Topic

# Flame spread

About: Flame spread is a research topic. Over the lifetime, 1907 publications have been published within this topic receiving 28698 citations. The topic is also known as: surface burning characteristics rating & Flame Spread Index.

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TL;DR: In this paper, a review of the recent developments concerning the use of layered silicates (clay) for designing polymer nanocomposites endowed with enhanced flame retardancy is presented.

Abstract: A review is presented of the recent developments concerning the use of layered silicates (clay) for designing polymer nanocomposites endowed with enhanced flame retardancy. Emphasis is placed on the fact that the effect of layered silicates is beneficial mostly for retarding flame spread in developing fires, but not at the stage of ignition or in the case of fully developed fires. Accordingly, the need for incorporating conventional flame retardants in nanocomposites is discussed, providing detailed examples reported in open literature.

862 citations

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TL;DR: In this paper, a method for solving the partial parabolic differential equation of turbulent flame spread has been developed, which is applied to the spread of flame behind a baffle in a plane-walled duct.

Abstract: A calculation procedure has been developed for solving the partial parabolic differential equation of turbulent flame spread. This procedure has been applied to the spread of flame behind a baffle in a plane-walled duct, with two distinct models for the kinetics of the reaction. In the first model, the time-mean reaction rate is related to the time-mean concentrations and temperature at the point in question by a bimolecular Arrhenius expression. In the second model, the local reaction rate is taken to depend also on the rate of break-up of the eddies by fits the experiemntal data better than the first; the eddy-break-up term appears to be essential if the dominance of hydrodynamic processes is to be correctly simulated. A third model of turbulent combustion is also described. It involves the calculation of the magnitude of the fluctuating concentrations, and correctly predicts themain features of turbulent diffusion flames. One of its implications is a finite reaction-zone thickness, even through there is no chemical-kinetic resistance.

660 citations

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21 Apr 2006

TL;DR: In this article, the authors present an overview of the history of fire and its application in the field of fire safety, including a discussion of the role of mass and energy conservation in chemical reactions.

Abstract: Preface. Nomenclature. 1 Introduction to Fire. 1.1 Fire in History. 1.2 Fire and Science. 1.3 Fire Safety and Research in the Twentieth Century. 1.4 Outlook for the Future. 1.5 Introduction to This Book. 2 Thermochemistry. 2.1 Introduction. 2.2 Chemical Reactions. 2.3 Gas Mixture. 2.4 Conservation Laws for Systems. 2.5 Heat of Formation. 2.6 Application of Mass and Energy Conservation in Chemical Reactions. 2.7 Combustion Products in Fire. 3 Conservation Laws for Control Volumes. 3.1 Introduction. 3.2 The Reynolds Transport Theorem. 3.3 Relationship between a Control Volume and System Volume. 3.4 Conservation of Mass. 3.5 Conservation of Mass for a Reacting Species. 3.6 Conservation of Momentum. 3.7 Conservation of Energy for a Control Volume. 4 Premixed Flames. 4.1 Introduction. 4.2 Reaction Rate. 4.3 Autoignition. 4.4 Piloted Ignition. 4.5 Flame Speed, Su. 4.6 Quenching Diameter. 4.7 Flammability Limits. 4.8 Empirical Relationships for the Lower Flammability Limit. 4.9 A Quantitative Analysis of Ignition, Propagation and Extinction. 5 Spontaneous Ignition. 5.1 Introduction. 5.2 Theory of Spontaneous Ignition. 5.3 Experimental Methods. 5.4 Time for Spontaneous Ignition. 6 Ignition of Liquids. 6.1 Introduction. 6.2 Flashpoint. 6.3 Dynamics of Evaporation. 6.4 Clausius-Clapeyron Equation. 6.5 Evaporation Rates. 7 Ignition of Solids. 7.1 Introduction. 7.2 Estimate of Ignition Time Components. 7.3 Pure Conduction Model for Ignition. 7.4 Heat Flux in Fire. 7.5 Ignition in Thermally Thin Solids. 7.6 Ignition of a Thermally Thick Solid. 7.7 Ignition Properties of Common Materials. 8 Fire Spread on Surfaces and Through Solid Media. 8.1 Introduction. 8.2 Surface Flame Spread - The Thermally Thin Case. 8.3 Transient Effects. 8.4 Surface Flame Spread for a Thermally Thick Solid. 8.5 Experimental Considerations for Solid Surface Spread. 8.6 Some Fundamental Results for Surface Spread. 8.7 Examples of Other Flame Spread Conditions. 9 Burning Rate. 9.1 Introduction. 9.2 Diffusive Burning of Liquid Fuels. 9.3 Diffusion Flame Variables. 9.4 Convective Burning for Specific Flow Conditions. 9.5 Radiation Effects on Burning. 9.6 Property Values for Burning Rate Calculations. 9.7 Suppression and Extinction of Burning. 9.8 The Burning Rate of Complex Materials. 9.9 Control Volume Alternative to the Theory of Diffusive Burning. 9.10 General Considerations for Extinction Based on Kinetics. 9.10.1 A demonstration of the similarity of extinction in premixed and diffusion flames. 9.11 Applications to Extinction for Diffusive Burning. 10 Fire Plumes. 10.1 Introduction. 10.2 Buoyant Plumes. 10.3 Combusting Plumes. 10.4 Finite Real Fire Effects. 10.5 Transient Aspects of Fire Plumes. 10.5.1 Starting plume. 10.5.2 Fireball or thermal. 11 Compartment Fires. 11.1 Introduction. 11.2 Fluid Dynamics. 11.3 Heat Transfer. 11.4 Fuel Behavior. 11.5 Zone Modeling and Conservation Equations. 11.6 Correlations. 11.7 Semenov Diagrams, Flashover and Instabilities. 12 Scaling and Dimensionless Groups. 12.1 Introduction. 12.2 Approaches for Establishing Dimensionless Groups. 12.3 Dimensionless Groups from the Conservation Equations. 12.4 Examples of Specific Correlations. 12.5 Scale Modeling. Appendix. Flammability Properties. Archibald Tewarson. Index.

