Impact of alternative fuels on the PM emissions characteristics of gas turbine engines

Lobo, Prem (2015) Impact of alternative fuels on the PM emissions characteristics of gas turbine engines. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The growth in the commercial aviation sector has raised concerns about the impact of emissions from aircraft operations on local and regional air quality, climate change, and health-related effects. The lack of Particulate Matter (PM) emissions data from gas turbine engines coupled with the increasing interest in the use of alternative fuels as a potential emissions mitigation strategy are the motivating factors behind this thesis. A total of seven peer-reviewed archival journal publications form the basis of this work. It commences with two field studies that were performed at the Oakland International Airport and the Hartsfield-Jackson Atlanta International Airport to measure the characteristics of aircraft engine specific PM emissions at the engine exit plane and in the near field as the exhaust plume expands and cools. Having characterised the PM emissions from various aircraft gas turbine engine types, the significant impact that alternative fuels can have on the PM emissions characteristics was explored and the results were correlated with fuel properties. A new robust and standardised methodology for the measurement of non-volatile PM emissions is described, and its reproducibility against other systems is demonstrated. Finally this standardized system was used in a detailed examination of the impact of fuel composition on the characteristics of the emitted non-volatile PM from a gas turbine engine. These publications and the resulting data improved the characterisation and quantification of PM emissions for a wide variety of gas turbine engines burning conventional and alternative fuels. PM emissions from aircraft gas turbine engines at airports were found to have bimodal size distributions, consisting of a nucleation mode with volatile PM and an accumulation mode with volatile PM condensed on the surface of non-volatile PM. Fuel properties were found to have a significant impact on the production of PM. The reductions in PM emissions with alternative fuels were best correlated with fuel hydrogen content. The data and analysis from these publications will be used to improve/validate current environmental impact predictive tools with real world aircraft gas turbine engine specific PM emissions inputs and develop effective emissions mitigation strategies.