Comparison of Real and Simulation Aerodynamic Coefficients for 155 mm Ammunition Using Open-Source Code SU2 Software

Abstract

In this study, density, energy, pressure, temperature changes, and drag coefficients occurring during the trajectory of movement for a 155 mm ammunition shell were simulated with the computational flow dynamics software Stanford University Unstructured (SU2). Reynolds-Averaged Navier-Stokes (RANS) equations, which are operationally simplified variations of the Navier-Stokes (N-S) flow solver, were used in the simulations. The Reynolds number based on the velocity was between 1.65x107 to 6.5x107 according to the Mach (M) number between 0.7 to 2.8 in the present simulation. The drag coefficients from 0.7 M to 2.8 M were obtained separately for each Mach 0.3 increase. The Free Computer-Aided Design (FreeCAD) program was used for geometrical drawings of the ammunition, the Geometry Description, Meshing, Solving, and Post-Processing (GMSH) software for mesh operations, and the Shear Stress Transport (SST) turbulence model to create a compressible finite volume. As well, 0 degrees was used as the angle of attack. For estimation of the aerodynamic coefficient percentage changes obtained from the simulations, exponential equations with the highest validity based on the R2 value were created. In addition, the calculated drag coefficients were compared with the actual values and a good fit was observed between them.