Effect of Mixing on the Anchoring and Combustion Regimes of Pure Hydrogen Flames in Sequential Combustors

Solana-Pérez, Roberto; Shcherbanev, Sergey; Ciani, Andrea; Noiray, Nicolas

doi:10.1115/1.4055509

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…[10,11,12,13,14]. The combustion behavior of hydrogen at auto-igniting conditions in a sequential combustor configuration has been experimentally investigated in our laboratory in [15]. The present study builds on this latter work, but focuses on the effects that methane enrichment with hydrogen has on combustion.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of ignition and combustion of hydrogen-enriched methane in a sequential combustor

Impagnatiello¹,

Malé²,

Noiray³

2022

Preprint

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Ignition and combustion behavior in the second stage of a sequential combustor are investigated numerically at atmospheric pressure for pure CH 4 fueling and for a CH 4 /H 2 fuel blend in 24:1 mass ratio using Large Eddy Simulation (LES). Pure CH 4 fueling results in a turbulent propagating flame anchored by the hot gas recirculation zone developed near the inlet of the sequential combustion chamber. Conversely, CH 4 /H 2 fueling results in a drastic change of the combustion process, with multiple auto-ignition kernels produced upstream of the main flame brush. Chemical Explosive Mode Analysis indicates that, when H 2 is added, flame stabilization in the combustion chamber is strongly supported by auto-ignition chemistry. The analysis of fuel decomposition pathways highlights that radicals advected from the first stage flame, in particular OH, induce a rapid fuel decomposition and cause the reactivity enhancement that leads to auto-ignition upstream of the sequential flame. This behavior is promoted by the relatively large mass fraction of OH radicals found in the flow reaching the second stage, which is approximately one order of magnitude greater than it would be at chemical equilibrium. The importance of the out-of-equilibrium vitiated air on the ignition behavior is proven via an additional LES that features weak auto-ignition kernel formation when equilibrium is artificially imposed. It is concluded, therefore, that parameters affecting the relaxation towards chemical equilibrium of the vitiated flow can have an important influence on the operability of sequential combustors fueled with varying fractions of H 2 blending.

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Section: Introductionmentioning

confidence: 99%

Numerical study of ignition and combustion of hydrogen-enriched methane in a sequential combustor

Impagnatiello¹,

Malé²,

Noiray³

2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Numerical Study of Ignition and Combustion of Hydrogen-Enriched Methane in a Sequential Combustor

Impagnatiello,

Malé,

Noiray

2024

Flow Turbulence Combust

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Ignition and combustion behavior in the second stage of a sequential combustor are investigated numerically at atmospheric pressure for pure $${\text{CH}}_{4}$$ CH 4 fueling and for two $${\text{CH}}_{4}$$ CH 4 -$${\text{H}}_{2}$$ H 2 fuel blends in 24:1 and 49:1 mass ratios , respectively, using Large Eddy Simulation (LES). Pure $${\text{CH}}_{4}$$ CH 4 fueling results in a turbulent propagating flame anchored by the hot gas recirculation zones developed near the inlet of the sequential combustion chamber. As the $${\text{H}}_{2}$$ H 2 content increases, the combustion process changes drastically, with multiple auto-ignition kernels produced upstream of the main flame brush. Analysis of the explosive modes indicates that, for the highest $${\text{H}}_{2}$$ H 2 amount investigated, flame stabilization in the combustion chamber is strongly supported by auto-ignition chemistry. The analysis of fuel decomposition pathways highlights that radicals advected from the first stage flame, in particular OH, induce a rapid fuel decomposition and cause the reactivity enhancement that leads to auto-ignition upstream of the sequential flame. This behavior is promoted by the relatively large mass fraction of OH radicals found in the flow reaching the second stage, which is approximately one order of magnitude greater than it would be at chemical equilibrium. The importance of the out-of-equilibrium vitiated air on the ignition behavior is proven via an additional LES that features weak auto-ignition kernel formation when equilibrium is artificially imposed. It is therefore concluded that parameters affecting the relaxation towards chemical equilibrium of the vitiated flow can have an important influence on the operability of sequential combustors fueled with varying fractions of $${\text{H}}_{2}$$ H 2 blending.

show abstract

Effect of Mixing on the Anchoring and Combustion Regimes of Pure Hydrogen Flames in Sequential Combustors

Cited by 2 publications

References 30 publications

Numerical study of ignition and combustion of hydrogen-enriched methane in a sequential combustor

Numerical study of ignition and combustion of hydrogen-enriched methane in a sequential combustor

Numerical Study of Ignition and Combustion of Hydrogen-Enriched Methane in a Sequential Combustor

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