Advanced Three-Phase Combustion Analysis

The systematic upgrade of a two-phase (gas/particle) missile propulsive Navier-Stokes code, CRAFT, to simulate the three-phase combustive processes occurring in rocket combustion chambers and nozzles is proposed. Preliminary emphasis is on upgrades that will improve the ability to analyze combustion processes in the secondary combustion chamber of ducted rocket engines (DRE). This will involve inclusion of heterogeneous surface-burn particulate combustion models into CRAFT which have nonequilibrium gas/particle interactions and interactive kinetics, competing with the nonequilibrium gas phase kinetics for reactants. Both Lagrangian and Eulerian particulate frameworks will be incorporated. Emphasis will be on heterogeneous carbon kinetics and metallic oxide kinetics whereby the oxidizer shell surrounding unburnt metals (Al, Zr, B, ...) can melt in combustion zones permitting further heat release downstream. The three-phase combustion framework formulated will serve as a stepping stone to extending this methodology into the primary chamber and analyzing detailed grain surface layer burning. This work takes very recent technology developed for gun propulsion and for metallic explosives and casts it into a framework for analyzing three-phase combustive processes in tactical missile propulsive systems. The synergism of analyzing all such processes in the same computational framework is of great benefit to the government. The commercial applications include thermal spray processes used to plate surfaces with molten metallic particles for coating cookware and automotive/airplane engine components which will also benefit from this new technology.