ANALYSIS OF THE COMBUSTION, BURN RATE, AND GRAIN STRUCTURE OF AMMONIUM NITRATE AND BADGE BASED PROPELLANT

Resumo

A rocket solid propellant is a compacted grain of a mixture of a fuel, an oxidant, and a binder. During the combustion process it produces a flux of hot gases intended to produce work through a rocket propulsion system. Two important and most desirable characteristics of a solid propellant are grain high stability and non-toxic trace. Ammonium nitrate oxidant releases low production of toxic traces, such as nitrogen oxides and chlorinated compounds. As a binder, BADGE presents easy handling and good resistance to shock and humidity when cured in a grain. Grains of ammonium nitrate and BADGE with aluminum and iron oxide III, as catalysts, were built and tested. Three different formulations were tested with fixed 8% in mass of aluminum or iron oxide, and varying ammonium nitrate from 60% up to 75%. The measurements of burn rate were conducted in standard ambient temperature and pressure. Gravimetric comparison of ashes and calculation of burning products via numerical simulation methods were carried out. The results presented a significant relationship between the burn rate and the ammonium nitrate concentration. The use of aluminum and iron oxide modified this relationship due to changes in oxygen consumption dynamics, leading to a change in flame temperature. It was also shown that a presence of aluminum elevates the production of CO, while iron oxide III maintained approximated values of non-catalyzed process. The soot formation was present in all formulations.