Behaviour of Premixed Sooting-Flame in A High-Pressure Burner

Abstract

The second-order factor effect of burner optical ports and Edge inter-matrices (EIM) and the first one of pressure on soot formation process and behaviour of premixed sooting-flame in a high-pressure burner are numerically investigated here. Three-dimensional CFD simulations of a premixed flame C2H4/air at p = 1.01 and 10 bar using one-step chemistry approach are first performed to justify satisfied predictability of prospective axisymmetric bi-dimensional (2D) and one- dimensional (1D) simulations. The justified 2D-simulation approach shows the generation of an axial vorticity around the EIM and axial multi-vorticities due to the high expansion rate of burnt gases at the high-pressure of 10 bar. This leads to the development of axial multi-sooting zones, which are manifested experimentally by visible luminous soot streaks, and to boosting soot formation conditions of relatively low-temperature field, < 1800 K, and high-mixing rate of gases in combustion around and above the EIM location. Nevertheless, tolerable effect on the axial soot volume fraction (fV) profile, fV < 3%, is manifested only at high heights above burner of the atmospheric sooting-flame C2H4/air phi = 2.1 and early at the high-pressure 10 bar of this flame, fV < 10%. Enhancing the combustion process reactivity by decreasing the rich equivalence ratio of fuel/air mixture and/or rising the pressure results prior formation of soot precursors which shifts the sooting zone upstream.