Aerodynamic Optimization of Essentially Three-Dimensional Shapes for Wing-Body Fairing

A new approach for the optimization of essentially three-dimensional aerodynamic shapes for minimum drag is proposed. The method allows the handling of the nonlinear surfaces that are typical of complex aircraft junctions such as a wing-body fairing. The optimization framework OPTIMAS, previously proposed and developed by the authors for the solution of the drag-minimization problem for two-dimensional airfoils, three-dimensional isolated wings, and three-dimensional wings in the presence of a body in succession, is extended in this paper to a significantly higher level of geometrical complexity of optimized aerodynamic configurations. The method is driven by accurate full Navier-Stokes evaluations of the objective function, and the optimization engine is based on genetic algorithms. The important features of the method are the ability to accurately handle multiple geometrical/aerodynamic constraints and a high level of computational efficiency, achieved through massive multilevel parallelization and a reduced-order-model approach. The method was applied to the optimization of a wing-body fairing for a generic business jet configuration at realistic transonic cruise flight conditions. The results demonstrate that the proposed approach achieves significant drag reduction in on- and offdesign conditions and can be used in an engineering environment.