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Author : Carsten Kaiser
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Diffusive-thermal Instability of Counter-flow Flames Ot Low Lewis Number written by Carsten Kaiser and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ehsan Abbasi Atibeh
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (111 download)
Download or read book The Effects of Differential Diffusion in Counter-flow Premixed Flames with Dilution and Enrichment written by Ehsan Abbasi Atibeh and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The continued combustion of fossil fuels to fulfill global energy demand is being questioned because of the well-known problem of greenhouse-gas (GHG) emissions, which introduces new carbon, in the form of carbon dioxide, into the environment causing climate change. However, the inherent advantages of combustion-based engines, e.g., energy and power densities, make it hard for other power systems to compete; hence, a leading strategy is to avoid burning fossil fuels by using alternative renewable fuels, such as hydrogen and renewable biofuels. Adaptability with alternative renewable fuels that have variable compositions is referred to as fuel flexibility, which is an important parameter of next-generation combustor design. However, fuel flexibility significantly affects combustor operability properties, such as blowout, flashback, and dynamic stability, mainly due to variations in turbulent burning rates. Changing the fuel and oxidizing-gas mixture composition affects flame characteristics and burning rates through changing: (1) mixture reactivity, which is represented by unstretched laminar flame speed, and (2) mixture diffusivity, i.e., the diffusivity of the deficient reactant and diffusivity of heat. The disparity between thermal and mass diffusivities at the flame front is known as "differential diffusion", which causes stretch sensitivity, and thermal-diffusive instabilities, in flame-front propagation, and is represented by Lewis number, a ratio of thermal-to-mass diffusivities.This thesis investigates the effects of differential diffusion and stretch sensitivity on propagation, stabilization, and structure of lean turbulent premixed flames in the thin reaction zone regime. In the context of fuel flexibility, various fuels and oxidizer-inert mixtures are used to form mixtures with distinct effective Lewis numbers, through changing both fuel diffusivity and thermal diffusivity of the mixture. In these experiments, the unstretched laminar flame speed is kept constant during mixture dilution, and hydrogen enrichment of hydrocarbon flames, through changing the mixture equivalence ratio, in order to minimize the effects of chemistry. Furthermore, bulk-flow properties and the temperature boundary condition are kept constant; hence, the study highlights the effects of differential diffusion. The experiments are carried out using strained counter-flow flames, in order to study the effects of both components of the flame stretch, i.e., hydrodynamic strain and curvature. Local instantaneous statistics of various flame parameters within the imaged plane are quantified using high-speed particle image velocimetry (PIV) and Mie scattering flame tomography at various levels of turbulence intensity. These statistics include flame location, flame velocity, and flame-front topology, such as flame stretch, flame-front curvature, and flame surface area.The statistics of various parameters of turbulent flames with distinct effective Lewis number show that the effects of differential diffusion on the burning rates and the structure of turbulent premixed flames are important in highly turbulent flames in the thin reaction zone of combustion. Furthermore, these results are not dependent on the fuel or oxidizing-gas mixture and can be described fully by the effective Lewis number and turbulence intensity. In addition, at constant turbulence intensities, differential diffusion increases the burning rate of turbulent flames in thermo-diffusively unstable mixtures through two main mechanisms: (1) increasing the local flamelet displacement velocity, and (2) increasing the flame surface area. This thesis shows the need to advance the combustion theory to produce models that can capture the effects of differential diffusion for flames in real-world combustion systems, in order to predict the performance of future fuel-flexible combustors. The experimental results of this thesis provide a valuable dataset for the validation of such theories." --
Author : Kenneth Kuan-yun Kuo
Publisher : John Wiley & Sons
ISBN 13 : 0470226226
Total Pages : 914 pages
Book Rating : 4.4/5 (72 download)
Download or read book Fundamentals of Turbulent and Multiphase Combustion written by Kenneth Kuan-yun Kuo and published by John Wiley & Sons. This book was released on 2012-04-24 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : Jozef Jarosinski
Publisher : CRC Press
ISBN 13 : 0849384095
Total Pages : 236 pages
Book Rating : 4.8/5 (493 download)
Download or read book Combustion Phenomena written by Jozef Jarosinski and published by CRC Press. This book was released on 2009-02-12 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensively using experimental and numerical illustrations, CombustionPhenomena: Selected Mechanisms of Flame Formation, Propagation, and Extinction provides a comprehensive survey of the fundamental processes of flame formation, propagation, and extinction. Taking you through the stages of combustion, leading experts visually display, mathematically explain, and clearly theorize on important physical topics of combustion. After a historical introduction to the field, they discuss combustion chemistry, flammability limits, and spark ignition. They also study counterflow twin-flame configuration, flame in a vortex core, the propagation characteristics of edge flames, instabilities, and tulip flames. In addition, the book describes flame extinction in narrow channels, global quenching of premixed flames by turbulence, counterflow premixed flame extinction limits, the interaction of flames with fluids in rotating vessels, and turbulent flames. The final chapter explores diffusion flames as well as combustion in spark- and compression-ignition engines. It also examines the transition from deflagration to detonation, along with the detonation wave structure. With downloadable resources of images that beautifully illustrate a range of combustion phenomena, this book facilitates a practical understanding of the processes occurring in the conception, spread, and extinguishment of a flame. It will help you on your way to finding solutions to real issues encountered in transportation, power generation, industrial processes, chemical engineering, and fire and explosion hazards.