589 citations

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TL;DR: In this article, a theoretical description of a laminar diffusion flame spreading against an air stream over a solid- or liquid-fuel bed is presented, where both a thin sheet and a semi-infinite fuel bed are considered.

Abstract: A theoretical description is presented for a laminar diffusion flame spreading against an air stream over a solid- or liquid-fuel bed. Both a thin sheet and a semi-infinite fuel bed are considered. The burning process is described as follows: The hot flame heats the unburned fuel bed, which subsequently vaporizes. The resulting fuel vapor reacts with the oxygen supplied by the incoming air, thereby producing the heat that maintains the flame-spread process. The formulated model treats the combustion as a diffusion flame, for which the details of the reaction kinetics can be ignored by assuming infinite reaction rates. The model includes the chemical stoichiometry, heat of combustion, gas-phase conductive heat transfer, radiation, mass transfer, fuel vaporization, and fuel-bed thermal properties. The radiation is mathematically treated as a heat loss at the flame sheet and a heat gain at the fuel-bed surface. The calculated flame-spread formulas are not inconsistent with available experimental data. These results reveal much of the physics involved in a spreading, flame. For instance, the flame-spread rate is strongly influenced by (1) the adiabatic stoichiometric flame temperature, and (2) the fuel-bed thermal properties, except for the fuel-bed conductivity parallel to the propagation direction.

324 citations

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TL;DR: In this article, an experimental study of laser-induced spark ignition of flammable, gaseous premixtures is reported, with theoretical interpretations, in an explosion bomb equipped with four variable-speed fans that facilitated the study of quiescent and isotropic turbulent conditions.

Abstract: An experimental study of laser-induced spark ignition of flammable, gaseous premixtures is reported, with theoretical interpretations. Ignition was in an explosion bomb, equipped with four variable-speed fans that facilitated the study of quiescent and isotropic turbulent conditions. Good optical access enabled the progress of plasma fronts, shock waves, igniting kernels, and propagating flames to be recorded with high-speed schlieren photography. A focused beam from a Q-switched Nd:YAG laser initiated electrical breakdown, with plasma energies between 85 and 200 mJ. Probabilities of breakdown were found for air and isooctane-air mixtures over ranges of pressures and temperatures. Blast-wave theory applied to shock-wave trajectories enabled initial plasma conditions to be inferred. This suggested electron temperatures of over 10 5 K and very high pressures. Calculated values of the absorption coefficient for the laser beam energy show these plasma properties to be commensurate with the observed energy and size. The ensuing rarefaction wave creates toroidal rings at the leading and trailing edges of the plasma. The former decays more rapidly and a third lobe of the kernel is generated that moves towards the laser. In flammable mixtures this enhances the flame spread. Laminar flame speeds are overdriven by this gasdynamic effect, as well as by the high energy of the plasma, to such an extent that the flame speed decays from elevated values as the flame stretch decreases, contrary to the increases that occur with normal flames with positive Markstein numbers. The extent to which turbulence narrows the ignition limits is found experimentally. For mixtures close to the lean flammability limit, strong gasdynamic flows induced by laser ignition can stretch the flames to extinction and narrow the ignition limits. If a flame becomes established, eventually the third lobe disappears as the initial gas dynamic effects decay and are overwhelmed by the imposed flow fields. Nevertheless, the overdrive effects persist for some time and overdriven flames were observed in regimes where normal flames would have quenched.

280 citations