![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
ABSTRACT
In this study, a new conservation scalar, sooting tendency parameter, which has the same control differential equation with mixture fraction except the boundary values at fuel inlets, is introduced to evaluate the average laminar smoke point (LSP) height of multiple fuels mixed in combustion region. According to theoretical analysis, the average LSP height of the mixed fuels in combustion region will be equivalent to the ratio of mixture fraction and sooting tendency parameter. The soot oxidation model is also modified in present work to allow it to be used with mixture fraction combustion model. Then this improved global soot model is implemented in Fire Dynamics Simulator and two different laminar flames are simulated in one case to validate the predictability. Good agreements between the predicted and measured soot volume fraction demonstrate the applicability of accounting for the sooting propensity of different fuels by the introduced scalar, and the reasonability of the modification of the soot oxidation model. The difference of stoichiometric mixture fraction between the fuel used in combustion model and the realistic fuels will lead to some error in soot prediction, yet which can be reduced by multiplying the boundary value of sooting tendency parameter by a safety factor (SF) greater than 1. The introduction of the SF is also very essential in fire protection design, because it will lead to the increase of predicted soot volume fraction, making the fire risk assessment more conservative.