The objective of reaching stable combustion has led to intensive studies of the processes involved in flame stabilization using flame holders. In the present work flame stabilization using flame holders is investigated to study the flame stability limits for a free jet premixed flame using a central flame holder burner. The stability limit (blow off) is examined through changing some parameters in particular flame holder geometry (disc and cone of 90o and 120o apex angle) with different diameters, blockage ratio of the flame holder and the burner exit velocity. The effect of these parameters on the flame stability, recirculation zone length and residence time is discussed. An experimental test rig is constructed to fulfill these objectives and different measurements are recorded and analyzed. The study showed that the flame holder has an impact on the recirculation zone, which leads to an improvement in the residence time of the hot gases, and also an increase in the heat and mass exchange between hot gases and reactants, and hence improving the flame stability. The blockage ratio gives a noticeable improvement on the flame stability limit. Disc flame holder showed better behavior than the cone flame holder regarding flame stability limit under the different operating conditions. |
