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Wingtip vortices are an important phenomenon in fluid dynamics due to their complex and negative impacts. Despite numerous studies, the current understanding of the inner vortex is very limited, thus a basis for the design of effective wingtip geometry and vortex manipulation is narrow. This work examines the structure of the trailing vortex shed from a swept-tapered wing; analogous to a commercial aircraft topology. Stereoscopic particle imaging velocimetry (sPIV) has been utilised to compare the vortex structure and development through several angles of attack at various downstream stations for a fixed Reynolds number (Re = 1.5 × 10 6). After correcting for vortex meander, through helicity-based spatial localisation of the vortex core, relationships between the vortex core velocity/vorticity fields, core shape, and turbulent properties have been examined. Subsequently, the vortex is found to exhibit a layered structure with slow linear rates of dissipation indicative of laminar diffusion mechanisms: despite being a turbulent vortex. The turbulent kinetic energy distribution in the vortex signals that relaminarisation of the inner core occurs. Consideration of the streamline curvature around the core, via examination of the local Richardson number, indicated that a laminar core structure had formed within which large scale turbulent eddies could not contribute to the turbulent diffusion of vorticity away from the core. The normalised circulation within the vortex core has been shown to exhibit self-similar behaviour typical of fully developed axisymmetric vortices.

Non-planar wing configurations are often hypothesised as a means for improving the aerodynamic efficiency of large transport aircraft; C-wings may have the ability to exploit and unify drag reduction, aeroelasticity, and dynamics and control but their capacity to do so is ambiguous. The purpose of this work is to provide an experimental demonstration with the aim of verifying the C-wing configurations practical application. Thus, the main objective of this investigation is to

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A novel population structured genetic algorithm (sGA) with embedded potential flow vortex ring panel method (VRM) has been developed to minimise induced and parasitic drag subject to constraints on lift, root bending moment, and longitudinal static stability. The optimisation architecture can activate up to four independent wing segments allowing up to 28 design variables. Minimum drag of wing tip extensions and winglet configurations are compared using the non-linear stochastic optimisation method. The optimiser identified joined box wings as offering the greatest induced efficiency followed by C-wings. With span and root bending moment constraints winglets offered best total drag reduction. C-wings are further investigated for potential to enhance longitudinal static stability performance by staggering the horizontal extension of the winglet to balance moments around the wing's centre of gravity. Preliminary results suggest that while longitudinal static stability can be reached it would be very poor. Inclusion of more design constraints and additional analysis of the structural dynamics of C-wings, especially effecting the torsional mode, is necessary.