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Author : G. Kosaly
Publisher :
ISBN 13 :
Total Pages : 10 pages
Book Rating : 4.3/5 (91 download)
Download or read book Evaluation of Closure Models of Turbulent Diffusion Flames written by G. Kosaly and published by . This book was released on 2000 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book Evaluation of Closure Models of Turbulent Diffusion Flames written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling methods applied in the field of turbulent combustion were investigated via Direct Numerical Simulations (DNS) and theoretical analysis with an emphasis on subgrid-scale modeling to be applied in Large Eddy Simulations (LES). The DNS results supported the conditional moment closure approximation, refuted the common modeling of differential diffusion effects, raised a suggestion for valid modeling of differential diffusion, resolved outstanding theoretical issues regarding mixing layers, and demonstrated the need for including flamelet/flamelet interactions in the modeling of extinction/reignition events. The DNS methodology was reconfirmed by comparison to the classical laboratory results of Comte-Bellot and Corrsin. A new subgrid-scale model (Large Eddy Laminar Flamelet; LELFM, a quasi-steady model) was established and applied to the prediction of laboratory results in a simulated mixing layer with nitric oxide/ozone reaction. The results support the modeling. New results were derived and confirmed via DNS regarding the subgrid-scale modeling of the filtered mixture fraction, its second moment and dissipation rate.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (227 download)
Download or read book Evaluation of Closure Models of Turbulent Diffusion Flames written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling methods applied in the field of turbulent combustion were investigated via Direct Numerical Simulations (DNS) and theoretical analysis with an emphasis on subgrid-scale modeling to be applied in Large Eddy Simulations (LES). The DNS results supported the conditional moment closure approximation, refuted the common modeling of differential diffusion effects, raised a suggestion for valid modeling of differential diffusion, resolved outstanding theoretical issues regarding mixing layers, and demonstrated the need for including flamelet/flamelet interactions in the modeling of extinction/reignition events. The DNS methodology was reconfirmed by comparison to the classical laboratory results of Comte-Bellot and Corrsin. A new subgrid-scale model (Large Eddy Laminar Flamelet; LELFM, a quasi-steady model) was established and applied to the prediction of laboratory results in a simulated mixing layer with nitric oxide/ozone reaction. The results support the modeling. New results were derived and confirmed via DNS regarding the subgrid-scale modeling of the filtered mixture fraction, its second moment and dissipation rate.
Author : Tarek Echekki
Publisher : Springer Science & Business Media
ISBN 13 : 9400704127
Total Pages : 496 pages
Book Rating : 4.4/5 (7 download)
Download or read book Turbulent Combustion Modeling written by Tarek Echekki and published by Springer Science & Business Media. This book was released on 2010-12-25 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent combustion sits at the interface of two important nonlinear, multiscale phenomena: chemistry and turbulence. Its study is extremely timely in view of the need to develop new combustion technologies in order to address challenges associated with climate change, energy source uncertainty, and air pollution. Despite the fact that modeling of turbulent combustion is a subject that has been researched for a number of years, its complexity implies that key issues are still eluding, and a theoretical description that is accurate enough to make turbulent combustion models rigorous and quantitative for industrial use is still lacking. In this book, prominent experts review most of the available approaches in modeling turbulent combustion, with particular focus on the exploding increase in computational resources that has allowed the simulation of increasingly detailed phenomena. The relevant algorithms are presented, the theoretical methods are explained, and various application examples are given. The book is intended for a relatively broad audience, including seasoned researchers and graduate students in engineering, applied mathematics and computational science, engine designers and computational fluid dynamics (CFD) practitioners, scientists at funding agencies, and anyone wishing to understand the state-of-the-art and the future directions of this scientifically challenging and practically important field.
Author : Santanu De
Publisher : Springer
ISBN 13 : 9811074100
Total Pages : 663 pages
Book Rating : 4.8/5 (11 download)
Download or read book Modeling and Simulation of Turbulent Combustion written by Santanu De and published by Springer. This book was released on 2017-12-12 with total page 663 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive review of state-of-the-art models for turbulent combustion, with special emphasis on the theory, development and applications of combustion models in practical combustion systems. It simplifies the complex multi-scale and nonlinear interaction between chemistry and turbulence to allow a broader audience to understand the modeling and numerical simulations of turbulent combustion, which remains at the forefront of research due to its industrial relevance. Further, the book provides a holistic view by covering a diverse range of basic and advanced topics—from the fundamentals of turbulence–chemistry interactions, role of high-performance computing in combustion simulations, and optimization and reduction techniques for chemical kinetics, to state-of-the-art modeling strategies for turbulent premixed and nonpremixed combustion and their applications in engineering contexts.
