旋翼自转状态在高速直升机升力转移过程中的应用

Application of Rotor Autoratation to Lift Transfer

近年来高速直升机的方案日新月异、层出不穷。但无论是哪一种方案都要解决导致直升机不能飞得更快的根本原因——气流分布的不对称性所造成的气流分离及激波问题。目前大多数高速方案都采用升力转移来解决这一问题 ,即从直升机模式由旋翼承担升力过渡到固定翼飞机模式由机翼承担升力。本文利用自转状态在相同临界迎角下可以承担更多升力的特点 ,提出将自转引入升力转移的过程中 ,并建立了速度与桨盘迎角的关系 ,研究了从正常直升机模态进入自转状态时的进入速度与桨盘迎角。通过算例说明将自转状态作为升力转移的过渡状态 ,可以达到减小机翼面积 ,从而降低机体重量、减小阻力的目的 ,并证明自转状态应用于升力转移过程中是实际可行的良好方案。

High speed helicopter is one of the goals since the helicopter was born.Recently,so many projects come out. However,every one must solve the problem related to main rotor stall and shock wave the reasons that restrict the forward speed of the helicopter.Most of the projects solve this problem by lift transfer, that is, to shift the lift from the main rotor in the helicopter model to the wing in the air plane model. In this paper, the state of rotor autorotation is introduced into lift transfer. A rotor can produce more lift in the autorotation state before stall than in the powered state.At the same time, the relationship between forward speed and the disk angle of attack is established for the autorotation rotor. The analysis shows that the wing area of the high speed rotorcraft scheme might be reduced if the autorotation state serves as the transition for lift shift. So the structure weight would be smaller and the drag as well as. It indicates that introducing rotor autorotation into the lift transfer is feasible.