CHEMICAL-COMPOSITION AND PHOTOCHEMICAL REACTIVITY OF EXHAUST FROM AIRCRAFT TURBINE-ENGINES

Assessment of the environmental impact of aircraft emissions is requir ed by planners and policy makers. Seveal areas of concern ace: 1. expo sure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi) on the ground; 2. contributions to urban photochemical air pollution of aircraft vola tile organic and nitrogen oxides emissions from operations around airp orts; and 3. emissions of nitrogen oxides and particles during high-al titude operation. The environmental impact of chemicals emitted from j et aircraft turbine engines has not been firmly established due to lac k of data regarding emission rates and identities of the compounds emi tted. This paper describes an experimental study of two different airc raft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at s everal engine power settings. Measurements were made of detailed organ ic composition from C-1 through C-17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons: Measurements were made using a multi-port samp ling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organ ic distribution by carbon number and the distribution by compound clas s at each engine power level. The sum of the organic species was compa red with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irr adiated in outdoor smog chambers to assess the photochemical reactivit y of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound cl ass.