Advances in understanding combustion phenomena using non-premixed and partially premixed counterflow flames: A review

Ravikrishna, RV; Sahu, Amrit Bikram

doi:10.1177/1756827717738168

Cited by 16 publications

(5 citation statements)

References 180 publications

(286 reference statements)

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“…The effect of mixing at the flame front has been analysed in detail both for laminar (Sirignano 2021) and turbulent (Bilger 1989) mixing layers. Flame fronts are also analysed in an applied counterflow (Ravikrishna & Sahu 2018), which allows for steady-state flame structures. Single-temperature combustion models are studied by Merzhanov & Khaikin (1988), with the domain divided into reaction zones, and travelling flame fronts are found.…”

Section: Introductionmentioning

confidence: 99%

Modelling and analysis of an endothermic reacting counter-current flow

Luckins

Oliver²,

Please³

et al. 2022

J. Fluid Mech.

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We study the endothermic reaction and flow of a granular solid reactant, where energy for the reaction is provided by a counter-current flow of hot gases through the porous reactant bed. Research into reacting flows typically focusses on exothermic combustion processes. However, endothermic processes are common in the metallurgy industry, including the production of cement, silicon and rutile titanium dioxide. Several common features are observed in experimental and numerical studies of these processes, including critical temperatures of the reactant at which the chemical reaction begins, and regions of the reactor with uniform reactant temperature. Motivated specifically by the processes in a silicon furnace, we analyse a model of endothermic, reacting counter-current flow using the method of matched asymptotic expansions. Assuming the Péclet number in the solid is large, we explore the full range of values for the dimensionless inter-phase heat-transfer rate, finding six distinguished limits. In all limits, we find a diffusive boundary layer in which there is a fast chemical reaction rate due to the high temperatures, analogous to exothermic flame fronts. Outside this region, the counter-current flow is crucial to the chemical processes. For intermediate values of the heat-transfer rate, we find the same qualitative properties as those observed across the metallurgy industry, and we quantify the dependence of these properties on the flow rate and heat-transfer rate. In the limit of large heat-transfer coefficient, we derive the single-temperature limit, in which the solution structure is dependent on the direction of net heat flux through the domain.

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Section: Introductionmentioning

confidence: 99%

Modelling and analysis of an endothermic reacting counter-current flow

Luckins

Oliver²,

Please³

et al. 2022

J. Fluid Mech.

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“…Investigations in counterflow burners are of great importance because knowledge of properties such as extinction strain rate is essential for development and validation of accurate chemical kinetic models. A recent review by Ravikrishna and Sahu highlights the importance and advances made in understanding combustion kinetics and dynamics with the use of counterflow flames. Numerous researchers have previously reported extinction strain rates of ethanol in comparison with isooctane − in a counterflow burner arrangement.…”

Section: Introductionmentioning

confidence: 99%

Experiments and Kinetic Modeling of Diffusion Flame Extinction of 2-Methylfuran, 2,5-Dimethylfuran, and Binary Mixtures with Isooctane

et al. 2020

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This work presents an experimental and numerical study of extinction properties of 2,5-dimethylfuran (DMF) and 2methylfuran (MF) in counterflow diffusion flames at atmospheric pressure. The impact of addition of isooctane to the fuels is presented with two degrees of blends (25:75 and 50:50). The analysis was carried out for different levels of fuel loading ranging from 0.10 to 0.24 (volumetric) with the rest of the component being N 2 as a carrier gas. Extinction limits are observed to increase with an increase in fuel loading, and the resistance to extinction follows the order MF > isooctane > DMF. Numerical predictions using the Tianjin mechanism are within 10% of the measurements for MF cases, while the Galway mechanism tends to underpredict at higher fuel loading conditions. For DMF flames, both the mechanisms perform relatively well at X F ≤ 0.14; however, they underpredict as the fuel loading is increased. Addition of isooctane to DMF led to an increase in the extinction limits at low fuel loading conditions, but the impact of blending diminished at higher fuel loading conditions. On the other hand, addition of isooctane had a minimum impact on MF flame's extinction limit at low fuel loading conditions, while it led to a reduction in the resistance to extinction at higher fuel loadings. Numerical simulations by a mechanism proposed for the isooctane-DMF-MF blend predict similar effects of blending, however, consistently tend to underpredict at higher fuel loading conditions. Quantitative reaction path diagrams show that the H-abstraction step is the dominant fuel consumption route for near-extinction MF and DMF flames. With an increase in fuel loading, the role of C 5 H 5 in the H-abstraction process increases in DMF/air flames. Reaction sensitivity analysis shows an increase in the importance of C 5 H 5 kinetics in X F = 0.24 DMF flames as compared to X F = 0.14 along with the ring-opening step converting DMF to 3,4-hexadiene-2-one. In MF/air flames, the degree of change in sensitivities with fuel loading was found to be significantly low as compared to the DMF/air flames. Finally, reaction rate analysis was carried out to reveal that the slower consumption of MF causes the underprediction of the extinction strain rate by the Galway mechanism as compared to the Tianjin mechanism.

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“…Counter-flow burners are suitable for studying laminar non-premixed (diffusion) and premixed or partially premixed flames, their structure (temperature and speciation) as well as parameters of flame stability (extinction/ignition) and propagation [4,5]. Following the formulation given in [6]: (I) double jet and (II) porous cylinder problems can be defined.…”

Section: Introductionmentioning

confidence: 99%

Experimental Apparatus and Modeling Framework for Studying Counter-Flow Laminar Flames

Nevrlý¹,

Klečka²,

Blejchař³

et al. 2019

Topical Problems of Fluid Mechanics 2019

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Laboratory scale platform suitable for investigations on the structure of laminar diffusion and premixed flames in a counter-flow burner configuration is reported within this work. In particular, it is focused on design and setup of counter-flow burner apparatus specifically aimed at stabilization of laminar premixed cool flames. One-dimensional numerical simulations of dimethyl ether-air flames with detailed chemical kinetics and multi-component transport were carried out. More complex, three-dimensional, numerical simulations were performed assuming axially symmetric flow fields in realistic burner geometry, when addressing the effect of different nozzle shape on the flow-fields and corresponding flame structure.

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Advances in understanding combustion phenomena using non-premixed and partially premixed counterflow flames: A review

Cited by 16 publications

References 180 publications

Modelling and analysis of an endothermic reacting counter-current flow

Modelling and analysis of an endothermic reacting counter-current flow

Experiments and Kinetic Modeling of Diffusion Flame Extinction of 2-Methylfuran, 2,5-Dimethylfuran, and Binary Mixtures with Isooctane

Experimental Apparatus and Modeling Framework for Studying Counter-Flow Laminar Flames

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