The Cellular Structure of LPG Reacting Fluid

Abstract

The unstable behavior of cellular premixed flames induced by intrinsic instability was investigated. In this paper, the focus was on the effects of diffusive‐thermal instabilities on the formation of LPG cellular flames. Various parameter are assessed which include air‐fuel ratio, mixtures velocity, temperature of the burner plate and liquefied petroleum gas (LPG) as the fuel to study the factors that influenced the formation of cellular flames. The flames propagation speed was determined by using heat flux method. From the observations, cellular flames which were occurs spontaneously, take on a non planar shape, often have structures most strongly affected by diffusive thermal phenomena. Cellular instability can occurred in fuel‐oxidizer mixture if the diffusivity (D) of the deficient reactant were larger than the thermal conductivity (α), which means the Lewis number is less than unity. In other words heavy‐fuel is found to exhibit cellular instability. Burner Plate temperature also contributed to the flame appearance and propagation speed of the cellular flames. From the observation, the cellular structures observed experimentally have no significant effect from the perforation pattern of the burner. The cell sizes of the flames are always larger than the perforation hole in the burner plate. From the result, increased in burner plate temperature would eliminated the cellular flame instability and by lowering the burner plate temperature would extended the range of the equivalence ratio which the cellular were observed.