HYPERGOLIC IGNITION AT REDUCED PRESSURES
Final rept. 1 Jun-30 Nov 1966
THIOKOL CHEMICAL CORP DENVILLE NJ REACTION MOTORS DIV
Pagination or Media Count:
The model applies to propellant combinations whose dominant ignition reactions are gas phase reactions, specifically N2O4hydrazine-type fuels. The model is based on both physical kinetics of propellant droplet evaporation and overall kinetics of ignition reactions. The refinements made on the earlier model are 1 incorporation of propellant flashing effects within the injector manifold volume following valve opening, 2 accounting for pre-ignition heat transfer between the thrust chamber walls and the vaporizing vapordrop system, and 3 accounting for formation of a reaction intermediate by N2O4MMH during the ignition delay period. For two different engine configurations, the resulting computerized model predicted pre-ignition chamber pressure histories and ignition delay times that agree well with experimental values. The N2O4MMH reaction intermediate, which was found to be a mixture of at least four compounds, of which the principal ones are MMHH2O and MMHHNO3, evolves heat upon its formation and consequently causes markedly shorter ignition delays than would otherwise occur. From the thermochemical determinations, it appears that the reaction intermediate plays an important role in severe ignition pressure spiking and, possibly, oxidizer manifold explosions as well.
- Combustion and Ignition