Stability analysis of whirl flutter in rotor-nacelle systems with freeplay nonlinearity
Stability analysis of whirl flutter in rotor-nacelle systems with freeplay nonlinearity
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DOI：
10.1007/s11071-021-06271-z
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发表时间：
2021-02
影响因子：
5.6
通讯作者：
C. Mair;B. Titurus;D. Rezgui
中科院分区：
文献类型：
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作者：
C. Mair;B. Titurus;D. Rezgui
倾转旋翼飞机由于其独特的飞行包线的实用性而越来越流行。然而，气动弹性稳定性，特别是涡动颤振稳定性，是一个主要的设计影响，需要准确的预测。倾转旋翼机系统中可能存在的几种非线性，如游隙，在建模或稳定性分析中，为了简单起见，常常被忽略。然而，这种非线性的影响可能是显著的，有时甚至使线性分析方法的稳定性预测无效。游隙是倾转旋翼机短舱旋转致动器中可能出现的一种非线性，这是由于它们所经受的拉伸-压缩载荷循环。本文研究了间隙结构非线性对短舱俯仰自由度的影响。两个转子短舱模型的对比复杂性进行了研究：一个代表经典的涡动颤振（螺旋桨），另一个捕获的倾转旋翼气动弹性（螺旋桨）的主要影响。利用连续化和分叉方法绘制出系统动力学行为中游隙的表现形式，从而量化了稳定边界的变化。此外，（a）模型的复杂性和（B）死区边缘的锐度的影响的游隙行为进行了研究。最终，自由间隙的非线性被证明有一个复杂的影响，这两个系统的动态，甚至创建的可能性，在参数范围内的线性分析方法预测是稳定的旋转颤振。虽然这个额外的涡动颤振区域的大小是有限的和有界的基本模型，它是无界的更高的复杂性模型。
Tiltrotor aircraft are growing in prevalence due to the usefulness of their unique flight envelope. However, aeroelastic stability—particularly whirl flutter stability—is a major design influence that demands accurate prediction. Several nonlinearities that may be present in tiltrotor systems, such as freeplay, are often neglected for simplicity, either in the modelling or the stability analysis. However, the effects of such nonlinearities can be significant, sometimes even invalidating the stability predictions from linear analysis methods. Freeplay is a nonlinearity that may arise in tiltrotor nacelle rotation actuators due to the tension–compression loading cycles they undergo. This paper investigates the effect of a freeplay structural nonlinearity in the nacelle pitch degree of freedom. Two rotor-nacelle models of contrasting complexity are studied: one represents classical whirl flutter (propellers) and the other captures the main effects of tiltrotor aeroelasticity (proprotors). The manifestation of the freeplay in the systems’ dynamical behaviour is mapped out using Continuation and Bifurcation Methods, and consequently the change in the stability boundary is quantified. Furthermore, the effects on freeplay behaviour of (a) model complexity and (b) deadband edge sharpness are studied. Ultimately, the freeplay nonlinearity is shown to have a complex effect on the dynamics of both systems, even creating the possibility of whirl flutter in parameter ranges that linear analysis methods predict to be stable. While the size of this additional whirl flutter region is finite and bounded for the basic model, it is unbounded for the higher complexity model.