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Investigating amplitude death in a coupled nonlinear aeroelastic system
International Journal of Non-Linear Mechanics ( IF 2.8 ) Pub Date : 2020-12-15 , DOI: 10.1016/j.ijnonlinmec.2020.103659
Ashwad Raaj , Sirshendu Mondal , Venkatramani Jagdish

Coupling nonlinear dynamical systems can lead to a host of phenomena, one of which leads to the complete cessation of their oscillations. This phenomenon is referred to as amplitude death (AD) in the dynamical systems literature. Recently, there is a growing interest to mitigate oscillatory or dynamic instabilities in a variety of engineering systems using AD. Deriving impetus from the same, we investigate the possibility of cessation of oscillatory instabilities in aeroelastic systems using the concept of AD. In specific, the suppression of flutter instability that arises in aeroelastic systems due to highly nonlinear fluid–structure interactions is investigated from the purview of AD. To that end, we consider two identical airfoils that are exposed to input fluid forces along the axial directions. The airfoils, via translational and rotational springs, are allowed to oscillate in plunge and pitch degrees of freedom. To augment the findings to in-field scenarios, we consider the individual cases of the input flow to be either uniform (deterministic) or possess randomly time varying components, respectively. To promote coupled interactions, the airfoils are coupled using a linear torsional spring. The coupled interaction of the airfoils at the flutter regime are then studied by obtaining the pitch and plunge responses. Further, the strength of the coupling and the time delay between the airfoils are systematically varied to investigate its effect on the regime of AD. The ability of AD to suppress flutter instability and thereby serve as a possible flutter suppression mechanism in both deterministic and stochastic input flow cases is then demonstrated. Finally, the phase delay values between the airfoils is computed to heuristically present a relationship between the coupling parameters and the post coupling signatures.



中文翻译:

耦合非线性气动弹性系统中的振幅衰减研究

耦合非线性动力学系统会导致一系列现象,其中之一导致其振荡完全停止。在动力学系统文献中,此现象称为振幅死亡(AD)。最近,人们越来越有兴趣减轻使用AD的各种工程系统中的振荡或动态不稳定性。从相同的推论中,我们使用AD概念研究了在气动弹性系统中停止振荡不稳定性的可能性。具体而言,从AD的角度研究了抑制由于高度非线性的流固耦合而在气动弹性系统中产生的颤动不稳定性的方法。为此,我们考虑两个相同的机翼,它们沿轴向方向承受输入流体力。机翼,通过平移和旋转弹簧,可允许其自由度和俯仰自由度摆动。为了将发现扩展到现场场景中,我们认为输入流的个别情况分别是统一的(确定性的)或随机随时间变化的分量。为了促进耦合相互作用,翼型使用线性扭转弹簧耦合。然后通过获得俯仰和俯冲响应来研究翼型在颤动状态下的耦合相互作用。此外,系统地改变了翼型之间的耦合强度和时间延迟以研究其对AD状态的影响。然后证明了AD具有抑制颤动不稳定性的能力,从而可以在确定性和随机输入流情况下充当可能的颤动抑制机制。

更新日期:2020-12-16
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