Flow simulation and drag decomposition study of N3-X hybrid wing-body configuration

Abstract

Flow simulation and drag decomposition study was conducted for the flow field around the clean airframe of the N3-X hybrid wing body configuration at a cruise flight condition. Adopted flow solver was GO-flow; an unstructured hybrid mesh cell-vertex finite volume RANS solver. The OVERFLOW code was also used to cross check the results. We have found that the major flow features such as surface pressure distributions and shock waves from the two flow solvers were almost identical to each other. Evaluation of drag force using near- and mid-field approaches was also conducted. Comparisons of various drag components between two tested CFD codes are examined with various grid resolutions for angle of attack sweep at the cruise condition. From the results, it is recommended for the computational mesh of the unstructured CFD code to have anisotropic (stretched) meshes near the leading and trailing edges and enough resolution in wake regions for accurate estimation of the drag coefficient. Nacelle installation effects were also tested using inviscid simulations by flow-through single-passage nacelle and mail slot nacelle, and it was found that fan suction effects should be properly considered for the accurate modeling of the nacelle installation effects. Lessons learned in this study enhance confidence in using CFD based integrative approach to encompass design of future hybrid wing body aircraft.