Design Optimization of Vortex Generator for a Junction Vortex of Wing-Body Configuration by Discrete Adjoint Approach

Abstract

This paper deals with an adjoint-based design optimization of vortex generators to control a junction vortex of wing-body aircraft. The target geometry isthe DLR-F6, which is known to have some undesirable flow features caused by a wing-body junction vortex; thus, a vortex generator was adopted and optimized to eliminate the junction vortex without additional geometric parts,such asfairings. To enhance computational efficiency, the effects of the vortex generator were presented as a mathematical source term model instead of a fully gridded vortex generator. To check out the flow characteristics of the wing-body junction and to confirm the effects of the vortex generator in handling the junction vortex, nine cases of parametric study were performed at first and three baseline configurations were selected. Gradient based design optimizations using discrete adjoint approach were then performed with five design parameters of the chord length, the height, the angle of incidence, the streamwise (x-directional) position, and the wing spanwise (y-directional) or body circumferential (z-directional) position of the vortex generators. As a result of the parametric study, the lift to drag ratio (L/D) of the DLR-F6 increased a maximum of 4% under the same flight conditions. After carrying out the optimization of the vortex generators, the junction vortex was shrunk and weakened enough; thus, the aerodynamic performance of the DLR-F6 was substantially improved over 5% even in operating offdesign conditions.