An experimental study of the nvPM emissions produced by alternative aviation fuels in a newly-developed RQL research combustor

Harper, Joseph 2022. An experimental study of the nvPM emissions produced by alternative aviation fuels in a newly-developed RQL research combustor. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Emissions from aircraft are known to impact both the local and global environment, and are expected to increase with the predicted rise in air travel in future years. Of these emissions, non-volatile Particulate Matter (nvPM) is known to negatively affect both the local and global environment. The use of Sustainable Aviation Fuels (SAF) has been shown to greatly reduce nvPM emissions due to reductions in aromatic compounds, and can also allow for offsetting of CO2. With the introduction of increasingly stringent regulations concerning nvPM following the CAEP/11 meeting, it is anticipated that SAF will see increased use in the commercial aviation sector in upcoming years. As such, there is a need to understand their behaviour in representative aero combustion environments. This thesis describes the development of a non-proprietary RQL combustion rig used for experimentation concerning the emissions produced by SAF, manufactured using a combination of Additive Manufacturing (AM) and conventional machining. Combustion emissions tests were undertaken using multiple iterations of the combustor, with a range of conventional fuels, SAF, and fuel blends. Emissions were sampled using ICAO compliant instrumentation, and corrected for system losses using size-dependant loss corrections. The effects of fuel properties and combustor operating conditions on loss corrected nvPM were explored, yielding a new proposed hydrogen content trend for correlating fuel properties to nvPM emissions. A systematic assessment of sample system loss correction procedures indicated that, without system loss corrections, reductions in nvPM number achievable through the use of a high hydrogen content SAF (as currently reported in literature) are overreported by 6-9%. Droplet sizing and spray imaging were used to characterise the atomisers developed for the combustor. Suitable correlations from the literature were subsequently optimised using a linear regression code for best quality of fit with experimental data. Spray experimentation showed that small variations in average droplet sizes may be expected across alternative fuels due to physical fuel properties (7-12% at the conditions tested). Using the correlation developed, small predicted increases in SMD of ~5% were found to reduce combustion stability and consistently exacerbate nvPM emissions, leading to relative increases of 5-72% for EImass, 11-89% for EInumber, and 1-7% for GMD.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Sustainable Aviation Fuel, SAF , RQL , non-volatile Particulate Matter, nvPM , Atomisation , Prefilming Airblast Atomiser , Additive Manufacturing
Date of First Compliant Deposit:	4 October 2022
Last Modified:	06 May 2023 02:38
URI:	https://orca.cardiff.ac.uk/id/eprint/153029

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