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 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 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 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 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 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 Advanced Chemistry Solver Development and Computational Diagnostics and Dynamic Adaptive Modeling of Turbulent Combustion written by Chao Xu and published by . This book was released on 2018 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three approaches toward efficient and predictive turbulent combustion modeling are investigated in this dissertation. The first approach focuses on the development of locally reduced chemistry and advanced solvers for efficient time integration of stiff chemical kinetic systems. In particular, a numerical technique using dynamic adaptive chemistry (DAC) with splitting schemes is developed and demonstrated in one-dimensional (1-D) premixed flames. A sparse stiff chemistry solver based on dynamic adaptive hybrid integration (AHI) and sparse matrix techniques (AHI-S), and an iterative uncoupled quasi-steady-state (IU-QSS) method for improved stability of explicit solvers, are further developed and shown to be more computationally efficient than other chemistry solvers in various flame configurations. In the second approach, a computational diagnostic tool, namely the chemical explosive mode analysis (CEMA), is extended to account for the interactions between chemical reactions and transport processes. Different local combustion modes, including the auto-ignition, diffusion-assisted ignition, and extinction modes, are demarcated by projecting the chemical and transport source terms to the chemical explosive mode. A criterion based on the local combustion modes is proposed to distinguish between two premixed flame propagation modes, that is the auto-ignition and diffusion-controlled deflagration waves, respectively. The new criterion is validated in 1-D premixed flames and 2-D homogeneous charge compression ignition (HCCI) systems. CEMA-based diagnostics are then employed to investigate the local structures of strongly turbulent premixed n-dodecane flames, and to understand the propagation modes and stabilization mechanisms of a turbulent lifted dimethyl ether (DME) jet flame, based on direct numerical simulation (DNS) data. The third approach is to construct a dynamic adaptive combustion modeling framework for turbulent flames that involve both premixed and non-premixed features. CEMA is adopted as a flame segmentation tool, and appropriate sub-models are assigned on-the-fly to different flame zones. The proposed modeling framework is tested in a turbulent lifted n-dodecane spray flame using large eddy simulations (LES). The new model is found to predict the ignition delay and lift-off length more accurately compared with the low-cost flamelet models, while the overall computational cost can be substantially reduced compared with the high-cost regime-independent models that incorporate finite rate chemistry.

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 and Modeling of Nitrogen Oxide Formation in Turbulent Premixed Flames written by Philipp Trisjono and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments and Numerical Simulations of Turbulent Combustion of Diluted Sprays written by Bart Merci and published by Springer Science & Business Media. This book was released on 2014-03-27 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reflects the results of the 2nd and 3rd International Workshops on Turbulent Spray Combustion. The focus is on progress in experiments and numerical simulations for two-phase flows, with emphasis on spray combustion. Knowledge of the dominant phenomena and their interactions allows development of predictive models and their use in combustor and gas turbine design. Experts and young researchers present the state-of-the-art results, report on the latest developments and exchange ideas in the areas of experiments, modelling and simulation of reactive multiphase flows. The first chapter reflects on flame structure, auto-ignition and atomization with reference to well-characterized burners, to be implemented by modellers with relative ease. The second chapter presents an overview of first simulation results on target test cases, developed at the occasion of the 1st International Workshop on Turbulent Spray Combustion. In the third chapter, evaporation rate modelling aspects are covered, while the fourth chapter deals with evaporation effects in the context of flamelet models. In chapter five, LES simulation results are discussed for variable fuel and mass loading. The final chapter discusses PDF modelling of turbulent spray combustion. In short, the contributions in this book are highly valuable for the research community in this field, providing in-depth insight into some of the many aspects of dilute turbulent spray combustion.

