Modeling of flame-generated turbulence based on direct numerical simulation databases

Nishiki, Shinnosuke; Hasegawa, Tatsuya; Borghi, R.; Himeno, Ryutaro

doi:10.1016/s1540-7489(02)80246-2

Cited by 90 publications

(172 citation statements)

References 17 publications

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“…The (near) planar nature of the flames suggests a possible approximation using a one-dimensional Favre-averaged Navier-Stokes formulation. The resulting flames propagate normal to themselves in a uniform stream of reactants featuring a constant initial turbulence field extracted from DNS data at the leading edge of the flames [17,33]. The thermodynamic parameters are consistent with the DNS databases as listed in Table 3.…”

Section: One-dimensional Planar Flamessupporting

confidence: 60%

“…However, such terms can play a role in inhomogeneous turbulence [49]. Furthermore, DNS studies of premixed turbulent flames [15,17] suggest that pressure transport terms can be of the same order as pressure dilatation terms inside the flame brush. Hence, such transport terms are included via a combination of isothermal and combusting contributions.…”

Section: Pressure Transport In the Flamelet Regimementioning

confidence: 99%

“…(29)- (30)) are independent of the form of the reaction rate. Lipatnikov et al [71] analysed the H, M and L flames (see Table 2) in the same DNS database [17,18] and showed that, compared to flame surface density expressions, the mean reaction rate is reduced at the leading edge (c ă 0.2) and increased at the trailing edge (c ă 0.8). The former effect, in particular, is important in the current context and a bridged mean reaction rate expression based on the two scale formulation of Lindstedt and Váos [31] is applied to approximately account for the impact,…”

Section: Reaction Rate Closurementioning

confidence: 99%

“…Databases [17,18] used here were generated for fully developed planar premixed flames featuring three different expansion ratios. A single-step irreversible chemical reaction was used to describe the chemistry.…”

Section: One-dimensional Planar Flamesmentioning

confidence: 99%

“…Discrepancies in the turbulent kinetic energy for r c ą 0.7 are apparent and may stem from highly curved flamelets that envelop "unburned mixture fingers" [83]. The budget of source terms for the turbulent kinetic energy is available for the current DNS database [17] and a comparison of major source terms, as listed in Eq. (43), is made for Case 3.…”

Section: Pressure Dilatation/flamelet Scrambling Effectsmentioning

confidence: 99%

See 4 more Smart Citations

The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

Tian

Lindstedt

2017

Combustion Theory and Modelling

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Premixed turbulent flames feature strong interactions between chemical reactions and turbulence that affect scalar and turbulence statistics. The focus of the present work is on clarifying the impact of pressure dilatation/flamelet scrambling effects with a comprehensive second-moment closure used for evaluation purposes. Model extensions that take into account flamelet orientation and molecular diffusion are derived. Isothermal pressure transport is included with an additional variable density contribution derived for the flamelet regime of combustion. The full closure is assessed by comparisons with direct numerical simulations (DNS) of statistically "steady" fully developed premixed turbulent planar flames at different expansion ratios. Subsequently, the prediction of lean premixed turbulent methane-air flames featuring fractal grid generated turbulence in an opposed jet geometry is considered. The overall agreement shows that "dilatation" effects contribute to counter-gradient transport and can also increase the turbulent kinetic energy significantly. Levels of anisotropy are broadly consistent with the DNS data and key aspects of opposed jet flames are well predicted. However, it is also shown that complications arise due to interactions between the imposed pressure gradient and combustion and that redistribution is affected along with the scalar flux at the leading edge. The latter is strongly affected by the reaction rate closure and, potentially, by pressure transport. Overall, the derived models offer significant improvements and can readily be applied to the modelling of premixed turbulent flames at practical rates of heat release.

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Section: One-dimensional Planar Flamessupporting

confidence: 60%

Section: Pressure Transport In the Flamelet Regimementioning

confidence: 99%

Section: Reaction Rate Closurementioning

confidence: 99%

Section: One-dimensional Planar Flamesmentioning

confidence: 99%

Section: Pressure Dilatation/flamelet Scrambling Effectsmentioning

confidence: 99%

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The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

Tian

Lindstedt

2017

Combustion Theory and Modelling

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Effects of Lewis and Karlovitz numbers on transport equations for turbulent kinetic energy and enstrophy

et al. 2022

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Statistical Analysis of Cross Scalar Dissipation Rate Transport in Turbulent Partially Premixed Flames: A Direct Numerical Simulation Study

Malkeson

Chakraborty

2010

Flow Turbulence Combust

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Statistically planar turbulent partially premixed flames for different initial intensities of decaying turbulence have been simulated for global equivalence ratios < φ > = 0.7 and < φ > = 1.0 using three-dimensional simplified chemistry based Direct Numerical Simulations (DNS). The simulation parameters are chosen such that the combustion situation belongs to the thin reaction zones regime and a random bi-modal distribution of equivalence ratio φ is introduced in the unburned gas ahead of the flame to account for mixture inhomogeneity. The DNS data has been used to analyse the statistical behaviour of the transport of the cross-scalar dissipation rate based on the fuel mass fraction Y F and the mixture fraction ξ fluctuationsε Yξ = ρ D∇Y F .∇ξ ρ (whereq,q = ρq ρ and q = q −q are Reynolds average, Favre mean and Favre fluctuation of a general quantity q) in the context of Reynolds Averaged Navier-Stokes simulations where ρ is the gas density and D is the gas diffusivity. The statistical behaviours of the unclosed terms in thẽ ε Yξ transport equation originating from turbulent transport T 1 , density variation T 2 , scalar-turbulence interaction T 3 , chemical reaction rate T 4 and the molecular dissipation rate D 2 have been analysed in detail. It has been observed that the contributions of T 2 , T 3 , T 4 and D 2 play important roles in theε Yξ transport for the globally stoichiometric cases, but in the globally fuel-lean cases the contributions of T 2 and T 4 become relatively weaker in comparison to the contributions of T 3 and D 2 . The term T 1 remains small in comparison to the leading order contributions of T 3 and D 2 for all cases, but the contribution of T 1 plays a more important role in the low Damköhler combustion cases. The term T 2 behaves as a sink term towards the unburned gas side but becomes a source term towards the burned gas side. The scalar-turbulence interaction term T 3 has been found to be generally positive throughout the flame brush, but in globally stoichiometric cases the contribution of T 3 becomes negative in regions of intense heat release. The combined contribution 314 Flow Turbulence Combust (2011) 87:313-349 of (T 4 -D 2 ) remains mostly as a sink in all cases studied here. Models are proposed for the unclosed terms of theε Yξ transport equation in the context of Reynolds Averaged Navier-Stokes simulations, which are shown to satisfactorily predict the corresponding quantities extracted from the DNS data for all cases.

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Modeling of flame-generated turbulence based on direct numerical simulation databases

Cited by 90 publications

References 17 publications

The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

The impact of dilatation, scrambling, and pressure transport in turbulent premixed flames

Effects of Lewis and Karlovitz numbers on transport equations for turbulent kinetic energy and enstrophy

Statistical Analysis of Cross Scalar Dissipation Rate Transport in Turbulent Partially Premixed Flames: A Direct Numerical Simulation Study

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