Military aircraft particulate emissions - Case of hercules C-130H cargo plane

A field campaign was executed during the first week of October 2005 at the Kentucky Air National Guard (KYANG) base in Louisville, KY to measure PM and gaseous emissions from a military C-130H aircraft. The characterization included particulate and gaseous pollutants by using in-situ extractive and remote optical sensing technologies. The characterization data show monotonically increased levels of particulate and gaseous emissions as the engine power setting increased. Similar relationships between the concentrations of gas species and engine power settings were observed at a location 15-m downstream of the engine exhaust plane (EEP). However, the relationship for engine-emitted particulate matter at the 15-m downstream location (Far-field location) was not a simple function of the engine power settings as that of the gas species was. The results clearly show that aircraft emission factor or index for particulate matter cannot be experimentally determined at a downstream location too far away from the exhaust exit and has to be determined right at the engine exhaust plane. While the geometric mean diameter of the major peak of the particle size distribution obtained under any engine power setting in this work was located in between 50 and 80 nm, burst in concentration of extremely small particles (less than 20-nm in electrical mobility diameter) at the Far-field location behind the engine exhaust plane was recorded. This increase in such small particles was not observed at the EEP suggesting that the formation was likely resulted from decrease in plume temperature caused by mixing and entraining cool ambient air when the initially hot plume traveling down 15-m distance from the exhaust exit. The peak size of these small particles was unidentified as the size distribution curves were open-ended due to the detection limitation of the sizer for very small particles (less than 10 nm). The number-based geometric mean diameters of the emitted non-volatile primary particles increased as the engine power settings increased, but the dispersion (measured by the geometric standard deviation) of the engine particle population was not. Emission indices of non-volatile particulate matter based on the number and mass concentrations are reported in a separate presentation (A-564-AWMA). There are also reports on extensive gas species emissions using extractive and remote sensing platforms by other authors in the same session, and they will not be included in this extended abstract.