Studies on Soot Formation and Combustion in Turbulent Spray Flames: Modeling and Experimental Measurement

The present study is concerned with measuring and simulating soot formation and combustion in turbulent liquid fuel spray flames. Soot concentrations inside the combustor are measured by filter paper technique. The simulation is based on the solution of the fully-coupled conservation equations for turbulent flow, chemical species kinetic modeling, fuel droplet evaporation and combustion and soot formation/oxidation. The soot formation is modeled by using the soot particle number density and the mass density based on acetylene concentrations. Two oxidation models simulate the rate of soot combustion: the O2-oxidation model, which assumes soot combustion is caused by oxygen molecules, and the O2-OH oxidation model, which assumes soot combustion occurrs by both hydroxide radicals and oxygen molecules. The experimental and numerical investigations are conducted for different fuel spray cone angles. The comparison of calculated results against experimental measurements shows good agreement. Both the numerical and experimental results show that the peak value of soot and its location in the furnace depend on fuel spray cone angle. An increase in spray angle enhances the evaporating rate and increases peak temperature near the nozzle. The results also show that the OH radical has major influence on soot combustion especially while O2 oxidation is minimal.