NUMERICAL ANALYSIS OF FLAME CHARACTERISTICS an‎d STABILITY FOR CONICAL NOZZLE BURNER

The stability and the mean structure of methane partially premixed conical burner flames was investigated numerically using ANSYS Fluent. The study presents and discusses the stability curves of the partially premixed flame and maps the mean flame structure based on contours of mass fraction of O2, CO and temperature. From the data obtained, it can be concluded that both premixed and non-premixed flames are less stable than the partially premixed flames. An optimum level of partially premixing was found and the flames beyond this threshold were found to be less stable. This optimum level was found, when the ratio of the mixing length to the nozzle diameter is equal to 5. At this specific degree of partially premixing, the flame exhibited triple interaction reaction zones. It was found that with an increase of the angle of the cone of the burner, the air entrainment increases which, in turns breaks the stabilization core and hence cause a reduction in the flame stability limit. The main role of the cone is to provide a protection from the surrounding environment at early phase of the reaction near the jet exit where turbulence with high intensity was observed.