Impacts of synthetic jet fuel on the emissions of a turbine engine combustor

The emissions characteristics of a swirl-stabilized research combustor fueled with conventional jet fuel (JP-8), a natural gas-derived synthetic jet (synjet) fuel and several blends of the two were investigated. Particulate matter (PM) and gaseous emissions were analyzed to assess the impacts of the aromatic- and sulfur-free synjet fuel on the combustion products of the atmospheric-pressure combustor operated at equivalence ratios ranging from 0.6 to 1.1. Results show significant reductions in combustor particle number density (PND) and particle mean diameter with the synjet fuel and blends relative to operation on JP-8. Reductions of up to 99% in PND for the higher equivalence ratios were observed. As expected, reductions in sulfur oxides and slight increases in water vapor were produced due to the sulfur-free nature and higher hydrogen-to-carbon ratio of the synthetic fuel. Minor impacts on other gaseous emissions were observed. ASTM fuel specifications tests show that up to a 50/50 by volume blend of conventional JP-8 and synjet fuel met the JP-8 specification, and that only the specific gravity specification was not met at higher synjet concentrations. Comparisons between the impacts of the synjet fuel on the emissions of the atmospheric combustor and a T63 engine, and preliminary results of laser-based measurements to assess fuel-air mixing and soot formation/oxidation processes in the combustor reaction zone are discussed.