Simulation of C-130 H/J troop doors and cargo ramp flow fields

This article presents the results of a continuing computational effort to understand the flow field characteristics of a C-130 Hercules aircraft configured for personnel airdrop operations. Flight operations with either the troop door or cargo open lead to vortical structures and unsteady flows which can adversely affect airdrop operations. Simulation results using the CFD solver Kestrel, developed within the High Performance Computing Modernization Program CREATETM-AV program, show vorticity generated behind the open cargo door and with the flaps extended, a relatively strong vortex forms along the fuselage which traverses above the troop door into the upsweep section of the aircraft tail. Open troop door simulations capture large velocity gradients and unsteadiness for configurations with and without actuator disk propeller models and with and without sideslip. Simulations are computed on both converged hybrid meshes on the order of 100 × 106 cells and near-body/Cartesian off-body grids, and these results reconfirm that vortex modeling is dependent on mesh resolution around troop door or cargo ramp. The addition of a refined mesh near the troop door, in conjunction with using a delayed detached-eddy turbulence model, provided highly resolved flow physics in this region of interest.