Session: 03-09 Digital applications

Paper Number: 125957

125957 - Large Eddy Simulation of Ammonia-Hydrogen Non-Premixed Flames Stabilized on a Bluff Body Burner 

The demand for carbon-free fuels such as ammonia (NH3) and hydrogen (H2) has been growing rapidly in the past decade due to stricter environmental policies being applied. The storage and transport of NH3 in the liquid form, at a relatively low tank pressure, are comparatively easier than those of H2. As a result, NH3 is considered as an alternative H2-carrier fuel. Since NH3 is a more economical and eco-friendly fuel (compared with hydrocarbon fuels such as natural gas), it has become a potential energy provider for the marine, aviation, and gas turbine industries.

However, the narrow flammability, low reactivity, and potential emission of nitrogen oxides (NOx) during its combustion have prevented NH3 from being a practical fuel for industrial combustors. Recent experiments have investigated the fundamental characteristics of NH3 flames under premixed and non-premixed combustion modes, focusing on flame speed, turbulence-chemistry interaction, and the impact of dissociation/cracking of NH3 into H2 and N2. Various computational fluid dynamics (CFD) simulations have also been performed, where a series of CFD combustion models have been evaluated and validated against experimental data. The validated numerical models and workflows can then be used to decrease the number of experiments needed and eventually to reduce the total costs of designing NH3-fueled burners. To predict the highly turbulent flame behavior, scale-resolving models such as Large Eddy Simulation (LES) have been proven to be more accurate than the Reynolds-Averaged Navier-Stokes (RANS) approach. 

In this work, the performance of the Flamelet Generated Manifold (FGM) combustion model in combination with the LES turbulence model has been evaluated using commercial CFD software to predict bluff-body stabilized NH3/H2 non-premixed jet flames. The experimental data were obtained by Alfazazi et al. at King Abdullah University of Science and Technology (KAUST) (Combustion and Flame, Volume 258, Part 2, 2023, 113066). The different cracking levels of NH3 into H2 and N2 result in four different NH3/H2 blending scenarios, ranging from a pure H2 flame (i.e., "fully cracked") to a flame with 72% volume of NH3. The flame shapes, temperature distribution, and NO and unburnt NH3 emissions have all been simulated, which generally match well the available experimental data and are found to be more accurate than previous RANS predictions. The numerical settings and workflow developed in this study may be applied to more complex configurations and contribute to a wider deployment of NH3 as a practical fuel for multiple industries.

Presenting Author: Yu Xia Ansys UK Ltd.

Presenting Author Biography: Yu Xia is currently an R&D Engineer II at Ansys UK and has been a member of the FBU Applications Team since 2018. Yu Xia received his PhD degree from Imperial College London in 2019 and has been a certified Chartered Engineer (CEng) and full Member of the Institute of Mechanical Engineers (MIMechE). His research focuses on combustion, thermoacoustic and entropy wave, etc., involving verification & validation, benchmarking, generating best practice & tutorial, etc. Yu has 10 years' experience on using CFD software. Yu also writes journal papers and attends technical conferences. He has published 6 top-journal articles and more than 20 conference proceedings in the last 7 years. For more details, please visit his personal website via
https://sites.google.com/view/steven-xia

Authors:

Yu Xia Ansys UK Ltd.
Ishan Verma ANSYS Software Pvt. Ltd.
Sourabh Shrivastava ANSYS Software Pvt. Ltd.
Pravin Nakod ANSYS Software Pvt. Ltd.
David F. Fletcher University of Sydney
Bassam Dally King Abdullah University of Science and Technology