Numerical study of aerodynamic performance of supersonic grid fin configurations

Abstract

This study investigates how interior lattice topology governs the supersonic aerodynamic performance of grid fins within a packaging-constrained design space using three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations. Because changes in subdivision level simultaneously modify frontal blockage, internal web area, and passage width, the resulting aerodynamic trade-off cannot be described by a single geometric parameter. Five representative configurations were examined over incidence conditions up to alpha = 10 degrees and Mach numbers from 1.5 to 5.0. The results show that lattice refinement produces a monotonic axial-force penalty, whereas lateral effectiveness exhibits a Mach-dependent optimum that shifts toward finer topologies as Mach number increases. Flow field analysis shows that this trend is governed by the Mach-dependent internal shock structure, which controls the onset of severe passage blockage and the associated aerodynamic losses. Additional diagnostic evaluations indicate that the overall aerodynamic response is determined primarily by the interior lattice topology, while perimeter trimming and moderate chordwise variations play secondary roles. Overall, the results suggest that the coupled fixed-envelope topology problem can be interpreted in terms of a Mach-dependent mechanism involving internal shock evolution and passage blockage, and that the resulting trends can serve as a compact basis for preliminary configuration screening within the present design space.