直升机悬停时涵道尾桨的需用功率计算

涵道尾桨是将一螺桨置于直升机尾斜梁的涵道中，通过改变螺桨叶片的安装角实现直升机的航向操纵。为了弄清涵道尾桨的拉力（或推力）和需用功率之间的关系，本文根据Ｒ·Ｋｒｉｅｂｅｌ关于薄圆柱涵道螺旋桨的研究结果，用叶栅理论分析了涵道尾浆的气动特性，并将动量理论、叶素理论和叶栅理论结合起来，推导出直升机悬停时的涵道尾浆的需用功率计算公式。最后计算了ＳＡ３６５Ｎ直升机涵道尾浆和Ｂｅｌｌ－２２２直升机常规尾桨在产生相同拉力时的需用功率，并对计算结果作了对比分析。

A Method for Predicting Ducted Tail Rotor Power Required in Hovering Flight

The shrouded propeller inside a fin,called ducted tail rotor or fan in fin,is a kind of advanced anti-torque and directional control system. It controls the helicopter heading by changing the pitch angle of the propeller blades. In order to relate ducted tail rotor thrust to its power required,the aerodynamics of shrouded propeller is analysed in this paper,based on the cascade theory and the results of R. Kriebel's research work on the thin cylindrical duct with a propeller. The expression of ducted tail rotor power required in hovering flight is derived using blade element theory and momentum theory combined with cascade theory. The power required for the same thrust produced by the SA365N ducted tail rotor and the Bell-222 conventional tail rotor in hovering flight is calculated and compared.