Experimental verification of principal losses in a regulatory particulate matter emissions sampling system for aircraft turbine engines

Abstract

A sampling system for measuring emissions of nonvolatile particulate matter (nvPM) from aircraft gas turbine engines has been developed to replace the use of smoke number and is used for international regulatory purposes. This sampling system can be up to 35 m in length. The sampling system length in addition to the volatile particle remover (VPR) and other sampling system components lead to substantial particle losses, which are a function of the particle size distribution, ranging from 50 to 90% for particle number concentrations and 10-50% for particle mass concentrations. The particle size distribution is dependent on engine technology, operating point, and fuel composition. Any nvPM emissions measurement bias caused by the sampling system will lead to unrepresentative emissions measurements which limit the method as a universal metric. Hence, a method to estimate size dependent sampling system losses using the system parameters and the measured mass and number concentrations was also developed (SAE 2017; SAE 2019). An assessment of the particle losses in two principal components used in ARP6481 (SAE 2019) was conducted during the VAriable Response In Aircraft nvPM Testing (VARIAnT) 2 campaign. Measurements were made on the 25-meter sample line portion of the system using multiple, well characterized particle sizing instruments to obtain the penetration efficiencies. An agreement of ± 15% was obtained between the measured and the ARP6481 method penetrations for the 25-meter sample line portion of the system. Measurements of VPR penetration efficiency were also made to verify its performance for aviation nvPM number. The research also demonstrated the difficulty of making system loss measurements and substantiates the E-31 decision to predict rather than measure system losses.

EDITOR:

• Jason Olfert

Acknowledgments

We like to acknowledge the support of Bryan Manning and Glenn Passavant of OTAQ. Additional support came from Edwin Corporan of the U.S. Air Force Research Laboratory at Wright Patterson Air Force Base, OH who supplied the Camelina fuels, and the technical support of Steve Garner, Brad Besheres, Roy Carroll, Jason Smith, Gary Storey, Robert Baltz, Todd Vanpelt, Brad Winkleman, Kathleen Jones, Gary Teal, Bryon Weatherford, Mike Ferris, John King, Charles Easley, and Brian Anderson of the Aerospace Testing Alliance at Arnold Air Force Base, TN. We would especially like to thank Aaron Avenido and Maynard Havlicek from TSI.

Additional information

Funding

Funding for this project was provided by the U.S. Environmental Protection Agency Office of Transportation and Air Quality (OTAQ) in Ann Arbor, MI, the U.S. Federal Aviation Administration under Grant No. 13-CAJFE-MST, Amendment 004, and in-kind support from the U.S. Air Force at AEDC.