Aerodynamics of interfering vortex systems at low aspect ratio wings with multiple swept leading-edge

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Using slender, highly swept wings to achieve high maneuverability in the subsonic and transonic regime on the one hand and low supersonic drag on the other hand can lead to problems that usually do not result from the fulfillment of aerodynamic performance requirements, but are associated with undesirable stability and controllability characteristics. Typical problems at higher angles of attack are related to pitch-up and the divergence in the rolling moment derivative due to sideslip. In this context, multiple vortex systems, which occur at double or triple swept leading edges, can advantageously be used with regard to longitudinal and lateral stability in the high angle of attack range. The project therefore aims at an improved understanding of the flow physics of multiple vortex systems at low aspect ratio wings with staggered leading edge sweep. In contrast to the large data base for leading edge vortices shed at a single swept leading edge, there is a significant gap in the investigation and analysis of interfering vortex systems at staggered leading edge sweep and their impact on aerodynamic properties and stability characteristics. The separation and vortex topologies related to interfering and merging leading-edge vortices associated with multiple vortex systems will be analyzed in detail and the interference and merging will be characterized depending on leading edge sweep, downstream distance, pitch and sideslip angle. Furthermore, the influence of the interfering vortices on vortex bursting is to be investigated in order to assess to which extent a stabilization of the vortical flow can be achieved, which leads to improved flight control and reduction of buffeting phenomena. For the second funding period, the investigations concentrate on interfering vortex systems in the case of vortex evolution at round leading edges and, in particular, on interfering vortex systems in the high subsonic Mach number range, in which shock-vortex interactions dominate.