Nonlinear Stability Analysis of Whirl Flutter in a Tiltrotor Rotor-nacelle System
Nonlinear Stability Analysis of Whirl Flutter in a Tiltrotor Rotor-nacelle System
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发表时间：
2017-09
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通讯作者：
C. Mair;D. Rezgui;B. Titurus
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作者：
C. Mair;D. Rezgui;B. Titurus
涡动颤振是一种气动弹性不稳定，会影响螺旋桨/转子及其安装的附近区域。随着非线性效应的加入，倾转旋翼的颤振分析变得越来越复杂。本文研究了非线性塔架刚度对基本旋翼-吊舱模型的颤振稳定性的影响，并与基线线性刚度模型进行了比较。本文研究的非线性是软化型材和硬化型材的立方刚化。通过仿真、特征值和分叉分析相结合的方法进行研究，以充分反映弹簧非线性对转子-吊舱系统动力学行为的影响。该分析提供了一个更完整的稳定包络，说明了在立方加强作用下旋翼-吊舱系统的复杂行为。结果表明，对于一系列参数值，系统存在稳定和不稳定的极限环和平衡点。研究结果也表明了非线性涡振模型和分析方法的重要性。特别令人感兴趣的是，尽管线性分析预测了稳定的行为，但机舱的动力学是不稳定的。
Whirl flutter is an aeroelastic instability that affects propellers/rotors and the vicinity in which they are mounted. Whirl flutter analysis in tiltrotors gets progressively more complicated with the addition of nonlinear effects. This paper investigates the impact of nonlinear pylon stiffness on the whirl flutter stability of a basic rotor-nacelle model, compared to a baseline linear stiffness version. The nonlinearity investigated in this paper is cubic stiffening of both softening and hardening profiles. The investigation is conducted through a combination of simulations, eigenvalue and bifurcation analyses, in order to fully capture the effects of spring nonlinearity on the dynamic behaviour of the rotor-nacelle system. The analysis provides a more complete stability envelope, demonstrating the complex behaviour of the rotor-nacelle system in the presence of cubic stiffening. The results illustrate the coexistence of stable and unstable limit cycles and equilibria for a range of parameter values. The results also demonstrate the importance of nonlinear whirl flutter models and analysis methods. Of particular interest are cases where the dynamics of the nacelle are unstable despite linear analysis predicting stable behaviour.