Jet Engine Exhaust Aerosol Characterization

ABSTRACT

Jet engine exhaust aerosol was characterized with respect to mass concentration and composition of the carbonaceous aerosol fraction and the particulate sulfate as a function of engine power setting for fuel with low-sulfur content (6 ppm) and high-sulfur content (3000 ppm). The ratio of black carbon (BC) to total carbon (TC) varied from 11% with the engine in idle run to >80% at take-off thrust. The corresponding BC emission index was <0.6 g kg⁻¹ fuel on a mass scale and <1.7 × 10¹⁵ kg⁻¹ fuel on a number scale. The optical specific absorption coefficient of the BC aerosol was measured to 6 ± 1 m² g⁻¹ by filter reflectance analysis (λ ≊ 0.8 μm). The carbon aerosol split into a primary soot mode at 0.045 μm diameter with geometric standard deviation 1.5 and a coagulation mode at 0.18 μm diameter with geometric standard deviation 1.42. The mass emission index of particulate sulfate remained almost constant at <0.05 g kg⁻¹ throughout the examined engine power setting between 11% and 71% take-off thrust. The conversion rate from SO₂molecules into particulate SO²⁻ ₄ within the young exhaust plume prior to sampling (plume age <0.1 s) was <0.5% with only a slight dependence on engine power setting.