Measurement of Emissions from Jet Engines in Altitude Test Cells

Abstract

An instrumentati on system for the measurement of selected exhaust emissions from jet engines operating under simulated flight conditions is described. The system is designed to function over a total pressure range of 2.5 to 40 psia at the exhaust exit plane, and at exhaust temperatures up to 3600°R. Species measured include CO, CO2, Hydrocarbons, NO, NO2, NOX, SOX, Water Vapor, and Particulate Matter. The system provides for redundant measurements of several species using dif- ferent techniques, and a comparison of these measurements is included. ALTHOUGH jet engine operations constitute the source of only a small part of those emissions defined as air pol- lution,1'2 the species, concentrations, and variations of these emissions with external variables such as altitude, Mach number and power setting is of considerable inter- est. Also, because jet engines operate a significant part of the time in a part of the atmosphere which is poorly un- derstood in terms of chemistry,3 considerable concern has been expressed over the possible detrimental effects of high altitude operations especially by supersonic aircraft and by other aircraft as well. Since facilities for testing and operation of jet engines under realistically simulated flight conditions, and over a wide range of altitudes and Mach numbers already exist at Arnold Engineering Development Center (AEDC), it was quite logical that the AEDC should develop a capa- bility for evaluation of engine emissions. The system that will be discussed in this paper was de- veloped to characterize the emitted concentrations of the pollutant components deemed most important to a study of the impact of an operating supersonic aircraft fleet upon the climate of the world. This evaluation program was conducted as a part of CIAP 4 (Climate Impact As- sessment Program) for the Department of Transportation (DOT). Also, the Transportation System Center, DOT, participated in the development of the measurement sys- tems, and furnished one of the particulate analysis sys- tems. The system conceptual design was initiated in No- vember 1971 and was first used in June 1972, in the En- gine Test Facility's J-2 Test Cell at the AEDC.