Additive manufacturing-induced roughness in hydrogen-fuelled jet burners: experimental characterisation and numerical modelling

Vivoli, Robin 2025. Additive manufacturing-induced roughness in hydrogen-fuelled jet burners: experimental characterisation and numerical modelling. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Achieving the UK government’s net-zero targets requires key transitions, notably the electrification of domestic heating and transport. While this shift reduces overall energy demand, it necessitates a significant expansion of electricity generation capacity. Although renewable energy sources are expected to dominate the UK’s electricity mix, their intermittent nature means Combined Cycle Gas Turbines (CCGTs) will remain essential for system balancing. CCGTs could play a pivotal role during the energy transition if adapted to operate with low- or zero-carbon fuels. Among these, hydrogen has emerged as a promising zero-carbon energy carrier; however, its distinct combustion characteristics demand substantial modifications to current GT combustors and fuel delivery systems to enable 100% hydrogen combustion and meaningful emission reductions. Additive Manufacturing (AM) is increasingly employed to produce critical gas turbine components such as burners, offering advantages that support designing for greater hydrogen capability. However, the relatively poor surface finish associated with AM has been shown to influence combustor performance and flow characteristics. This study investigates the impact of AM-induced surface roughness on state-of-the-art burner configurations operating with hydrogen, focusing on its effects on stability limits and flow-field behaviour. A series of parametric experimental combustion tests at atmospheric pressure under hydrogen-firing conditions were conducted using two simplified jet burners: a perfectly premixed jet burner (PJB) and jet-in-crossflow (JICF) burner. Both designs allow for inserts representative of conventional machining and AM surface finishes. The objective was to evaluate how surface roughness affects operability and performance across different fuel injection strategies. Experimental findings, combined with insights from numerical simulations of legacy swirl burners with known roughness sensitivity, were used to develop a validated roughness correlation for the PJB under both reacting and isothermal conditions. This correlation was subsequently applied to the JICF configuration to infer additional roughness effects. The integration of experimental data with the developed numerical framework provides a basis for incorporating surface roughness effects into CFD models, informing gas turbine manufacturers on design adjustments and post-processing considerations for AM-produced burners. This work also lays the foundation for more detailed experimental and computational investigations into roughness-induced phenomena in hydrogen-fuelled combustion systems.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Engineering
Uncontrolled Keywords:	1. Surface Roughness 2. Hydrogen 3. Combustion 4. Numerical Modelling 5. Stability Limits 6. CFD
Date of First Compliant Deposit:	6 January 2026
Last Modified:	06 Jan 2026 14:54
URI:	https://orca.cardiff.ac.uk/id/eprint/183579

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