直升机剪刀式尾桨气动特性的研究

对剪刀式尾桨的气动特性进行了实验和分析研究。描述了在模型旋翼台上进行的实验 ,给出了拉力和扭矩随剪刀角变化的实验结果 ,对比了“下旋翼在前”和“上旋翼在前”2种不同布置的影响。实验表明 :“下旋翼在前”布置时的拉力大于“上旋翼在前”布置时的拉力 ;在某些剪刀角布置下会导致较强烈的桨 -涡干扰。然后 ,建立了一个剪刀式尾桨气动特性计算的分析模型 ,并进行了验证。应用这个模型 ,计算了剪刀式尾桨的桨叶诱速分布、升力分布以及桨尖涡位移 ,解释了拉力随不同剪刀角布置而变化的实验结果和实验中出现桨 -涡干扰的原因。最后 ,提出了几点结论。

Experimental and Analytical Investigation on Aerodynamic Characteristics of Helicopter Scissors Tail Rotor

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.