A STAGNATION-POINT GASOLINE-SPRAY PREMIXED FLAME

摘要

In order to understand interactions of droplets, flamelets, and flows in the process of spray premixed burning, we have experimentally investigated the flow and flame characteristics and concentration field of a stagnation-point gasoline-spray premixed flame. As might be expected, similar to the diesel-spray flame, the gasoline-spray flame was found to be composed of a weak blue flame zone, indicating the burning of gaseous fuel, and a strong luminous zone, containing many distinct lines of bright yellow color showing the trajectories of burning gasoline drops. Distributions of drop size, drop axial velocity, and the gas-phase temperature for the flow field of the gasoline-spray flame were similar to the previous findings for the diesel-spray flame. Concentration measurements further show that, in the center core of the flow, the O_2 concentrations are nearly 20% in the upstream region and decrease slowly in the preheat zone of the blue flame; while passing through the thin blue flame, the O_2 concentrations decrease more pronouncedly in the droplet-burning zone and almost remain constant in the downstream region. It was also shown that the increase of the CO_2 concentrations follow the decrease of the O_2 concentrations, and the CH_4 variation is similar to the O_2 variation. For the spray flow examined in this study, the increase of CO concentration simply corresponded with the droplets burning after the blue flame.