Computational study of enhanced soot production in a time-varying laminar non-premixed flame

This paper presents numerical simulations of both a steady and time-varying ethylene/nitrogen non-premixed flames. The numerical model solves the two-dimensional, axisymmetric flow field using SIMPLEC algorithm. The chemical mechanism employed involves 32 species and 206 reactions. A Method-of-Moments model is used to simulate soot formation. The predicted soot is then used to estimate radiative cooling, although this is over-predicted due to errors in the calculated soot distribution. Other aspects of the model are validated using experimental data from the literature. The results show that the residence time of gas mixtures in the region where soot is present is longer for the forced flame than the steady flame, providing an explanation for the increased soot formation. It also predicts the flame length of the steady flame to within 4% of the measured length. Additionally, the comparisons show good agreement for the radial location of the peak temperature at each height, although some discrepancies are found at the flame tip.