Aerodynamic Design of Wing-Body-Nacelle-Pylon Configuration

Aerodynamic design optimization is conducted for DLR-F6 wing-body-nacelle-pylon configuration adopting an efficient surface mesh movement method. A three-dimensional unstructured Euler solver and its discrete adjoint code are utilized for flow and sensitivity analysis respectively. The design objective is to minimize drag and reduce shock strength on pylon surface to decrease buffet risk at a climb condition. Shape deformation is made by variation of inboard wing and pylon section shape, nacelle vertical location and nacelle pitch angle. Hicks-Henne shape functions are adopted for the inboard wing shape and pylon shape perturbation. Totally 82 design variables are defined. Four design constraints are considered in the optimizer, three for wing section and one for pylon section maximum thickness. Lift constraint and Mach number constraint on pylon surface are satisfied by adding relevant penalty terms to the objective function. Design iterations converged to obtain a drag coefficient reduced by 16 counts retaining specified lift coefficient and satisfying the constraints. Shock wave strength around pylon surface was remarkably reduced by the design. The successful design results validate effectiveness and efficiency of the present design approach.