Experimental methods for studying the combustion of granular powders in a broad range of process parameters

The combustion of granular powders is studied in a broad range of loading densities. The nontraditonal design of manometric bombs and the model ballistic installations on which the conditions close to a real detonation were simulated were used. It was established experimentally that the instability of a shot from a light–gas gun is caused by poor reproducibility of the ignition and combustion of powders fired at a loading density of $\Delta\lesssim$ 0.5 g/cm$^3$. It is shown that the differences between the specific features of gas formation upon combustion of fine tubular and multiperforated powders under conditions of a classical manometric bomb ($\Delta\le$ 0.3 g/cm$^3$) and in a real shot ($\Delta\ge$ 0.6 g/cm$^3$) are connected not only with the nonstationary character of combustion, but also with the dependence of the shape of a burning grain (area of the burning surface) on experimental conditions and, in particular, on the loadng density. It is shown that the use of a stepwise dependence of the factor in a geometrical law of combustion allows one to obtain a good agreement between the experimental and calculated pressure curves, including the ignition period, which makes it possible to describe the combustion of combined charges more correctly.