Role of Oxygen-Enriched Atomization in Kerosene Spray Flames

Abstract

Theeffectofoxygen enrichmentto theatomization airis examined herein a twin-e uid atomizer. Acommercially available solid-cone, air-assist atomizer 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% O2 because air is the most commonly used mode of operation for twin-e uid atomizers. Data were obtained on droplet size, number density, and velocity at several spatial locations in the spray e ames using a two-component phase Doppler interferometer. The global features of the spray e ames, recorded photographically, were affected dramaticallybyoxygenenrichmentoftheatomizationair.Specie cally,thee ameluminosityincreases,andthee ame height and volume decreases with an increase in oxygen concentration supplied to the atomization air. A moderate increase in oxygen concentration produced a whitish color high-temperature violent combustion zone near the nozzle exit. In addition, e ames with oxygen-enriched atomization air reduced the number of unburned droplets escaping thee ameplumeinto the surrounding environment. Thisobservation wassupported by the phaseDoppler measurements in which droplet mean size and velocity increased and droplet numberdensity decreased as a result of enhanced droplet vaporization. The results suggest that oxygen enrichment of the atomization air provides a signie cant improvement to the initial mixing between the reactants immediately downstream of the nozzle exit. Thisimprovement,inturn,ine uencesdropletvaporizationandtransport,e amestability,andcombustion intensity.