Simultaneous Multiline Emission Absorption Measurements in Optically Thick Turbulent Flames

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Abstract
Simultaneous transient emission/absorption measurements at five wavelengths in strongly radiating, optically thick, turbulent diffusion flames burning acetylene in air were completed. The data were processed to obtain CO2, mole fractions, temperatures and soot volume fractions spatially resolved to the estimated local integral length scale of mixture fraction fluctuations. Temperatures and soot volume fractions based on emission intensities showed strong negative correlation due to radiative cooling effects. Probability density functions of soot volume fractions conditioned on CO2, mole fractions showed similarities with position. However, probable effects of negligible diffusivity of soot particles were observed. Probability density functions of soot volume fractions conditioned on both CO2, concentrations and temperature illustrate the important role of radiative heal transfer in determining the flame structure. A multivariate stochastic analysis resulted in good predictions of radiation intensities.