Simulation of combustion of a powder sample with grains distributed according to the normal law

Currently, pyrotechnic devices are widely used in rocketry. They are described by the same system of equations as a muzzle-loading smooth-bore gun. Meanwhile, as shown in the previous works of the authors, modern ideas about the internal ballistics of these weapons, apparently, are not correct. The article continues the cycle of works on the creation of a mathematical model of these systems. The article assesses the degree of influence on the muzzle velocity of the heterogeneity of the powder grains. It is shown that, regardless of the distribution law (normal or not), with a sufficient degree of accuracy (about 1.5%), the combustion of such grains can be approximated by the combustion of identical grains of any diameter from the selected range. The only prerequisite is the condition of equality of the initial combustion area.