Fuel-Rich Particle-Laden Plume Combustion
Theme I ducted rockets using boron-loaded solid propellants, primary chamber reaction products containing unreacted gaseous and particulate fuels mix, ignite, and burn with a subsonic airstream in a secondary chamber. It is generally known that the overall efficiency of these systems decreases with decreasing secondary chamber pressure, increasing air-to-fuel ratio, and decreasing propellant mass flow. Based on systematic tests in a subscale rocket motor,' it was determined that ignition of the gaseous fuel components of the primary chamber with the airstream is critical if high combustion efficiency of the boron components is to be achieved. This study provides additional insight into the ignition and combustion processes of the gaseous components with and without boron particles. It will be shown that reduction of the primary exhaust velocity to subsonic speed significantly improves the ignition process of the gaseous components and the boron particle combustion efficiency.