Measurement of smoke point in velocity-matched co-flow laminar diffusion flames with pure and diluted fuels at elevated pressures

Using a co-flow burner, a quartz chimney, and a pressure vessel with good optical access, smoke points of pure and diluted fuels were measured in a laminar jet diffusion flame. The smoke point is a fundamental kinetic parameter, as this is the point where production of soot is exactly off-set by its oxidation. Ethylene and methane, burning in a velocity matched, over-ventilated co-flow of air, were tested over the range of one to sixteen atmospheres. The volumetric fuel flow, diluent flow, and flame height were measured as a function of pressure to determine the functional relationship between these parameters and pressure. For undiluted flames, the volumetric fuel flow at the smoke point is observed to scale as a power law with pressure, while the smoke point height is best described by a logarithmic law with pressure. For diluted flames, the smoke point increases as the percentage of diluent increases at both atmospheric and elevated pressure conditions.