Relative roles of tempurature and fuel concentration in single-step and two - step soot formation models

This paper presents a comparison between the roles of fuel concentration and temperature distribution in the prediction of three widely used single – step and two – step soot formation models. The single – step soot models calculate soot formation directly while the two-step model computes soot through the formation of nuclei radicals. The comparison is carried out numerically in a turbulent spray flame. In order to model the reactive flowfield , a hybrid Eulerian-Lagragian methods in employed. Equations governing the gas phase are solved by a control – volume based semi-implicit iterative procedure while the time-dependent differential equations for fuel droplets are integrated by a semi-analytic method. The results reveal that the role of fuel concentration is higher than temperature in the Khan’s single – step model. The results also show that in the Edelman’s single-step model and the two – step model, the roles of temperature in the process of soot formation are inadequately exaggerated. By increasing the role of fuel concentration on soot formation, a new version of the two – step model is proposed which makes the best agreement with experimental data.

Keywords:

soot formation model , temperature , fuel concentration , spray flame