Ducted kerosene spray flames

Reaction progress in premixed methane-air flames in round ducts without and with kerosene sprays has been quantified on the basis of species concentration measurements for different fueling arrangements of kerosene with equivalence ratio, proportion of liquid to gaseous fuel, duct length and air preheat temperature as variables in smooth and in rough combustion. The intensity of heat release close to the flame holder in rough combustion was greater than that in smooth combustion, and the duct length necessary to ensure complete combustion decreased with air preheat temperature and upstream turbulence intensity and was weakly dependent on the proportion of methane to kerosene in flow arrangements where the kerosene was sprayed upstream of the flame-holder. The injection of kerosene through the flame holder at a velocity larger than that of the mean flow past the disk led to uneven mixing and incomplete combustion. Pulsed injection of kerosene through a pintle-type injector also resulted in incomplete combustion due to the larger droplet size than in arrangements with a steady flow of kerosene. Oscillations of large amplitude were induced at equivalence ratios usually associated with smooth combustion and oscillations in rough combustion ameliorated by pulsed injection of kerosene comprising around 10 percent of the total fuel.