Flutter Suppression Enhancement in Coupled Nonlinear Airfoils with Intermittent Mixed Interactions

Abstract

Flutter suppression facilitates the improvement of structural reliability to ensure the flight safety of an aircraft. In this study, we propose a novel strategy for enlarging amplitude death (AD) regime to enhance flutter suppression in two coupled identical airfoils with structural nonlinearity. Specifically, we introduce an intermittent mixed coupling strategy, i.e., a linear combination of intermittent instantaneous coupling and intermittent time-delayed coupling between two airfoils. Numerical simulations are performed to reveal the influence mechanisms of different coupling scenarios on the dynamical behaviors of the coupled airfoil systems. The obtained results indicate that the coupled airfoil systems experience the expected AD behaviors within a certain range of the coupling strength and time-delayed parameters. The continuous mixed coupling favors the onset of AD over a larger parameter set of coupling strength than the continuous purely time-delayed coupling. Moreover, the presence of intermittent interactions can lead to a further enlargement of the AD regions, that is, flutter suppression enhancement. Our findings support the structural design and optimization of an aircraft wing for mitigating the unwanted aeroelastic instability behaviors.

Figures (17)

• Figure 1: Typical intermittent coupling signals $\chi_{T,\theta} \left( t \right)$ for a fixed on-off period $T=10$ and different on-off ratio $\theta$. (a) $\theta=1$; (b) $\theta=0.50$; (c) $\theta=0.25$; (d) $\theta=0$.
• Figure 2: Bifurcation behaviors for the pitch motion of the uncoupled airfoil system (\ref{['eq:uncoupled-airfoil-state-equation']}).
• Figure 3: Typical responses of pitch and plunge motions of the uncoupled airfoil system (\ref{['eq:uncoupled-airfoil-state-equation']}) for the airflow velocity $U^{*}=12$. (a) Time responses; (b) Power spectrum density.
• Figure 4: The RMS displacements of the coupled airfoil systems (\ref{['eq:coupled-airfoil1-state-equation']})-(\ref{['eq:coupled-airfoil2-state-equation']}) for the Case I (i.e., $\varrho=1$ and $\chi_{T,\theta} \left( t \right)\equiv1$). (a) Plunge motion; (b) Plunge motion.
• Figure 5: The results of the coupled airfoil systems (\ref{['eq:coupled-airfoil1-state-equation']})-(\ref{['eq:coupled-airfoil2-state-equation']}) for the Case I under $\tau=20$. (a) RMS displacements of the first airfoil versus $K$; (b) Bifurcation behaviors of the first and second airfoils versus $K$ (green marker: local maximum values, light red marker: local minimum values).