n the Prediction of Thermal Diffusion Effects in Laminar ne-Dimensional Flames

Greenberg, Barry

doi:10.1080/00102208008952426

Cited by 21 publications

(12 citation statements)

References 15 publications

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“…For premixed, hydrogen-air, flat flames, Bongers and de Goey [12] found different transport models had a large effect on predicted speeds in rich mixtures, but "for low values of the fuel equivalence ratio, φ, the choice of the diffusion model is insignificant." Further, the Soret effect can be important, corroborating an early study of rich flames by Greenberg [13], but for low values of φ the effect is negligible. For example, with φ = 0.37 under atmospheric conditions, the speed calculated by [14,15] is 15.52 cm/s for a mixture model, and is 15.49 cm/s for a multicomponent model including the Soret effect.…”

Section: Introductionsupporting

confidence: 58%

The Soret effect in naturally propagating, premixed, lean, hydrogen–air flames

Grcar

Bell

Day

2009

Proceedings of the Combustion Institute

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Section: Introductionsupporting

confidence: 58%

The Soret effect in naturally propagating, premixed, lean, hydrogen–air flames

Grcar

Bell

Day

2009

Proceedings of the Combustion Institute

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“…The same observation was made by Greenberg (1980) in the study of one-dimensional hydrogen/air flames using a one-step chemistry model and phenomenological expressions for the thermal diffusion coefficients. Later it was found by Warnatz (1982) that the laminar flame speeds of both lean and rich hydrogen/air flames were lower when thermal diffusion was taken into account, although only the thermal diffusion fluxes of atomic and molecular hydrogen were considered in the simulation.…”

Section: Introductionmentioning

confidence: 61%

A Numerical Investigation of Thermal Diffusion Influence on Soot Formation in Ethylene/Air Diffusion Flames

Guo¹,

Liu²,

Smallwood³

et al. 2004

International Journal of Computational Fluid Dynamics

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Thermal diffusion, caused by temperature gradients, tends to draw lighter molecules to warmer regions and to drive heavier molecules to cooler regions of a mixture. The influence of thermal diffusion on soot formation in coflow laminar ethylene/air diffusion flames is numerically investigated in this paper. Detailed reaction mechanisms and complex thermal and transport properties are employed. The fully elliptic governing equations are solved. Radiation heat transfer from the flames is calculated by the discrete-ordinates method coupled to an SNBCK-based wide band model. A simplified two-equation soot model is used. The interactions between soot and gas-phase chemistry are taken into account. The thermal diffusion velocities are calculated according to the thermal diffusion coefficients evaluated based on multicomponent properties.The results show that thermal diffusion does affect soot formation in ethylene/air diffusion flames. Although the effect on soot formation in pure ethylene/air flame is not significant, the influence is enhanced if lighter species, such as helium, are added to the fuel or the air stream. The peak integrated soot volume fraction doubles if thermal diffusion is not taken into account in the simulation of the flame with helium addition to the air stream.

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“…In the general case, the diffusion matrices usually have off-diagonal terms and nonidentical diagonal elements. Diagonalization of the diffusion matrix has been the subject of several studies on both non-reactive flows [6] and reactive flows [7][8][9][10][11][12]. The present paper deals directly with a general-diffusion matrix without attempting to diagonalize it, shows that the same simplifications available under the classic ALeU assumption can be available under less-restrictive conditions, and provides the means to check whether a system of equations satisfies these conditions.…”

Section: Introductionmentioning

confidence: 97%