Thermodiffusively-unstable lean premixed hydrogen flames: Phenomenology, empirical modelling, and thermal leading points

Howarth, T.L.; Hunt, Eric; Aspden, A. J.

doi:10.1016/j.combustflame.2023.112811

Cited by 29 publications

(1 citation statement)

References 51 publications

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“…In order to achieve energy, transport and industrial decarbonization, fuel-flexible combustion devices must be designed and deployed to accommodate hydrogen, ammonia and a wide range of biofuels. In this context, PeleLMeX can prove a valuable tool to study alternative fuels combustion characteristics, flame dynamics or pollutant formation mechanisms, both in academic idealized cases (Howarth et al, 2023) as well as in device scale simulations (Appukuttan et al, 2023).…”

Section: Statement Of Needmentioning

confidence: 99%

PeleLMeX: an AMR Low Mach Number Reactive Flow Simulation Code without level sub-cycling

Esclapez,

Day,

Bell

et al. 2023

JOSS

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PeleLMeX simulates chemically reacting low Mach number flows with block-structured adaptive mesh refinement (AMR). The code is built upon the AMReX (Zhang et al., 2019) library, which provides the underlying data structures and tools to manage and operate on them across massively parallel computing architectures. PeleLMeX algorithmic features are inherited from its predecessor PeleLM (PeleLM Team, 2022) but key improvements allow representation of more complex physical processes. Together with its compressible flow counterpart PeleC (Henry de Frahan et al., 2023), the thermo-chemistry library PelePhysics and the multi-physics library PeleMP, it forms the Pele suite of open-source reactive flow simulation codes.

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Section: Statement Of Needmentioning

confidence: 99%

PeleLMeX: an AMR Low Mach Number Reactive Flow Simulation Code without level sub-cycling

Esclapez,

Day,

Bell

et al. 2023

JOSS

View full text Add to dashboard Cite

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DNS of Turbulent Premixed Ammonia/Hydrogen Flames: The Impact of Thermo-Diffusive Effects

Gaucherand,

Laera,

Schulze-Netzer

et al. 2023

Flow Turbulence Combust

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Direct Numerical Simulations (DNS) of three-dimensional premixed turbulent hydrogen-air flames enriched with 19%, 36%, 44% and 57% of NH$$_3$$ 3 (in volume) are performed. Starting from an equivalence ratio of 0.44 for the case with 19% of NH$$_3$$ 3 , richer mixtures of $$\phi =$$ ϕ = 0.54, 0.69 and 0.95 are considered when increasing NH$$_3$$ 3 concentration to obtain comparable laminar flame speeds, i.e., 0.17 m/s for 19% and 36 % NH$$_3$$ 3 enriched case, and 0.30 m/s when NH$$_3$$ 3 concentration is increased to 44 and 57%. The composition and characteristics of the studied mixtures enable to investigate the effects of thermo-diffusivity in a turbulent flow and the role of chemistry and stretch effects in the development of the flames. Given a composition of ammonia and hydrogen and an equivalence ratio, a predictive method is described to identify compositions where thermo-diffusive effects impact the flame and predict the stretch factors. Two maps are proposed to achieve this: the first one is based on the Markstein number and the second one is based on the ratio of consumption speed of strained flames over the laminar unstretched flame speed. This prediction can guide model selection and help manufacturers and experimentalists identify relevant operating points based on desired energy output.

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Spatiotemporal Surface Temperature Measurements Resolving Flame-Wall Interactions of Lean H2-Air and CH4-Air Flames Using Phosphor Thermometry

Ojo,

Padhiary,

Peterson

2024

Flow Turbulence Combust

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Spatiotemporal wall temperature (Twall) distributions resulting from flame-wall interactions of lean H2-air and CH4-air flames are measured using phosphor thermometry. Such measurements are important to understand transient heat transfer and wall heat flux associated with various flame features. This is particularly true for hydrogen, which can exhibit a range of unique flame features associated with combustion instabilities. Experiments are performed within a two-wall passage, in an optically accessible chamber. The phosphor ScVO4:Bi3+ is used to measure Twall in a 22 × 22 mm2 region with 180 µm/pixel resolution and repetition rate of 1 kHz. Chemiluminescence imaging is combined with phosphor thermometry to correlate the spatiotemporal dynamics of the flame with the heat signatures imposed on the wall. Measurements are performed for lean H2-air flames with equivalence ratio Φ = 0.56 and compared to CH4-air flames with Φ = 1. Twall signatures for H2-air Φ = 0.56 exhibit alternating high and low-temperature vertical streaks associated with finger-like flame structures, while CH4-air flames exhibit larger scale wrinkling with identifiable crest/cusp regions that exhibit higher/lower wall temperatures, respectively. The underlying differences in flame morphology and Twall distributions observed between the CH4-air and lean H2-air mixtures are attributed to the differences in their Lewis number (CH4-air Φ = 1: Le = 0.94; H2-air Φ = 0.56: Le = 0.39). Findings are presented at two different passage spacings to study the increased wall heat loss with larger surface-area-to-volume ratios. Additional experiments are conducted for H2-air mixtures with Φ = 0.45, where flame propagation was slower and was more suitable to resolve the wall heat signatures associated with thermodiffusive instabilities. These unstable flame features impose similar wall heat fluxes as flames with 2–3 times greater flame power. In this study, these flame instabilities occur within a small space/time domain, but demonstrate the capability to impose appreciable heat fluxes on surfaces.

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Thermodiffusively-unstable lean premixed hydrogen flames: Phenomenology, empirical modelling, and thermal leading points

Cited by 29 publications

References 51 publications

PeleLMeX: an AMR Low Mach Number Reactive Flow Simulation Code without level sub-cycling

PeleLMeX: an AMR Low Mach Number Reactive Flow Simulation Code without level sub-cycling

DNS of Turbulent Premixed Ammonia/Hydrogen Flames: The Impact of Thermo-Diffusive Effects

Spatiotemporal Surface Temperature Measurements Resolving Flame-Wall Interactions of Lean H2-Air and CH4-Air Flames Using Phosphor Thermometry

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