Numerical Analysis of Gun Barrel Pressure Blast Using Dynamic Mesh Adaption

A Computational Fluid Dynamics (CFD) method has been applied to simulate the pressure blast of the projectile which is launched from a barrel and to investigate the pressure distribution and sound pressure level (dB) along different positions away from the gun axis and towards the fuselage of the aircraft. Fluent was employed to simulate the unsteady flow using dynamic mesh with moving boundary. Most CFD based ballistics-model requires additional thermodynamic functions which must be derived from the Noble-Abel equation of state. The unsteady, axisymmetric Navier Stokes equation systems were numerically solved using the Advection Upstream Splitting Method (AUSM) scheme; with third-order Monotone Upstream centered Scheme for Conservation Laws (MUSCL) approach. The computed results reasonably capture the major flow features such as shock waves, blast waves, vortical flows, etc. which are generated in launching a projectile up to supersonic speed. The projectile mass and the initial conditions behind the projectile for inviscid cases have been varied to investigate its effect on the flow field and were compared with other available CFD results. Viscous effects of unsteady projectile aerodynamics were studied and conclude that the inclusion of viscous terms is essential for a more realistic mathematical model of the muzzle blast