Author :
Publisher :
ISBN 13 :
Total Pages : 92 pages
Book Rating : 4.:/5 (317 download)
Download or read book A Second-order Closure Analysis of Turbulent Diffusion Flames written by and published by . This book was released on 1977 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Nedunchezhian Swaminathan
Publisher : Cambridge University Press
ISBN 13 : 1139498584
Total Pages : 447 pages
Book Rating : 4.1/5 (394 download)
Download or read book Turbulent Premixed Flames written by Nedunchezhian Swaminathan and published by Cambridge University Press. This book was released on 2011-04-25 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: A work on turbulent premixed combustion is important because of increased concern about the environmental impact of combustion and the search for new combustion concepts and technologies. An improved understanding of lean fuel turbulent premixed flames must play a central role in the fundamental science of these new concepts. Lean premixed flames have the potential to offer ultra-low emission levels, but they are notoriously susceptible to combustion oscillations. Thus, sophisticated control measures are inevitably required. The editors' intent is to set out the modeling aspects in the field of turbulent premixed combustion. Good progress has been made on this topic, and this cohesive volume contains contributions from international experts on various subtopics of the lean premixed flame problem.
Author :
Publisher :
ISBN 13 :
Total Pages : 704 pages
Book Rating : 4.:/5 (31 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Model-Based Closure Approach for Turbulent Combustion Using the One-Dimensional Turbulence Model written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new model-based closure approach for turbulent combustion using the One-Dimensional turbulence model (ODT) is developed and validated in context to a turbulent jet diffusion flame. The interaction of turbulence and chemistry provides interesting finite rate chemistry effects including the phenomena of extinction and re-ignition. The ODT model resolves both spatially and temporally all the scales in a turbulent reaction flow problem, thus, combining the accuracy of a DNS like solver with efficiency by reduction in the number of dimensions. The closure approach is based on identifying the mechanisms responsible for the above mentioned effects and parameterizing the ODT results with a minimum set of scalars transported in the coarse grained solvers like the Reynolds-Averaged Navier-Stokes (RANS) or Large Eddy Simulation (LES). Thus, the closure from ODT is based on a "one-way" coupling between the coarse grained solvers and ODT. Two approaches for closure are developed in the present work with respect to a RANS solver; however, they can be easily extended to LES. The first approach relies on ODT to provide the history effects associated with the geometry, which represent the interactions of turbulence and chemistry, by tabulating scalar statistics (first and second moments) on two parameters measuring, the extent of mixing, the radial mean mixture fraction, and the extent of entrainment, the centerline mean mixture fraction. However, based on the above parameterization, the approach is limited to jet diffusion flame geometry. Furthermore, the closure requires a one to one correspondence between the flames simulated in the coarse grained solver and ODT. As a second approach, the results from ODT are parameterized based on general representative scalars; mixture fraction, which specifies the mixedness of the mixture and temperature, which specifies the reactedness of the mixture. The history effects associated with the flow geometry are provided by the RANS solver in t.
Author : Yuji Hasemi
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (116 download)
Download or read book Deterministic Modeling of Unconfined Turbulent Diffusion Flames written by Yuji Hasemi and published by . This book was released on 1983* with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Building and Fire Research Laboratory (U.S.)
Publisher :
ISBN 13 :
Total Pages : 85 pages
Book Rating : 4.:/5 (52 download)
Download or read book Mixing and Radiation Properties of Buoyant Turbulent Diffusion Flames written by Building and Fire Research Laboratory (U.S.) and published by . This book was released on 1995 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Present measurements emphasized self-preserving conditions far from the source where effects of source momentum and other source disturbances have been lost. The results show that earlier measurements in the literature were not carried out at sufficient distances from the source to reach self-preserving conditions, and provide measured properties at self-preserving conditions needed to develop and evaluate higher-order models of buoyant turbulent flows. The measurements were used to evaluate a simple k-E-g turbulence model finding good agreement between measured and predicted mean velocities and mixture fractions based on standard turbulence model constants, which is not unusual for a simple classical flow like the self-preserving buoyant turbulent plume.
