Flamelet LES of swirl-stabilized oxy-fuel flames using directly coupled multi-step solid fuel kinetics

Nicolai, Hendrik; Debiagi, Paulo; Wen, Xu; Dreßler, Louis; Maßmeyer, A.; Janicka, J.; Hasse, Christian

doi:10.1016/j.combustflame.2022.112062

Cited by 15 publications

(1 citation statement)

References 79 publications

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“…The kinetic parameters of these subprocesses are affected under oxyfuel conditions. According to [40][41][42], using simplified models for devolatilisation and char conversion can deliver good agreement if the kinetic parameters are accurately determined for these simple models. In this regard, the single first-order reaction (SFOR) model [43] for devolatilisation and the Baum and Street model [44,45] for char conversion are used with the kinetic parameters applied by Nicolai et al [21].…”

Section: Particle Reaction Kineticsmentioning

confidence: 99%

Investigation of the Coupling Schemes between the Discrete and the Continuous Phase in the Numerical Simulation of a 60 kWth Swirling Pulverised Solid Fuel Flame under Oxyfuel Conditions

Askarizadeh,

Pielsticker,

Nicolai

et al. 2024

Fire

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Detailed numerical analyses of pulverised solid fuel flames are computationally expensive due to the intricate interplay between chemical reactions, turbulent multiphase flow, and heat transfer. The near-burner region, characterised by a high particle number density, is particularly influenced by these interactions. The accurate modelling of these phenomena is crucial for describing flame characteristics. This study examined the reciprocal impact between the discrete phase and the continuous phase using Reynolds-averaged Navier–Stokes (RANS) simulations. The numerical model was developed in Ansys Fluent and equipped with user-defined functions that adapt the modelling of combustion sub-processes, in particular, devolatilisation, char conversion, and radiative heat transfer under oxyfuel conditions. The aim was to identify the appropriate degree of detail necessary for modelling the interaction between discrete and continuous phases, specifically concerning mass, momentum, energy, and turbulence, to effectively apply it in high-fidelity numerical simulations. The results of the numerical model show good agreement in comparison with experimental data and large-eddy simulations. In terms of the coupling schemes, the results indicate significant reciprocal effects between the discrete and the continuous phases for mass and energy coupling; however, the effect of particles on the gas phase for momentum and turbulence coupling was observed to be negligible. For the investigated chamber, these results are shown to be slightly affected by the local gas phase velocity and temperature fields as long as the global oxygen ratio between the provided and needed amount of oxygen as well as the thermal output of the flame are kept constant.

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Section: Particle Reaction Kineticsmentioning

confidence: 99%

Investigation of the Coupling Schemes between the Discrete and the Continuous Phase in the Numerical Simulation of a 60 kWth Swirling Pulverised Solid Fuel Flame under Oxyfuel Conditions

Askarizadeh,

Pielsticker,

Nicolai

et al. 2024

Fire

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LES of Biomass Syngas Combustion in a Swirl Stabilised Burner: Model Validation and Predictions

Papafilippou,

Pignatelli,

Subash

et al. 2024

Flow Turbulence Combust

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In this work, numerical investigations were performed using large eddy simulations and validated against detailed measurements in the CeCOST swirl stabilised burner. Both cold and reactive flow have been studied and the model has shown a good agreement with experiments. The verification of the model was done using the LES index of quality and a single grid estimator. The cold flow simulations predicted results closely to experiments setting baseline for the reactive simulations. Coherent structures like the vortex rope above the swirler and a precessing vortex core in the combustion chamber were identified. The reactive conditions were modelled with the Flamelet generated manifold and artificially thickened flame models. Simulations were performed for an experimental syngas composition from black liquor gasification at three different CO2 dilution levels. Three different Reynolds numbers were investigated with the model matching closely to experimentally detected 2D flow field and OH for the most CO2 diluted mixture. It was found that the opening angles of the flames differ by a maximum of 13% between experiments and simulations. The most diluted fuel investigated experienced a liftoff distance of 23.5 mm at the Re 25 k. This was also the highest liftoff distance experienced in this cohort of fuels. The same fuel also proved to have the thickest flame annulus at 78.5 mm. Overall, in cases with no experimental data available the predictions made by the model follow the same trends which hints its applicability to higher Re cases.

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Flame propagation modes for iron particle clusters in air — Part I: Transition from continuous to discrete propagation mode under weak convection effects

Vance,

Scholtissek,

Nicolai

et al. 2024

Combustion and Flame

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Flamelet LES of swirl-stabilized oxy-fuel flames using directly coupled multi-step solid fuel kinetics

Cited by 15 publications

References 79 publications

Investigation of the Coupling Schemes between the Discrete and the Continuous Phase in the Numerical Simulation of a 60 kWth Swirling Pulverised Solid Fuel Flame under Oxyfuel Conditions

Investigation of the Coupling Schemes between the Discrete and the Continuous Phase in the Numerical Simulation of a 60 kWth Swirling Pulverised Solid Fuel Flame under Oxyfuel Conditions

LES of Biomass Syngas Combustion in a Swirl Stabilised Burner: Model Validation and Predictions

Flame propagation modes for iron particle clusters in air — Part I: Transition from continuous to discrete propagation mode under weak convection effects

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