Influence of surface roughness and fuel delivery strategy on hydrogen combustion stability in turbulent jet burners

Vivoli, Robin ORCID: https://orcid.org/0009-0008-5736-4784, Pugh, Daniel ORCID: https://orcid.org/0000-0002-6721-2265, Davies, Tomas, Morris, Steven ORCID: https://orcid.org/0000-0001-5865-8911 and Valera-Medina, Agustin ORCID: https://orcid.org/0000-0003-1580-7133 2026. Influence of surface roughness and fuel delivery strategy on hydrogen combustion stability in turbulent jet burners. Proceedings of the Combustion Institute 42 , 106718. 10.1016/j.proci.2026.106718

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Abstract

The influence of internal surface roughness on the performance and operability of atmospheric hydrogen jet burners was investigated under both fully and partially premixed conditions. A modular burner architecture, representative of practical combustion systems, was employed, enabling systematic variation of surface finish and fuel-air delivery strategy to isolate roughness effects from other geometric or flow influences. High-speed OH* chemiluminescence imaging was used to characterize flame morphology, and flashback dynamics across a range of operating conditions, complemented by roughness-sensitive RANS simulations. The study demonstrates that surface roughness strongly affects flame morphology and stability, with the nature of these effects dependent on the degree of premixing. The rough insert (R2) presenting enhanced flashback resistance in both burner configurations, yielding steeper critical velocity gradients and prolonged pre-flashback stability; the effect was most pronounced under fully premixed conditions. In fully premixed operation, use of the R2 insert shifts flames upstream and is associated with a transition to boundary-layer flashback. Partially premixed flames remain dominated by boundary layer flashback across all cases; however, roughness-induced changes in the flow field are consistent with fuel redistribution as a plausible mechanism for the observed shift in flame anchoring behavior, resulting in an inversion of flame location trends. Numerical results suggest that roughness modifies local equivalence ratio distributions at the nozzle exit without altering the global mixture equivalence ratio. Together, the experimental observations and numerical results suggest that the coupled influence of roughness, mixing quality, and momentum interaction plays an important role in determining flashback behavior. Underscoring the potential importance of surface finish considerations in the design of hydrogen-fueled combustion systems.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Engineering
Publisher:	Elsevier BV
ISSN:	1540-7489
Date of First Compliant Deposit:	26 October 2026
Date of Acceptance:	19 June 2026
Last Modified:	26 Oct 2026 12:16
URI:	https://orca.cardiff.ac.uk/id/eprint/190421

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