Download or read book Effects of Swirl on the Stability and Turbulent Structure of Jet Diffusion Flames written by F. Takahashi and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Swirling Flows and Flames written by Toufik Boushaki and published by BoD – Books on Demand. This book was released on 2019-06-26 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Swirl flows are used in a wide range of industrial applications. In non-reacting cases, examples of applications include vortex amplifiers and reactors, heat exchangers, jet pumps, and cyclone separators. In reacting cases, swirlers are widely used in combustion systems, such as gas turbines, industrial furnaces, boilers, gasoline and diesel engines, and many other practical heating devices. Effects of using swirl on flow and combustion are significant and varied, and concern, for example, aerodynamics, mixing, flame stability, intensity of combustion, and pollutant emissions. The purpose of this book is to present recent research efforts to understand and characterize swirling flows of different types and in different applications. These include gaseous, liquid, and solid fuels in order to enhance combustion systems and their energy efficiency. Swirl flows are very complex and the studies proposed in this project are based on different means, including theoretical calculations, numerical modeling, and experimental measurements.
Download or read book Turbulent Structure and Emissions of Strongly pulsed Jet Diffusion Flames written by Mathieu Fregeau and published by . This book was released on 2007 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Combustor Physics written by Tim C. Lieuwen and published by Cambridge University Press. This book was released on 2012-08-27 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developing clean, sustainable energy systems is a pre-eminent issue of our time. Most projections indicate that combustion-based energy conversion systems will continue to be the predominant approach for the majority of our energy usage. Unsteady combustor issues present the key challenge associated with the development of clean, high-efficiency combustion systems such as those used for power generation, heating or propulsion applications. This comprehensive study is unique, treating the subject in a systematic manner. Although this book focuses on unsteady combusting flows, it places particular emphasis on the system dynamics that occur at the intersection of the combustion, fluid mechanics and acoustic disciplines. Individuals with a background in fluid mechanics and combustion will find this book to be an incomparable study that synthesises these fields into a coherent understanding of the intrinsically unsteady processes in combustors.
Download or read book Coarse Grained Simulation and Turbulent Mixing written by Fenando F. Grinstein and published by Cambridge University Press. This book was released on 2016-06-30 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews our current understanding of the subject. For graduate students and researchers in computational fluid dynamics and turbulence.
Download or read book Effect of Nozzle Geometry on the Stability of a Turbulent Jet Flame with and Without Swirling Co flow written by Christopher Omokhowa Iyogun and published by . This book was released on 2009 with total page 406 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 Opposed Jet Turbulent Diffusion Flames written by Lawrence Talbot and published by . This book was released on 1990 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combustion Stability Limits of Coflowing Turbulent Jet Diffusion Flames written by Werner J.A. Dahm and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flame Structure and Emissions of Strongly pulsed Turbulent Diffusion Flames with Swirl written by Ying-Hao Liao and published by . This book was released on 2012 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work studies the turbulent flame structure, the reaction-zone structure and the exhaust emissions of strongly-pulsed, non-premixed flames with co-flow swirl. The fuel injection is controlled by strongly-pulsing the fuel flow by a fast-response solenoid valve such that the fuel flow is completely shut off between pulses. This control strategy allows the fuel injection to be controlled over a wide range of operating conditions, allowing the flame structure to range from isolated fully-modulated puffs to interacting puffs to steady flames. The swirl level is controlled by varying the ratio of the volumetric flow rate of the tangential air to that of the axial air. For strongly-pulsed flames, both with and without swirl, the flame geometry is strongly impacted by the injection time. Flames appear to exhibit compact, puff-like structures for short injection times, while elongated flames, similar in behaviors to steady flames, occur for long injection times. The flames with swirl are found to be shorter for the same fuel injection conditions. The separation/interaction level between flame puffs in these flames is essentially governed by the jet-off time. The separation between flame puffs decreases as swirl is imposed, consistent with the decrease in flame puff celerity due to swirl. The decreased flame length and flame puff celerity are consistent with an increased rate of air entrainment due to swirl. The highest levels of CO emissions are generally found for compact, isolated flame puffs, consistent with the rapid quenching due to rapid dilution with excess air. The imposition of swirl generally results in a decrease in CO levels, suggesting more rapid and complete fuel/air mixing by imposing swirl in the co-flow stream. The levels of NO emissions for most cases are generally below the steady-flame value. The NO levels become comparable to the steady-flame value for sufficiently short jet-off time. The swirled co-flow air can, in some cases, increase the NO emissions. The elevated NO emissions are due to a longer combustion residence time due to the flow recirculation within the swirl-induced recirculation zone. The reaction zone structure, based on OH planar laser-induced fluorescence (PLIF) is broadly consistent with the observation of luminous flame structure for these types of flames. In many cases, the reaction zone exhibits discontinuities at the instantaneous flame tip in the early period of fuel injection. These discontinuities in the reaction zone likely result from the non-ignition of injected fuel, due to a relatively slower reaction rate in comparison with the mixing rate. The discontinuity in the OH zone is generally seen to diminish with increased swirl level. Statistics generated from the OH PLIF signals show that the reaction zone area generally increases with increased swirl level, consistent with a broader and more convoluted OH-zone structure for flames with swirl. The reaction zone area for swirled flames generally exhibits a higher degree of fluctuation, suggesting a relatively stronger impact of flow turbulence on the flame structure for flames with swirl.
