Direct Numerical Simulation of premixed ammonia/hydrogen flames: the effects of thermo-diffusive instabilities
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In order to phase out traditional fuel from the energy mix to reduce CO2 emissions and meet the large energy demand, the combustion of carbon-free fuels needs to be considered. This thesis investigates the combustion of premixed ammonia/hydrogen mixtures in order to gain insights into their fundamental structure. In particular, the work focuses on 1) dispersion relation in the linear phase as an indicator of thermo-diffusive instabilities propensity and 2) turbulence interaction with flames which are thermo-diffusively unstable. This work is performed numerically through Direct Numerical Simulations using the CFD code AVBP. Different mixture ratios of ammonia to hydrogen in the fuels are investigated, as well as different equivalence ratios, with a focus on lean conditions. The imposed initial pressure and temperature are mostly under atmospheric conditions. The work aims to investigate the fundamental properties of the combustion of these carbon-free fuels, to develop models for simulations of combustion processes, and to gain insights into what to expect in experimental or industrial apparatus. Preferential diffusion of light hydrogen atoms is seen to have a great impact in ammonia/hydrogen premixed flames, leading to instabilities, super adiabaticity, higher flame speed and heat release rate.
Består avPaper 1: Coulon, Victor; Gaucherand, Jessica; Xing, Victor; Laera, Davide; Lapeyre, Corentin; Poinsot, Thierry. Direct numerical simulations of methane, ammonia-hydrogen and hydrogen turbulent premixed flames. Combustion and Flame 2023 ;Volum 256. s. 112933- © 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Available at: https://doi.org/10.1016/j.combustflame.2023.112933
Paper 2: Gaucherand, Jessica; Laera, Davide; Netzer, Corinna; Poinsot, Thierry. Intrinsic instabilities of hydrogen and hydrogen/ammonia premixed flames: Influence of equivalence ratio, fuel composition and pressure. Combustion and Flame 2023 ;Volum 256. © 2023 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1016/j.combustflame.2023.112986
Paper 3: Gaucherand, Jessica; Laera, Davide; Schulze-Netzer, Corinna; Poinsot, Thierry. DNS of turbulent premixed ammonia/hydrogen flames: the effects of thermo-diffusive instabilities. This paper is submitted for publication and is therefore not included.