舰载直升机旋翼/机体非线性耦合稳定性分析

基于多体动力学方法建立了舰载直升机旋翼/机体耦合系统的动力学模型,其中机体起落架模型由非线性的液压作动器和橡胶轮胎两部分组成,而舰船的横摇和纵摇以简谐激励的形式通过起落架传递给旋翼/机体系统.针对不同的舰船激振频率,研究舰载直升机起动过程中旋翼/机体系统的时间响应历程和动力学稳定性.结果表明:舰载直升机的机体和桨叶摆振自由度在舰船激励下均会出现极限环振动现象,并且当舰船激振频率与旋翼旋转频率相等时会激发出旋翼的摆振后退型模态的极限环振动,使旋翼重心偏离桨毂中心,进而可能导致“舰面共振”事故发生. 

Nonlinear dynamics of coupled rotor/fuselage system for shipboard helicopter

The coupled rotor/fuselage system was developed using multibody dynamics approach. The undercarriage of helicopter comprised the oleo and tyre as a nonlinear system. The ship had the roll and pitch motion in the form of harmonic oscillation. Under different rotor speeds and excited frequencies, the response and dynamic stability of the rotor/fuselage system had been investigated. The result shows that the fuselage and the rotor oscillations may generate limit cycle oscillations under the excitement of ship. When the rotor oscillation is equal to the excited frequency of ship, the response of regressing lag will bring about limit cycle oscillations, and the center of gravity of rotor will shift from the hub, leading to ship resonance.