3D Flow Visualization of a Micro Air Vehicle with Winglets
Department of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales, (Oktober 2006)Zusammenfassung
The three-dimensional flow about a Micro Air Vehicle with winglets has been investigated using computational fluid dynamics. The wing tip vortex is resultant from the mixing of the high pressure flow under the wing with the low pressure flow over the wing at the wing tips. In low aspect ratio wings, such as those of MAVs, the wing tip vortex effects up to forty percent of the span. Winglets can be used to reduce the impact of the wingtip vortex by pushing it upward and outward of the wing.
The flow solver used is the open-source available Gerris Flow Solver developed by Stephane Popinet. Gerris is a laminar flow solver, solving the incompressible Euler equations. The GTSwing is a library of functions for Matlab and Octave that was developed to enable the three-dimensional representation of wings in the GTS format. The GTSwing library can generate a three-dimensional representation for a set of airfoil data and planform parameters. The source code for the GTSwing library is listed here, as well as the methodology of its operation.
Verification is always important in computation simulation of physical phenomena, and grid convergence studies for NACA0012 and NACA2412 airfoils were conducted to increase the level of confidence in the discretisation methods used.
In conclusion, the addition of winglets can delay the rollup of the tip vortex. Thus the effect of the sidewash and downwash is reduced. The results show that the effect of the wingtip vortex can be reduced by using a correctly designed winglet.