Condensed combustion products of aluminized propellants. IV. Effect of the nature of nitramines on aluminum agglomeration and combustion efficiency

The condensed combustion products of two model propellants consisting of ammonium perchlorate, aluminum, nitramine, and an energetic binder were studied by a sampling method. One of the propellants contained HMX with a particle size $D_{10}\approx490$ $\mu$m, and the other RDX with a particle size $D_{10}\approx380$ $\mu$m. The particle-size distribution and the content of metallic aluminum in particles of condensed combustion products with a particle size of $1.2$ $\mu$m to the maximum particle size in the pressure range of $0.1$–$6.5$ MPa were determined with variation in the particle quenching distance from the burning surface to $100$ mm. For agglomerates, dependences of the incompleteness of aluminum combustion on the residence time in the propellant flame were obtained. The RDX-based propellant is characterized by more severe agglomeration than the HMX-based propellant – the agglomerate size and mass are larger and the aluminum burnout proceeds more slowly. The ratio of the mass of the oxide accumulated on the agglomerates to the total mass of the oxide formed is determined. The agglomerate size is shown to be the main physical factor that governs the accumulation of the oxide on the burning agglomerate.