On the Vortex Flow Phenomena of a Triple-Delta-Wing Aircraft Configuration in Transonic Flows

Abstract

The present work focuses on the experimental investigation and characterization of vortex-flow phenomena of a generic triple-delta-wing configuration, like the DLR-F23 aircraft, under various transonic speeds and angles of attack. This experimental study is conducted at the Transonic Wind Tunnel in Göttingen, which allows for the exploration of multiple transonic flow regimes and several angles of attack using two advanced flow visualization techniques, namely stereoscopic particle-image velocimetry and fast-response, unsteady pressure-sensitive paint. From these flow visualizations, it is found that three distinct vortex systems develop over the surface of the DLR-F23 wing, namely an inboard, midboard, and outboard vortex, which respectively develop from the model forebody, strake, and main wing. These vortical structures are strongly dependent on the flow conditions, whether this concerns low-to-high transonic conditions and/or the wing angle of attack. In particular at higher transonic flows, significant compressible effects, such as shock fronts, develop that noticeably affect the vortices characteristics and behavior, including - but not limited to - vortex-vortex and vortex-shock interactions, their breakdown and/or merging. Upon these observations, future work may be directed towards further exploring these complex vortex-dominated flows under trans- and even supersonic flow conditions, whether this being done through dedicated experimental efforts and/or by employing advances numerical means. All this would allow developing more efficient and high performant triple-delta-wing aircraft configurations that could operate robustly across a wide range of flight conditions, (i.e., Mach numbers, pitch angles).