Role of oxygen-enriched atomization in kerosene spray flames

The effect of oxygen enrichment to the atomization air is examined here in a twin-fluid atomizer. A commercially available solid-cone, air-assist atom izer was used in which the atomization airstream was enriched to contain a volume fraction of 35 and 45% oxygen in nitrogen. The results are compared with the baseline case of 21% O-2 because air is the most commonly used mod e of operation for twin-fluid atomizers. Data were obtained on droplet size , number density, and velocity at several spatial locations in the spray da mes using a two-component phase Doppler interferometer, The global features of the spray flames, recorded photographically, were affected dramatically by oxygen enrichment of the atomization air Specifically, the flame lumino sity increases, and the flame height and volume decreases with an increase in oxygen concentration supplied to the atomization air. A moderate increas e in oxygen concentration produced a whitish color high-temperature violent combustion zone near the nozzle exit. In addition, dames with oxygen-enric hed atomization air reduced the number of unburned droplets escaping the da me plume into the surrounding environment. This observation was supported b y the phase Doppler measurements in which droplet mean size and velocity in creased and droplet number density decreased as a result of enhanced drople t vaporization. The results suggest that oxygen enrichment of the atomizati on air provides a significant improvement to the initial mixing between the reactants immediately downstream of the nozzle exit. This improvement, in turn, influences droplet vaporization and transport, dame stability, and co mbustion intensity.