Effects of Viscous Unsteady Aerodynamics on Nonlinear Aeroelastic Model

A nonlinear aeroelastic model for a flexible panel is expanded to consider the effect of the viscous boundary layer using a Reynolds-averaged Navier–Stokes (RANS) solver. This study presents the use of the dynamically linearized time-domain approach reduced-order model to compute the generalized aerodynamic force from a computational fluid dynamics (CFD) simulation within the nonlinear aeroelastic solver. Results obtained using the RANS approach are compared with those using an inviscid CFD solver and also the full potential flow. The flutter onset critical condition is obtained based on the limit cycle oscillation amplitudes for a range of supersonic Mach numbers. Additionally, the effect of different viscous boundary-layer thicknesses is explored. Conclusions are made based on the application of this more complete aerodynamic theory, particularly for near-transonic Mach numbers.