Methods for reducing pollutant emissions from jet aircraft.

The purpose of this paper is to define the problem of pollutant emissions from jet aircraft and to review NASA-Lewis combustion research aimed at reducing these emissions. The problem of smoke formation and results achieved in smoke reduction from commercial combustors are discussed. Experimental results of parametric tests performed on both conventional and experimental combustors over a range of combustor-inlet conditions are presented. Combustor design techniques for reducing pollutant emissions are discussed. Improved fuel atomization resulting from the use of air-assist fuel nozzles has brought about significant reductions in hydrocarbon and carbon monoxide emissions at idle. Diffuser tests have shown that the combustor-inlet airflow profile can be controlled through the use of diffuser-wall bleed and that it may thus be possible to reduce emissions by controlling combustor airflow distribution. Emissions of nitric oxide from a shortlength annular swirl-can combustor were significantly lower than those from a conventional combustor operating at similar conditions.