Studying the Formulation Effects on Steady-State and Transient Combustion Behavior of Aluminized Propellants

摘要

A new approach based on use of special 'super heterogeneous' propellants that generate during combustion the model agglomerates with given reproducible size and structure has been elaborated for study of model agglomerate evolution. The experiments with agglomerates of 395/540 micron size and initial aluminum content 42.6 % were carried out in pressure range 1-80 atm. The characteristics of condensed combustion products (CCP) were measured via sampling technique at pressure 46 atm (argon or nitrogen) for 12 metalized propellant formulations manufactured using well characterized ingredients. All compositions were based on energetic binder (20%). They included totally 18 % aluminum (commercial or ultra fine particles in various proportion) and contained AP or AP and HMX as oxidizer. The replacement of commercial aluminum by electrically exploded aluminum (Alex) lead to increase of burning rate, decrease of agglomerate mass and increase of metal conversion completeness. All propellant formulation exhibited very effective aluminum conversion (total unburnt aluminum content in CCP did not exceed 9%). The listed trends are mostly expressed in combustion of HMX containing propellants and even small additive of Alex (Alex/Al = 8.3/91.7) gives sizable effect. For oxide particles in the size range 0.5-100 microns the typical three-peak structure of mass size distribution was found. The replacement of aluminum by Alex and using argon instead of nitrogen affects slightly the CCP size distribution. Thermal decomposition of different types of the binders and mixtures modeling the pocket matter was investigated at low (10 K/min) and fast (> 450 K/min) heating rate. Data obtained are not sufficient to make clear the cause of difference in agglomeration behavior for propellant formulations based on these types of binders.