Wing Tip Vortices from an Exergy-Based Perspective
2015; American Institute of Aeronautics and Astronautics; Volume: 52; Issue: 4 Linguagem: Inglês
10.2514/1.c032854
ISSN1533-3868
AutoresMuhammad Omar Memon, Kevin Wabick, Aaron Altman, Rainer Buffo,
Tópico(s)Computational Fluid Dynamics and Aerodynamics
ResumoThe lens of exergy is used to investigate a wingtip vortex in the near wake over a range of angles of attack. Exergy is the measure of thermodynamically “available” energy as determined through the more discriminating second law of thermodynamics. Experiments were conducted in a water tunnel at Institute of Aerospace Systems at Aachen. The data were taken three chord lengths downstream in the Trefftz plane of an aspect ratio 5 Clark-Y wing with a square-edged wing tip using particle image velocimetry. Intuitively, the minimum available energy state is expected to correspond to the maximum lift-to-drag ratio angle of attack. This, however, is not the case here. Most interestingly, although only two-dimensional Trefftz plane data were used to obtain the exergy distribution across the individual wing-tip vortices, the crossover point for the out-of-plane change from wakelike to jetlike wing-tip vortex core axial flow (indicating the peak lift-to-drag ratio) is identified by the in-plane exergy distribution. This crossover point is not identifiable in the evaluation of any other characteristics calculated from in-plane quantities. Consequently, the exergy method holds promise as a metric for the improvement of aircraft performance through the reduction of lift-induced drag.
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