Critical appraisal of integrated CFD/surface roughness models for additive manufactured swirl burners

Al-Ajmi, Rashed, Al-Shaghdari, Mohammed, Goktepe, Burak, Psomoglou, Ianos and Bowen, Philip ORCID: https://orcid.org/0000-0002-3644-6878 2025. Critical appraisal of integrated CFD/surface roughness models for additive manufactured swirl burners. Journal of Engineering for Gas Turbines and Power , pp. 1-29. 10.1115/1.4067738

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Abstract

Additive manufacturing technology creates complex parts that are impossible to be manufactured by traditional methods. However, the process often results in rough and irregular surfaces that can affect performance. Here Computational Fluid Dynamics (CFD) is considered to optimise component design for use in applications such as gas turbine. However, modelling the interactions between turbulent flows and Additive Manufacture (AM)-generated wall roughness affects the predictive capability of numerical models due to difficulty in thoroughly characterising rough wall texture. To address this issue, this study aims to appraise two common wall roughness approaches within the RANS framework: the modified law-of-the-wall and roughness-resolving approaches. The modified law-of-the wall is based on the correlation that converts the measured surface roughness parameters to the equivalent sand-grain roughness height. The latter approach involves the resolution of the roughness elements within the computational grid. The simulations were validated and compared against the velocity data published for the burner with AM swirl nozzle inserts of different surface finishes. The Realizable k-ɛ turbulence model was selected for all the CFD simulations, as it has been already validated for swirling flows. The results showed that the roughness-resolving approach was more accurate than the modified law-of-the wall correlation, with a good match with the experimental velocity data, predicting the velocity shift to the center. The model also revealed the shortened recirculation zone with increasing surface roughness. This is important in predicting flame stability and emissions performance.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Engineering
Additional Information:	License information from Publisher: LICENSE 1: URL: https://www.asme.org/publications-submissions/publishing-information/legal-policies, Start Date: 2025-01-28
Publisher:	American Society of Mechanical Engineers
ISSN:	0742-4795
Date of First Compliant Deposit:	7 February 2025
Date of Acceptance:	17 January 2025
Last Modified:	07 Feb 2025 09:45
URI:	https://orca.cardiff.ac.uk/id/eprint/176018

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