结构参数对无轴承旋翼悬停气弹稳定性的影响

Influence of Structural Parameters of Bearingless Rotors on Its Aeroelastic Stability in Hover

为了准确分析结构参数在悬停状态下对无轴承旋翼气动弹性稳定性的影响,建立一种基于有限状态入流的直升机气弹稳定性分析的新模型。采用Green-Lagrange应变张量推导无轴承旋翼桨叶的非线性应变-位移关系,把桨叶作为多路传力系统进行处理并根据Hamilton原理建立桨叶运动的有限元方程,非定常气动力采用有限状态状态入流模型,旋翼的气弹稳定性根据桨叶摄动方程的特征值进行判断,研究结构参数对无轴承旋翼在悬停状态下气弹稳定性的影响。结果表明:(1)无轴承旋翼气弹稳定性分析采用模型比以往的动力入流模型或均匀入流模型与实验结果吻合更好;(2)桨毂预锥角、桨叶的摆振刚度及挥舞刚度对无轴承旋翼气弹稳定性的影响很大。

A new model of bearingless rotors for aeroelastic stability analysis was presented based on finite-state unsteady aerodynamics. Nonlinear strain-displacement relations were built using Green-Lagrange strain tensor. The blades were modeled as a multiple-load-path system and the finite element equations of dynamics for bearingless rotors were obtained from Hamilton＇ s principle. Finite-state induced flow model was used to evaluate unsteady aerodynamics effect. The nature of complex eigenvalues of flutter equations of blades was employed to judge the aeroelastic stability of the rotors. Effect of structural parameters on the aeroelastic stability of the bearingless rotors in hover was investigated. It is shown that the numerical results of the stability analysis using this model can more precisely agree with those of experiments using dynamic inflow model or uniform inflow model. Hub pre-conical angle, blade＇ s chordwise stiffness and flapwise stiffness have substantial influence on aeroelastic stability of bearingless rotors.