Accelerating computational fluid dynamics based aeroelastic predictions using system identification

System identification is evaluated as an efficient and accurate technique for modeling unsteady aerodynamic forces for use in time-domain aeroelastic analysis. In the system identification methodology, the constant coefficients of a linear system model are fit to the computed response time histories from a three-dimensional, unsteady computational fluid dynamics (CFD) solver. The resulting model of the unsteady CFD solution is independent of both dynamic pressure and structural parameters. Hence, this methodology has the advantage that only one CFD flowfield computation for each Mach number must be completed to determine the aeroelastic instability boundary. Results show that system identification can accurately model the unsteady aerodynamic forces for complex aerospace structures of practical interest. The methodology results in a substantial savings in computational time when predicting aeroelastic instabilities.