Download or read book Direct Numerical Simulations of Strained Laminar and Turbulent Nonpremixed Flames written by Chunsang Yoo and published by . This book was released on 2005 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Objets d art anciens et objets d ameublement tableaux et aquarelles miniatures written by and published by . This book was released on 1918 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation for Turbulent Reacting Flows written by Thierry Baritaud and published by Editions TECHNIP. This book was released on 1996 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Description of accurate boundary conditions for the simulation of reactive flows. Parallel direct numerical simulation of turbulent reactive flow. Flame-wall interaction and heat flux modelling in turbulent channel flow. A numerical study of laminar flame wall interaction with detailed chemistry: wall temperature effects. Modeling and simulation of turbulent flame kernel evolution. Experimental and theoretical analysis of flame surface density modelling for premixed turbulent combustion. Gradient and counter-gradient transport in turbulent premixed flames. Direct numerical simulation of turbulent flames with complex chemical kinetics. Effects of curvature and unsteadiness in diffusion flames. Implications for turbulent diffusion combustion. Numerical simulations of autoignition in turbulent mixing flows. Stabilization processes of diffusion flames. References.
Download or read book Direct Numerical Simulations of Premixed Turbulent Flame with Variable Density written by Songwei Zhang and published by . This book was released on 1994 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
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.
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.
Download or read book Experiments and Numerical Simulations of Diluted Spray Turbulent Combustion written by Bart Merci and published by Springer Science & Business Media. This book was released on 2011-06-20 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reflects the outcome of the 1st International Workshop on Turbulent Spray Combustion held in 2009 in Corsica (France). The focus is on reporting the progress of experimental and numerical techniques in two-phase flows, with emphasis on spray combustion. The motivation for studies in this area is that knowledge of the dominant phenomena and their interactions in such flow systems is essential for the development of predictive models and their use in combustor and gas turbine design. This necessitates the development of accurate experimental methods and numerical modelling techniques. The workshop aimed at providing an opportunity for experts and young researchers to present the state-of-the-art, discuss new developments or techniques and exchange ideas in the areas of experimentations, modelling and simulation of reactive multiphase flows. The first two papers reflect the contents of the invited lectures, given by experts in the field of turbulent spray combustion. The first concerns computational issues, while the second deals with experiments. These lectures initiated very interesting and interactive discussions among the researchers, further pursued in contributed poster presentations. Contributions 3 and 4 focus on some aspects of the impact of the interaction between fuel evaporation and combustion on spray combustion in the context of gas turbines, while the final article deals with the interaction between evaporation and turbulence.
Download or read book Direct Numerical Simulation of Lean Premixed Turbulent Flames at High Karlovitz Numbers Under Elevated Pressures written by Xujiang Wang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Reversible and Irreversible Chemical Reactions in Turbulent Non premixed Flames written by N. Swaminathan and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non premixed Combustion Full Numerical Simulation of a Coflowing Axisymmetric Jet Inviscid and Viscous Stability Analysis written by Stanford University. Thermosciences Division. Thermosciences Division and published by . This book was released on 1989 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulations of Turbulent Nonpremixed Hydrogen oxygen Combustion written by Christopher James Montgomery and published by . This book was released on 1995 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dilatation Flame Strain Displacement Speed and Curvature in Turbulent Premixed Flames Using Direct Numerical Simulation written by Nasim Shahbazian and published by . This book was released on 2008 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiscalar Measurements of Turbulence chemistry Interactions in Nonpremixed Flames written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selected results from experiments conducted over the past several years involving simultaneous multiscalar point measurements in turbulent nonpremixed flames are reviewed in this paper. In these experiments, spontaneous Raman scattering and Rayleigh scattering measurements of the major species and temperature were combined with laser-induced fluorescence measurements of minor species. The most important feature of these experiments is that they provide detailed data on the instantaneous relationships among species concentration, temperature, and derived scalar quantities that reflect the state of mixing or the progress of reaction. The data allow quantitative comparisons of the thermochemical states in turbulent flames with those in idealized representations, such as steady strained laminar flames, perfectly stirred reactors, or adiabatic equilibrium. The data may also be compared with results (measured or calculated) from unsteady laminar flames and from direct numerical simulations (DNS) of turbulent reacting flows. such comparisons provide insights into the fundamental nature of turbulence-chemistry interactions, and they allow one to examine the validity of some of the basic assumptions that turbulent combustion models are built upon. Furthermore, these data allow quantitative evaluations of the predictive accuracy, strengths, and limitations of a wide variety of combustions models.
