前飞状态直升机旋翼/机体耦合动稳定性分析模型

 建立了前飞状态的旋翼/机体耦合动稳定性分析模型。采用扩展的Pitt/Peters动力入流模型将悬停与前飞状态统一起来;提出了一种适用性很强的隐式多桨叶坐标转换方法,进而取消了量纲分析及桨叶定常挥舞、摆振的小角度假设,结合Floquet传递矩阵法对系统进行了动稳定性分析。应用此分析模型对无铰旋翼直升机地面共振、前飞时孤立旋翼动稳定性进行了计算验证,分析结果与试验值吻合。

An Analytical Model of Coupled Rotor/Airframe Helicopter Dynamic Stability in Forward Flight

An analytical model is presented for helicopter rotor/airframe coupled dynamic stability in forward flight. Extended Pitt/Peters dynamic inflow model is employed in perturbed motion in order to integrate hovering and forward flight cases. A method of implicit multi-blade coordinate transformation (MCT) is presented and applied in the derivations of linear differential equations of rotor/airframe coupled system, and the order schemes as well as the hypothesis of low displacement of blade steady flap and lead-lag motion are retracted. By Floquet theory and transition matrix resolution,the dynamic instabilities of coupled rotor/airframe system are analyzed. The analytical model is then applied in the predictions of hingeless rotor helicopter ground resonance and isolated rotor instabilities in forward flight. The predictions correlate well with the test data of references.