Examining the effects of different winglet designs on aerodynamic forces using computational fluid dynamics

Abstract

The pursuit of better aerodynamic efficiency in aircraft design has led to significant advancements, with winglets being one of the most impactful innovations. Winglets are aerodynamic extensions at the tips of an aircraft’s wings designed to reduce induced drag by minimizing wingtip vortices. This reduction in drag improves lift-to-drag ratios, leading to fuel savings, extended range, lower carbon emissions, and quieter flight operations. Over time, various winglet designs have emerged, including bio-inspired configurations, each offering distinct aerodynamic advantages. While traditional wind tunnel tests remain useful, Computational Fluid Dynamics (CFD) has become essential for optimizing winglet geometry, providing insights into flow fields and aerodynamic forces under various conditions. Despite progress, designing universally optimal winglets remains challenging due to the need to balance lift, drag, structural strength, and manufacturing feasibility. This thesis uses CFD to examine the effects of different winglet geometries on aerodynamic performance, contributing to a deeper understanding of their impact on efficiency. First, an intensive review of the current literature related to CFD studies of winglets was carried out. The different setups used in literature combined with further information obtained through background theory research were used to determine the set up used for the simulations carried out in this thesis. Within this study, no winglet, raked winglet, fenced winglet, blended winglets and split winglet models were analysed. In this thesis, the end section of the winglet attached to the full wing geometry and the end geometry by themselves were analysed and compared. These results provided similar trends for both geometries, with the raked winglet providing the highest lift-to-drag ratio, followed closely by the blended winglet. From this study, the split and fenced winglet provided the lowest values of lift-to-drag ratio meaning that these winglets were the least efficient. Furthermore, to analyse clearly the trailing vortices formed behind the winglet, another set of simulations were carried out with the same geometry and domain, only editing the mesh to be more refined behind the wing. This resulted in a more clear display of the vortices, making it easier to compare how the different winglets effected the formation of these vortices. The effect of the Cant angle on blended winglets was also analysed, to see which model produced the best lift-to-drag ratio. The results were very close to each other. The 45° Cant angle winglet produced the best results, closely followed by the 30° Cant angle model and lastly by the 60° Cant angle model.