Effect of Lift-Share Ratio on Aerodynamic Performance of Winged Compound Helicopter

Abstract

The influence of the lift-share ratio between a rotor and a wing on the aerodynamic performance of a winged compound helicopter in high advance ratio flight is investigated through numerical simulations in this paper. A simplified model constructed with only a rotor and a winged body is considered to focus on the aerodynamic interactions between the rotor and the wing. The effect of the interaction is evaluated through comparison to the isolated rotor and the isolated wing in the same flight condition. A cruising flight condition at which the rotor advance ratio is about 0.7 is considered where the rotor rotational speed is reduced to 75% revolutions per minute. The lift-share ratio between the rotor and the wing is changed by adjusting the wing incidence angle and the wing area. Numerical simulation results show that the aerodynamic performances against the lift-share ratio follow similar trends regardless of the wing incidence change or the wing area change. The lift-to-drag ratios of the rotor and the winged body both degrade due to the aerodynamic interaction between the rotor and the winged body as compared with the isolated configurations. The optimal lift-share ratio of the rotor is about 6–7% of the total lift. When the lift share of the rotor is larger than the optimal value, the overall performance is drastically reduced by the rotor/wing aerodynamic interaction.