Testing Premixed Turbulent Combustion Models by Studying Flame Dynamics

Lipatnikov, Andrei

doi:10.1260/175682709788083362

Cited by 14 publications

(5 citation statements)

References 52 publications

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“…Criterion for transition from pulled to pushed flames, see Eq. (57). The transition can occur not only due to interplay of the nonlinear reaction term and a nonlinear convection term associated with CGT (an increase in N B promotes the transition to the pushed flames), but also due to the change of the shape of the reaction term even in the absence of CGT, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…see Table 1 in Ref. [57]. For the goals of the present work, a particular expression for s f is not required, provided that this time scale is independent of t, x, orc (this assumption is required in order to derive exact analytical solutions in Section 4, whereas conclusion regarding transition from pulled to pushed TW solutions at a sufficiently large U B P 0, which will be drawn later, holds even if the time scale depends onc, as discussed in the end of Section 3).…”

Section: Mathematical Formulation and Governing Equationsmentioning

confidence: 99%

“…The value of N cr B < 2 cannot be determined from the linear analysis and will be found in Section 5, see Eq. (57). To solve the eigenvalue BVP in this case, the behavior of trajectories pð cÞ in the entire phase space should be analyzed.…”

Section: Substitution Ofmentioning

confidence: 99%

See 2 more Smart Citations

Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Sabelnikov

Lipatnikov

2015

Combustion and Flame

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Section: Discussionmentioning

confidence: 99%

Section: Mathematical Formulation and Governing Equationsmentioning

confidence: 99%

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Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Sabelnikov

Lipatnikov

2015

Combustion and Flame

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“…As a premixed turbulent flame develops, both the burning velocity and mean flame brush thickness grow, but these processes slow down with time [28,30,31]. Accordingly, the function (θ) decreases (initially, is large due to a low u t ) and transition from gradient to countergradient transport occurs at θ tr provided that l > 0.…”

Section: Discussionmentioning

confidence: 99%

“…As shown elsewhere [27], (31) and (32) are equivalent to the Favre-averaged continuity and combustion progress variable balance equations. Moreover, the sum of (33) and (34) yields the Favre-averaged Navier-Stokes equation or the Favreaveraged Euler equation if conditioned viscous terms that involve τ ik are neglected at high Reynolds number.…”

Section: Standard Governing Equationsmentioning

confidence: 99%

Transient Behavior of Turbulent Scalar Transport in Premixed Flames

Lipatnikov

2010

Flow Turbulence Combust

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Transition from gradient to countergradient scalar transport in a statistically planar, one-dimensional, developing, premixed turbulent flame is studied both theoretically and numerically. A simple criterion of the transition referred to is derived from the balance equation for the combustion progress variable, with the criterion highlighting an important role played by flame development. A balance equation for the difference in velocitiesū b andū u conditioned on burned and unburned mixture, respectively, is numerically integrated. Both analytical and computed results show that; (1) The flux ρu c is gradient during an early stage of flame development followed by transition to countergradient scalar transport at certain instant t tr . (2) The transition time is increased when turbulence length scale L is increased or when the laminar flame speed S L and/or the density ratio are decreased. (3) The transition time normalized using the turbulence time scale is increased by u . Moreover, the numerical simulations have shown that the transition time is increased by u if a ratio of u /S L is not large. This dependence of t tr on u is substantially affected by (i) the mean pressure gradient induced within the flame due to heat release and (ii) by the damping effect of combustion on the growth rate of mean flame brush thickness. The reasonable qualitative agreement between the computed trends and available experimental and DNS data, as well as the agreement between the computed trends and the present theoretical results, lends further support to the conditioned balance equation used in the present work. Nomenclaturesimplified Bray number n = {n x , n y , n z } unit vector normal to flame surface p pressure Re t = u L/D u turbulent Reynolds number q an arbitrary quantity S L laminar flame speed t time U b mean normal velocity in products far behind flame U t turbulent burning velocityfully-developed turbulent burning velocity u = {u, v, w} = {u 1 , u 2 , u 3 } velocity vector and its components u rms turbulent velocity u t = U t /U t,∞ normalized turbulent burning velocity W mass rate of product creation in a turbulent flame X distance from flame stabilization region x = {x, y, z} = {x 1 , x 2 , x 3 } spatial coordinatesGreek symbols α parameter in the Bray number, see (2) see criterion given by (22) γ probability of finding flamelet t turbulent flame brush thickness u =ū b −ū u slip velocity vector δ t = t /L normalized turbulent flame brush thickness ε viscous dissipation rate θ = t/τ t normalized time κ molecular heat diffusivity ξ normalized distance, see (17) ρ density σ = ρ u /ρ b density ratio τ = ρ u /ρ b − 1 heat release factor τ c = κ u /S 2 L = δ L /S L laminar flame time scale τ ij viscous stress tensor τ t = L/u turbulent time scale ω = W t,∞ /(ρ u U t,∞ ) normalized mean rate of product creation Flow Turbulence Combust (2011) 86:609-637 611

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Effects of ignition position on explosion of premixed propane‐air in a T‐type pipe

Zhou

Chen³

et al. 2020

Process Safety Progress

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Ignition position has an important influence on gas explosion, but few researches have been done on the ignition position in T‐type pipe. In this paper, an experimental and numerical study of horizontal and vertical ignition positions in a T‐type pipe has been presented. Results show that the ignition position has a great influence on the flame propagation velocity, flame structure and explosion pressure. In the case of vertical ignition, the maximum pressure appears near the T‐type bifurcation, and there is an obvious stress concentration on the upper side wall of the bifurcation. In the case of horizontal ignition, the maximum pressure appears at the right end of the pipe, and a weak stress concentration occurring at the splitting point. When flame passing through the bifurcation, it takes 12 ms longer than ignition on horizontal, but the time for flame propagates from ignition to the end is less. The “tulip flame” forms three times after flame propagates the bifurcation when ignition on horizontal, but there is no “tulip flame” while ignition on vertical. In the case of vertical ignition, the scale of the vortex at the bifurcation is larger than that in the horizontal. The turbulent kinetic energy is mainly in the horizontal section when ignition on vertical, while it is mainly in the vertical pipe if ignition on horizontal.

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Testing Premixed Turbulent Combustion Models by Studying Flame Dynamics

Cited by 14 publications

References 52 publications

Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Transient Behavior of Turbulent Scalar Transport in Premixed Flames

Effects of ignition position on explosion of premixed propane‐air in a T‐type pipe

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