RADIATIVE PROPERTIES OF BURNING ALUMINUM DROPLETS

The spectral intensity (790 nm) emitted during the combustion of pressed pellets composed of ammonium perchlorate (AP) and aluminum has been measured. Aluminum mass fraction content was varied from 0. 5% to 6. 0%. The combustion bomb pressure ranged from the low pressure deflagration limit (near 650 psia or 4. 5 MPa) to 1100 psia or 7. 6 MPa. Based on the intensity measurements, the effective blackbody emission temperature of the burning droplets was well above the local gas temperature and in excess of the adiabatic flame temperature assuming complete Al combustion. The higher intensities were attributed to continuous emission by molten Al//2O//3 in the flame envelope surrounding the molten Al droplets as well as emission by the Al droplets themselves. A two part model of the radiant transport in the burning droplet system and between droplets was developed.