The impact of sustainable aviation fuels on nvPM emissions, structure, and morphology from gas turbine engines

McPherson, George 2025. The impact of sustainable aviation fuels on nvPM emissions, structure, and morphology from gas turbine engines. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Increased concerns of CO2 and environmental impacts of aircraft emissions have led to a drive towards the adoption of Sustainable Aviation Fuels (SAFs). The fuel composition of SAF reduces the mass, number and size of aircraft non-volatile Particulate Matter (nvPM), which is the largely carbonaceous material leaving an aircraft engine, formally called soot/smoke. However, the impacts of fuel composition on the morphological properties of nvPM is less understood. The morphological properties of nvPM impact human health and the optical properties of nvPM. Changes in a particle's optical properties impact both its environmental impact and measurement accuracy. The aim of this research was therefore to determine if fuel composition variations, witnessed in ‘drop in’ ASTM approved SAFs impact the morphological properties of the emitted nvPM. Real-time nvPM morphological measurements were developed and deployed at two full-scale Gas turbine tests examining four engines and eight fuels. A novel ‘fast’ DMA-ELPI+ effective density measurement method was developed, refined and successfully demonstrated, quantifying size resolved effective density, during certification-type engine testing. Although uncertainties in the developed method were observed, following optimisation, effective density derived nvPM mass, was predicted to within 16% of regulatory mass measurements for a Turboprop engine, highlighting the potential of the method. No fuel composition impact was observed in the case of nvPM effective density, across the engine technologies and fuels tested. Offline nvPM samples, from two of the engines, were analysed with a Transmission Electron Microscope (TEM) and Raman spectroscopy. These methods indicated that primary particle size and composition at a given particle size are not impacted by SAF. Although smaller primary particles were observed with SAF, this reduction was driven by the reduction in aggregate size witnessed for SAF. Given the lack of observed variation in the morphology of nvPM at a given size with the use of SAFs, the conclusions of this thesis are that the adoption of ASTM approved SAFs should not inadvertently, negatively impact health, environmental effects or the uncertainty associated with nvPM regulatory measurements due to the morphological and structural properties of the nvPM.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Engineering
Uncontrolled Keywords:	1. nvPM 2. Effective Density 3. Morphology 4. DMA-ELPI+ 5. SAF 6. Aircraft emissions
Date of First Compliant Deposit:	28 July 2026
Last Modified:	28 Jul 2026 10:27
URI:	https://orca.cardiff.ac.uk/id/eprint/188403

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