Flame Quenching

Potter, A. E.

doi:10.1016/b978-0-08-009468-7.50009-5

Cited by 19 publications

(9 citation statements)

References 27 publications

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“…This phenomenon of a spark not igniting a flammable mixture between two parallel plates is discussed by Metzler [10] with relation to the prediction of minimum ignition energy. The quenching of flames by parallel surfaces in close proximity has also been investigated by Potter [11], who found that hydrocarbons have quenching distances of 2-3 mm. Similarly, the breakdown strength of air is not constant at small gaps, as discussed by Glor [12], but for the purposes of this illustration, it can be assumed to be constant at the distances and potentials under discussion.…”

Section: Spark Discharges From Isolated Conductorsmentioning

confidence: 97%

Spontaneous ignition of hydrogen leaks: A review of postulated mechanisms

Astbury

Hawksworth

2007

International Journal of Hydrogen Energy

187

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Section: Spark Discharges From Isolated Conductorsmentioning

confidence: 97%

Spontaneous ignition of hydrogen leaks: A review of postulated mechanisms

Astbury

Hawksworth

2007

International Journal of Hydrogen Energy

187

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“…This is a little higher than the majority of the reported experimental values for the propane-air mixture, which hover about approximately 0.21 cm. 15 This difference may be attributed to the approximate nature of the numerical data chosen to represent the kinetics and transport properties.…”

Section: B the Stoichiometric Flame At Atmospheric Pressurementioning

confidence: 99%

Numerical Solution of the Two-Dimensional Premixed Laminar Flame Equations

1979

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The present paper presents a numerical solution method for the two-dimensional elliptic partial differential equations modeling a premixed laminar flame freely propagating at constant pressure between parallel plates having a constant, cool wall temperature. The technique developed is an efficient, semidirect (semi-iterative) method termed "multistep damped Picard iteration." Picard linearization of the nonlinear terms together with variable damping as the solution progressed and a sparse matrix elliptic solver allowed rapid solution to be obtained as a limit of a convergent sequence of solutions. The flame-quenching limit was determined by iterating the solution with respect to the distance separating the plates and approaching the limit state to within a specific criterion. Global kinetics and average transport properties were used for a simulated propane-air mixture; radiation loss was neglected throughout the analysis. The method was used to study the effect of the "ignition temperature" on the flame parameters as well as to reveal the two-dimensional structure of the flame at the quenching limit. Nomenclature= cross-sectional area, Sec. IV B, cm 2 = specific heat at constant pressure of the mixture, cal/g K = diffusion coefficient for the fuel species cm 2 /s = hydraulic (equivalent) diameter of the parallel plates, cm = activation energy, cal/mole = mass flow rate (mass burning rate), g/cm 2 s; eigenvalue of the flame equations = heat of combustion of the fuel, -cal/g = frequency factor (reaction rate constant), units depend on reaction order = distance separating the parallel plates, cm = reaction order = perimeter, Sec. IV B, cm = pressure, atm = quenching Peclet number = quenching distance, cm = universal gas constant, 1.986 cal/mole K = surface of the upstream boundary, cm 2 , Sec. Ill B = surface of the downstream boundary cm 2 , Sec. Ill B = temperature, K = ignition (cutoff) temperature, K = ambient temperature, K = x component of the mixture velocity, cm/s = volume in Sec. Ill B cm 3 = flame speed in Eq. (22), cm/s = velocity of the mixture at the downstream boundary (_L toS out ),cm/s = rate of consumption of fuel per unit volume and time, g/cm 3 s = mass of reactant (fuel) per unit mass of mixture -mass of reactant (fuel) in unburned mixture per unit mass of that mixture A = thermal conductivity of the mixture cal/cm s K p = local mixture density, g/cm P 0 = density of unburned mixture, g/cm 3 Pom = density of the mixture at the downstream boundary, Sec. Ill B Subscript 0 = upstream boundary (reactants or cold)

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“…A value of 28 !LAmp was selected since for laminar combustion at 0 percent EGR this current corresponds to a dead space thickness of 635 !Lm. This calibration is obtained by taking 40 percent of the smallest quenching thickness reported in the literature (Potter, 1960) The line with a slope equal to three has been added to the figure in accordance with the formula K )3…”

Section: The Minimum Ignition Energymentioning

confidence: 99%

The Effect of Exhaust Gas Recirculation and Turbulence on the Burning Velocity, Dead Space Thickness, and Minimum Ignition Energy in Premixed Methane-Air Combustion

Gat

Kauffman

1980

Combustion Science and Technology

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The dilution of a homogeneous combustible mixture with products of combustion has proven to be a successful method of reducing the oxides of nitrogen produced by a combustion process. The Exhaust Gas Recirculation (EGR) affects the flame velocity, ignition energy, and quenching behavior. An experimental program has been conducted to determine the effects of EGR on these fundamental aspects of a turbulent methane/air flame in a constant volume bomb. Data are presented showing that the decrease in flame velocity caused by the EGR can to some extent be compensated for by an increase in the turbulence intensity at a price of increased ignition difficulty. The effect of the EGR, as determined from both heat transfer and ionization measurements, is to increase the single-wall quenching distance.

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Flame Quenching

Cited by 19 publications

References 27 publications

Spontaneous ignition of hydrogen leaks: A review of postulated mechanisms

Spontaneous ignition of hydrogen leaks: A review of postulated mechanisms

Numerical Solution of the Two-Dimensional Premixed Laminar Flame Equations

The Effect of Exhaust Gas Recirculation and Turbulence on the Burning Velocity, Dead Space Thickness, and Minimum Ignition Energy in Premixed Methane-Air Combustion

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