Who do Diffusion flames Emit smoke

Abstract

The causes of smoke emission from free gaseous laminar diffusion flanles are investi-gated. Soot concentration, temperature and velocity profiles were measured around the smokepoint for a range of fuels. Smoke was emitted when the temperature in the burnout region droppedbelow about 1300 K.A smoking flame stopped emitting smoke when the temperature in the burnout region wasslightly raised locally by absorption of energy from a COz laser beam.The temperature drop in the flame is strongly coupled to soot concentration through radiationlosses. Soot formation rates are in turn influenced by heat losses and residence times near thefuel nozzle tip. Thus conditions near the nozzle influence the smoke point. The results are alsodiscussed in context with turbulent diffusion flame smoke emission.