Numerical Analysis Of Flame Characteristics and Stability for Conical Nozzle Burner

Abstract

The stability and the mean structure of methane partially premixed conical burner flames was investigated numerical ly 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 O 2, CO and temperature. From the data obtained, it can be concluded that bo th 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 incre ases 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 turbul ence with high intensity was observed.