Reduced-Order Nonlinear Unsteady Aerodynamic Modeling Using a Surrogate-Based Recurrence Framework

摘要

A reduced-order nonlinear unsteady aerodynamic modeling approach suitable for analyzing pitching/plungingnairfoils subject to fixed or time-varying freestream Mach numbers is described. The reduced-order model usesnkriging surrogates to account for flow nonlinearities and recurrence solutions to account for time-history effectsnassociated with unsteadiness. The resulting surrogate-based recurrence framework generates time-domainnpredictions of unsteady lift,moment, and drag that accurately approximate computational fluid dynamics solutions,nbut at a fraction of the computational cost. Results corresponding to transonic conditions demonstrate that thensurrogate-based recurrence framework can mimic computational fluid dynamics predictions of unsteadynaerodynamic responses when flow nonlinearities are present. For an unsteady aerodynamic modeling problemnconsidered in this study, an accurate reduced-order model was generated by the surrogate-based recurrencenframework approach with significantly fewer computational fluid dynamics evaluations compared to resultsnreported in the literature for a similar problem in which a proper-orthogonal-decomposition-based approach wasnapplied. Furthermore, the results show that the surrogate-based approach can accurately model time-varyingnfreestream Mach number effects and is therefore applicable to rotary-wing applications in addition to fixed-wingnapplications.