FORMATION AND STRUCTURE OF VORTEX SYSTEMS GENERATED BY UNFLAPPED AND FLAPPED WING CONFIGURATIONS

The formation and structure of concentrated vortices in the wake of li fting wings is a topic of great basic and practical interest. In this paper vortex systems, generated by unflapped and napped wing configura tions with rectangular planform, were investigated by LDA measurements and flow visualization techniques in a water tunnel and a towing tank . The experimental results are used for a comparison with three theore tical approaches. Numerical solutions of a modified Birkhoff/Rott (B/R ) equation and a two-dimensional vortex transport equation (VTE) are p resented. Moreover, a modification of known parametric vortex models i s proposed and applied to the simpler unflapped case. Both numerical a pproaches are, in principle, suitable to describe the development also of multi-vortex systems. But in cases where vortices coalesce or the ageing process is of interest, the application of the VTE-method is ma ndatory. If the initial distribution of vorticity is given, the result s of the two-dimensional VTE-method are found in very good agreement w ith experiments both with regard to the vortex structure and the locat ions of the vortices.