EXHAUST EMISSIONS FROM GAS TURBINE AIRCRAFT ENGINES NATIONAL INDUSTRIAL POLLUTION CONTROL COUNCIL

摘要

The gas turbine engine is the most efficient internal combustion engine in transport use today, from the standpoint of air pollution. Exhaust emissions from gas turbine powered aircraft, when com¬pared with the total emissions from all other sources, contribute only a small fraction, perhaps no more than one percent, to the nation's air pollution. Nevertheless the attainment of even higher levels of efficiency and freedom from pollution is a proper responsibility of the aviation community.nSignificant progress has been made in reducing the visible par¬ticulate matter (smoke) emission from aircraft gas turbine engines. The benefit from the airlines' programs to install the reduced smoke burner in JT8D engines is now becoming evident around airports, and these programs should show significant effects by the end of 1972 when the retrofit program will be substantially completed. Further progress will result as the new wide-bodied aircraft, whose engines are equipped with low-smoke combustors, come into service.nEfforts are now being directed to investigation of the invisible aircraft exhaust emissions. Although aircraft emissions of carbon monoxide and unburned and partially oxidized hydrocarbons are small in comparison with those of the automobile, there are changes in operating procedures available to further reduce these emissions. Additional technological studies are required in order to modify combustor designs to minimize these emissions in the idle and low power engine operating regimes.nStudies have only recently been initiated to understand the formation of the oxides of nitrogen during the gas turbine engine combustion process. It is known that aircraft emissions of these oxides are presently only a fraction of those emitted by automotive engines. Additional analytical studies and test programs are required to determine if this exhaust emission can be significantly reduced.nThe emission of sulfur oxides is low for gas turbine aircraft engines as compared with the emissions from other sources, since commercial aviation jet fuels normally contain less than 0.06 percent sulfur. The formation of sulfur oxides is in direct relation to the amount of sulfur contained in the fuel, however, and further reduction can be obtained only by reducing the already low sulfur content of the fuel.nOdors associated with aircraft operations around airports are a local problem and could benefit from research programs aimed at their abatement.nGas turbine aircraft emissions may become a more significant pollution factor in the future because of increased aircraft operations and may constitute a larger portion of total emissions as a result of reductions achieved by the imposition of abatement programs and regulations on other mobile and stationary sources of emissions. Improved techniques and industry-wide standardized measurement methods are required, however, to determine more accurately the contribution of aircraft engine emissions to the overall air pollution problem, both at sea level and in the upper atmosphere.