Characterising Particulate Matter in the Evolving Exhaust Plume of an Aircraft Engine in a Test Cell

Lukas Durdina

The evolution of Particulate Matter (PM) emissions from a CFM56-7B aircraft engine in a controlled test cell was investigated in terms of their physical, chemical, and optical properties. Measurements were performed at the engine exit plane (P1), in front of the silencer (P2), and at the stack exit (P3) of the test cell at SR Technics, Zurich, Switzerland. Black carbon (BC) mass was measured using Micro Soot Sensor (MSS), Laser Induced Incandescence (LII), and Photoacoustic Extinctiometer (PAX). Elemental carbon (EC) and organic carbon (OC) analyses were performed using the Sunset Labs EC-OC analyser. Effective density was measured using a Centrifugal Particle Mass Analyzer (CPMA). Particle size distributions were measured with a Scanning Mobility Particle Sizer (SMPS). A nucleation mode was observed at low thrust for measurements at P2 and P3, which was not present at P1. The single scattering albedo (SSA) was determined at P1 and P2 with two PAX monitors (λ = 870 nm), and two Cavity Attenuated Phase Shift SSA monitors (CAPS PMSSA, λ = 660 and 532 nm), both operated at P2. A significant increase in the SSA was observed between P1 and P2 for thrust levels below 30%. The increase in SSA is most likely related to an increase in the light scattering due to condensed volatile material at P2.

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