Hypergolic Ignition of Gelled Propellants

Hypergolic propellant gels offer improved safety and performance flexibility. However, their longer ignition delays endanger engine health and preclude widespread use. Understanding the physical and chemical paths to ignition can enable improving ignition and realizing favorable IM characteristics of gels. ORBITEC and JHU propose targeted laboratory and modeling experiments to elucidate phenomena fundamental to the ignition delay of hypergolic gelled propellants. Study of atomization, vaporization, mixing, and kinetics and the effects of the gel phase on these phenomena, will clarify the ignition of hypergolic propellant gels. Spray tests will explore the effects of gel elasticity, gel type, and injector geometry on atomization. Phase equilibrium modeling of propellant gels will predict the vapor pressure and determine if the gel phase slows evaporation. PLIF experiments and FLUENT modeling will assay the effects of gel viscoelastic properties on mixing. Kinetics calculations and sensitivity analysis will identify key reaction pathways to ignition. Engine tests will measure ignition delays for liquid and gelled propellants. Subsequent analysis will define timescales and dimensionless numbers for pre-ignition phenomena. The results of the Phase II project will be in-depth understanding of hypergolic ignition of propellant gels and the basis for a comprehensive predictive model and improved engine design.