Triple flame: Inherent asymmetries and pentasectional character

Juanós, Albert Jordà; Sirignano, William A.

doi:10.1080/13647830.2014.923116

Cited by 8 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The well known triple flame exhibits that character. This is well known for triple flames where several flame branches can appear (Jordà Juanós and Sirignano, 2014;Rajamanickam et al, 2019). It also is found in counterflows (Sirignano, 2019a;López-Cámara et al, 2019.…”

Section: Multiple Flamesmentioning

confidence: 73%

Mixing and Combustion in a Laminar Shear Layer with Imposed Counterflow

Sirignano

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Three-dimensional laminar flow structures with mixing, chemical reaction, normal strain, and shear strain qualitatively representative of turbulent combustion at the small scales are analyzed. A mixing layer is subjected to counterflow in the transverse y-and z-directions. Both non-reactive and reactive flows are examined. Reduction of the threedimensional boundary-layer equations to a one-dimensional similar form is obtained allowing for heat and mass diffusion with variations in density and properties. In steady configurations, a set of ODEs governs the three velocity components as well as the scalar-field variables. The transverse velocity is determined as a functional of the similarity coordinate. A generalization is found extending the Crocco integral for non-unitary Prandtl number and for imposed normal strain. A flamelet model for individual diffusion flames with combined shear and normal strain is developed. Another model with solution in similar form is obtained for a configuration with a dominant diffusion flame and a weaker fuel-rich premixed flame. Results for the velocity and scalar fields are found for ranges of Damköhler number Da, normal strain rate due to the counterflow, streamwise-velocity ratio across the mixing layer, Prandtl number, and Mach number. For the flamelet model, a conserved scalar is cast as the independent variable to give an alternative description of the results. The imposed normal strain decreases mixing-layer thickness and increases scalar gradients and transport rates. There is indication of diffusion control for partially premixed flames in the multi-branched flame situation. The enhancement of the mixing and combustion rates by imposed normal strain on a shear layer can be very substantial. Also, the imposition of shear strain and thereby vorticity on the counterflow can be substantial indicating the need for flamelet models with both shear strain and normal strain. Superscripts * Dimensional values ′ Ordinary derivative with respect to η Subscripts m Integer for species designation ∞ Conditions at positive infinite y −∞ Conditions at negative infinite y

show abstract

Section: Multiple Flamesmentioning

confidence: 73%

Mixing and Combustion in a Laminar Shear Layer with Imposed Counterflow

Sirignano

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the present case, Z varies smoothly from Z = 0 to Z = 1 when y extends from −∞ to +∞. The mixture fraction is a useful property when the fuel and oxidizer have equal Lewis numbers, i.e., Le F = Le O = Le because, according to Equation (7), it satisfies…”

Section: The Fast Chemistry Limitmentioning

confidence: 85%

“…A notable difference compared to the previous two non-symmetric cases is that now the edge flame loses its tribrachial structure; instead, it takes on a hook-like shape with only the fuel-rich branch retained, while the fuel-lean branch appears to completely degenerate into the diffusion flame. Asymmetry in the combustion field can also result from chemistry imbalance, for example, unequal reaction orders as demonstrated by Juanos and Sirignano [7] for a propane-air mixture with n F = 0.1 and n O = 1.65, or from the interaction of two adjacent flames as illustrated by Kurdyumov and Jimenez [40].…”

Section: Asymmetric Edge Flamesmentioning

confidence: 99%

“…Edge flames have also been studied in other contexts, such as weakly curved premixed flames in stratified mixtures [4][5][6][7] and in strained mixing layers in premixed [8][9][10][11] and nonpremixed [12,13] systems, and have been addressed in a number of model problems [14][15][16]. They are also relevant to studies of turbulent diffusion flames acting as an agent for reestablishing combustion in a hole formed on the flame surface [17].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Matalon

2023

Symmetry

View full text Add to dashboard Cite

Numerous combustion applications are concerned with the stabilization of diffusion flames formed by injecting gaseous fuels into a co-flowing stream containing an oxidizer. The smooth operation of these devices depends on the attachment and lift-off characteristics of the edge flame at the base of the diffusion flame. In this paper, we address fundamental issues pertinent to the structure and dynamics of edge flames, which have attributes of both premixed and diffusion flames. The adopted configuration is the mixing layer established in the wake of a splitter plate where two streams, one containing fuel and the other oxidizer, merge. The analysis employs a diffusive-thermal model which, although it excludes effects of gas expansion, systematically includes the influences of the overall flow rate, unequal strain rates in the incoming streams, stoichiometry, differential and preferential diffusion, heat loss and gas–solid thermal interaction, and their effect on the edge structure, speed, and temperature. Conditions when the edge flame is anchored to the plate, lifted-off and stabilized in the flow, or blown-off, are identified. Two stable modes of stabilization are observed for lifted flames; the edge flame either remains stationary at a specified location or undergoes spontaneous oscillations along a direction that coincides with the trailing diffusion flame.

show abstract

Edge flames in mixing layers: Effects of heat recirculation through thermally active splitter plates

Matalon

2020

Combustion and Flame

View full text Add to dashboard Cite

Triple flame: Inherent asymmetries and pentasectional character

Cited by 8 publications

References 29 publications

Mixing and Combustion in a Laminar Shear Layer with Imposed Counterflow

Mixing and Combustion in a Laminar Shear Layer with Imposed Counterflow

Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Edge flames in mixing layers: Effects of heat recirculation through thermally active splitter plates

Contact Info

Product

Resources

About