MODELING AND VALIDATION OF SOOT CONCENTRATION PATTERNS OF TURBULENT-DIFFUSION FLAMES BASED ON DATA FROM PLUG-FLOW REACTOR EXPERIMENTS

Since soot content and emission of technical hydrocarbon flames are im portant parameters for the design and application of combustion proces ses, quantitative prediction of soot concentration fields in turbulent flames remains to be a major topic in combustion research. The work r eported here makes a contribution towards the predictability of soot f ormation based upon semi-empirical models. A plug flow reactor, as an experimental system to generate soot growth data under well defined co nditions, is described. Measurements of soot, gas species concentratio ns and temperatures are implemented into a global soot growth kinetics correlation with temperature, stoichiometry and residence time being the main influencing parameters. The correlation enables the predictio n of soot growth rates as a function of temperature and residence time which are in agreement with results from other experimental systems. To apply this correlation to technical flames, extensive field measure ments in free turbulent jet diffusion flames including precursor hydro carbon species were performed. Measurements of soot mass concentration s in the plug flow reactor and in the turbulent diffusion flames, both performed by a gravimetrical soot sampling method, are compared with those determined by an optical extinction technique. The values of the gravimetrical technique agree well with those of the multiple wavelen gth extinction method. Soot growth kinetics from the plug flow reactor , combined with a soot oxidation model from literature, was used to pr edict the soot concentration field in a turbulent propane diffusion fl ame. The computed results compare favourably with measured data and pr ove the applicability of global kinetic equations for soot prediction in turbulent flames.