Experimental Investigations of Vortex Flow Phenomena on the DLR-F23 Combat Aircraft Configuration at Transonic Speeds

Abstract

Modern high-agility aircraft are designed to cover a wide range of flight maneuvers, from transonic and supersonic performance to high maneuverability at subsonic speeds. The required flight envelope and mission spectrum of future multi-role combat aircraft lead to the development of new configurations with low aspect-ratio hybrid-delta wing planforms, consisting of multiple swept leading edges (LE). The corresponding flow field is dominated by complex vortex flows even at small angles of attack (AOA), vortex-vortex interactions and vortex-shock interactions, as well as vortex breakdown. These unsteady flow phenomena interact with the aircraft structure. The structural dynamics excitation, which is called buffeting, affects the maneuverability of the aircraft and reduces the lifespan of structural components. The design of the wing planform in terms of different leading edges with different LE sweep angles and additional leading-edge extensions (LEX) has, for this reason, a significant impact on the complexity of the vortex-dominated flow field and the occurring unsteady flow phenomena.