Two-dimensional soot distributions in buoyant turbulent fires

Spatially resolved two-dimensional soot volume fractions were measured using laser-induced incandescence in 7.1 cm methane and ethylene turbulent buoyant flames to study the distributions of soot in vertical and horizontal planes, and to provide data for soot model validation. Factors affecting the LII signals were considered including the laser energy profile and the laser attenuation effects. The absolute soot volume fractions were obtained by comparison to existing extinction measurements. The instantaneous soot images were collected to cover the entire flame height. Statistical quantities of soot volume fractions including mean, root mean square, probability density function, and spatial correlation coefficient were calculated at five downstream locations. The results show that instantaneous distributions of soot volume fractions exhibit significant differences compared to the ensemble averages, strong fluctuation around the mean, relatively homogeneous probability density function, and highly anisotropic spatial correlation.