Quasi-periodic Time-Spectral Methods for Flutter and Gust Response

Periodic and quasi-periodic time-spectral methods are applied to the demanding problems of aeroelastic flutter and gust response. Both a standard time-implicit method and a quasi-periodic time-spectral method are developed that take into account the coupling among the three fundamental aspects of computational aeroelastic calculations: unsteady flow equations, time dependent structural response to aerodynamic loads, and moving meshes. Results from the timeimplicit and time-spectral methods are then compared in order to demonstrate the capability of time-spectral methods to solve aeroelastic and gust response problems. Results from many different coupled fluid/structure problems are presented for two-dimensional representations of both fixed-wing and rotary-wing aeroelastic response both with and without gusts of different lengths. It is shown that time-spectral based methods can be used to solve every reasonable combination of airfoil motion and gust response that has thus far been attempted, as presented in the current work.