In the article we give the theoretical and numerical modeling of two-phase flow during the propagation of the flame in a granular medium. The theoretical model includes the balance equations for the two phases, as well as the necessary constitutive laws. The discretized equations of the model are incorporated into the calculation process, ensuring a convergent solution of the system of equations. Verification of the theoretical-numerical access is carried out by comparison with the experimental results. General access allows better resolution of many problems of interior ballistics.