Investigation of the fuel effects on burning velocity and flame structure of turbulent premixed flames based on leading points concept

Zhang, Weijie; Wang, Jinhua; Yu, Qianqian; Jin, Wu; Zhang, Meng; Huang, Zuohua

doi:10.1080/00102202.2018.1451848

Cited by 33 publications

(25 citation statements)

References 33 publications

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“…[4,5] as recent examples. The same phenomenon is also documented for lean turbulent flames of various H 2 /CO/CH 4 /O 2 /N 2 mixtures [6][7][8][9][10][11], but the magnitude of the effect is decreased when the mole fraction of hydrogen in the fuel blend is decreased by retaining the same equivalence ratio.…”

Section: Introductionsupporting

confidence: 67%

“…2 to Eq. (9) written for yields (11) where the term is re-written in the spherical or cylindrical coordinate framework in cases (1) or (2) and (3), respectively.…”

Section: Theoretical Studymentioning

confidence: 99%

“…4 provide a clue to understanding why the leading edge of a premixed turbulent flame brush can control the flame speed , as hypothesized within the framework of the leading point concept put forward by Zeldovich [12]. The concept is discussed in details elsewhere [1][2][3], with the body of evidences in favor of it has been growing over the past years [9][10][11][37][38][39][40]. Indeed, if the turbulent flux is weak when compared to the mean flux , as shown recently [22], then, for qualitative discussion, Eq.…”

Section: 3 See Eq (16)mentioning

confidence: 99%

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Transport equations for reaction rate in laminar and turbulent premixed flames characterized by non-unity Lewis number

Lipatnikov

Chakraborty

Sabelnikov

2018

International Journal of Hydrogen Energy

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Transport equations for (i) the rate of product creation and (ii) its Favre-averaged value are derived from the first principles by assuming that depends solely on the temperature and mass fraction of a deficient reactant in a premixed turbulent flame characterized by the Lewis number different from unity. The right hand side of the transport equation for involves seven unclosed terms, with some of them having opposite signs and approximately equal large magnitudes when compared to the left-hand-side terms. Accordingly, separately closing each term does not seem to be a promising approach, but a joint closure relation for the sum of the seven terms is sought. For this purpose, theoretical and numerical investigations of variously stretched laminar premixed flames characterized by are performed and the linear relation between integrated along the normal to a laminar flame and a product of (i) the consumption velocity and (ii) the stretch rate evaluated in the flame reaction zone is obtained. Based on this finding and simple physical reasoning, a joint closure relation of is hypothesized, where is the density and is the stretch rate. The joint closure relation is tested against 3D DNS data obtained from three statistically 1D, planar, adiabatic, premixed turbulent flames in the case of a single-step chemistry and , 0.6, or 0.8. In all three cases, agreement between and extracted from the DNS is good with exception of large () values of the mean combustion progress variable in the case of. The developed linear relation between and helps to understand why the leading edge of a premixed turbulent flame brush can control its speed.

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Section: Introductionsupporting

confidence: 67%

“…2 to Eq. (9) written for yields (11) where the term is re-written in the spherical or cylindrical coordinate framework in cases (1) or (2) and (3), respectively.…”

Section: Theoretical Studymentioning

confidence: 99%

Section: 3 See Eq (16)mentioning

confidence: 99%

See 1 more Smart Citation

Transport equations for reaction rate in laminar and turbulent premixed flames characterized by non-unity Lewis number

Lipatnikov

Chakraborty

Sabelnikov

2018

International Journal of Hydrogen Energy

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“…Accordingly, as reviewed elsewhere [1][2][3], S T and U T were in the focus of experimental research into premixed combustion for many years. In particular, over the past decade, such measurements were conducted by various research groups, e.g., [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. However, values of U T and S T obtained from different experiments under similar conditions, i.e., comparable rms turbulent velocities u , close unburned gas temperatures, the same pressure, the same fuel, and the same equivalence ratio, are strongly scattered, e.g., see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…[3], but also recent experimental data on S T and U T show significant scatter of the aforementioned scaling exponents. For instance, the scaling exponent q v for S T or U T vs. the rms velocity u , e.g., S T ∝ u q v , was reported to be (i) less than unity [5, 7-14, 16, 19-21], e.g., q v = 0.49 [16], q v = 0.55 [21], q v = 0.63 [8], (ii) equal to unity [6], or (iii) even equal to two [17]. The fitted values of the scaling exponent q s for S T or U T vs. S L range from 0.37 [8] to 0.74 [10].…”

Section: Introductionmentioning

confidence: 99%

A DNS Study of Sensitivity of Scaling Exponents for Premixed Turbulent Consumption Velocity to Transient Effects

Lipatnikov

2018

Flow Turbulence Combust

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3D Direct Numerical Simulations of propagation of a single-reaction wave in forced, statistically stationary, homogeneous, isotropic, and constant-density turbulence, which is not affected by the wave, are performed in order to investigate the influence of the wave development on scaling (power) exponents for the turbulent consumption velocity U T as a function of the rms turbulent velocity u , laminar wave speed S L , and a ratio L 11 /δ F of the longitudinal turbulence length scale L 11 to the laminar wave thickness δ F. Fifteen cases characterized by u /S L = 0.5, 1.0, 2.0, 5.0, or 10.0 and L 11 /δ F = 2.1, 3.7, or 6.7 are studied. Obtained results show that, while U T is well and unambiguously defined in the considered simplest case of a statistically 1D planar turbulent reaction wave, the wave development can significantly change the scaling exponents. Moreover, the scaling exponents depend on a method used to compare values of U T , i.e., the scaling exponents found by processing the DNS data obtained at the same normalized wave-development time may be substantially different from the scaling exponents found by processing the DNS data obtained at the same normalized wave size. These results imply that the scaling exponents obtained from premixed turbulent flames of different configurations may be different not only due to the well-known effects of the mean-flame-brush curvature and the mean flow non-uniformities, but also due to the flame development, even if the different flames are at the same stage of their development. The emphasized transient effects can, at least in part, explain significant scatter of the scaling exponents obtained by various research groups in different experiments, thus, implying that the scatter in itself is not sufficient to reject the notion of turbulent burning velocity. Keywords Premixed turbulent combustion • Burning velocity • Consumption velocity • Turbulent flame development • DNS Nomenclature a heat diffusivity of a mixture c combustion progress variable

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Modeling of the turbulent burning velocity for planar and Bunsen flames over a wide range of conditions

Yang

2022

Acta Mech. Sin.

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Investigation of the fuel effects on burning velocity and flame structure of turbulent premixed flames based on leading points concept

Cited by 33 publications

References 33 publications

Transport equations for reaction rate in laminar and turbulent premixed flames characterized by non-unity Lewis number

Transport equations for reaction rate in laminar and turbulent premixed flames characterized by non-unity Lewis number

A DNS Study of Sensitivity of Scaling Exponents for Premixed Turbulent Consumption Velocity to Transient Effects

Modeling of the turbulent burning velocity for planar and Bunsen flames over a wide range of conditions

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