Investigation of soot formation and temperature field in laminar diffusion flames of LPG–air mixture
Soot formation and burnout were studied at atmospheric pressure in co-flowing, axisymmetric, buoyant laminar diffusion flames and double flames of liquefied petroleum gases (LPG)–air mixtures. In diffusion flames, two different fuel flow rates were examined. In double flames, three different primary air flow rates were examined. A soot sampling probe and a thermocouple were used to measure the local soot mass concentration and flame temperature, respectively. Flame residence time was predicted using a uniformly accelerated motion model as a function of axial distance of the flame. The increase of primary air flow rate was found to suppress the energy transfer from the annular region, at which the soot is produced, to the flame axis. The time required to initiate soot formation at the flame axis becomes longer as the primary air is increased. The trend rate of soot formation was found to be similar along the flame