Author : Sally Ann Cheatham
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (373 download)
Download or read book On the Structure and Stability of Diffusion Flames written by Sally Ann Cheatham and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : Derek Dunn-Rankin
Publisher : MDPI
ISBN 13 : 3039214772
Total Pages : 196 pages
Book Rating : 4.0/5 (392 download)
Download or read book Cleaner Combustion written by Derek Dunn-Rankin and published by MDPI. This book was released on 2019-11-20 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides unique views of combustion from many technical and international research perspectives. Combustion science is often considered from its negative environmental impact, where we find, instead, that energy release from fuels of all kinds have promoted human endeavor throughout history. This volume tries to capture some of these positive features by showing a range of work examining unusual fuels and controlling the pollution from them.
Author : Tariq Shamim
Publisher :
ISBN 13 :
Total Pages : 382 pages
Book Rating : 4.3/5 (91 download)
Download or read book A Study of Transient Counterflow Diffusion Flames with Radiation written by Tariq Shamim and published by . This book was released on 1997 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Serguei Victorovich Kochevets
Publisher :
ISBN 13 :
Total Pages : 128 pages
Book Rating : 4.:/5 (435 download)
Download or read book Cellular Instability of Diffusion Flames in the Counterflow Configuration written by Serguei Victorovich Kochevets and published by . This book was released on 1999 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 584 pages
Book Rating : 4.0/5 ( download)
Download or read book 38th Aerospace Sciences Meeting and Exhibit written by and published by . This book was released on 2000 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Boris E. Gelfand
Publisher : Springer Science & Business Media
ISBN 13 : 3642253512
Total Pages : 339 pages
Book Rating : 4.6/5 (422 download)
Download or read book Thermo-Gas Dynamics of Hydrogen Combustion and Explosion written by Boris E. Gelfand and published by Springer Science & Business Media. This book was released on 2012-02-13 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: The potential of hydrogen as an important future energy source has generated fresh interest in the study of hydrogenous gas mixtures. Indeed, both its high caloricity and reactivity are unique properties, the latter underscoring safety considerations when handling such mixtures. The present monograph is devoted to the various aspects of hydrogen combustion and explosion processes. In addition to theoretical and phenomenological considerations, this work also collates the results of many experiments from less well known sources. The text reviews the literature in this respect, thereby providing valuable information about the thermo-gas-dynamical parameters of combustion processes for selected experimental settings in a range of scientific and industrial applications.
