INVESTIGATION OF ALUMINUM PARTICLE COMBUSTION IN THE FLAME OF SOLID ROCKET PROPELLANTS

Aluminum is widely used in modem solid rocket propellants for many pur poses, but mainly to increase the specific impulse by raising the flam e temperature. Most of the aluminum present in the powder state in the propellant does not vaporize on the burning surface, tending later to agglomerate into large particles difficult to burn even in the flame. The aim of this work is to study the behavior of the aluminum particl es on the burning surface and in the gaseous region of the propellant flame structure. Different diagnostic techniques have been used: SEM o n the burning surface of extinguished samples, pictures taken during c ombustion by filtered still camera, and a newly developed laser diagno stic. By the use of an UV laser beam and a high-speed-shutter TV camer a, the Al particles on the burning surface have been visualized. A sui table image processor to extract information from the frames has been adopted. Tests on an HTPB.12/AP.68/Al.20 propellant in the pressure ra nge 10-50 atm have been performed. Results show the reliability of the diagnostics used here and have contributed to a better characterizati on of tested propellant.