Numerical Investigation of Blended Winglet Effects on Wing Performances: Winglet Aerodynamics
Author
Lambert, Dimitri
Term
10. term
Education
Publication year
2008
Pages
98
Abstract
Brændstofpriserne har været stigende i årtier, og kommerciel luftfart er meget følsom over for omkostninger og rentabilitet. En måde at sænke brændstofforbruget på er at bruge vingespids-enheder (winglets), små flader ved vingens spids, der kan begrænse tab fra vingespidshvirvler. Men det er stadig vanskeligt at simulere luftstrømmen omkring winglets præcist. I dette arbejde modelleres tre typer winglets: en simpel winglet, en blended winglet og en nedstrøms-forskudt winglet. Da eksisterende analytiske modeller for 3D-vinger ikke kan beskrive effekterne af vingespids-enheder, udføres undersøgelsen numerisk. Der bygges to geometriske modeller med forskellig tykkelse for at repræsentere to yderpunkter. Resultaterne viser, at winglets giver bedre aerodynamisk ydeevne med hensyn til løft og modstand. Trykgradienterne bevares helt ud til vingespidsen, så vingen forbliver effektiv over hele spændvidden. Winglets svækker og flytter den primære vingespidshvirvel ud mod winglettens spids, hvilket giver en mere ensartet strømning nær spidsen. Hvis winglettens vinkel er for skarp, kan der dog opstå en hjælpehvirvel ved samlingen. Blandt koncepterne passer den blended winglet bedst til vingespidsen og hjælper med at undgå en sådan hvirvel ved samlingen. Selv om modellerne er idealiserede, giver de et første, overordnet billede af, hvordan winglet-geometri påvirker aerodynamikken omkring en vinge.
Fuel costs have risen for decades, and commercial aviation is highly sensitive to fuel efficiency and profitability. One way to cut fuel use is to add wingtip devices (winglets), small surfaces at the wing tip that can limit losses from wingtip vortices. However, accurately simulating the airflow around winglets remains challenging. This thesis models three winglet types: a simple winglet, a blended winglet, and a winglet shifted downstream. Because existing analytical models for 3D wings do not capture wingtip device effects, the study is conducted with numerical simulations. Two geometric models with different thicknesses are built to represent extreme cases. Results show that winglets improve aerodynamic performance in terms of lift and drag. Pressure gradients are maintained up to the wing tip, so the wing remains effective across its span. Winglets weaken and displace the main tip vortex toward the winglet tip, leading to more uniform flow near the tip. If the winglet angle is too sharp, an auxiliary vortex can form at the junction. Among the concepts, the blended winglet fits the wing tip best and helps avoid this junction vortex. Although simplified, these models offer an initial, general picture of how winglet geometry influences wing aerodynamics.
[This abstract was generated with the help of AI]
Keywords