Investigation of aluminum agglomeration characteristics in solid propellants with Al/Mg particle additives

To investigate the behaviors and processes of aluminum agglomeration, a study was conducted on the ignition, combustion and agglomeration properties of fuel-rich propellant containing Al/Mg particles additives. This research employed scanning electron microscopy along with optical visualization experimental technique within a small-scale sealed laser ignition apparatus. The results indicate that the agglomeration of aluminum particles occurs not only on the burning surface of the composite propellant but also following detachment from it. Upon detachment, these agglomerates undergo various processes, including coalescence, expansion, ejection, and fragmentation. It is found that the content of metal particles significantly affects both combustion and agglomeration properties. Under the condition of constant total metal content of 40%, the burning rate increases by 7.7% on average when the aluminum particle content increases from 20 to 35%. A novel model for predicting agglomeration size has been developed, clearly illustrating the influence of composition and burning rate on the agglomeration size after detachment from the burning surface.