A theory of flame propagation limits due to heat loss

Mayer, E.

doi:10.1016/0010-2180(57)90005-6

Cited by 78 publications

(12 citation statements)

References 3 publications

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“…For the equivalence ratio ranging from 0.5 to 1.10, the difference between the predicted and the measured flame temperature is less than 4%. In this case, the Nusselt number 13,14 of Nu = 4.364 leads to better results. Based on the previous results, we propose that the Nusselt number for predicting the flame temperature using Eq.…”

Section: Experimental Investigation and Discussionmentioning

confidence: 84%

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Predicting the temperature of a premixed flame in a microcombustor

Chou

Chen

et al. 2004

Journal of Applied Physics

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We apply the scale analysis and the simulation to relate the flame temperature in a microcombustor to the external wall surface temperature. In deriving the equation for predicting the flame temperature, we account for the detailed reaction mechanisms in the combustion process and we assume that the flow in the combustor tube is laminar. Experimental investigations have been conducted to validate the equation. We employ hydrogen as a fuel and obtain a stable flame in microcombustors with internal radii of 3, 4 and 6mm. Good agreement between the measured and the predicted flame temperature has been achieved. In predicting the flame temperature, we use a Nusselt number Nu=3.650 and 4.363 for the tube diameters of 6mm and above and 4mm and below, respectively.

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Section: Experimental Investigation and Discussionmentioning

confidence: 84%

“…For a premixed laminar flame in a narrow tube or a duct, Drysdale and Mayer 12,13 suggested Nu = 3.65. However, we have found that a Nusselt number 14,15 Nu = 4.364 leads to a better agreement with an experiment for microcombustors having radii 1.5 mm and 2 mm.…”

Section: ͑17͒mentioning

confidence: 98%

Predicting the temperature of a premixed flame in a microcombustor

Chou

Chen

et al. 2004

Journal of Applied Physics

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“…Also by introducing the Arrhenius relation between the flame speed and temperature (see, for example, Mayer [ 16]…”

Section: Qmo~ ~Aeb 06mentioning

confidence: 99%

Radiation-affected laminar flame quenching

Arpacı

Tabaczynski

1984

Combustion and Flame

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Under the influence of radiation, the increase in Peclet number characterizing the flame quench distance A, p.cpSu Tb ° adiabatic flame enthalpy flow Pe-hTb°/A conduction and the decrease in flame temperature are shown in terms of an original radiation number T/T(I-6./2)Bb 0 total radiation I + 3~'2(2/¢.-1)/(1-o~) adiabatic flame ethalphy flow where p is the density, cp the specific heat at constant pressure, Su the laminar flame speed, Tb the flame temperature, subscript u the unburned gas and superscript 0 the adiabatic gas,), the thermal conductivity, 7/= (rp/rR)"2 the weighted nongrayness, rp and rR being the Planck mean and the Rosseland mean of the absorption coefficient, ¢. the wall emissitivity, r= rMI the optical thickness, XM = (rpxR)~/2 being the mean absorption coefficient and I a characteric length (related to geometry or quench distance), o~ the albedo of single scattering, and Bb ° the adiabatic flame Boltzmann number. 4Eb ° emission Bb0=-p,cpS. °T b° adiabatic flame enthaipy flow where Eb is the blackbody emissive power. It is qualitatively shown that the contribution of radiation to the heat transfer and the laminar flame quenching in small diesel engines can be as much as 35%. I. INTRODUCTION A recent study by Arpaci and Tabaczynski [1], hereafter called P1, introduces a radiative heat flux which includes the emission, absorption,

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“…The need for such restriction requires in turn the existence of some mechanism which limits the residence time in the high temperature region of the flame. By far the most likely such mechanisms are radiative loss (Zel'dovich 1941;Mayer 1957;Spalding 1957), flame stretch, or some combination of the two. Strong support for the radiative loss hypothesis has been provided by the extensive experimental and theoretical studies of spherically expanding near-limit flames under micro-gravity conditions by Ronney (1985Ronney ( , 1988a, Ronney & Wachman (1985), Abbud-Madrid & and Farmer & Ronney (1990); from numerical studies of such flames by Lakshmisha et al (1988Lakshmisha et al ( , 1990, Sibulkin & Frendi (1990) and Frendi & Sibulkin (1991); and further from a study of unstrained planar flames by Law & Egolfopoulos (1992).…”

Section: Introductionmentioning

confidence: 99%

Laminar premixed flame extinction limits. II Combined effects of stretch and radiative loss in the single flame unburnt-to-burnt and the twin-flame unburnt-to-unburnt opposed flow configurations

Dixon‐Lewis

2005

Proc. R. Soc. A.

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Numerical methods have been used to examine the effects of (a) stretch alone, and (b) a combination of stretch and radiative loss, on the properties and extinction limits of methane–air flames near the lean flammability limit. Two axisymmetric opposed flow configurations were examined: (i) a single flame, unburnt-to-burnt (UTB) system in which fresh reactant is opposed by a stream of its own combustion products at the unburnt temperature, and (ii) a symmetric unburnt-to-unburnt (UTU) configuration where twin flames are supported back to back, one on each side of the stagnation plane. The maximum temperatures achieved in the UTB system are always away from the stagnation plane. For a fixed sufficiently sub-adiabatic product stream temperature, increasing flame stretch or gaseous radiative emissivity, or a combination of both, will augment downstream conductive heat loss, leading to a reduction in T max and eventually to an abrupt extinction if the loss rate is sufficiently large. The UTU system is more complex, and offers the additional possibility of purely stretch-induced extinctions where the flames are forced together back-to-back so that radiative loss is restricted to upstream of the maximum temperature. Extinction in these cases occurs by straightforward truncation of the hot sides of the reaction zones. At sufficiently low stretch, near and at the standard flammability limit, radiative loss makes a major contribution to the overall extinction mechanism in both configurations. The detailed effects of flame stretch on extinction behaviour depend on the diffusion characteristics within the near-limit mixtures, in particular the Lewis number, Le, of the deficient component. The effect of high stretch is always to attenuate the composition range of flammability. However, for Le<1 this range is extended at low to moderate stretch, particularly in the UTU situations where downstream radiative loss is not present at extinction. Lewis number effects for a global methane–air chemistry, and with assumed Le≥1, are discussed in the light of numerical results previously presented by Ju et al . ( Ju et al . 1998 Combust. Flame 113 , 603–614).

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A theory of flame propagation limits due to heat loss

Cited by 78 publications

References 3 publications

Predicting the temperature of a premixed flame in a microcombustor

Predicting the temperature of a premixed flame in a microcombustor

Radiation-affected laminar flame quenching

Laminar premixed flame extinction limits. II Combined effects of stretch and radiative loss in the single flame unburnt-to-burnt and the twin-flame unburnt-to-unburnt opposed flow configurations

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