直升机涵道尾桨与孤立尾桨的气动特性对比研究

Comparison and Analysis of Aerodynamic characteristics between Helicopter Shrouded and Isolated Tail Rotors

本文推导了涵道尾桨的叶素理论公式，将文献［１］的滑流理论与叶素理论公式组合，建立了计算直升机悬停和侧风状态下涵道尾桨气动特性的方法。文中以某直升机涵道尾桨为算例，对比计算了涵道尾桨和孤立尾桨的拉力和功率。计算结果表明：保持桨盘面积相等，在小桨距角时涵道尾桨的拉力比孤立尾桨的小，但在大奖距角时悬停涵道尾桨拉力可大于孤立尾桨的拉力，这一结论证实了文献［２］的类似试验结果。在相同拉力或相同功率条件下，随着涵道拉力在总拉力中所占比例的增大，涵道尾桨比孤立尾桨的气动效能不断增加。

A method of combined blade element theory and slipstreamtheory is developed and formula for numerical calculation are derived inthis paper to evaluate the aerodynamic characteristics of the shroudedtail rotor. As an example,the thrust and required power of a helicoptershrouded tail rotor are calculated and compared with those of the isolatedtail rotor's. The results show that the shrouded tail rotor produces lessthrust than the isolated one when pitch angles are small, but it can pro-duce larger thrust when pitch angles are large.This conclusion verifiesthe result which was found but not explained in reference￣[4].In thepaper, it is also shown that the shrouded tail rotor requires less powerunder the condition of same thrust or it produces larger thrust underthe condition of same required power. Moreover, the improvelnent ofaerodynamic characteristics increases with the ratio of shroud thrust tototal thrust of the shrouded tail rotor.