https://doi.org/10.1140/epjs/s11734-025-01969-2
Regular Article
Combined effect of momentum ratio, swirl strength, and injector position on MGT combustor performance
Department of Mechanical Engineering, IIT Jodhpur, 342030, Jodhpur, India
a
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Received:
10
July
2025
Accepted:
16
September
2025
Published online:
23
September
2025
Abstract
The transition to clean and decentralized energy generation can be achieved through fuel-flexible micro gas turbines (MGTs) using renewable fuels such as biogas. However, the stable operation of MGT combustors fueled with biogas is challenging due to the low calorific value of biogas. This study presents a comprehensive numerical investigation of the combined effects of air–fuel momentum ratio, swirl strength, and fuel injector recess on the combustion characteristics of a swirl-stabilized, non-premixed MGT combustor. A finite volume method (FVM) solver, with the realizable k–
turbulence model and the steady laminar flamelet model for turbulence chemistry interaction using the GRI-3.0 chemical mechanism, is used for the study. The numerical setup is validated satisfactorily with the experimental results of the Sydney Swirl Burner Database (SM1). It is observed that a high momentum ratio (
) results in complete combustion across all swirl strengths (Sn = 0.5, 1, 1.5), while excessive swirl (Sn = 1.5) induces upstream flame movement or flame ring around the fuel injector, which can affect injector life. The fuel injector recess affects the flame ring formation as well as the 
emission, and 10 mm recess for moderate swirl strength (Sn = 1) is found to be a good trade-off. It is also observed that the average outlet temperature is highly dependent on the air preheat level. Finally, the combustor, when using biogas, achieves combustion efficiency comparable to that with methane, but the emissions are reduced significantly (by almost 74%) as compared to methane operation.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
