A combustion model for premixed flames with varying stoichiometry

Bondi, Scott N.; Jones, W.P.

doi:10.1016/s1540-7489(02)80258-9

Cited by 22 publications

(3 citation statements)

References 14 publications

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“…The time is advanced by an implicit scheme and typically results in 10-5 to 10-6 seconds time step sizes. The FlameMaster code is well-validated and widely used for hydrocarbon flames [41]. Nonetheless, since the fuel and kinetic mechanism are new, a validation study is presented in the next section.…”

Section: Descriptionmentioning

confidence: 99%

Measurements and modeling of spherical CH2F2-Air flames

Hegetschweiler¹,

Pagliaro²,

Berger³

et al. 2020

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The burning velocity of mixtures of refrigerant R-32 (CH2F2) with air over a range of equivalence ratios are studied via spherically expanding flames (SEFs) in a large, optically accessible spherical chamber at constant pressure. Shadowgraph images from a high-speed video camera are analysed to yield flame radius as a function of time. Data reduction techniques are explored and direct numerical simulations of the flames are performed with the FlameMaster code, using detailed kinetics. The flame radius as a function of time is accurately predicted by the simulations. Flame stretch and thermal radiation (using an optically thin model) occur simultaneously and make extraction of the unstretched burning velocity from the experimental data difficult. For these low burning velocity flames, the numerical simulations show that stretch and radiation effects are particularly important, and different data reduction schemes can have large effects on the inferred burning velocity.

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Section: Descriptionmentioning

confidence: 99%

Measurements and modeling of spherical CH2F2-Air flames

Hegetschweiler¹,

Pagliaro²,

Berger³

et al. 2020

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“…If the shape of P(ξ) is specified, the PDF may be determined by using the first ξ, second ρ(ξ)ξ 2 /ρ, and eventually higher moments ρ(ξ)ξ n /ρ, with these moments being computed by solving proper balance equations closed by invoking P(ξ). Such an approach was already used for evaluating W = 1 0 W(c)P(c)dc [6][7][8][9][10], or 1 0 W( c, f )P( f )df and ρ b = 1 0 ρ b ( f )P( f )df [11][12][13], or S t = 1 0 S t ( f )P( f )df and ρ b [14][15][16][17][18][19], or W = 1 0 W(c, f )P(c, f )dcdf and ρ = 01 ρ(c, f )P(c, f )dcdf [20][21][22][23][24][25]. Note that the use of the G-equation to simulate partially premixed burning [14][15][16][17][18][19] implies that (1) holds provided that ρ u and ρ b are substituted with ρ u ( f ) and ρ b ( f ), respectively, with the dependence of the unburned density on the mixture fraction being commonly disregarded.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Presumed PDF Models of Turbulent Flames

Huang

Lipatnikov

2012

Journal of Combustion

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Over the past years, the use of a presumed probability density function (PDF) for combustion progress variable or/and mixture fraction has been becoming more and more popular approach to average reaction rates in premixed and partially premixed turbulent flames. Commonly invoked for this purpose is a beta-function PDF or a combination of Dirac delta functions, with the parameters of the two PDFs being determined based on the values of their first and second moments computed by integrating proper balance equations. Because the choice of any of the above PDFs appears to be totally arbitrary as far as underlying physics of turbulent combustion is concerned, the use of such PDFs implies weak sensitivity of the key averaged quantities to the PDF shape. The present work is aimed at testing this implicit assumption by comparing mean heat release rates, burning velocities, and so forth, averaged by invoking the aforementioned PDFs, with all other things being equal. Results calculated in the premixed case show substantial sensitivity of the mean heat release rate to the shape of presumed combustion-progress-variable PDF, thus, putting the approach into question. To the contrary, the use of a presumed mixture-fraction PDF appears to be a sufficiently reasonable simplification for modeling the influence of fluctuations in the mixture fraction on the mean burning velocity provided that the mixture composition varies within flammability limits.

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“…There are a number of modeling studies concerning stratified/partially premixed flames, for example using the Reynolds Averaged Navier-Stokes (RANS) equations, based on the mixture fraction and progress variable/presumed probability density function (pdf) [9] and a RANS based flame surface density model [10]. Another approach that has been used to simulate premixed turbulent flames is the level-set G-equation model [7,[11][12][13][14][15]; the flame front is simulated by the Gequation, and the temperature and species fields are determined by coupling with detailed chemistry, tabulated as flamelet manifolds.…”

Section: Introductionmentioning

confidence: 99%