Author :
Publisher :
ISBN 13 :
Total Pages : 520 pages
Book Rating : 4.:/5 (26 download)
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1972 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 650 pages
Book Rating : 4.E/5 ( download)
Download or read book Thermophysics and Aeromechanics written by and published by . This book was released on 2002 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Michael F. Modest
Publisher : Springer
ISBN 13 : 3319272918
Total Pages : 167 pages
Book Rating : 4.3/5 (192 download)
Download or read book Radiative Heat Transfer in Turbulent Combustion Systems written by Michael F. Modest and published by Springer. This book was released on 2016-01-06 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This introduction reviews why combustion and radiation are important, as well as the technical challenges posed by radiation. Emphasis is on interactions among turbulence, chemistry and radiation (turbulence-chemistry-radiation interactions – TCRI) in Reynolds-averaged and large-eddy simulations. Subsequent chapters cover: chemically reacting turbulent flows; radiation properties, Reynolds transport equation (RTE) solution methods, and TCRI; radiation effects in laminar flames; TCRI in turbulent flames; and high-pressure combustion systems. This Brief presents integrated approach that includes radiation at the outset, rather than as an afterthought. It stands as the most recent developments in physical modeling, numerical algorithms, and applications collected in one monograph.
Author : Combustion Institute (U.S.). Eastern States Section. Fall Technical Meeting
Publisher :
ISBN 13 :
Total Pages : 464 pages
Book Rating : 4.E/5 ( download)
Download or read book Chemical and Physical Processes in Combustion written by Combustion Institute (U.S.). Eastern States Section. Fall Technical Meeting and published by . This book was released on 2005 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Satoru Ishizuka
Publisher : Momentum Press
ISBN 13 : 1606503057
Total Pages : 381 pages
Book Rating : 4.6/5 (65 download)
Download or read book Tubular Combustion written by Satoru Ishizuka and published by Momentum Press. This book was released on 2013-11-04 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tubular combustors are cylindrical tubes where flame ignition and propagation occur in a spatially confined, highly controlled environment, in a nearly flat, elongated geometry. This allows for some unique advantages where extremely even heat dispersion is required over a large surface while still maintaining fuel efficiency. Tubular combustors also allow for easy flexibility in type of fuel source, allowing for quick changeover to meet various needs and changing fuel pricing. This new addition to the MP sustainable energy series will provide the most up-to-date research on tubular combustion--some of it only now coming out of private proprietary protection. Plentiful examples of current applications along with a good explanation of background theory will offer readers an invaluable guide on this promising energy technology. Highlights include: * An introduction to the theory of tubular flames * The "how to" of maintaining stability of tubular flames through continuous combustion * Examples of both small-scale and large-scale applications like steel making, chemical processing, flexible-fuel-source heaters, efficient boilers, and other similar uses
Author : John D. Buckmaster
Publisher : SIAM
ISBN 13 : 9781611971064
Total Pages : 266 pages
Book Rating : 4.9/5 (71 download)
Download or read book The Mathematics of Combustion written by John D. Buckmaster and published by SIAM. This book was released on 1985-01-01 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book delves into the rapidly changing area of combustion, in which asymptotic methods and bifurcation theory have made a significant impact as have the constant-density, small-heat-release models and other important contributions.
Download or read book The Frequency Response of Counterflow Diffusin Flames written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Most practical combustion processes rely on turbulent diffusion flames due to their higher heat release rates when compared to laminar diffusion flames. The higher heat release rates occur because of the increased mixing that results from the flame's interaction with the turbulent flow field. Unfortunately, the turbulent combustion process is very complex; therefore, simplified models have been constructed. Flamelet Theory is a method that characterizes turbulent diffusion flames as a collection of strained, laminar, one-dimensional flamelets. One caveat of this model is the flamelets are assumed to respond quasi-steadily to the applied flow field. The focus of my research has been to elucidate the influence of a time varying flow field on the combustion process. To test the response, the reaction zone of a propane-air counter-flow diffusion flame was subjected to time varying flow fields using speakers. The results of the experiments illustrate a reaction zone that responds quasi-steadily at forcing frequencies up to 50 Hz. Above this threshold, significant departures occur from steady flame behavior. At elevated frequencies, conditions were found where the reaction zone temperature was found to be in phase with the strain rate, signaling a significant deviation from the quasi-steady state assumption. In diffusion flames, the limiting step for the transport of reactants to the flame front is a diffusion process. The time associated with the increasing phase difference is likely a result of the time necessary for reactants to travel through the diffusion layer. As the forcing frequency is increased, the time rate of change of reactants delivered to the edge of the diffusive zone increases; however, a finite amount of time is still necessary for the reactants to diffuse to the flame front. As the forcing frequency increases, this diffusion time becomes larger relative to the cycle time of the oscillation, which in turn shows up as an increasing phase difference. Anot.
