直升机后掠桨尖旋翼气弹稳定性研究

Aeroelastic Stability Analysis of Helicopter Rotor Blade with Swept Tips

通过建立具有后掠桨尖旋翼气弹稳定性的分析模型 ,研究后掠桨尖旋翼气弹的稳定性。结构模型考虑了旋翼桨叶的偏置、预锥、预掠、预扭以及桨尖的后掠等多种旋翼参数及非线性影响 ,分析了不同桨尖后掠角几何参数对旋翼气弹稳定性的影响。数值结果表明 ,桨尖后掠对旋转旋翼桨叶气弹稳定性影响较大 ,桨尖后掠使一阶扭转频率增加 ,同时使一阶摆振阻尼降低 ,后掠桨尖单元的非线性转换关系对气弹分析结果有影响 ,桨尖后掠角越大这种影响越显著。

Aeroelastic model is developed to analyze aeroelastic stability of helicopter rotor blade with swept tips. Parameters of blade pre cone, pre twist and tip sweep angle are considered in model involving nonlinear effects. Nonlinear transformation relations are specially derived for swept tip of blade. The partial differential equations of motion are discretized by finite element in space using Hamilton's principle. Influence study of tip angle on aeroelastic stability of helicopter rotor is implemented by developing computer codes. Validation studies are first carried out for ITR rotor with straight tip in hover to correlate the calculated results with experimental data. Secondly aeroelastic stability correlation studies are implemented on Bo 105 rotor with swept tip in forward flight to correlate the calculated results by developed codes with the results of UMARC. Numerical results show that the influence of tip sweep angle on aeroelastic stability is considerable in hover and forward flight. The first lag mode damping of blade decreases with tip sweep angle. Nonlinear transformation relations are very important for aeroelastic stability analysis of rotor blade with swept tip, especially in case of large sweep angle.