Author : Pradeep Kumar Jha
Publisher :
ISBN 13 : 9780494782439
Total Pages : 374 pages
Book Rating : 4.7/5 (824 download)
Download or read book Modelling Detailed-Chemistry Effects on Turbulent Diffusion Flames Using a Parallel Solution-Adaptive Scheme written by Pradeep Kumar Jha and published by . This book was released on 2011 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capturing the effects of detailed-chemistry on turbulent combustion processes is a central challenge faced by the numerical combustion community. However, the inherent complexity and non-linear nature of both turbulence and chemistry require that combustion models rely heavily on engineering approximations to remain computationally tractable. This thesis proposes a computationally efficient algorithm for modelling detailed-chemistry effects in turbulent diffusion flames and numerically predicting the associated flame properties. The cornerstone of this combustion modelling tool is the use of parallel Adaptive Mesh Refinement (AMR) scheme with the recently proposed Flame Prolongation of Intrinsic low-dimensional manifold (FPI) tabulated-chemistry approach for modelling complex chemistry. The effect of turbulence on the mean chemistry is incorporated using a Presumed Conditional Moment (PCM) approach based on a beta-probability density function (PDF). The two-equation k-w turbulence model is used for modelling the effects of the unresolved turbulence on the mean flow field. The finite-rate of methane-air combustion is represented here by using the GRI-Mech 3.0 scheme. This detailed mechanism is used to build the FPI tables. A state of the art numerical scheme based on a parallel block-based solution-adaptive algorithm has been developed to solve the Favre-averaged Navier-Stokes (FANS) and other governing partial-differential equations using a second-order accurate, fully-coupled finite-volume formulation on body-fitted, multi-block, quadrilateral/hexahedral mesh for two-dimensional and three-dimensional flow geometries, respectively. A standard fourth-order Runge-Kutta time-marching scheme is used for time-accurate temporal discretizations. Numerical predictions of three different diffusion flames configurations are considered in the present work: a laminar counter-flow flame; a laminar co-flow diffusion flame; and a Sydney bluff-body turbulent reacting flow. Comparisons are made between the predicted results of the present FPI scheme and Steady Laminar Flamelet Model (SLFM) approach for diffusion flames. The effects of grid resolution on the predicted overall flame solutions are also assessed. Other non-reacting flows have also been considered to further validate other aspects of the numerical scheme. The present schemes predict results which are in good agreement with published experimental results and reduces the computational cost involved in modelling turbulent diffusion flames significantly, both in terms of storage and processing time.
Author : Norbert Peters
Publisher : Cambridge University Press
ISBN 13 : 1139428063
Total Pages : 322 pages
Book Rating : 4.1/5 (394 download)
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author : F. Jia
Publisher :
ISBN 13 : 9781899991082
Total Pages : pages
Book Rating : 4.9/5 (91 download)
Download or read book Combustion Models of Turbulent Diffusion Flames written by F. Jia and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Heinrich Eickhoff
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (17 download)
Download or read book Model investigations on turbulent diffusion flames written by Heinrich Eickhoff and published by . This book was released on 1980 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : S-M. Jeng
Publisher :
ISBN 13 :
Total Pages : 75 pages
Book Rating : 4.:/5 (5 download)
Download or read book An Investigation of Axisymmetric Buoyant Turbulent Diffusion Flames written by S-M. Jeng and published by . This book was released on 1982 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation considered measurements of the structure of axisymmetric, buoyant, turbulent diffusion flames in still air. Profiles of mean temperature, mean velocity, velocity fluctuations and total radiant heat flux were completed for methane flames, including careful characterization of burner exit conditions, in order to provide data for the evaluation of models of the process. Preliminary tests also provided mean temperature profiles for propane flames. Test conditions were chosen so that the flow was turbulent near the burner exit while effects of buoyancy were significant over most of the luminous portion of the flames. Both the present measurements and those of other investigators were compared with predictions of a k-E-g differential model, which included effects of buoyancy in the transport equations for turbulence quantities. The results indicated anisotropic effects in regions where buoyancy dominates flow properties suggesting the eventual desirability of multi-stress models for buoyant flames, although extensive recalibration of model constants from a limited data based would be required if this step were taken. Additional measurements and analysis of methane flames are in progress, in order to investigate the flame radiation properties and provide additional data on turbulence properties needed for model development.
Author : S-M. Jeng
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (1 download)
Download or read book An Investigation of Axisymmetric Buoyant Turbulent Diffusion Flames: Flow Structure and Radiation Properties written by S-M. Jeng and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
