Experimental and numerical analysis of wake vortex evolution behind transport aircraft with oscillating flaps

The aim of this study is to impose a disturbance on the velocity field already in the near field of the wake vortex system of a generic high-lift transport aircraft configuration by oscillating flaps. This should result in an excitation of long wave instabilities in the downstream development of the wake vortex system. For transient fast-response pressure probe measurements, experiments are carried out in the Göttingen-type low-speed wind tunnel C of the Chair of Aerodynamics and Fluid Mechanics of the Technical University of Munich. The vortex wake is captured at cross flow planes orientated perpendicularly to the freestream direction at nondimensional distances with respect of wing span b of x/b=0.5 and x/b=6. By means of the experimental data at x/b=0.5, a large eddy simulation (LES) is initialized, which solves the downstream development of the wake vortex system. A baseline configuration with statically deflected flaps is compared to a configuration with actuated flaps. It can be shown experimentally as well as numerically that a significant disturbance can be imposed already in the extended near field of the wake vortex system by oscillating flaps. Furthermore, there is a good agreement between the experimental and numerical data. Based on these results, the numerical model can be used for investigations of the farther downstream development of the wake vortex system up to vortex decay in future work.