Numerical modeling of wave processes accompanying combustion of inhomogeneously distributed composite propellant

A mathematical model and a numerical method are proposed for studying the interior ballistic process related to combustion of inhomogeneously distributed propellant in the two-dimensional axisymmetric approximation. The gas–propellant mixture is modeled by a two-phase nonequilibrium heterogeneous medium consisting of a multicomponent gas phase of combustion products and a polydisperse solid phase of propellant granules. The mathematical model of nonequilibrium two-phase flow is based on the nonconservative Euler equations. A Godunov-type scheme with an approximate Riemann solver is developed for their solution. The propellant combustion is considered taking into account the motion of the projectile, which is modelled using the free-boundary method. Results are represented concerning the origin and evolution of the interior ballistic wave process proceeding during the combustion of an inhomogeneously distributed propellant charge and the motion of the projectile. A comparative analysis with the case of static (nonmoving) propellant is carried out.