Linear reduced order modelling for gust response analysis using the DLR-TAU code

Abstract

A unified modelling approach, using computational fluid dynamics, to calculate the flutter stability and dynamic gust response of realistic aircraft models is outlined. The approach uses an eigenmode decomposition of the coupled problem combined with a (linear or nonlinear) Taylor expansion of the nonlinear, full order residual function. The necessary information for the flutter stability analysis, aerodynamic influence coefficients, is readily calculated. The aerodynamic influence is presented in a form which is in line with industrial practice using corrected doublet lattice method aerodynamics. Based on the stability analysis, eigenmodes are used to produce a reduced model for the gust response analysis. With the projection of the full order system on the eigenmode basis, a small set of equations governing the dominant dynamics is found. The approach is general to work with a variety of numerical schemes for the different physics involved in the coupled problem. In addition, arbitrary parameter variations can be included in the reduced model. The methods are used herein for the computational fluid dynamics solver DLR–TAU, which is adopted by industry throughout Europe, for aerodynamics. Structures are described by the standard modal form of a finite–element model. While pre–computations to evaluate the reduced order model require heavy computational resources, the reduced model can be solved in a matter of seconds on a desktop machine. The test cases presented to demonstrate the modelling capability include a wing structure and a realistic passenger aircraft

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ORCID for A. Da Ronch: orcid.org/0000-0001-7428-6935

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