Download or read book AIAA 28th Aerospace Sciences Meeting written by and published by . This book was released on 1990 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals and Technology of Combustion written by F El-Mahallawy and published by Elsevier. This book was released on 2002-07-10 with total page 863 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals and Technology of Combustion contains brief descriptions of combustion fundamental processes, followed by an extensive survey of the combustion research technology. It also includes mathematical combustion modeling of the processes covering mainly premixed and diffusion flames, where many chemical and physical processes compete in complex ways, for both laminar and turbulent flows. The combustion chemistry models that validate experimental data for different fuels are sufficiently accurate to allow confident predictions of the flame characteristics. This illustrates a unique bridge between combustion fundamentals and combustion technology, which provides a valuable technical reference for many engineers and scientists. Moreover, the book gives the reader sufficient background of basic engineering sciences such as chemistry, thermodynamics, heat transfer and fluid mechanics. The combustion research and mathematical models fit between small-scale laboratory burner flames, and large-scale industrial boilers, furnaces and combustion chambers. The materials have been collected from previous relevant research and some selected papers of the authors and co-workers, which have been presented mainly in different refereed journals, international conferences and symposia, thus providing a comprehensive collection. Furthermore, the book includes some of the many recent general correlations for the characteristics of laminar, turbulent, premixed and diffusion flames in an easily usable form. The authors believe that further progress in optimizing combustion performance and reducing polluting emissions can only be treated through understanding of combustion chemistry.
Download or read book Swirl Flows written by Ashwani K. Gupta and published by Routledge. This book was released on 1984 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Swirl on Turbulent Gaseous Jet Diffusion Flames written by Kevin Hugh Bassindale and published by . This book was released on 1971 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASME Technical Papers written by and published by . This book was released on 1995 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Numerical Simulations of Vortex Breakdown in Swirling Jets and Diffusion Flames written by Benjamin Keeton and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In combustion applications such as gas turbines, swirling jets are used to generate a vortex breakdown recirculation region that serves as a non-invasive flame stabilizer. The present work performs direct numerical simulations to study the effects of vortex breakdown on the structure and stabilization of laminar low-Mach-number gaseous diffusion flames. Vortex breakdown transitions are first studied for heated/cooled variable-density, non-reacting jets in solid body rotation issuing into an unconfined ambient atmosphere. For increasing values of the swirl number S, two vortex breakdown modes are observed, the bubble and the cone, and the associated transitions S[superscript]*[subscript]B and S[superscript]*[subscript]C are determined for different values of the ambient-to-jet temperature ratio [lambda]. Both axisymmetric and three-dimensional simulations show decreasing values of S[superscript]*[subscript]B with increasing lambda, while critical swirl numbers for the transition to the cone S[superscript]*[subscript]C, remain relatively constant for a fixed effective Reynolds number. The first study is then extended to evaluate the same transitions in axisymmetric methane-air flames in the Burke-Schumann limit of infinitely fast chemistry. Transitions S[superscript]*[subscript]B are relatively unaffected by fuel-feed dilution, and result in jet-like flames. For moderate values of dilution, further increase in S to S[superscript]*[subscript]C generates a steady conical breakdown, with the flame sheet again passing around the recirculating fuel and products. Extreme dilution, on the other hand, generates an enlarged cone that recirculates the ambient air, stabilizing the flame near the jet inlet. Effects of bubble vortex breakdown are then explored for finite-rate chemistry flames in an axisymmetric concentric swirling jet configuration, for which a central fuel jet is surrounded by a swirling co-annular stream of air. Liftoff and blow-off are analyzed by systematically varying the two relevant parameters, the swirl number S and the Damköhler number, D[subscript]N. For sufficiently low values of D[subscript]N, and large values of S, flames lift off the injector, and thermal expansion at the base of the triple flame redirects the flow radially inward, promoting the formation of a small recirculation zone. Axisymmetric and three-dimensional simulations of the isothermal flow are used to analyze the mechanism for the onset of the bubble, and identify post-breakdown flow structure for larger values of the Reynolds number.