Download or read book Direct Numerical Simulation of Extinction and Reignition in a Nonpremixed Turbulent Ethylene Jet Flame written by and published by . This book was released on 2007 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Numerical Simulation of Non premixed Flame Extinction Phenomena written by Praveen Narayanan and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mixing Chemical Reactions and Combustion in High Speed Turbulent Flows written by and published by . This book was released on 2004 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research conducted under the sponsorship of this grant focused on fundamental investigations of mixing, chemical-reaction and combustion processes; in turbulent, subsonic, and supersonic flows. Research on hydrocarbon-combustion was on methane and ethane flames. Flame extinction strain-rate measurements, flame speed, and detailed experiment-simulation comparisons indicate difficulties in modeling of fuel-rich flames. Direct Numerical Simulations (DNS) of axisymmetric unsteady flows in both cold and hot impinging jets were also performed. The research included work on high-speed internal flows of interest to scramjet mixing and combustion, aimed at flow-control and flameholding issues. DNS and Large Eddy Simulations (LES) of Rayleigh-Taylor instability flows studied Reynolds number effects on mixing in this important flow. Advances in high-performance digital-imaging systems were transferred to the laboratory environment enabling measurements unachievable by other means.

Download or read book Micro mixing in Turbulent Premixed Flames written by Michael Joseph Kuron and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate turbulent combustion models are key to establishing a predictive capability for combustion simulations at the device level. The transported probability density function (TPDF) methods provide an elegant solution to the challenge of closing the mean chemical source term in turbulent combustion modelling as it appears in closed form in the TPDF equations and thus the turbulence-chemistry interaction can be solved for without aggressive assumptions. This is crucial for predicting low temperature combustion, turbulent flames with the presence of local limit phenomena, and pollutant emissions. Despite some reported success in the literature, challenges remain when applying the TPDF method to turbulent premixed flames as the molecular mixing or micro-mixing term is unclosed, the modeling of which is considered to be a primary challenge. The objective of this dissertation is to evaluate the application of existing mixing models to turbulent premixed flames and to create high-fidelity scalar dissipation rate models to predict turbulent premixed combustion. In this dissertation, direct numerical simulation (DNS) data is utilized at each stage to obtain statistical information on the scalar dissipation rate and mixing timescales for turbulent premixed flames. In the first step, DNS of a temporally evolving premixed flame is used as a numerical test bed to evaluate commonly used mixing models in the context of turbulent premixed flames. This study demonstrates that the Euclidean Minimum Spanning Tree (EMST) model is capable of predicting the behavior of a turbulent premixed flame assuming that an accurate model for the scalar mixing rate, and thus the scalar dissipation rate, can be provided. In the next stage of the dissertation, chemical explosive mode analysis (CEMA) and DNS data with realistic chemistry are used to identify physiochemical processes that govern the conditional scalar dissipation rate behavior in a turbulent premixed flame and evaluate mixing timescales. A local Damköhler number is defined based on the CEMA results and four flame zones are identified. It is found that large fluctuations in the instantaneous scalar dissipation rate occur in the explosive zone, where the local Damköhler number is much larger than unity. Two mechanisms are identified to account for the large degree of scatter in the explosive zone: flame-flame interactions and flame-assisted ignition. A model for the Favre-averaged scalar dissipation rate is subsequently developed based on the insight gleaned from the DNS analysis. The new hybrid mixing rate model is developed to account for the scalar mixing rate behavior in both the turbulent mixing limit and the flamelet limit. The new hybrid timescale model is notable for its treatment of the flamelet mixing limit, an area where existing timescale models do not properly recover the correct mixing behavior. Comparisons to the DNS are performed with both a priori and a postereori comparisons, with the new hybrid model performing exceptionally well. Finally, in the last stage of the dissertation, a transport equation for the conditional scalar dissipation rate of a reactive scalar is derived and an order of magnitude analysis is performed to evaluate the importance of each term in the governing equation. The order of magnitude analysis is verified with the DNS data of turbulent premixed flames and an equation of the leading order terms is identified. Models for the unclosed terms in the leading order equation are developed and evaluated with DNS data, and a modelled equation for the conditional scalar dissipation rate is proposed. The modelled equation is then compared to the DNS data, and excellent agreement between the new model and the DNS is observed.

Download or read book Direct Numerical Simulation of Turbulent H2 02 Combustion Using Reduced Chemistry written by C. J. Montgomery 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 Direct Numerical Simulation of Premixed Turbulent Combustion written by Theodoor Cornelis Treurniet and published by . This book was released on 2002 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: