MODELING AND MEASUREMENTS OF SOOT AND SPECIES IN A LAMINAR DIFFUSION FLAME

A model of laminar, soot-laden ethene diffusion flames has been develo ped and compared with measurements in nonsooting and sooting flames. C oncentrations of stable gas-phase species were measured with mass spec trometry; laser-induced fluorescence was used to measure the OH concen trations. A system of elementary reactions was used to describe the ga s-phase chemistry. The model incorporated a simple description of the growth of soot which assumed that acetylene was the only growth specie s. Soot formation was coupled with the flame chemistry via the loss of acetylene and OH on soot and the production of CO during soot oxidati on. The model predicted most of the gas-phase species quite well, with the exception of OW. The loadings of soot in the flames were reproduc ed adequately, although less success was achieved in predicting the tr ansition from nonsooting to sooting conditions. Details concerning the products of soot oxidation by OH were found to be important with rega rd to the flame chemistry. The inclusion of soot in the flame model ha d a significant impact on tile predicted structure of the flame as see n in changes to the formation and destruction rates of OH on the fuel side of the flame. The rate of OH reaction with soot in the midregion of the flame was small compared with the rate of reaction of OH with C O. However, the two rates became comparable in the soot burnout zone, Copyright (C) 1996 by The Combustion Institute