Stability Minimum Limits and Behavior of The Diffusion Flame

The flame stability limits essentially define the fundamental operation of the combustion system. The critical conditions at the stability limits are highly dependent on flow configurations and some species of fuels. For various species of fuels (Methane, Propane and Hydrogen), the flame-base stability mechanism for flame holding has been studied. In this study, the transition behavior from the stable flame attached to nozzle rim to lifting and blow off is observed experimentally in unconfined, quiescent atmosphere air. The lifting and blow-off criteria are proposed for the diffusion flame. Experiments were conducted to investigate the flame structure for various nozzle diameters from 0.14 to 8.1 mm. The results obtained are as follows. It turns out that the minimum limit of a stable flame is not dependent on average jet speed, but it is dependent on fuel flow rate. Regarding to the micro scale nozzle, the flame length of the laminar flow is decided by fuel flow rate.