DeLuca L.T.,Polytechnic of Milan |
DeLuca L.T.,Space Propulsion and Nanoenergetics Laboratory |
Galfetti L.,Polytechnic of Milan |
Galfetti L.,Space Propulsion and Nanoenergetics Laboratory |
And 8 more authors.
Journal of Propulsion and Power | Year: 2010
Experiments concerning the ballistic characterization of several nanoaluminum (nAl) powders are reported. Most studies were performed with laboratory composite solid rocket propellants based on ammonium perchlorate as oxidizer and hydroxyl-terminated polybutadiene as inert binder. The ultimate objective is to understand the flame structure of differently metallized formulations and improve their specific impulse efficiency by mitigating the two-phase losses. Ballistic results confirm, for increasing nAl mass fraction or decreasing nAl size, higher steady burning rates with essentially the same pressure sensitivity and reduced average size of condensed combustion products. However, aggregation and agglomeration phenomena near the burning surface appear noticeably different for microaluminum (μAl) and nAl powders. By contrasting the associated flame structures, a particle-laden flame zone with a sensibly reduced particle size is disclosed in the case of nAl. Propellant microstructure is considered the main controlling factor. A way to predict the incipient agglomerate size for μAl propellants is proposed and verified by testing several additional ammonium perchlorate/hydroxyl-terminated polybutadiene/ aluminum formulations of industrial manufacture. Copyright © 2010 by L.T. DeLuca.