Modeling and Simulation of the Combustion of Heterogeneous Solid Gun Propellant in Closed Vessels

A primary objective in propellant development is to increase the performance of gun systems. Additive manufacturing processes offer completely new and innovative possibilities for this purpose due to the great freedom in geometry and structure design. This work presents a model for simulating the combustion of propellants with complex grain geometry and macroscopic heterogeneous grain structure in a closed vessel. Since the burning velocity is a local quantity due to the heterogeneity, the surface regression can no longer be computed separately from the pressure evolution. The description of the surface propagation of the propellant grain during combustion is based on the level set method by Gomes and Faugeras. In every timestep the grain volume is determined using Monte-Carlo integration. The model of STANAG 4367 is used in a simplified form to describe the pressure evolution in a closed vessel. The presented model is used to simulate the surface regression of homogeneous and heterogeneous geometries, whereby each structure has its own constant velocity. Furthermore, the pressure evolution and the vivacity of the combustion of a homogeneous ball propellant is presented compared to the analytical approach.