Turbulent flows with nonpremixed reactants

Bilger, R.W.

doi:10.1007/3540101926_9

Cited by 258 publications

(113 citation statements)

References 57 publications

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“…8 (26) that can be easily obtained due to Z d = z = z c = 0, statistical independence of β, z (1) and z (2) and also the equation…”

Section: Etc and Note The Following Identitiesmentioning

confidence: 99%

“…The models of nonpremixed turbulent combustion are traditionally divided into two categories the mixture fraction-based models (fast chemistry [1] and Flamelet [2]) and the Probability Density Function (PDF) models [3,4]. The appearance of Conditional Moment Closure (CMC, [5]) seems to blur this division since CMC has links with the both categories.…”

Section: Introductionmentioning

confidence: 99%

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Matching conditional moments in PDF modelling of nonpremixed combustion

Klimenko

2005

Combustion and Flame

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The rate of generation of fluctuations with respect to the scalar values conditioned on the mixture fraction, which significantly affects turbulent non-premixed combustion processes, is examined in the paper. Simulation of the rate in major mixing model is investigated and the derived equations can assist in selecting the model parameters so that level of conditional fluctuations is better reproduced by the models. A more general formulation of the Multiple Mapping Conditioning (MMC) model that distinguishes the reference and conditioning variables is suggested. This formulation can be viewed as methodology of enforcing certain desired conditional properties onto conventional mixing models. Examples of constructing consistent MMC models with dissipation and velocity conditioning as well as of combining MMC with Large Eddy Simulations (LES) are also provided in the paper.

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“…8 (26) that can be easily obtained due to Z d = z = z c = 0, statistical independence of β, z (1) and z (2) and also the equation…”

Section: Etc and Note The Following Identitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Matching conditional moments in PDF modelling of nonpremixed combustion

Klimenko

2005

Combustion and Flame

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“…If the reaction is infinitely fast and irreversible, the product concentration will be dictated by the reactant in short supply and is given by (e.g. Bilger 1980) Op(g; gs) = {0 10 g for g < g 8 ,…”

Section: Laser-induced Fluorescence (Lif)mentioning

confidence: 99%

“…While these liquid-layer studies confirmed the important role of the large-structure dynamics, Breidenthal's work also suggested that the amount of chemical product in the liquid layer is less than that in the gas-phase case and that, therefore, the Schmidt number plays a role in turbulent mixing of high-Reynolds-number shear layers. We should point out that most models of turbulent transport and mixing take no explicit account of molecular transport (Bilger 1980;Pope 1981;Kollmann & Janicka 1982;Jones & Whitelaw 1982) and are, therefore, incapable of addressing Schmidt-number effects. In these models molecular diffusion is neglected in comparison with turbulent diffusion and transport and mixing are modelled as separate processes.…”

Section: Introductionmentioning

confidence: 99%

Mixing and chemical reactions in a turbulent liquid mixing layer

1986

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An experimental investigation of entrainment and mixing in reacting and nonreacting turbulent mixing layers at large Schmidt number is presented. In nonreacting cases, a passive scalar is used to measure the probability density function (p.d.f.) ofthe composition field. Chemically reacting experiments employ a diffusionlimited acid-base reaction to directly measure the extent of molecular mixing. The measurements make use of laser-induced fluorescence diagnostics and high-speed, real-time digital image-acquisition techniques.Our results show that the vortical structures in the mixing layer initially roll-up with a large excess of fluid from the high-speed stream entrapped in the cores. During the mixing transition, not only does the amount of mixed fluid increase, but its composition also changes. It is found that the range of compositions of the mixed fluid, above the mixing transition and also throughout the transition region, is essentially uniform across the entire transverse extent of the layer. Our measurements indicate that the probability of finding unmixed fluid in the centre of the layer, above the mixing transition, can be as high as 0.45. In addition, the mean concentration of mixed fluid across the layer is found to be approximately constant at a value corresponding to the entrainment ratio. Comparisons with gas-phase data show that the normalized amount of chemical product formed in the liquid layer, at high Reynolds number, is 50% less than the corresponding quantity measured in the gas-phase case. We therefore conclude that Schmidt number plays a role in turbulent mixing of high-Reynolds-number flows.

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“…In the context of mixing and the resulting range of mixed fluid compositions within the shear layer, it is useful to define a conserved scalar which denotes the mole fraction of high speed stream fluid in the molecularly mixed fluid (e.g., Bilger 1980). Accordingly, = 0 corresponds to pure low-speed-stream fluid, = 1 represents pure high-speed-stream fluid, and = 1/2 represents a 50:50 mixture.…”

Section: Ir S; M() -+ 0s = 1;m(')mentioning

confidence: 99%

Turbulent Free Shear Layer Mixing and Combustion

1991

High-Speed Flight Propulsion Systems

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PasadenaApproved for public release; distribution is unlimited ABSTRACT (Maximum 200 wods)Some experimental data on turbulent free-shear-layer growth, mixing, and chemical reactions are reviewed. The dependence of these phenomena on such fluid and flow parameters as Reynolds number, Schmidt number, and Mach number are discussed, with the aid of some direct consequences deducible from the large-scale organization of the flow as well as from some recent models.14.

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Turbulent flows with nonpremixed reactants

Cited by 258 publications

References 57 publications

Matching conditional moments in PDF modelling of nonpremixed combustion

Matching conditional moments in PDF modelling of nonpremixed combustion

Mixing and chemical reactions in a turbulent liquid mixing layer

Turbulent Free Shear Layer Mixing and Combustion

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