摘要
An experimental and analytical investigation on the aerodynamic characteristics of a helicopter scissors tail rotor has been made. The experiments are carried out on a model rotor rig and the variations of the rotor thrust and torque with scissors angles are investigated. The effects of two different configurations, i.e., Configuration L in which the lower blade is in front of the upper blade and Configuration U in which the upper blade is in front of the lower blade, on rotor performance are compared. The experimental results have shown that the thrust for Configuration L is greater than that for Configuration U, and the strong blade-vortex interaction may occur at some scissors angles. A free-wake analytical model is then developed for predicting the aerodynamic characteristics of a scissors tail rotor and validated by numerical examples. By using the model, the blade induced velocity, lift distribution and tip vortex displacement of the scissors rotor are calculated. Based upon the calculations, the variations of the thrust with scissors angles in the experiments are analyzed and the strong blade-vortex interaction occurring in the experiments is explained. Finally, several conclusions are presented.
An experimental and analytical investigation on the aerodynamic characteristics of a helicopter scissors tail rotor has been made. The experiments are carried out on a model rotor rig and the variations of the rotor thrust and torque with scissors angles are investigated. The effects of two different configurations, i.e., Configuration L in which the lower blade is in front of the upper blade and Configuration U in which the upper blade is in front of the lower blade, on rotor performance are compared. The experimental results have shown that the thrust for Configuration L is greater than that for Configuration U, and the strong blade-vortex interaction may occur at some scissors angles. A free-wake analytical model is then developed for predicting the aerodynamic characteristics of a scissors tail rotor and validated by numerical examples. By using the model, the blade induced velocity, lift distribution and tip vortex displacement of the scissors rotor are calculated. Based upon the calculations, the variations of the thrust with scissors angles in the experiments are analyzed and the strong blade-vortex interaction occurring in the experiments is explained. Finally, several conclusions are presented.
