重型直升机飞行动力学刚弹耦合建模及空中共振稳定性分析

针对重型直升机（HLH）大重量、低转速的固有特性，提出了一种适用于重型直升机的飞行动力学刚弹耦合建模方法。该方法结合传统直升机飞行动力学与旋翼机体耦合动力学，将传统飞行力学的分析频段拓展到了5 Hz，额外考虑了桨叶和机体的弹性变形，基于阻抗匹配法推导出了显式的旋翼/机体耦合动力学方程，模拟了真实飞行状态下的直升机气弹耦合特性，利用该模型计算并分析了算例重型直升机的悬停飞行特性和空中共振稳定性。结果表明：旋翼机体耦合导致摆振前进型和机体弹性模态的阻尼-转速曲线先相互靠近至同一点再分离，可能引起直升机的高频瞬态振动；在摆振等效阻尼不足时，旋翼摆振后退型是不稳定的，但随着等效阻尼增加，摆振二阶周期型模态和机体弹性模态会出现耦合；桨叶弹性变形与机体弯曲模态及挥舞集合型耦合，但不会引起明显的不稳定现象。

Rigid-elastic coupled flight dynamic modeling and air resonance stability analysis for heavy lift helicopter

This paper presents a rigid-elastic coupled flight dynamic modeling method for a Heavy Lift Helicopter (HLH), considering the inherent characteristics of heavy weight and slow rotational speed. The method bridges flight dynamics and coupled rotor-fuselage aeroelastic dynamics, expanding the interested range of frequency to 5 Hz with an additional consideration of the elastic fuselage and blades. Based on the impedance matching method, explicit coupled dynamic equations were derived to simulate the helicopter aeroelastic characteristics in real flight. Finally, this model was used to calculate and analyze the flight and air resonance characteristics for an example HLH in hover. The results show that rotor-fuselage coupling causes the progressive lag mode and fuselage bending mode to approach each other and then separate after arriving at the same point with the increase of the rotational speed, which might result in high frequency transient vibration. The regressive lag mode is unstable without sufficient lag damping; however, with the increase of equivalent lag damping, the second order periodic lag mode will be coupled with the fuselage bending mode. The blade elastic modes are coupled with the fuselage bending mode and the collective flap mode without obvious instability.