Methodology for Particle Characterization in the Exhaust Flows of Gas Turbine Engines

The University of Missouri-Rolla (UMR) has developed, constructed, and employed a trailer-housed mobile aerosol sampling system (MASS) for the physical characterization of particles extracted from the exhaust flows of gas turbine engines. The MASS has been designed for a range of sampling conditions typically encountered at exit planes of combustors, angular sector rigs, flame tubes, and actual engines. To date measurements have been conducted in test cells, altitude chambers, on the wing (on the ground), and in flight. Reaching beyond the historically used but limited concept of smoke number, the MASS relies on differential mobility analysis, laser particle sizing, transmission electron microscopy, and molecular absorption spectroscopy to measure directly particle number concentration and size distribution (0.01 to<25μm), water mixing ratio, particle morphology, and carbon dioxide (CO₂). Combined with key combustor/engine operating conditions and fuel properties the MASS provides a series of derived parameters including mean particle diameter and number-, surface-, and mass-based emission indices, which are important parameters for the performance characterization and environmental assessment of gas turbine engines. In this article we describe the technical details of the UMR MASS, discuss data reduction and experimental uncertainties, and show some example data sets.