Reduced order modeling of limit-cycle oscillation for aeroelastic systems

Limit-cycle oscillations of a nonlinear panel in supersonic flow are computed using a reduced-order aeroelastic model. Panel dynamics are governed by the large-deflection, nonlinear, von Karman equation as expressed in low-order form through a Galerkin approximation. The aerodynamics are described by the Euler equations, which are reduced in order using proper orthogonal decomposition. The coupled system of equations is implicitly time integrated with second-order temporal accuracy to predict limit-cycle oscillation (LCO) amplitude, and linearly analyzed to predict LCO onset. The fluid is synchronized with the structure in time through subiteration, using only 18 degrees of freedom to describe the aeroelastic system. The Jacobian employed in the fully implicit analysis is of equivalently low rank, enabling rapid analysis. Using the reduced order model, LCO onset is predicted directly at a computational cost of approximately 400 time steps with a high accuracy verified by full-order analysis.