AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Determination of Particle Counting Pressure Correction for Turbine Engine Exhaust Sampling
MATTHEW DEWITT, Edwin Corporan, Christopher Klingshirn, Air Force Research Laboratory/Propulsion Directorate
Abstract Number: 342 Working Group: Instrumentation and Methods
Abstract Characterization and quantitation of particulate matter (PM) emissions from turbine engines are of continued interest due to potential environmental and health implications. Since the majority of PM from turbine engines is emitted as sub-micrometer sized particles, there is interest in quantifying the Total Number Concentration (TNC) of particles (total number of particles per volume of exhaust gas) in the engine exhaust stream. Condensation Particle Counters (CPC) are used to quantify the TNC, but these require sampling, conditioning and transport of the exhaust sample from the engine to the instrument, which can result in a varying absolute pressure at the CPC (typically ~10-15 psia) depending on these factors. Two prevalent units currently in use are the TSI Models 3022A and 3025A CPCs, which quantify the TNC via optical measurement of particles in the sample stream while controlling the sample flow rate. Experimental measurements and analyses were performed to determine if the measured TNC with these CPCs is affected by instrument pressure and if normalization to a standard condition is required for data comparison. It was found that the sample inlet pressure affected the measured TNC by influencing both the sample gas density and volumetric control flow rate, of which the latter effect has not been previously reported in the literature. Therefore, correction of the indicated TNC for both of these factors is necessary to quantitatively compare measurements obtained under different conditions. The experimental methodology employed, analyses performed and resulting correction factor relationship are presented. Implications to next-generation CPCs is also discussed.