CHEMISTRY IN PLUMES OF HIGH-FLYING AIRCRAFT WITH H-2 COMBUSTION ENGINES - A MODELING STUDY

Recent discussions on high-speed civil transport (HSCT) systems have r enewed the interest in the chemistry of supersonic-aircraft plumes. Th e engines of these aircraft emit large concentrations of radicals like O, H, OH, and NO. In order to study the effect of these species on th e composition of the atmosphere, the detailed chemistry of an expandin g and cooling plume is examined for different expansion models. For a representative flight at 26 km the computed trace gas concentrations d o not differ significantly for different models of the expansion behav iour. However, it is shown that the distributions predicted by all the se models differ significantly from those adopted in conventional meso -scale and global models in which the plume chemistry is not treated i n detail. This applies in particular to the reservoir species HONO and H2O2.