Investigation Of The Ground Effect On Wingtip Vortex Generated By A Rectangular Naca0012 Wing

Download or read book Investigation of the Ground Effect on Wingtip Vortex Generated by a Rectangular NACA0012 Wing written by Anan Lu and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The two stream-wise counter-rotating wingtip vortices generated behind aircraft and their interactions with the runway have always been a concern to aviation, airport traffic control, and aircraft manufacturers alike. For aircraft flying at constant distance from ground (i.e. Ground Effect Vehicles), the behavior of wake vortices and the lift-induced drag are being investigated as well. It was observed that lift increase and drag reduction are experienced by wings in ground effect. To further understand the phenomenon both qualitatively and quantitatively, the ground effect on the aerodynamics and tip vortex flow of a rectangular wing was investigated experimentally at Re=2.71×10^5. The results showed that there was a large lift increase with reducing ground distance. By contrast, a small drag increase was observed in ground effect except in close ground proximity for which a significant drag decrease appeared. The tip vortex also moved further outboard and upward with reducing ground distance. Near the ground, there was the presence of a corotating ground vortex (produced by the rolling up of the boundary layer developed on the ground surface), leading to an increased vortex strength. In extreme ground proximity, a counterrotating secondary vortex (SV) (induced by the crossflow of the tip vortex), relative to the tip vortex, appeared, which caused a reduced vortex strength and a lowered lift-induced drag, as well as a vortex rebound. The impact of ground effect on the vortex flow properties was also discussed. The lift-induced drag, computed based on the crossflow measurements via the Maskell wake integral method, in ground effect was compared against the inviscid flow predictions and wind tunnel total drag force measurements"--