Interior ballistics simulation of the AGARD gun using two-dimensional axisymmetric solid/gas two-phase flow model and effectiveness of simulation method

The interior ballistics simulations were carried out using the developed codes of the lumped parameter method and the solid/gas two-phase flow model for two-dimensional axisymmetric calculation, in order to reproduce the combustion process of the granular solid propellant in the chamber of projectile accelerator. Predicted results for AGARD gun condition by the lumped parameter method and two-dimensional axisymmetric calculation code using the representative particle method were compared with the results of the other codes for validation, and were in good agreement with that of the other codes. The predicted histories of the breech pressure and projectile muzzle velocities well agreed between the lumped parameter method and two-dimensional axisymmetric calculation codes, but there was clear difference in these histories of differential pressure since the pressure distribution in the two-dimensional axisymmetric simulation are quite different from the assumption in the Lagrange pressure gradient model of the lumped parameter method. Two-dimensional axisymmetric calculation predicted that the projectile base pressure rises and the differential pressure takes negative value in the ignition stage due to the movement of solid propellant grains. The predictive capability and effectiveness of solid/gas two-phase flow simulation for interior ballistics events, where the large distribution of solid phase volume exists, were shown by the simulated results.