Development of a Cool Composite Propellant Based on Guanidinium Azotetrazolate for Air Heater Igniter Application

Abstract

Guanidinium azotetrazolate (GZT) based cool gas generator is being successfully used for a variety of applications in space exploration systems. In this work, an air heater igniter with a cool gas generating composite propellant (GGC) based on GZT was designed and developed for residue less combustion of fuel-air-oxygen mixture of the scramjet propulsion test facility. GGC was formulated with guanidinium azotetrazolate as fuel and ammonium perchlorate as oxidizer. The composition of GGC was selected based on theoretical study carried out using REAL software and the finalized composite propellant was processed and cast under vacuum. The thermal, ballistic, mechanical and safety properties of the GGC were determined. The propellant showed acceptable mechanical properties, fit for use as a pyrogen igniter composition for the present application. Hyphenated TG-GC/MS technique was used to reveal the evolved gas composition during decomposition. The propellant showed limited dependency of burn rate on pressure, with 'n' value of 0.61 and 'a' value of 1.361 mm s À 1 MPa À 1 . Based on the propellant energetics and experimentally devised burn rate law, a pyrogen igniter with an end burning propellant grain configuration, was designed, processed, and tested at stand-alone mode.