates higher thrust coefficient than either the upper or the lower rotor of the coaxial twin-rotor in hover. The thrust ration between the coaxial twin-rotor and the single rotor reaches 1.844 in present simulation. The thrust ratio decreases with the increase of the rotating speed. In level flight, to avoid the windmill effect, the coaxial twin-rotor is better than the single rotor, and a small space between upper and lower rotors is preferred.