Abstract
Winglets are commonly used drag-reduction and fuel-saving technologies in today’s aviation. The primary purpose of the winglets is to reduce the lift-induced drag, therefore improving fuel efficiency and aircraft performance. Traditional winglets are designed as fixed devices attached at the tips of the wings. However, because they are fixed surfaces, they give their best lift-induced drag reduction at a single design point. In this work, we propose the use of variable cant angle winglets which could potentially allow aircraft to get the best all-around performance (in terms of lift-induced drag reduction), at different angle-of-attack values. By using computational fluid dynamics, we study the influence of the winglet cant angle and sweep angle in the performance of a benchmark wing at a Mach number of 0.8395. The results obtained demonstrate that by carefully adjusting the cant angle, the aerodynamic performance can be improved at different angles of attack.
Highlights
Aircraft winglets are small wing extensions attached at the wingtips, which are angled upward or downward.They can bend smoothly up like birds’ wingtip feathers in flight
We discuss the results of the aerodynamic performance of the wing with a variable cant angle winglet in reference to the baseline wing
By looking at these figures, we can notice the influence of the sweep angle on the drag polars, that is, as we increase the sweep angle, the drag polar curves are shifted upwards and this trend contributes to an improvement of the aerodynamic performance, i.e., for the same lift coefficient less drag is produced
Summary
Aircraft winglets are small wing extensions attached at the wingtips, which are angled upward or downward (but operational requirements and ground clearances favor winglets bent upwards). They can bend smoothly up like birds’ wingtip feathers in flight. This wingtip feather slotted configuration is thought to reduce the lift-induced drag caused by wingtip vortices. Tucker [1] showed that the presence or absence of these tip slots has a significant effect on the drag of birds. The slots appear to reduce drag by vertical vortex spreading, because the greater wingspan and other differences in the bird with intact tip slots did not entirely account for its lower drag
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