Numerical simulation and reduced-order modeling of airfoil gust response

Computational fluid dynamics (CFD) based simulations, along With parametric and nonparametric reduced-order models for gust responses are presented. A CFD code is enhanced to simulate responses of an airfoil to arbitrary-shaped gust inputs. Time-domain autoregressive-moving-average 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 reduced-order models and compared to responses simulated directly by the CFD code. The reduced-order models 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, because only one CFD run is required for reduced-order model identification, from which responses to arbitrary-sbaped gusts can be rapidly estimated. The combination of reduced-order models and full CFD simulation offers a computationally efficient tool set of various-fidelity time-domain models for gust responses. The reduced-order model 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.