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 3-D, unsteady 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 flow-field 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.
Research presented in this paper illustrates the implementation of the transpiration boundary condition in steady and unsteady aeroelastic and aeroservoelastic simulations. For two reference cases, the AGARD 445.6 wing and the BACT wing with a finite-span flap, application of the transpiration method has demonstrated the effectiveness of applying the transpiration boundary condition at a variety of Mach numbers on configurations of practical interest. Additionally, the effectiveness of the transpiration method is demonstrated by its ability to model large scale continuous and discontinuous surface deflections without the computational expense of re-meshing at each CFD time-step. Nomenclature CFD Computational Fluid Dynamics M Mach Number ASE Aeroservoelasticity C P Pressure Coefficient α Angle of Attack (deg) δ Control Surface Deflection (deg) q Generalized Displacement Φ Modal Displacement Matrix η Generalized Displacement Vector
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.