NUMERICAL STUDY OF 2-DIMENSIONAL SOLID-GAS COMBUSTION THROUGH GRANULATED PROPELLANTS

In this paper, we deal with the governing equations of solid-gas two-p hase fluid flow and transient combustion processes of granular propell ants taking place in a gun chamber with a mobile projectile. We resort to a two-phase fluid dynamics model to model the solid-gas flow field . Due to the projectile motion, it is necessary to make the transforma tion from the coordinate parallel to the projectile motion to a new co ordinate that remains invariant with time. Too sets of transformed bas ic equations for each phase are analyzed numerically, together with th e constitutive equations for the intergranular stress, interphase drag , interphase heat transfer, diffusivity coefficients, and burning rate . In addition, an ignition criterion for the propellant grains must be given. The Noble-Abel equation of state was used for the gas phase in the present analysis. A finite volume method was employed to discreti ze the basic equations for both the compressible gas phase and propell ant solid phase. The derived algebraic equations in a staggered grid s ystem, by using an upwind scheme to approximate total fluxes, were sol s,ed iteratively by the newly proposed SIMPLE-COM solution algorithm. In this study, we address the variations of flow structure and physica l properties during the ballistic cycle.