Aircraft exhaust sulfur emissions

The conversion of fuel sulfur to S(VI) (SO 3 + H 2 SO 4 ) in supersonic and subsonic aircraft engines is estimated numerically. Model results indicate between 2% and 10% of the fuel sulfur is emitted as S(VI). It is also shown that, for a high sulfur mass loading, conversion in the turbine is kinetically limited by the level of atomic oxygen. This results in a higher oxidation efficiency at lower sulfur loadings. SO 3 is the primary S(VI) oxidation product and calculated H 2 SO 4 emission levels were less than 1% of the total fuel sulfur. This source of S(VI) can exceed the S(VI) source due to gas phase oxidation in the exhaust wake.