直升机旋翼/机身耦合系统气动/机械稳定性分析

考虑了铰接式旋翼桨叶绕挥舞、摆振和变距铰的整体刚性运动与桨叶中等弹性变形之间的动力学耦合作用 ,将直升机机身和传动轴作为弹性体。通过构造一种特殊的 2 4自由度刚柔混合单元得到旋翼 /机身耦合系统的周期时变动力学方程 ,根据 Floquet理论对稳态周期解的稳定性进行研究。计算结果表明 ,旋翼轴的截面刚度对旋翼 /机身耦合系统的气动 /机械稳定性有一定的影响。

Aeromechanical Stability Analysis of the Coupled Rotor/Fuselage System

The periodic time-varying equations for motion of the coupled rotor/fuselage system are formulated by building a new 24DOF coupled rigid/elastic element which includes 15 nodal deformation from the finite element discretization,3 rigid rotation of the flap,lag and pitch motion and 6 elastic deformation of the hub.Then they can analyze the elasticity of shaft and fuselage of helicopters by the finite element method.The dynamic coupling effects between the rigid motion of blades about the flap,lag and pitch hinges and moderately large elastic deflections are taken into account.After deriving linearized perturbation equations about the known equilibrium position,the stability is studied with the Floquet theory.Results show that the sectional stiffness of the shaft has a considerable effect on the stability of the coupled rotor/fuselage system.