Recent combustion bomb testing of RSRM propellant

Assessment of the Performance of Ablative Insulators Under Realistic Solid Rocket Motor Operating Conditions

“…Unlike the nonmetallic constituents of the solid propellant, aluminum does not complete its combustion within microns of the propellant surface, but burns relatively slowly after departing the propellant surface, a process potentially extending throughout the internal port of the motor [93]. According to the aluminum burning time correlation of Beckstead [94], particles with a diameters larger than 75 μm (between 14 and 28% of condensed-phase particles [95]) will be undergoing combustion within view of the radiometer when the burning surface of the propellant is at its initial location, and particles with diameters larger than 107 μm (between 10 and 22% [95]) will be burning within view of the radiometer just before burnout. As burning aluminum droplets are potentially a significant source of thermal radiation from the flow channel to the SRM wall [96], the presence of a larger number of these droplets within the view of the radiometer will likely increase the radiation measured by the radiometer relative to a smaller number.…”