Techniques and Procedures for the Measurement of Aircraft Gas Turbine Engine Emissions

Abstract

In 1968 the Society of Automotive Engineers formed the Committee on Aircraft Exhaust Emissions Measurement (E-31) whose charge was the development of acceptable standards of measurement for the characterization of aircraft engine exhaust. This committee’s efforts have resulted in the issuance of two Aerospace Recommended Practices, ARP 1179 “Aircraft Gas Turbine Exhaust Smoke Measurement” and ARP 1256 “Procedure for the Continuous Sampling and Measurement of Gaseous Emissions from Aircraft Turbine Engines.” These Recommended Practices have in large part been adopted by the Environmental Protection Agency and promulgated in Federal Register Volume 38, Number 136, Tuesday, July 17, 1973. For the past three years Pratt & Whitney Aircraft has been measuring emissions from aircraft gas turbine engines using on-line instrumentation systems designed both in accordance with these Aerospace Recommended Practices and in response to the operational needs of a large experimental engineering test facility. In addition to a discussion of these systems this paper describes the experience derived from continuous testing programs in support of this test facility with consideration being given to the specific problems of sampling, sample handling, system accuracy, and data recording and reduction. Comment is made as to the practical limitations of the recommended methods and procedures as applied to emission control technology programs and suggestions are presented for improving the measurement technology.