### 变转速旋翼直升机单发失效低速回避区分析

1. 南京航空航天大学 直升机旋翼动力学国家级重点实验室, 南京 210016
• 收稿日期:2018-03-02 修回日期:2018-05-07 出版日期:2018-10-15 发布日期:2018-05-11
• 通讯作者: 陈仁良 E-mail:crlae@nuaa.edu.cn
• 基金资助:
国家自然科学基金（11672128）

### Analysis of low-speed height-velocity diagram of variable speed rotor helicopter in one engine inoperative situation

YAN Xufei, CHI Cheng, CHEN Renliang, LI Pan

1. National Key Laboratory of Science and Technology on Rotorcraft Aeromechanics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
• Received:2018-03-02 Revised:2018-05-07 Online:2018-10-15 Published:2018-05-11
• Supported by:
National Natural Science Foundation of China (11672128)

Abstract: The optimal control method is used to study the effects of variable rotor speed on the helicopter low-speed Height-Velocity (H-V) diagram in the One Engine Inoperative (OEI) situation and the corresponding optimal autorotation landing procedure. First, a three-dimensional rigid body flight dynamics model for a UH-60A helicopter is established, and the effect of rotor speed on the helicopter required power in the low-speed range is analyzed. Then, equations for the engine output shaft power and rotor speed during autorotation landing in OEI are added into the flight dynamics model. The helicopter autorotation landing procedure in OEI is converted into a nonlinear optimal control problem by using the direct multiple shooting method, and solved numerically. Finally, based on the idea of minimizing the area of the avoidance zone, the H-V diagrams and the optimal autorotation landing procedures in OEI at three key points (high, knee and low) of the H-V diagrams with various operational rotor speeds are investigated. The results show that the reduction of operating rotor speed will cause gradual shrink of the H-V diagram area first and rapid expansion then. In addition, the rotor speed corresponding to the minimum H-V diagram is slightly higher than the rotor speed corresponding to the minimum required power. Properly reducing the rotor speed can effectively reduce the helicopter required power, and can also improve the autorotation landing performance in OEI.