AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Evaluation of Uncertainties in Aircraft Engine Soot Emissions Derived from Engine Smoke Number
MARC STETTLER, Adam M Boies, University of Cambridge
Abstract Number: 333 Working Group: Combustion
Abstract Aircraft gas turbine engines emit particles with a geometric mean particle diameter less than 100 nm consisting of non-volatile and volatile particles. The non-volatile component is primarily black carbon soot (BC). Current regulation is concerned with the visibility of aircraft exhaust, quantified via the engine smoke number (SN) and each engine type is measured before entering service. However, impact assessment of BC on climate and air quality requires mass based emissions estimates. As a result, a method called the First Order Approximation v3.0 (FOA3) is currently endorsed by the US Federal Aviation Administration and the International Civil Aviation Organization to estimate mass emissions of BC. This method relies on an empirical relationship between BC mass concentration in an exhaust sample and resultant SN. We describe how this method, relying on SN, shows a factor of ten or more discrepancy with recently published measurement data for 40% of cases compared. Flexibility within the SN measurement standard procedure is potentially a significant contributing factor. We describe results from a recent experimental study to examine the influence of changing incident flow velocity (a function of filter diameter), sampling line temperature and sample line length within the prescribed ranges. These results are important to quantify the error associated with current estimation methods used in airport emissions inventories and motivate the development of alternative methods independent of SN.