Showing papers on "Laminar flame speed published in 1974"
TL;DR: In this paper, the gas flow in the vicinity of a spreading flame, which depended on the inclined angle, was found to be closely related to the heat-transfer phenomena to the unburnt material.
73 citations
TL;DR: In this paper, Schlieren photography was used to qualitatively assess heat transfer to the unburnt material in front of the pyrolysis zone, where two different types of flame spread were observed.
64 citations
TL;DR: In this article, the frontal propagation velocity of a spherically symmetric flame converging to a focussing center is investigated under the assumption of strong temperature-dependence for the reaction rate.
47 citations
TL;DR: In this paper, it was shown that turbulent flame speed increases with scale under conditions of weak turbulence and decreases with increase in scale under condition of strong turbulence, and the two regions are separated by a transition region, which occurs when the turbulence intensity is about twice the laminar flame speed.
41 citations
TL;DR: An experimental study has been made of a pure gaseous turbulent diffusion flame issuing from a circular orifice into stagnant room temperature air surroundings as mentioned in this paper, where measurements have been made in the flame and corresponding nonburning jet, of temperature, velocity, specie concentration and turbulence intensity by the gas tracer diffusion method.
Abstract: An experimental study has been made of a pure gaseous turbulent diffusion flame issuing from a circular orifice into stagnant room temperature air surroundings. Measurements have been made in the flame and corresponding nonburning jet, of temperature, velocity, specie concentration and turbulence intensity by the gas tracer diffusion method. The potential core region in the flame is longer than in the cold jet and the rate of spread of the flame is slower than in the corresponding cold jet. Empirical equations are given for the decay along the axis of velocity and concentration as well as for the radial profiles. Diffusion coefficients in the flame are lower than those in the cold jet near the nozzle and this situation is reversed in the far flow region. Turbulence intensities are lower in the flame than in the cold jet. The diffusion coefficient in a flame is not constant. Turbulence intensities determined by the gas tracer diffusion method compares favourably with alternative methods of measuri...
28 citations
TL;DR: In this paper, the authors measured the shape of liquid fuel fires in the laminar flame region, i.e., the burning rate and shape of the flame etc., using vessels of various materials and thicknesses in various ambient atmospheres.
24 citations
TL;DR: In this article, the characteristics of flame propagation along the interface between a solid fuel and a gaseous oxidizer are considered, and it is found that difficulties in a study of this problem are related to the eigenvalue character of the relative velocity of the flame with respect to the oxidizer flow.
Abstract: The characteristics of flame propagation along the interface between a solid fuel and a gaseous oxidizer are considered. It is found that difficulties in a study of this problem are related to the eigenvalue character of the relative velocity of the flame with respect to the oxidizer flow. In the proposed model of flame spreading the difficulties are overcome by retaining the ellipticity of the governing equations and by taking the surface pyrolysis into account. The solution procedure makes use of a sink-source approach and the Fourier-transform method. Flame propagation velocity data computed on the basis of the described approach are compared with experimental results.
20 citations
TL;DR: In this article, it was shown that the measure of the inhibition of a quenched flame whose burning velocity is maintained constant (by heat transfer to a flame holder) is a rise in flame temperature on inhibition.
15 citations
TL;DR: In this paper, a theoretical analysis for the extinction of a homogeneous counterflow diffusion flame due to limitations in the reaction kinetics is presented, where experimental measurements of the extinction conditions (apparent flame strengths) can be used to evaluate quantitatively such kinetic parameters as the overall activation energy, the preexponential Arrhenius term, and the order of reaction.
12 citations
TL;DR: In this paper, the authors describe the flame in the wake of a hydrocarbon droplet by a model which combines recent experimental evidence on a large simulated droplet and the early concepts of Wohl et al. [10] on laminar diffusion flames.
8 citations
TL;DR: In this paper, the authors measured the active reaction volume in a turbulent flame and correlated it with the flow velocity, burner diameter, laminar flame speed and fuel mass fraction in the form of a power law by regression technique.
TL;DR: In this article, a model for the stability of swirling flames is presented, where the Zukowski-Marble criteria for flame stability behind bluff bodies is extended to flows exhibiting a recirculation region such as observed in strongly swirling jets.
Abstract: A model for the stability swirling flames is presented. The Zukowski-Marble criteria for flame stability behind bluff bodies is extended to flows exhibiting a recirculation region such as observed in strongly swirling jets. Both the recirculation distance and the effective flame speed are shown to be functions of the swirl parameter, S. An effective turbulent diffusivity relationship is obtained from an extension of the Prandtl mixing length theory and shown to be em = KR(l +/?2S2)1/2£700. By characterizin g the combustion zone as a free shear layer, an effective flame speed is obtained in terms of the diffusivity expression. The stability of the flame is obtained from the blowoff velocity model UBG = K'R •$>($)' V^/OL which is compared with available data. It is concluded that for strongly swirling flows, the principal fluid dynamic variable, 5, controls the process. The limits of applicability are reached when the recirculation zone produced by swirl extends to form a rotating Taylor column.
TL;DR: In this article, a model was developed to predict the behavior of a radially symmetric premixed laminar flame governed by a first order reaction, and a technique for the solution of the governing equations has been proposed which allows both of the unknown initial derivatives to be accurately determined in a reasonable amount of computation time.
TL;DR: In this article, a tractable, simple model for the prediction of flame velocities and reaction zone properties is proposed, where major chemical aspects of the flame are retained, but the spatial flame structure is approximated as a single, uniform reaction zone whose temperature and composition are calculated.
TL;DR: In this article, the results of a brief experimental investigation are presented which confirm the expectation that cool flame quenching distances should be larger than hot fire quenchings distances.