The objective of NASA's Atmospheric Effects of Aviation Project (AEAP) is to develop scientific bases for assessing atmospheric impacts of the exhaust emissions discharged by fleets of subsonic and supersonic civil aircraft. Emissions Characterization (Element 9.6 of AEAP) is tasked with determining the constituents discharged under cruise operating conditions for current and future subsonic-transport engines as well as ultra-low-emission future supersonic-transport engines. Near-Field Interactions (Element 9.5) explores how chemical, dynamic, or physical processes in aircraft wakes can alter these constituents. This interim assessment reviews the status of these elements, and suggests some change in priorities within each one.
The discussion of the Emissions Characterization element examines the selection of the constituents to be measured, the venue for conducting the measurements, and the methods of obtaining the measurements. The panel recommends that measurements of SO2, SO3, and OH be given a higher priority, and that methods for measuring these constituents and characterizing soot particulate be refined. Also recommended is increased emphasis on testing actual subsonic engines (preferably engine models recently introduced into operational service), rather than relying heavily on combustor test rigs. Tests of an advanced military supersonic aircraft engine are recommended to assess the degree of SOx, oxidation.
For the Near-Field Interactions element, the development of analytical models and the current measurement activities are reviewed. The panel recommends that the completion of at least preliminary versions of plume and wake models be given top priority so that their integration to form a suite can begin soon; corollary to this is a recommendation for prompt dissemination of flight-test datasets.