Ignition and combustion of fuel pockets moving in an oxidizing atmosphere

Daou, Joe͏̈l

doi:10.1016/s0010-2180(98)00005-4

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…As the subsequent diffusion between adjacent flame elements depletes the concentration of reactants, the reactant consumption rate decreases, reducing the risk of local extinction, until the two flame sheets eventually annihilate each other. This leads to the formation of pockets of unburned reactants surrounded by diffusion flames, 53 which increases the effective flame area and enhances the overall combustion process. 38 As can be seen, previous to this roll-up process the mixing layer is strongly deformed in the rear part of the vortices, eventually developing a sharp bend, where, obviously, the assumption of negligible curvature leading to Eq.…”

Section: A Two-dimensional Casementioning

confidence: 99%

On the interaction of vortices with mixing layers

Vera

Liñán

2004

Physics of Fluids

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We describe the perturbations introduced by two counter-rotating vortices-in a two-dimensional configuration-or by a vortex ring-in an axisymmetric configuration-to the mixing layer between two counterflowing gaseous fuel and air streams of the same density. The analysis is confined to the near stagnation point region, where the strain rate of the unperturbed velocity field, A 0 , is uniform. We restrict our attention to cases where the typical distance 2r 0 between the vortices-or the characteristic vortex ring radius r 0 -is large compared to both the thickness, ␦ v , of the vorticity core and the thickness, ␦ m ϳ(/A 0 ) 1/2 , of the mixing layer. In addition, we consider that the ratio, ⌫/, of the vortex circulation, ⌫, to the kinematic viscosity, , is large compared to unity. Then, during the interaction time, A 0 Ϫ1 , the viscous and diffusion effects are confined to the thin vorticity core and the thin mixing layer, which, when seen with the scale r 0 , appears as a passive interface between the two counterflowing streams when they have the same density. In this case, the analysis provides a simple procedure to describe the displacement and distortion of the interface, as well as the time evolution of the strain rate imposed on the mixing layer, which are needed to calculate the inner structure of the reacting mixing layer as well as the conditions for diffusion flame extinction and edge-flame propagation along the mixing layer. Although in the reacting case variable density effects due to heat release play an important role inside the mixing layer, in this paper the analysis of the inner structure is carried out using the constant density model, which provides good qualitative understanding of the mixing layer response.

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Section: A Two-dimensional Casementioning

confidence: 99%

On the interaction of vortices with mixing layers

Vera

Liñán

2004

Physics of Fluids

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“…Según la difusión reduce la concentración de reactante entre los elementos de llama adyacentes, el ritmo de consumo de los reactantes disminuye, lo que reduce el riesgo de extinción local de la llama, hasta que las dos capas de reacción acaban aniquilándose la una a la otra. Esto conduce a la formación de embolsamientos de reactantes sin quemar rodeados por llamas de difusión (Daou [27]), lo que incrementa el area efectiva de la llama aumentando así el ritmo global del proceso de combustión.…”

Section: Caso Bidimensionalunclassified

Efectos no estacionarios, de difusión preferencial y de liberación de calor en modelos de llamas laminares

Coello¹

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más rápida cuando se retienen los efectos de densidad variable, mientras que la respuesta en amplitud cambia muy poco cuando se retienen las variaciones de densidad. También se discuten brevemente las dificultades que surgen cuando la capa de mezcla constituye además una entrefase de densidad. Para ello, se presenta una solución exacta de las ecuaciones de Euler para la propagación de torbellinos en presencia de entrefases abruptas de densidad que permite aclarar algunos aspectos relevantes de este tipo de flujos.

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Ignition and combustion of a gaseous fuel pocket array in an oxidizing environment

Caldeira

2016

Numerical Heat Transfer, Part A: Applications

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Ignition and combustion of fuel pockets moving in an oxidizing atmosphere

Cited by 4 publications

References 17 publications

On the interaction of vortices with mixing layers

On the interaction of vortices with mixing layers

Efectos no estacionarios, de difusión preferencial y de liberación de calor en modelos de llamas laminares

Ignition and combustion of a gaseous fuel pocket array in an oxidizing environment

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