Effect of Stoichiometry and Strain Rate on Transient Flame Response PDF Download
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Author:
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Category :
Languages : en
Pages : 8
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Book Description
The interaction of a premixed methane/air flame with a counter-rotating vortex pair is analyzed using a parallel low-Mach-number computational model that is based on a detailed C1C2 chemical mechanism. Attention is focused on the transient response of the heat release rate and the flame structure at the centerline of the vortex pair. Results are obtained for vortex pairs of different strengths under lean, stoichiometric, and rich conditions. For the range of vortex strengths considered, the computations indicate that the heat release rate in the rich flame decays significantly faster than in the stoichiometric flame; this behavior is consistent with recent experimental measurements. Meanwhile, the heat release rate in the lean flame decays at a slightly slower rate than in the stoichiometric flame. The transient response of flame radicals such as H, CH, OH, and HCO is also analyzed. The analysis reveals a complex nonlinear dependence of the transient structure on both the vortex strength and the stoichiometry.
Author:
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Category :
Languages : en
Pages : 8
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Book Description
The interaction of a premixed methane/air flame with a counter-rotating vortex pair is analyzed using a parallel low-Mach-number computational model that is based on a detailed C1C2 chemical mechanism. Attention is focused on the transient response of the heat release rate and the flame structure at the centerline of the vortex pair. Results are obtained for vortex pairs of different strengths under lean, stoichiometric, and rich conditions. For the range of vortex strengths considered, the computations indicate that the heat release rate in the rich flame decays significantly faster than in the stoichiometric flame; this behavior is consistent with recent experimental measurements. Meanwhile, the heat release rate in the lean flame decays at a slightly slower rate than in the stoichiometric flame. The transient response of flame radicals such as H, CH, OH, and HCO is also analyzed. The analysis reveals a complex nonlinear dependence of the transient structure on both the vortex strength and the stoichiometry.
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Category :
Languages : en
Pages : 5
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The detailed dynamical response of flames in turbulent reacting flow involves a complex interaction between unsteady flow structures and flame chemistry. Two essential features of this interaction are the unsteady strain-rate and curvature disturbances to the reaction zone. In this work, the authors focus on a single flow length/time scale feature in two dimensions (2D), and its effect on a premixed flame for a range of mixture conditions. In particular, they study the interaction of a premixed freely propagating methane-air flame with a 2D counter-rotating vortex pair in an unbounded domain. In earlier work, they studied this flow using C1 kinetics, at stoichiometric conditions. Notable observations include the shift of the reaction zone into the products on the vortex-pair centerline, leading to depletion of H, O and OH, and the consequent general drop in reaction rates on the centerline flame segment. Curvature-induced focusing/defocusing effects were observed at the positively curved flame cusp, leading to modifications in internal transport fluxes of various species and radicals in the flame, and associated effects on H production and fuel consumption rates. These results were extended to more detailed kinetics, using other C1 and C2 mechanisms, which demonstrated the effect of choice of chemical mechanism on the observed transient flame response. The present study focuses on the dependence of the transient flame response on reactants mixture equivalence ratio. Two reactants mixture conditions are studied: case 1 is a stoichiometric conditions - equivalence ratio [Phi] = 1.0, and case 2 is rich at [Phi] = 1.2. In both cases, the reactants are 20% N2-diluted.
