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Author: James S. T'ien
Publisher:
ISBN:
Category : Flame
Languages : en
Pages : 7
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Book Description
The inadequacy of using a single Damkohler number extinction criterion for diffusion flames is discussed and a direction for generalization is proposed. (Author).
Author: James S. T'ien
Publisher:
ISBN:
Category : Flame
Languages : en
Pages : 7
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Book Description
The inadequacy of using a single Damkohler number extinction criterion for diffusion flames is discussed and a direction for generalization is proposed. (Author).
Author: Siavash Haghighat Sohrab
Publisher:
ISBN:
Category : Polymerization
Languages : en
Pages : 502
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Book Description
Author:
Publisher:
ISBN:
Category : Fire testing
Languages : en
Pages : 740
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Book Description
Author: F Dryer
Publisher: CRC Press
ISBN: 9789056995843
Category : Science
Languages : en
Pages : 524
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Book Description
This book contains a collection of papers prepared by leading experts on selected areas of particular importance to researchers in combustion science. The editors have gathered writings on fundamental physical and chemical aspects of combustion, including combustion chemistry, soot formation, and condensed phase and turbulent combustion intended to be a source of current understanding on the topics covered. The materials were originally presented as part of a Colloquium on Combustion held in honor of Professor Irvin Glassman.
Author: Anthony Hamins
Publisher:
ISBN:
Category : Fire extinction
Languages : en
Pages : 552
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Book Description
Author: Sally Ann Cheatham
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Diffusion flames are flames in which fuel and oxidant, initially separate, come together to react chemically in a relatively thin combustion zone. Asymptotic methods, supplemented by numerical computation, are used to analyze the structure and dynamical properties of such flames. Attention is first focused on diffusion flames in arbitrary fluid flows for general fuel and oxidant Lewis numbers, in which the combustion is complete or nearly complete. Thus the limit of large Damkohler number and large activation energy is considered. The resulting mathematical formulation consists of a free boundary problem, with the flame as the free boundary. Such a treatment greatly simplifies the governing system of equations, and provides a framework for the analysis of the flame structure as well as its dynamical properties. The stability of a planar flame is next considered, with attention focused on diffusional-thermal effects. A dispersion relation is obtained, which relates the growth parameter and wavenumber of disturbances to the fuel and oxidant Lewis numbers, supply temperatures, and supply concentrations. Analysis of the dispersion relations indicates that instability corresponding to cellularity of the flame may occur for lean flames under near extinction conditions when the Lewis numbers of fuel and oxidant are sufficiently low. The asymptotic model is also used to identify conditions under which flame extinction occurs. In particular, the burning characteristics of a dilute spray diffusion flame have been examined. The presence of fuel droplets in the fuel supply is shown to alter the extinction characteristics of the flame. The onset of oscillations in the spherical diffusion flame surrounding a fuel droplet is also considered. Motivated by recent microgravity candle flame experiments, the constraint of a weak oxidant environment is imposed. A linear stability analysis indicates that oscillations may indeed result when radiative heat losses and the Lewis numbers of fuel and oxidant are sufficiently large. Estimates for the critical conditions are given, along with a prediction of the resulting frequency of oscillation. A weakly non-linear analysis is then used to more fully investigate the transition to an oscillatory burning state.
Author: Howard D. Ross
Publisher: Elsevier
ISBN: 0080549977
Category : Technology & Engineering
Languages : en
Pages : 601
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Book Description
This book provides an introduction to understanding combustion, the burning of a substance that produces heat and often light, in microgravity environments-i.e., environments with very low gravity such as outer space. Readers are presented with a compilation of worldwide findings from fifteen years of research and experimental tests in various low-gravity environments, including drop towers, aircraft, and space.Microgravity Combustion is unique in that no other book reviews low- gravity combustion research in such a comprehensive manner. It provides an excellent introduction for those researching in the fields of combustion, aerospace, and fluid and thermal sciences. * An introduction to the progress made in understanding combustion in a microgravity environment* Experimental, theoretical and computational findings of current combustion research* Tutorial concepts, such as scaling analysis* Worldwide microgravity research findings
Author: Alejandro Sanchez (Jr.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 44
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Book Description
"Two combustion systems that are extensively studied for chemical reaction processes are premixed flames and non-premixed flames. A premixed flame has oxidizer mixed with fuel causing flame front to be a thin reaction sheet (flame) that moves from burnt side to reactant side. Plenty of theoretical and physical experiments have already been contributed into modeling and characterizing premixed flames. Only as of late, has the theoretical and physical experiments towards non-premixed flames, been identified in the literature. This research focuses on non-premixed flames, diffusion flames. A diffusion flame is where oxidizer and fuel are initially separated and come together via some external forces at a reaction sheet. As a flame cools down, or slows down, the flame gets closer to extinction. Before extinction the flame will become unstable and may oscillate or show cellular instabilities. This model will focus on diffusion flames in a closed chamber with fuel being supplied in the flow and oxidizer diffusing against the gradient. The model allows for convection and radiative heat loss, which represents the heat transfer of a hot object to its cooler surroundings. Appropriate boundary conditions are implemented for the three differential equations that include temperature, oxidizer, and fuel. The system of equations are coupled, and each has a nonlinear reaction term. The bvp4c function in MATLAB is used to numerically solve these differential equations, with their boundary conditions, to identify flame location and flame extinctions for diffusion flames. Flame extinction occurs at a particular Damköhler number D, representing the ratio of diffusion time to chemical reaction time. Results from the numerical analysis are compared to numerical results of other models that are similar to this model."--
Author: Jennifer L. Rhatigan
Publisher:
ISBN:
Category : Dynamics
Languages : en
Pages : 158
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Book Description
This is the first attempt to analyze both radiation and detailed kinetics on the burning and extinction of a solid fuel in a stagnation-point diffusion flame. We present a detailed and comparatively accurate computational model of a solid fuel flame along with a quantitative study of the kinetics mechanism, radiation interactions, and the extinction limits of the flame. A detailed kinetics model for the burning of solid trioxane (a trimer of formaldehyde) is coupled with a narrowband radiation model, with carbon dioxide, carbon monoxide, and water vapor as the gas-phase participating media. The solution of the solid trioxane diffusion flame over the flammable regime is presented in some detail, as this is the first solution of a heterogeneous trioxane flame. We identify high-temperature and low-temperature reaction paths for the heterogeneous trioxane flame. We then compare the adiabatic solution to solutions that include surface radiation only and gas-phase and surface radiation using surface model.
Author: Anjan Ray
Publisher:
ISBN: 9780591135442
Category : Diffusion
Languages : en
Pages : 204
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Book Description
