Abstract An innovative collection methodology based on a recently developed supersonic probe enabled the collection of alumina particulate from the exhaust plume of a sub-scale solid propellant rocket motor and the comparison with quench collection bomb analysis of propellant incipient agglomeration. Laser diffraction, scanning electron microscopy, and X-ray spectroscopic methods were used to determine particle size, morphology, crystalline nature, and elemental composition. A significant reduction of the particle size occurred across the rocket nozzle. The size distribution resulting from the expansion was monomodal and centered around 2m to 3m. Propellants containing lower aluminum mass fraction led to number-based distribution in the sub-micrometric region while, for higher metal loading, particle distributions were sensibly shifted towards larger size in the same rocket operative conditions. Similarly, the size was identified to be weakly dependent on chamber pressure, with an increase of the former as the latter decreased. The Hermsen correlation supported and verified the experimental analysis. The majority of the particles was composed by -alumina phase, had a typical size lower than 3m, and was characterized by smooth surfaces. Occurrences of spitting and collision-to-coalescence phenomena were identified and analyzed.
Highlights Alumina particles are collected in proximity of the nozzle exit of a sub-scale solid rocket motor. PSD and morphology are determined by laser diffraction and SEM analysis. Crystal phase and elemental composition are studied through X-ray methods. The influence of rocket motor relevant parameters is studied.
Experimental techniques for characterization of particles in plumes of sub-scale solid rocket motors
Acta Astronautica ; 186 ; 496-507
2021-06-07
12 pages
Article (Journal)
Electronic Resource
English
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