Direct particle motion and interaction modeling method applied to simulate propellant burn

Abstract

A direct particle motion and particle interaction modeling method was developed to provide an alternative means of capturing the fundamental phenomena occurring during the burning of propellant grains. Individual propellant grains and other moving components are directly incorporated into the computational domain, removing the need for correlations for particle drag and interaction effects. The motion of the individual particles is calculated from the locally acting fluid induced and collision effect forces and moments. Particle/object interactions are handled through a soft particle collision algorithm. Localized mass and energy sources, accompanied by a shrinking particle size, simulate the effects of the combustion process.The method is applied to the burning of propellant in a two-dimensional planar gun type system. Parametric studies were performed varying the parameters related to the propellant and projectile to explore the capabilities of the current modeling method and to determine the sensitivity of the gas, propellant, and projectile conditions. The model captured the local pressure waves moving between the breech and the bullet base not observed using a bulk effect model. The results also indicated that the conditions in the system that are most sensitive to the burn rate exponent where a 24% increase in the exponent produced a 200% increase in the peak pressure at the breech. The study demonstrated the utility of this new model in exploring in particular the localized phenomena and conditions that develop during the burning of propellant.