Three Unstructured Computational Fluid Dynamics Studies on Generic Unmanned Combat Aerial Vehicle

Abstract

Three independent studies from the United States (NASA), Sweden (Swedish Defense Research Agency), and Australia (Defense Science and Technology Organization) are analyzed to assess the state of current unstructured grid computational fluid dynamic tools and practices for predicting the complex static and dynamic aerodynamic and stability characteristics of a generic 53-deg swept, round-leading-edge uninhabited combat air vehicle configuration, calledSACCON (which stands for “stability and control configuration”). NASAexercised theUSM3D tetrahedral cell-centered flow solver, while the Swedish Defense Research Agency and the Defense Science and Technology Organization applied the Swedish Defense Research Agency/EDGE general-cell vertex-based solver. The authors primarily employ the Reynolds-averaged Navier–Stokes assumption, with a limited assessment of the EDGEdetached eddy simulation extension, to explore sensitivities to grids and turbulencemodels. Correlations with experimental data are provided for force and moments, surface pressure, and off-body flow measurements. The vortical flowfield over SACCON proved extremely difficult to model adequately. As a general rule, the prospect of obtaining reasonable correlations of SACCON pitching moment characteristics with the Reynolds-averaged Navier–Stokes formulation is not promising, even for static cases. However, dynamic pitch oscillation results seem to produce a promising characterization of shapes for the lift and pitching moment hysteresis curves. Future studies of this configuration should include more investigation with higher-fidelity turbulence models such as detached eddy simulation.