Author: K.J. Bathe
Publisher: Elsevier
ISBN: 0080552811
Category : Technology & Engineering
Languages : en
Pages : 975
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The MIT mission - "to bring together Industry and Academia and to nurture the next generation in computational mechanics is of great importance to reach the new level of mathematical modeling and numerical solution and to provide an exciting research environment for the next generation in computational mechanics." Mathematical modeling and numerical solution is today firmly established in science and engineering. Research conducted in almost all branches of scientific investigations and the design of systems in practically all disciplines of engineering can not be pursued effectively without, frequently, intensive analysis based on numerical computations.The world we live in has been classified by the human mind, for descriptive and analysis purposes, to consist of fluids and solids, continua and molecules; and the analyses of fluids and solids at the continuum and molecular scales have traditionally been pursued separately. Fundamentally, however, there are only molecules and particles for any material that interact on the microscopic and macroscopic scales. Therefore, to unify the analysis of physical systems and to reach a deeper understanding of the behavior of nature in scientific investigations, and of the behavior of designs in engineering endeavors, a new level of analysis is necessary. This new level of mathematical modeling and numerical solution does not merely involve the analysis of a single medium but must encompass the solution of multi-physics problems involving fluids, solids, and their interactions, involving multi-scale phenomena from the molecular to the macroscopic scales, and must include uncertainties in the given data and the solution results. Nature does not distinguish between fluids and solids and does not ever repeat itself exactly.This new level of analysis must also include, in engineering, the effective optimization of systems, and the modeling and analysis of complete life spans of engineering products, from design to fabrication, to possibly multiple repairs, to end of service.
Author: Ashwani K. Gupta
Publisher: Springer Nature
ISBN: 9811626480
Category : Technology & Engineering
Languages : en
Pages : 597
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This book provides state-of-the-art advances in several areas of importance in energy, combustion, power, propulsion, environment using fossil fuels and alternative fuels, and biofuels production and utilization. Availability of clean and sustainable energy is of greater importance now than ever before in all sectors of energy, power, mobility and propulsion. Written by internationally renowned experts, the latest fundamental and applied research innovations on cleaner energy production as well as utilization for a wide range of devices extending from micro scale energy conversion to hypersonic propulsion using hydrocarbon fuels are provided. The tailored technical tracks and contributions from the world renowned technical experts are portrayed in the respective field to highlight different but complementary views on fuels, combustion, power and propulsion and air toxins with special focus on current and future R&D needs and activities. The energy and environment sustainability require a multi-pronged approach involving development and utilization of new and renewable fuels, design of fuel-flexible combustion systems that can be easily operated with the new fuels, and develop novel and environmentally friendly technologies for improved utilization of all kinds of gas, liquid and solid fuels. This volume is a useful book for practicing engineers, research engineers and managers in industry and research labs, academic institutions, graduate students, and final year undergraduate students in Mechanical, Chemical, Aerospace, Energy and Environmental Engineering.
Author: Erhvervs- og byggestyrelsen
Publisher:
ISBN:
Category :
Languages : en
Pages : 53
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Author: Tariq Shamim
Publisher:
ISBN:
Category :
Languages : en
Pages : 382
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Author:
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ISBN:
Category : Chemistry
Languages : en
Pages : 2710
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Author: Norbert Peters
Publisher: Springer Science & Business Media
ISBN: 3540475435
Category : Science
Languages : en
Pages : 364
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In general, combustion is a spatially three-dimensional, highly complex physi co-chemical process oftransient nature. Models are therefore needed that sim to such a degree that it becomes amenable plify a given combustion problem to theoretical or numerical analysis but that are not so restrictive as to distort the underlying physics or chemistry. In particular, in view of worldwide efforts to conserve energy and to control pollutant formation, models of combustion chemistry are needed that are sufficiently accurate to allow confident predic tions of flame structures. Reduced kinetic mechanisms, which are the topic of the present book, represent such combustion-chemistry models. Historically combustion chemistry was first described as a global one-step reaction in which fuel and oxidizer react to form a single product. Even when detailed mechanisms ofelementary reactions became available, empirical one step kinetic approximations were needed in order to make problems amenable to theoretical analysis. This situation began to change inthe early 1970s when computing facilities became more powerful and more widely available, thereby facilitating numerical analysis of relatively simple combustion problems, typi cally steady one-dimensional flames, with moderately detailed mechanisms of elementary reactions. However, even on the fastest and most powerful com puters available today, numerical simulations of, say, laminar, steady, three dimensional reacting flows with reasonably detailed and hence realistic ki netic mechanisms of elementary reactions are not possible.
Author:
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Category : Power resources
Languages : en
Pages : 872
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Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 252
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