Numerical Simulation and Reduced-Order Modeling of Airfoil Gust Response

Abstract

I. Abstract Computational Fluid Dynamics (CFD) based simulations, along with parametric and non-parametric Reduced-Order Models (ROM) for gust responses are presented. A CFD code is enhanced to simulate responses of an airfoil to arbitrary shaped gust inputs. Time-domain Auto-Regressive-Moving-Average (ARMA) models are identified based on CFD responses to random gust excitations, using system-identification methods. Responses to discrete gusts of various shapes, amplitudes and gradient lengths are computed via the ROMs and compared to responses simulated directly by the CFD code. The ROMs predict the lift and pitching moment histories accurately throughout the subsonic and transonic regimes. They offer significant savings in computational resources compared to the full CFD simulation, since only one CFD run is required for ROM identification, from which responses to arbitrary shaped gusts can be rapidly estimated. The combination of ROMs and full CFD simulations offers a computationally efficient tool set of various-fidelity time-domain models for gust responses. The ROMs can be used for rapid tuned-gust analyses, and the critical cases can be simulated with a full CFD run, providing pressure distribution for airframe structural design.