Using an Anti-Fairing to Reduce Drag at Wing/Body Junctions

Junction flows occur when a boundary layer develops on a wall and encounters an obstacle protruding from this surface. When the obstacle generates enough of an adverse pressure gradient to separate the flow, the aerodynamic drag is increased. In this paper, aerodynamic shape optimization (ASO) is employed to optimize a wing/body junction geometry at a chord Reynolds number of ReC=9.7⋅105, where the wing is the protrusion and the body is represented by a flat plate. In contrast to conventional ASOs, the wing shape is kept fixed and only deformations of the body are allowed in order to study its influence on the junction drag. The obtained optimized design is characterized by a concave shape similar to a dent in the junction area and differentiates itself from the traditional convex fairings. For this reason, it is named the anti-fairing. Wind-tunnel experiments using stereoscopic particle image velocimetry in the wake of the junction area and a new set of Reynolds-averaged Navier–Stokes simulations with a ...