Abstract
This work describes the aerodynamic characteristics of an aircraft wing model with a Rüppell’s griffon vulture (RGV)-type winglet. A computational fluid dynamics (CFD) study using ANSYS 15.0 was conducted to study the effect of the RGV winglet on a rectangular wing. The NACA 65(3)-218 wing consists of 660 mm span and 121 mm chord length where the aspect ratio is 5.45. Eight different winglet configurations have been studied. Furthermore, the study is extended to study effect of cant angle and different angles of attack (AOA) to the winglet. A comparative study is done on aerodynamic features such as lift coefficient (CL), drag coefficient (CD), lift/drag ratio (CL/CD) and tip vortices to get the best RGV winglet design. The RGV winglet achieved highest CL compared to other types of winglets configuration. Based on contour plot analysis, the RGV winglet shows lower vortex formation compared to without winglet. The results show about 15 to 30% reduction in drag coefficient and 5 to 25% increase in lift coefficient by using an RGV winglet.
Highlights
One of the primary obstacles limiting the performance of an aircraft is the drag that stems from the vortices shed by an aircraft’s wings
The Rüppell’s griffon vulture (RGV) winglet lift coefficient (CL) and (CD) by simulation is compared with the experimental results
Further analysis revealed that the RGV (2) winglet decreases CD output to 15 to 30% and increases lift/drag ratio up to 25 to 75% compared to other type of winglets configuration
Summary
One of the primary obstacles limiting the performance of an aircraft is the drag that stems from the vortices shed by an aircraft’s wings. The strength of this induced drag is proportional to the spacing and radii of these vortices (Anderson 2004). The idea is to diffuse the strong vortices released at the wingtip and optimize the span wise lift distribution, while maintaining the additional moments on the wing within certain limits (McCormick 1967). Because the vortices shed by the wing are strongest at the tip of the wing, the addition of the wingtip surfaces can reduce and diffuse the strength of these vortices, reducing the overall induced drag of the aircraft. The minimum induced drag for planar wings is achieved for an elliptical lift distribution across the span which produces a constant wing downwash according to Munk’s theory (Houghton and Carpenter 2003)
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