Published 6 issues per year
ISSN Print: 2150-766X
ISSN Online: 2150-7678
Indexed in
ON THERMOCHEMICAL CHARACTERISTICS OF AP/NSAN/HTPB COMPOSITE PROPELLANTS
ABSTRACT
The first part of the work concerned the evaluation of the environmental impact of ammonium perchlorate / non-stabilised ammonium nitrate / hydroxyl terminated polybutadiene composite propellants and determination the HCl concentration in the combustion products of the propellants. The results, obtained by electrometry and precipitation titration, were compared with those obtained with a numeric code that allows to consider up to m (m < 20) reacting atomic species and the possibility of formation of n (n < 40) chemical components, by combination of the m atomic specks. There is good correlation between experimental and theoretical values. The influence of non-stabilised ammonium nitrate content on linear regression rates of the propellants was assessed. The experimental results, obtained in a classic Crawford bomb by the fuse wires method, allowed the determination of the Vr (P) evolution of the formulations. The ignition delay, τi, of the formulations was also studied. Small test samples of the propellants were submitted to radiative beating in an electrical furnace. The ignition instant was determined by the simultaneous obtainement of a sharp rise of the output of a thermocouple and a minimum surface temperature. The analysis of the results showed that increasing weight content of non-stabilised ammonium nitrate originates shorter values of τi. Further interpretation showed that the evolution of in τi, could be described in two linear Phases. The transition temperatures between Phases were calculated, and the results obtained showed that partial substitution of ammonium perchlorate by non-stabilised ammonium nitrate increased the domain of occurrence of homogeneous ignition.