State-Space Models from CFD-Based Pulse Responses

A method for computing discrete-time state-space models of linearized unsteady aerodynamic behavior directly from aeroela_tic CFD codes is presented. The method involves the treatment of CFD-based pulse responses as Markov parameters for use in a system identification/realization algorithm. Results are presented for the AGARD 445.6 Aeroelastic Wing with four aeroelastic modes at a Mach number of 0.96 using the EZNSS Euler/Navier-Stokes flow solver with aeroelastic capability. The System/Observer/Controller Identification Toolbox (SOCIT) algorithm, based on the HoKalman realization algorithm, is used to generate 15th- and 32nd-order discrete-time state-space models of the unsteady aerodynamic response of the wing over the entire frequency range of interest.

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