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The focus of this paper is on methods to solve problems of transonic flow during an aircraft design study. The methods are based on the theory of the infinite shearing wing, refined by understanding of finite wing effects and isobar pattern. The equations required for plan form design and optimization are derived in order to give an aero-structural-design-tool the boundary requirements related to transonic flow. Empirical estimations to link Mach number lift coefficient and thickness are as far as possible avoided. Consequently airfoil data like the pressure distributions as well as the drag and lift divergence Mach numbers and so on are obtained from CFD calculations. The difference of effective sweep in the results of a Vortex Lattice Method and CFD codes are demonstrated on a finite wing as an example. It's shown that the effective sweep angle of a forward swept wing has the tendency to increase depending on the calculation error in contrast to a conventional backward swept wing where the sweep angle decreases. Furthermore a method is demonstrated which allows an easy and fast adaptation of the wing geometry, based on 2D airfoil data in order to achieve a design point with desired sweep and lift distribution. The methods are suited for single finite wings or joint and non-planar wing systems. The setup and grid generation of 2D and 3D models for turbulent CFD analysis at transonic speeds will not be regarded in this paper.
Deutscher Luft- und Raumfahrtkongress 2013, Stuttgart
Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn, 2014
21,0 x 29,7 cm, 10 Seiten
Stichworte zum Inhalt:
highly non-planar, transonic aerodynamics