PARTICULATE SIZING AND EMISSION INDEXES FOR A JET ENGINE EXHAUST SAMPLED AT CRUISE

Particle size and emission indices measurements for jet engines, prima rily the Rolls Royce RB211 engines on a NASA 757 aircraft are reported . These data were used to estimate the fraction of fuel sulfur that wa s converted to particulates. These measurements were made in-situ with the sampling aircraft several kilometers behind the source. Some comp limentary ground measurements on the same source aircraft and engines are also reported. Significant differences are seen between the ground observations and the in-situ observations, indicating that plume proc esses are changing the aerosol's characteristics.