Solid Fuel Combustion in a Forced, Turbulent, Flat Plate Flow PDF Download
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Author: Liming Zhou
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 4
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Book Description
An experimental study is conducted of the effect of flow velocity, grid-generated turbulence and buoyancy on the combustion of a solid fuel in a flat plate boundary layer flow. The effect of buoyancy is determined by comparing the surface regression rates, flame characteristics, and exhaust products composition for the solid burning in a flow and ceiling orientation. Measurements are presented for the ceiling surface regression rate of PMMA sheets burning in air, and compared with previously obtained floor data. It is concluded that buoyancy has two major, and counteracting, effects. One is to affect the heat transfer by shifting the flame away from the surface in the floor burning and closer to the surface in the ceiling. The other is also due to the flame shifting and the instabilities associated with it that favors, in the floor case, the mixing of the reactants, and consequently the overall heat release rate. In the ceiling, the proximity of the flame to the cold surface causes quenching of the reaction, and the stability of the flame hampers reactants mixing, both of which reduce the heat generation rate. The overall result of these two counteracting mechanisms is that the surface regression rates are not that different in both geometries, although the composition of the combustion products are quite different.
Author: Liming Zhou
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 4
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Book Description
An experimental study is conducted of the effect of flow velocity, grid-generated turbulence and buoyancy on the combustion of a solid fuel in a flat plate boundary layer flow. The effect of buoyancy is determined by comparing the surface regression rates, flame characteristics, and exhaust products composition for the solid burning in a flow and ceiling orientation. Measurements are presented for the ceiling surface regression rate of PMMA sheets burning in air, and compared with previously obtained floor data. It is concluded that buoyancy has two major, and counteracting, effects. One is to affect the heat transfer by shifting the flame away from the surface in the floor burning and closer to the surface in the ceiling. The other is also due to the flame shifting and the instabilities associated with it that favors, in the floor case, the mixing of the reactants, and consequently the overall heat release rate. In the ceiling, the proximity of the flame to the cold surface causes quenching of the reaction, and the stability of the flame hampers reactants mixing, both of which reduce the heat generation rate. The overall result of these two counteracting mechanisms is that the surface regression rates are not that different in both geometries, although the composition of the combustion products are quite different.
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: Liming Zhou
Publisher:
ISBN:
Category : Ceilings
Languages : en
Pages : 480
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Book Description
The flow turbulence also has a significant effect on the flame extinction conditions, resulting in a smaller extinction velocity for larger flow turbulence intensity. For concurrent flow flame spread, it is found that the flow turbulence decreases the flame spread rate for both floor and ceiling geometries, mainly as a result of the flame length shortening at high turbulence intensity. It is also found that flow velocity intensifies the spread of the flame. The experimental data of flame spread rate, flame length and surface heat flux agree well with the formula obtained from a simplified thermal model, indicating that the heat transfer from flame to solid surface is the dominant controlling mechanism in the turbulent concurrent flame spread and, that the gas phase chemical reaction is of secondary importance.
Author: Jeffrey S. West
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 842
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Book Description
A detailed numerical model of opposed-flow flame spread over solid fuels is developed. The model is used to study flame spread in three regimes of flame spread; the Thermal, Chemical Kinetic and Near Quiescent Regimes. Simplifying assumptions that have been historically applied to this problem are investigated and their effect on the flame spread rate and flame structure are quantified in each regime. A semi-empirical flame spread formula for thermally thick fuels is developed from knowledge of the dominant simplifying assumptions in this regime. Spread rate predictions compare well to experimental and computed results. This semi-empirical model provides field variables which previous theories are unable to predict. Mechanisms of heat transfer ahead of the flame are studied in each regime. Forward heat transfer though the solid fuel becomes more important in the Chemical Kinetic and Near Quiescent Regimes, a previously unknown result. The rate and path of forward heat transfer is found to depend strongly on simplifying assumptions and the flame anchor location. These results explain the relationship between previous analytical and experimental forward heat transfer results. A dimensionless criterion predicting the fuel thickness at which transition from thermally thick to thermally thin is developed which compares well with experimental and computed results. Finite-rate gas-phase chemical kinetics are found to be the cause of the super-thin regime of flame spread. A formula for the limiting flame spread rate in this regime is developed. Correlation of computed spread rates with the Damkohler number is revisited. Uncertainty in residence time due to uncertainties in characteristic velocity and gas-phase properties is found to be the cause of spread in the correlation. The Damkohler number alone explains variations in many parameters although it alone cannot explain changes in gas-phase activation energy. The boundary between the Near Quiescent and Thermal Regime is quantified using a dimensionless radiation number. A new extinction limit for thick fuels in the Near Quiescent Regime is discovered. Radiative losses cause the flame to grow small and spread so slowly that sufficient oxygen is not available to sustain the flame. Recent experimental results confirm this conclusion.
Author: Kenneth Kuan-yun Kuo
Publisher: John Wiley & Sons
ISBN: 0470226226
Category : Science
Languages : en
Pages : 914
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Book Description
Detailed coverage of advanced combustion topics from the author of Principles of combustion, Second Edition Turbulence, turbulent combustion, and multiphase reacting flows have become major research topics in recent decades due to their application across diverse fields, including energy, environment, propulsion, transportation, industrial safety, and nanotechnology. Most of the knowledge accumulated from this research has never been published in book form—until now. Fundamentals of Turbulent and Multiphase Combustion presents up-to-date, integrated coverage of the fundamentals of turbulence, combustion, and multiphase phenomena along with useful experimental techniques, including non-intrusive, laser-based measurement techniques, providing a firm background in both contemporary and classical approaches. Beginning with two full chapters on laminar premixed and non-premixed flames, this book takes a multiphase approach, beginning with more common topics and moving on to higher-level applications. In addition, Fundamentals of Turbulent and Multiphase Combustion: Addresses seven basic topical areas in combustion and multiphase flows, including laminar premixed and non-premixed flames, theory of turbulence, turbulent premixed and non-premixed flames, and multiphase flows Covers spray atomization and combustion, solid-propellant combustion, homogeneous propellants, nitramines, reacting boundary-layer flows, single energetic particle combustion, and granular bed combustion Provides experimental setups and results whenever appropriate Supported with a large number of examples and problems as well as a solutions manual, Fundamentals of Turbulent and Multiphase Combustion is an important resource for professional engineers and researchers as well as graduate students in mechanical, chemical, and aerospace engineering.
Author: N. Swaminathan
Publisher: Cambridge University Press
ISBN: 1108572758
Category : Technology & Engineering
Languages : en
Pages :
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Book Description
Explore a thorough and up to date overview of the current knowledge, developments and outstanding challenges in turbulent combustion and application. The balance among various renewable and combustion technologies are surveyed, and numerical and experimental tools are discussed along with recent advances. Covers combustion of gaseous, liquid and solid fuels and subsonic and supersonic flows. This detailed insight into the turbulence-combustion coupling with turbulence and other physical aspects, shared by a number of the world leading experts in the field, makes this an excellent reference for graduate students, researchers and practitioners in the field.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 692
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 232
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Book Description
Author:
Publisher:
ISBN:
Category : Fluids
Languages : en
Pages : 558
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Book Description
Author: Norbert Peters
Publisher: Cambridge University Press
ISBN: 1139428063
Category : Science
Languages : en
Pages : 322
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Book Description
The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
