On an Innovative Approach to account for Gust Aerodynamic Nonlinearities

This paper presents a novel approach to computing aircraft total loads generated by a gust encounter. Nonlinear aerodynamic effects, especially relevant in transonic regime, are accounted for. The use of panel-method aerodynamics including some steady corrections is common practice in the industry. The proposed Reduced Order Model (ROM) includes CFD predicted nonlinear unsteady aerodynamic effects by correcting the Aerodynamic Influence Coefficient (AIC) matrix in a certain reduced frequency range. In a linear gust aerodynamic region only one CFD computation is needed to generate the ROM. In a nonlinear region the aircraft motion is considered together with the gust in order to account for the aerodynamic nonlinearities by using one CFD computation for the specific gust. The methodology is described and applied to a relevant transonic case.