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Proposing Institution

Deutsches Zentrum für Luft- und Raumfahrt e.V. Göttingen
Project Manager

Dr. Axel Probst
Bunsenstraße 10
37073 Göttingen
Engine nacelles of modern commercial aircraft are often equipped with small vortex generators (strakes) to avoid early flow separation of the boundary layer of the main wing in low-speed flight. Without strakes, for high angles of attack massive flow separation appears on the main wing downstream the area where the slat is cut out due to the nacelle-wing connection. The longitudinal vortices generated by the strakes hit the upper side of the main wing and interact with the boundary layer. The details of this vortex-boundary-layer interaction are not yet well understood. Existing experimental and numerical results indicate that the interaction of the strake vortex with the boundary layer on the main wing is of significant importance to understand the stabilizing effect of the strake vortex on the main-wing boundary layer in order to optimize given strake/slat-cut-out/main-wing configurations.Therefore, the objective of this project is to establish a simulation method to predict and understand this strake-vortex-boundary-layer interaction for an airfoil in high-lift configuration at flight Reynolds numbers. To investigate the open questions of mesh design and resolution, as well as the modeling requirements in detail, a simplified test-case setup is introduced, in which a Delta wing generates a strake-like longitudinal vortex which interacts with the boundary layer on the two-element DLR F15 airfoil with deployed flap. To reproduce the longitudinal vortex and the vortex/boundary-layer interaction as realistic as possible, hybrid RANS/LES methods are applied. As the hybrid RANS/LES method, the Improved Delayed Detached Eddy Simulation (IDDES) is applied using the SSG/LRR-ω RSM as the underlying RANS turbulence model.Additionally, a synthetic turbulence generator is used here to introduce resolved structures at the RANS/LES interface.We want to perform a systematic study of the different simulation methods and to compare and assess the outcome of hybrid RANS/LES simulations in comparison to the pure RANS simulations and to experimental reference data.

Impressum, Conny Wendler