带机体状态反馈的直升机地面共振分析

建立了带机体状态反馈的直升机旋翼/机体耦合动稳定性分析模型,研究了机体反馈系数对直升机地面共振的影响。根据Floquet理论采用传递矩阵法计算了系统的模态频率及模态阻尼,并用非线性模型的数值仿真进行了验证。结果表明,机体滚转角位移和角速度反馈能有效地提高摆振后退型模态阻尼;但当机体滚转姿态角反馈系数过大时,以挥舞后退型模态为主的旋翼挥舞与机体运动之间相互作用,导致直升机出现动不稳定性。

Analysis of Helicopter Ground Resonance with Fuselage State Feedback

An analytical model of helicopter rotor/airframe coupled system with fuselage state feedback is presented,and the effects of feedback coefficients on the helicopter ground resonance stability are investigated.By Floquet theory and transition matrix technology,the modal frequency and damping values are resoluted and verified by numerical simulations for nonlinear model. Analytical results show that the regressive lag modal damping levels can be increased efficiently with fuselage roll state feedback introduced.However,the excessive roll amplitude feedback coefficients may result in significant decrements of helicopter dynamic stability while the regressive flap mode becomes dominant and unstable.The phenomenon arises physically from rotor flapping and fuselage mutual excitations in phase.