A400M Wake Flow Studies Based on RANS CFD Methods on Hybrid Meshes

Knowledge of flow conditions in the vicinity of the aft section of military transport aircraft is crucial to ensure the safe and precise deployment of personnel and material. CFD methods used by Airbus and DLR allow valuable predictions of these conditions, taking into account the influence of flow deflectors, sponsons, open cargo hold doors/ramps, as well as propulsion slip-streams. With the requirement of precisely delivering personnel and/or equipment into an area of limited size, while guaranteeing safe conditions for the airframe (as well as paratroops/dropped equipment), military transport aircraft pose unique challenges to aerodynamics. Among them: Guaranteeing the safety of parachutists, whose near aircraft trajectory is significantly influenced by the aircraft wake shedding substantial vorticity (the safe separation problem); and providing safe operational conditions within the aircraft, while open doors strongly influence the internal air flow. Within this study, the hybrid Reynolds-averaged Navier-Stokes (RANS) multigrid flow-solver TAU, developed by the German research centre DLR, is used to assess the possibility of providing CFD support to such complex flow conditions as those occurring in the A400M military transport programme context. See also ADM202394. Presented at the Specialists' Meeting of the Applied Vehicle Technology (AVT) Panel entitled Fluid Dynamics of Personnel and Equipment Precision Delivery from Military Platforms held in Vilnius, Lithuania, on 2-3 Oct 2006. Published in the proceedings of the meeting, RTO-MP-AVT-133, p7-1 through 7-12, 2006. Prepared in cooperation with Institute of Aerodynamics and Flow Technology, DLR Braunschweig, Germany. The original document contains color images.