Download or read book Numerical Simulation of Non premixed Laminar and Turbulent Flames by Means of Flamelet Modelling Approaches written by Kilian Claramunt i Altimira and published by . This book was released on 2005 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High fidelity Computation and Modeling of Turbulent Premixed Combustion written by Yunde Su and published by . This book was released on 2020 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-fidelity simulation of turbulent premixed combustion is desirable for the design of advanced energy-efficient and environmentally-friendly combustion engines. An attractive high-fidelity simulation approach that is applicable to practical combustion problems is the large eddy simulation (LES), in which the large-scale dynamics of flame-turbulence interaction are resolved down to a filter scale while the sub-filter phenomena are modeled. Since the grid size in practical LES is typically comparable to or larger than the flame front thickness, the filtered flame front is not well resolved when the filter size is taken as the grid size. Under such a condition, the spurious propagation of the filtered flame front can occur. To overcome this challenge, the front propagation formulation (FPF) method that was originally proposed to simulate propagating reaction fronts on under-resolved grids is extended to LES of turbulent premixed combustion. The closure of the regularized Dirac delta function, which FPF uses to minimize the spurious propagation, is investigated using direct numerical simulation (DNS) data for statistically planar premixed flames propagating in homogeneous isotropic turbulence. As a key ingredient in the sub-filter flame speed model that is required for the FPF method and many other combustion models, the flame wrinkling in the DNS dataset is studied in the context of fractals. The results show that, for the flames investigated in the DNS, the fractal dimension increases with the Reynolds number and the inner cut-off scale is on the order of the flame thickness. The FPF-LES framework is validated for a non-piloted Bunsen flame in the corrugated flamelet regime and a piloted Bunsen flame in the thin reaction zone regime. In both cases, the predicted results compare reasonably well with experimental measurements, demonstrating the performance of the FPF-LES framework. In LES of the non-piloted Bunsen flame, it is found that neglecting the stretch effects can cause the flame length and radius to be clearly under-predicted, which suggests the necessity to include stretch effects in LES. It is also found that the strain rate in the stretch effect model needs to be evaluated on the unburned side of the filtered flame to avoid the artificial modification of the flame wrinkling. Finally, the FPF-LES framework is applied to an experimentally studied spark-ignition (SI) engine with the emphasis on the prediction of cycle-to-cycle variations (CCVs), which are known to limit engine performance. To capture the degree of CCVs observed in the experiments, a laminar-to-turbulent flame transition model that describes the non-equilibrium sub-filter flame speed evolution during an early stage of flame kernel growth is developed. The multi-cycle LES with the proposed flame transition model under the FPF framework is found to reproduce experimentally-observed CCVs satisfactorily. The simulation results indicate the importance of modeling the laminar-to-turbulent flame transition and the effect of turbulence on the transition process, when predicting CCVs, under certain engine conditions.
Download or read book The Interaction of High Speed Turbulence with Flames Turbulent Flame Speed written by and published by . This book was released on 2010 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct numerical simulations of the interaction of a premixed flame with subsonic, high-speed, homogeneous, isotropic, Kolmogorov-type turbulence in an unconfined system show anomalously high turbulent flame speeds, S(T) . Data from these simulations are analyzed to identify the origin of this anomaly. The simulations were performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive-flow code. A simplified reaction-diffusion model represents a stoichiometric H2-air mixture under the assumption of the Lewis number L(e) = 1. Global properties and the internal structure of the flame were analyzed in an earlier paper, which showed that this system represents turbulent combustion in the thin reaction zone regime with the average local flame speed equal to its laminar value, S(L). This paper shows that: (1) Flamelets inside the flame brush have a complex internal structure, in which the isosurfaces of higher fuel mass fractions are folded on progressively smaller scales. (2) Global properties of the turbulent flame are best represented by the structure of the region of peak reaction rate, which defines the flame surface. (3) The observed increase of S(T) relative to S(L) exceeds the corresponding increase of the flame surface area, A(T), relative to the surface area of the planar laminar flame, on average, by 30% and occasionally by as much as 50% in the course of system evolution. This exaggerrated response of S(T) shows that Damkohler's paradigm breaks down for sufficiently high-intensity turbulence, namely at Karlovitz numbers Ka ~ 20, even in the flows characterized by L(e) = 1. (4) The breakdown is the result of tight flame packing by turbulence, which causes frequent flame collisions and formation of regions of high flame curvature 1/ L, or "cusps," where L is the thermal width of the laminar flame.
