Combustion Processes in Consolidated Propellants

The use of consolidated or compacted conventional gun propellants offers the ballistician the opportunity for significant performance increases through effective use of very high loading densities on the order of 1.2 g/cc. Such loading densities will only be effective, however, if accompanied by an increase in surface area progressivity. We report the results of an experimental program surveying the effects of ignition stimulus and compaction density on the combustion of simple wafers of consolidated charges of single and double base propellants. We have found that sample confinement, surface inhibition, and grain geometric factors, have significant effects on charge break-up and propellant mass burning rate. In effect, the samples can behave with strong surface area progressivity. With a knowledge of the base grain propellant linear burning rate, independently arrived at, we have extracted instantaneous surface area profiles for burning consolidated propellants. The progressive character of the gas generation rate from burning consolidated charge samples can be explained on the basis of 'macroscopic progressivity' defined as the controlled release of surface area through a continuous deconsolidation process.