Simulating the sooting propensity of JP-8 with surrogate fuels from hydrocarbon fluids

Surrogate fuel mixtures were formulated using hydrocarbon fluids to investigate the ability of different surrogate formulations to match the sooting characteristics of a specific jet fuel (JP-8 POSF 5699). Three different surrogates were studied: two binary mixtures and a ternary mixture. The first surrogate matched the threshold soot index and average molecular weight of the JP-8; the second matched the threshold soot index and hydrogen-to-carbon; and the third matched the threshold soot index, hydrogen-to-carbon, and derived cetane number. For the second and third surrogates, average molecular weight was within 10% of the estimated average molecular weight of the target JP-8. Soot distributions of JP-8 and its surrogates were compared in wick-fed coflow diffusion flames, and net soot production was compared in a model gas turbine combustor. Line-of-sight and local soot volume fraction measurements were obtained using laser extinction on the wick burner for flames at their smoke point. Line-of-sight soot volume fractions for the fuels were measured at different equivalence ratios in the model gas turbine combustor. All three surrogates were found to match the soot production of JP-8 within the experimental uncertainty of ± 15% in the flame and model gas turbine combustor experiments.