Session: Student Poster Competition

Submission Number: 184709

Impact of Low-Carbon Fuels on Flame Dynamics in a Gas-Turbine Relevant Combustion Systems 

Ammonia is a promising carbon-free fuel for gas turbines; however, its low flame speed and narrow flammability range introduce challenges to flame stability and thermoacoustic performance. This study presents an experimental comparison of the dynamic response of premixed, swirl-stabilized cracked ammonia (NH₃-H₂-N₂) and ammonia methane blends (NH₃-CH₄), compared against a CH₄-CO₂ biogas surrogate fuel. All mixtures were operated under matched conditions of laminar burning velocity, bulk flow velocitym and flame thermal power. Flame transfer functions (FTFs) were calculated from velocity and OH* chemiluminescence fluctuations measurements to quantify the thermoacoustic response of the flames. Phase-locked OH* imaging provided insight into the fluctuations of the flame front. The results show that all flames act as low-pass filter behavior with a gain approaching unity at low frequencies. The NH₃-H₂-N₂ flame showed the lowest phase gradient, attributed to its compactness and low effective Lewis number. In contrast, NH₃-CH₄ and CH₄-CO₂ flames exhibited longer flames and steeper phase gradients. When scaling the results with Strouhal number, both FTF gain and phase collapsed across all flames, confirming that convective time scales govern the flame dynamic response. These findings demonstrate that ammonia-based fuels can achieve a dynamic response comparable to conventional hydrocarbon flames when operated under matched operating conditions. The scaling framework offers a good tool for evaluating the flame response in multi-fuel combustors, helping the design of fuel-flexible, low-emission gas turbine systems.

Presenting Author: Ahmed Gaber H. Saif King Fahd University of Petroleum & Minerals (KFUPM)

Presenting Author Biography: Ahmed Gaber H. Saif is a PhD student in Mechanical Engineering at King Fahd University of Petroleum & Minerals (KFUPM). His research focuses on gas-turbine-relevant combustion, with emphasis on hydrogen/ammonia flames, thermoacoustic instability, and emissions behavior in swirl-stabilized combustors. He has conducted advanced experimental work at KAUST on low-carbon fuels and diagnostic techniques for high-precision flame characterization.
Ahmed has authored multiple Q1 journal publications on hydrogen-enriched combustion, ammonia combustion technologies, and flame dynamics in dual-annular burners. He has presented his work at international combustion conferences and is currently a member of ASME, ACS, and The Combustion Institute (Saudi Section). His ongoing research contributes to developing cleaner, more stable combustion strategies for next-generation gas turbine systems.

Authors:

Ahmed Gaber H. Saif King Fahd University of Petroleum & Minerals (KFUPM)
Nader N. Shohdy King Abdullah University of Science and Technology (KAUST)
Thibault F. Guiberti King Abdullah University of Science and Technology (KAUST)
Esmail M. A. Mokheimer King Fahd University of Petroleum & Minerals (KFUPM)
Deanna A. Lacoste King Abdullah University of Science and Technology (KAUST)