Spectral studies of the gas component of an aluminum dust flame

The combustion zone of a steady-state laminar diffusion flame of aluminum particles of diameter 4.8 mu m at a metal weight percentage of 0.4 kg/m(3) was studied by atomic and molecular emission spectra. Absolute measurements of the luminosity of the sequence of bands due to AlO made it possible to determine the gas-phase temperature (3200 +/- 100 K) and the AlO vapor concentration [(1.5 +/- 0.5) center dot 10(21) m(-3)] at the flame front. From an analysis of measurement data on the intensity and contour of the resonance line of aluminum, it is concluded that the metal particles burn individually to form microflames. Estimates were made of the size of the combustion zone of an individual particle and the gas-phase temperature near a particle (3150 +/- 200 K). Some features of the combustion mechanism of fine aluminum particles in the dust flame are analyzed. The capabilities of spectral methods for studying the thermal and concentration structures of dust flames are demonstrated.