Turbulence and turbulent flame propagation—A critical appraisal
TL;DR: In this article, the compatibility of theories of turbulence with different turbulent flame models is discussed, and it is suggested that the turbulent Reynolds number, Rλ, of the reactants is an important controlling parameter in turbulent flame propagation.
About: This article is published in Combustion and Flame.The article was published on 1975-02-01. It has received 228 citations till now. The article focuses on the topics: Laminar flame speed & Flame structure.
Citations
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TL;DR: In this paper, the steady laminar counterflow diffusion flame exhibits a very similar scalar structure as unsteady distorted mixing layers in a turbulent flow field, and the conserved scalar model is interpreted as the most basic flamelet structure.
1,933 citations
TL;DR: In this paper, an asymptotic nonlinear integrodifferential equation for spontaneous instability of the plane front of a laminar flame is derived, and it is shown that in all cases spontaneous instability implies an increase in its propagation velocity.
1,265 citations
TL;DR: In this article, the lift-off heights and visible-flame lengths of jet diffusion flames in still air have been determined for hydrogen, propane, methane and ethylene, and the results support the assumption that if the burner exit flow is choked the burner can be approximated by an equivalent convergent-divergent nozzle at whose exit the flow has expanded to ambient pressure.
Abstract: The lift-off heights and visible-flame lengths of jet diffusion flames in still air have been determined for hydrogen, propane, methane and ethylene. The flame lift-off height varies linearly with the jet exit velocity and is independent of the burner diameter for a given gas. The results support the assumption that if the burner exit flow is choked the burner can be approximated by an equivalent convergent-divergent nozzle at whose exit the flow has expanded to ambient pressure. The data for different gases can be collapsed onto a single curve if they are plotted in terms of the appropriate non-dimensional groupings. These results and previous results for blow-out stability suggest that diffusion flames blow out when the base is lifted to between 0.65 and 0.75 times the height at which stoichiometric concentration is reached at the jet axis. It can be deduced from the experimental results that, at the base of the flame. the ratio of turbulent burning velocity to laminar burning velocity varies a...
376 citations
TL;DR: In this paper, a turbulent non-premixed burning mixture is considered at a state close to extinction, expressed by an instantaneous scalar dissipation rate, and the extinction condition of the whole turbulent flame is derived on the basis of the percolation theory.
Abstract: A turbulent non-premixed burning mixture is considered at a state close to extinction. The turbulent flame is conceived as an ensemble of thin laminar diffusion flamelets that are highly distorted and stretched such that they may be quenched locally. The structure of the laminar diffusion flamelets is analysed in the limit of a large activation energy and the results of Linan's analysis of counterflow diffusion flames are used to derive the quenching condition. This condition is expressed by an instantaneous scalar dissipation rate. Statistics of the scalar dissipation rate are discussed on the basis of Kolmogoroff's third hypothesis. Extinction condition of the whole turbulent flame are derived on the basis of the percolation theory.
356 citations
TL;DR: In this article, a dimensionless correlation of experimental values of turbulent burning velocities is presented and a distribution function of stretch rates in turbulent flames is proposed and the experimental data are well predicted by a theory based on flamelet extinction by flame stretch with this distribution.
Abstract: A rational basis for correlating turbulent burning velocities is shown to involve the product of the Karlovitz stretch factor and the Lewis number. A generalized expression is derived to show how flame stretch is related to the velocity field. A new dimensionless correlation of experimental values of turbulent burning velocities is presented. Dimensionless groups also are used in correlations of laminar and turbulent flame extinction stretch rates. A distribution function of stretch rates in turbulent flames, based on an earlier one of Yeung et al ., is proposed and the experimental data are well predicted by a theory based on flamelet extinction by flame stretch with this distribution. Uncertainties arise concerning the role of negative stretch rate. Laminar flamelet modelling of complex combustion appears to have a broader validity than might be expected and some explanation for this is offered.
295 citations
References
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Book•
01 Jan 1972
TL;DR: In this paper, the authors present a reference record created on 2005-11-18, modified on 2016-08-08 and used for the analysis of turbulence and transport in the context of energie.
Abstract: Keywords: turbulence ; transport ; contraintes ; transport ; couche : limite ; ecoulement ; tourbillon ; energie Reference Record created on 2005-11-18, modified on 2016-08-08
8,276 citations
Book•
19 Dec 1975
TL;DR: In this paper, the authors present a method to find the optimal set of words for a given sentence in a sentence using the Bibliogr. Index Reference Record created on 2004-09-07, modified on 2016-08-08
Abstract: Note: Bibliogr. : p. 413-424. Index Reference Record created on 2004-09-07, modified on 2016-08-08
3,758 citations
TL;DR: In this paper, the previous equation of Buddenberg and the author has been modified to give a general equation for viscosity as a function of molecular weights and viscosities of the pure components of the mixture.
Abstract: By application of the kinetic theory, with several simplifying assumptions, the previous equation of Buddenberg and the author has been modified to give a general equation for viscosity as a function of molecular weights and viscosities of the pure components of the mixture. Agreement of the equation with experimental data is demonstrated for a number of highly irregular binary gas systems and mixtures of three to seven components.
2,183 citations
Book•
01 Jan 1961
TL;DR: The second edition of this book has been in short supply for some time and the authors have decided in favor of a reprint of the book rather than an extensive revision at this time.
Abstract: For some time copies of the second edition of this book have been in short supply. In order to meet, the demand for additional copies the authors have decided in favor of a reprint of the book rather than an extensive revision at this time. The justification for this lies in the character of the book. It was conceived as an exposition of basic concepts of gaseous combustion phenomena. Since the publication of the second edition in 1961 the literature on the subject has grown in volume very greatly. However, virtually no new concepts in gaseous combustion have evolved. For this reason we feel that the book, in its present form, continues to serve well the purpose for which it was intended, namely, to provide a systematic presentation of the fundamentals of combustion for scientists and engineers. In addition, we feel that the present edition has not yet outlived its usefulness as a source of data. Furthermore, the utility of certain concepts is only now beginning to be appreciated. This applies in particular to the concept of flame stretch which permits a unified approach to seemingly widely different sets of phenomena, including ignition, flame extinction, stabilization, quenching, flammability limits, and maximum heat release rates.
1,857 citations
TL;DR: In this article, it was shown that the general character of the motion of fluids in contact with solid surfaces depends on the relation between a physical constant of the fluid and the product of the linear dimensions of the space occupied by the fluid.
Abstract: 1. Objects and results of the investigation.—The results of this investigation have both a practical and a philosophical aspect. In their practical aspect they relate to the law of resistance to the motion of water in pipes, which appears in a new form, the law for all velocities and all diameters being represented by an equation of two terms. In their philosophical aspect these results relate to the fundamental principles of fluid motion; inasmuch as they afford for the case of pipes a definite verification of two principles, which are— that the general character of the motion of fluids in contact with solid surfaces depends on the relation between a physical constant of the fluid and the product of the linear dimensions of the space occupied by the fluid and the velocity.
1,820 citations