Correction of Linearized CFD-Based Unsteady Aerodynamic Models

With the increase of computational power, the use of linearized frequency domain computational fluid dynamics (LFD) has become feasible for modeling unsteady aerodynamic gust loads. Compared to potential flow theory, LFD allows to incorporate more realistic geometries, viscous and transonic effects. Still, means to update the LFD aerodynamic model to measurements from wind tunnel experiments or flight test are needed. In the current paper, this is achieved by combining LFD with potential flow theory in a hybrid fashion. That is, the LFD flexible aerodynamic models are adapted to aerodynamic data by an increment derived using a linear panel method. To validate the method, an aerodynamic model of rigid and flexible modes of the LANN wing is computed using LFD linearized about alpha 1. This model is corrected using the rigid body mode aerodynamic model of a second linearization alpha 2. The resulting flexible mode aerodynamics of the corrected model is subsequently compared against a direct computation at alpha 2, and a model corrected using simple pressure factors. The results show a signifi�cant improvement of the flexible modes' lift and moment gradient distributions over the pressure factor correction approach.