Open/closed-loop aeroservoelastic predictions via nonlinear, reduced-order aerodynamic models

Recently, the parallel cascade reduced-order modeling approach has been successfully used for the flutter prediction of a two-degree-of-freedom wing section. However, this approach has been less successful when applied to reveal other important aeroelastic phenomena, such as the transonic aeroservoelastic behaviors of a threedimensional wing with a trailing-edge control surface. Because of the complexity introduced by the forced controlsurface deflection, effects of oscillating shock waves, and aerodynamic viscosity, the stability of the dynamic linear parts of the parallel cascade reduced-order model cannot be guaranteed. In this paper, a novel, stable representation of the parallel cascade reduced-order model is explored in which the linear part is identified by using a predictorbased subspace scheme. To demonstrate the performance of the present parallel cascade reduced-order model in modeling the aeroservoelastic behaviors of a three-dimensional wing with a trailing-edge control surface, the Benchmark Active Control Technology wing is used as an illustrative example. The numerical results demonstrate that the parallel cascade reduced-order models are capable of modeling open/closed-loop aeroservoelastic behaviors. Moreover, the effects of the aerodynamic nonlinearity on the dynamic behaviors of the aeroservoelastic systems are investigated always based on the proposed reduced-order model. 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.