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Research Papers: Gas Turbines: Controls, Diagnostics, and Instrumentation

Minimizing Sampling Loss in Trace Gas Emission Measurements for Aircraft Engines by Using a Chemical Quick-Quench Probe

[+] Author and Article Information
Elena de la Rosa Blanco1

Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821-3976

Jay Peck, Richard C. Miake-Lye, Frank B. Hills, Ezra C. Wood, Scott C. Herndon, Kurt D. Annen

Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821-3976

Paul E. Yelvington2

Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821-3976

Timothy Leach3

CFD Research Corp., 215 Wynn Drive, Huntsville, AL 35805

$EI X[g X/kg fuel]=ER X(MWX/MWCO2)EI CO2$ where ER X is the emission ratio (mol pollutant/mol $CO2$) of pollutant X (i.e., the concentration ratio of the pollutant to aircraft $CO2$), $MWX$ and $MWCO2(g∕mol)$ are the molecular weights of pollutant and $CO2$, respectively, and $EI CO2$ is the emission index of $CO2$, which was assumed to be 3160 g/kg fuel.

1

Corresponding author. Present address: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139.

2

Present address: Mainstream Engineering Corp., 200 Yellow Place, Rockledge, FL 32955.

3

Present address: The Johns Hopkins University, Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723.

J. Eng. Gas Turbines Power 133(7), 071602 (Mar 16, 2011) (7 pages) doi:10.1115/1.4002665 History: Received April 27, 2010; Revised May 13, 2010; Published March 16, 2011; Online March 16, 2011

Abstract

This paper describes the development and testing of a gas sampling probe that quenches chemical reactions by using supersonic expansion and helium dilution. Gas sampling probes are required for accurate measurement of exhaust emissions species, which is critical to determine the performance of an aircraft engine. The probe was designed through rounds of computational modeling and laboratory testing and was subsequently manufactured and then tested at the University of Tennessee Space Institute behind a General Electric J85 turbojet engine at different power settings: idle, maximum military, and afterburning. The experimental test results demonstrated that the chemical quick-quench (CQQ) probe suppressed the oxidation of carbon monoxide (CO) inside the probe system and preserved more CO at afterburning conditions. In addition, the CQQ probe prevented hydrocarbons from being partially oxidized to form CO at idle powers and measured higher hydrocarbons and lower CO emission compared with a conventional probe at that low power condition. The CQQ probe also suppressed nitrogen dioxide $(NO2)$ to nitric oxide (NO) conversion through all engine power settings. These data strongly support the conclusion that the CQQ probe is able to quench unwanted chemical reactions inside the probe for all engine power levels.

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Figures

Figure 1

Comparison of 1m and >30 m EI-NO2 data for APEX-2 and APEX-3 field campaigns

Figure 2

Schematic of the chemical quick-quench probe (not to scale)

Figure 3

(a) Temperature distribution for the ceramic probe tip with 10 cm2 K/W of contact resistance and (b) von Mises stress analysis (shown with the outer sheath removed)

Figure 4

Photographs of (a) probe/rake assembly before the exterior skins were welded and (b) the final rake

Figure 5

Schematic of the experimental setup describing dilution locations, flow paths, and instrument layout

Figure 6

CO emissions indices for different engine power settings

Figure 7

HCHO emissions indices for different engine power settings

Figure 8

C2H4 emissions indices for different power settings

Figure 9

NO2/NO ratios for different power settings

Figure 10

Impact of the amount of helium dilution on CQQ probe performance at idle power

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