Coherent fine-scale eddies in turbulent premixed flames

Tanahashi, Mamoru; Fujimura, Masanari; Miyauchi, Toshio

doi:10.1016/s0082-0784(00)80252-0

Cited by 162 publications

(80 citation statements)

References 9 publications

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“…In comparison to the large body of literature on local flow topologies in nonreacting turbulent flows, relatively little attention has been paid to their analysis in turbulent reacting flows [13][14][15][16]. Shown on top is the classification of S1−S8 topologies in the Q−R plane for (left to right) P > 0, P = 0, and P < 0.…”

Section: Introductionmentioning

confidence: 99%

“…Tanahashi et al [13] used Q to distinguish strain-dominated and vorticity-dominated regions in a premixed flame and concluded that the vorticity vector remains perpendicular to the flame normal vector and that small-scale turbulence can survive even beyond the flame front. Grout et al [14] analyzed the local flow topology of a nonpremixed jet in crossflow and reported that the highest heat release rates of the flame are associated with the regions with S8 topology.…”

Section: Introductionmentioning

confidence: 99%

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Flow topologies in different regimes of premixed turbulent combustion: A direct numerical simulation analysis

et al. 2016

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The distributions of flow topologies within the flames representing the corrugated flamelets, thin reaction zones, and broken reaction zone regimes of premixed turbulent combustion are investigated using direct numerical simulation data of statistically planar turbulent H 2 -air flames with an equivalence ratio φ = 0.7. It was found that the diminishing influence of dilatation rate with increasing Karlovitz number has significant influences on the statistical behaviors of the first, second, and third invariants (i.e., P , Q, and R) of the velocity gradient tensor. These differences are reflected in the distributions of the flow topologies within the flames considered in this analysis. This has important consequences for those topologies that make dominant contributions to the scalar-turbulence interaction and vortexstretching terms in the scalar dissipation rate and enstrophy transport equations, respectively. Detailed physical explanations are provided for the observed regime dependences of the flow topologies and their implications on the scalar dissipation rate and enstrophy transport.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow topologies in different regimes of premixed turbulent combustion: A direct numerical simulation analysis

et al. 2016

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“…All of these 3D studies were based on simplified chemistry. More recently Tanahashi et al [10,11] performed simulations of this type for turbulent premixed hydrogen flames with detailed hydrogen chemistry. Bell et al [12] performed a similar study for a turbulent methane flame.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of Lewis number effects on lean premixed turbulent flames

Bell

Cheng

Day

et al. 2007

Proceedings of the Combustion Institute

113

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A dominant factor in determining the burning rate of a premixed turbulent flame is the degree to which the flame front is wrinkled by turbulence. Higher turbulent intensities lead to greater wrinkling of the flame front and an increase in the turbulent burning rate. This picture of turbulent flame dynamics must be modified, however, to accommodate the affects of variations in the local propagation speed of the flame front. Classical flame analysis characterizes these local variations in propagation speed by the Markstein number which represents the response of the flame front to curvature and strain. In this paper, we consider lean premixed flames for three different fuels having widely varying fuel Lewis numbers corresponding to widely varying Markstein numbers. In particular, we present numerical simulations of premixed turbulent flames for lean hydrogen, propane and methane mixtures in two dimensions. Each simulation is performed at turbulence conditions similar to those found in laboratory-scale experiments and is performed using detailed chemical kinetics and transport properties. We discuss the effect of Lewis number on the overall flame morphology and explore the dependence of local flame propagation speed on flame curvature. We also explore the relationship between local flame speed and experimentally accessible variables such as OH concentration. Finally, we focus on the low Lewis number case, hydrogen, in which the flame front is broken indicating local extinction.

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“…Comparisons are made between the mixture-averaged diffusion model, and the multicomponent model with Dufour and Soret effects; the Soret effect is most relevant for the flames of interest. Previous computational studies of this type of flame, [17,18,19,20,21,22], have neglected thermal diffusion. Photographs of laminar flames [4,23] and planar laser induced fluorescence imaging of turbulent flames [18] indicate the natural shape of these fames consists of cellular structures that are convex to the fresh gas.…”

Section: Introductionmentioning

confidence: 99%