Download or read book Spark Ignited Turbulent Flame Kernel Growth Annual Report January December 1992 written by and published by . This book was released on 1994 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cyclic combustion variations in spark-ignition engines limit the use of dilute charge strategies for achieving low NO(subscript x) emissions and improved fuel economy. Results from an experimental study of the effect of incomplete fuel-air mixing (ifam) on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of ifam was evaluated in terms of the flame kernel growth rate, cyclic variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to ifam cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of ifam. Ifam was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994-12 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1995 with total page 1686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book Turbulent Premixed Flame Kernel Growth During The Early Stages Using Direct Numerical Simulation written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis Direct Numerical Simulation (DNS) is used to investigate the development of turbulent premixed flame kernels during the early stages of growth typical of the period following spark ignition. Two distinct aspects of this phase are considered: the interaction of the expanding kernel with a field of decaying turbulence, and the chemical and thermo-diffusive response of the flame for different fresh-gas compositions. In the first part of the study, three-dimensional, repeated simulations with single-step chemistry are used to generate ensemble statistics of global flame growth. The surface-conditioned mean fluid-velocity magnitude is found to vary significantly across different isosurfaces of the reaction progress variable, and this is shown to lead to a bias in the distribution of the Surface Density Function (SDF) around the developing flame. Two-dimensional simulations in an extended domain indicate that this effect translates into a similar directional bias in the Flame Surface Density (FSD) at later stages in the kernel development. Properties of the fresh gas turbulence decay are assessed from an independent, non-reacting simulation database. In the second part of this study, two-dimensional simulations with a detailed 68-step reaction mechanism are used to investigate the thermo-diffusive response of pure methane-air, and hydrogen-enriched methane-air flames. The changes in local and global behaviour due to the different laminar flame characteristics, and the response of the flames to strain and curvature are examined at different equivalence ratios and turbulence intensities. Mechanisms leading to flame quenching are discussed and the effect of mean flame curvature is assessed through comparison with an equivalent planar flame. The effects of hydrogen addition are found to be particularly pronounced in flame kernels due to the higher positive stretch rates and reduced thermo-diffusive stability of hydrogen-enriched flames.
Download or read book Combustion in Turbulent Jets and Buoyant Flames written by and published by . This book was released on 1992 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of a Spark Ignition Flame Kernel Interacting with a Laminar Vortex Toroid written by Yin Xiong and published by . This book was released on 2001 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: flame kernel, turbulent combustion, vortex, Lewis number.
Download or read book A Modern Approach to Regression with R written by Simon Sheather and published by Springer Science & Business Media. This book was released on 2009-02-27 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on tools and techniques for building regression models using real-world data and assessing their validity. A key theme throughout the book is that it makes sense to base inferences or conclusions only on valid models. Plots are shown to be an important tool for both building regression models and assessing their validity. We shall see that deciding what to plot and how each plot should be interpreted will be a major challenge. In order to overcome this challenge we shall need to understand the mathematical properties of the fitted regression models and associated diagnostic procedures. As such this will be an area of focus throughout the book. In particular, we shall carefully study the properties of resi- als in order to understand when patterns in residual plots provide direct information about model misspecification and when they do not. The regression output and plots that appear throughout the book have been gen- ated using R. The output from R that appears in this book has been edited in minor ways. On the book web site you will find the R code used in each example in the text.
Download or read book Automotive Spark Ignited Direct Injection Gasoline Engines written by F. Zhao and published by Elsevier. This book was released on 2000-02-08 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: The process of fuel injection, spray atomization and vaporization, charge cooling, mixture preparation and the control of in-cylinder air motion are all being actively researched and this work is reviewed in detail and analyzed. The new technologies such as high-pressure, common-rail, gasoline injection systems and swirl-atomizing gasoline fuel injections are discussed in detail, as these technologies, along with computer control capabilities, have enabled the current new examination of an old objective; the direct-injection, stratified-charge (DISC), gasoline engine. The prior work on DISC engines that is relevant to current GDI engine development is also reviewed and discussed. The fuel economy and emission data for actual engine configurations have been obtained and assembled for all of the available GDI literature, and are reviewed and discussed in detail. The types of GDI engines are arranged in four classifications of decreasing complexity, and the advantages and disadvantages of each class are noted and explained. Emphasis is placed upon consensus trends and conclusions that are evident when taken as a whole; thus the GDI researcher is informed regarding the degree to which engine volumetric efficiency and compression ratio can be increased under optimized conditions, and as to the extent to which unburned hydrocarbon (UBHC), NOx and particulate emissions can be minimized for specific combustion strategies. The critical area of GDI fuel injector deposits and the associated effect on spray geometry and engine performance degradation are reviewed, and important system guidelines for minimizing deposition rates and deposit effects are presented. The capabilities and limitations of emission control techniques and after treatment hardware are reviewed in depth, and a compilation and discussion of areas of consensus on attaining European, Japanese and North American emission standards presented. All known research, prototype and production GDI engines worldwide are reviewed as to performance, emissions and fuel economy advantages, and for areas requiring further development. The engine schematics, control diagrams and specifications are compiled, and the emission control strategies are illustrated and discussed. The influence of lean-NOx catalysts on the development of late-injection, stratified-charge GDI engines is reviewed, and the relative merits of lean-burn, homogeneous, direct-injection engines as an option requiring less control complexity are analyzed.
Download or read book Ignition Systems for Gasoline Engines written by Michael Günther and published by Springer. This book was released on 2016-11-18 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume includes selected and reviewed papers from the 3rd Conference on Ignition Systems for Gasoline Engines in Berlin in November 2016. Experts from industry and universities discuss in their papers the challenges to ignition systems in providing reliable, precise ignition in the light of a wide spread in mixture quality, high exhaust gas recirculation rates and high cylinder pressures. Classic spark plug ignition as well as alternative ignition systems are assessed, the ignition system being one of the key technologies to further optimizing the gasoline engine.
Download or read book Combustion Flames and Explosions of Gases written by Bernard Lewis and published by Academic Press. This book was released on 2013-10-22 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion, Flames, and Explosions of Gases, Second Edition focuses on the processes, methodologies, and reactions involved in combustion phenomena. The publication first offers information on theoretical foundations, reaction between hydrogen and oxygen, and reaction between carbon monoxide and oxygen. Discussions focus on the fundamentals of reaction kinetics, elementary and complex reactions in gases, thermal reaction, and combined hydrogen-carbon monoxide-oxygen reaction. The text then elaborates on the reaction between hydrocarbons and oxygen and combustion waves in laminar flow. The manuscript tackles combustion waves in turbulent flow and air entrainment and burning of jets of fuel gases. Topics include effect of turbulence spectrum and turbulent wrinkling on combustion wave propagation; ignition of high-velocity streams by hot solid bodies; burners with primary air entrainment; and description of jet flames. The book then takes a look at detonation waves in gases; emission spectra, ionization, and electric-field effects in flames; and methods of flame photography and pressure recording. The publication is a valuable reference for readers interested in combustion phenomena.
Download or read book Inventing the Future written by Nick Srnicek and published by Verso Books. This book was released on 2015-11-17 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This major new manifesto offers a “clear and compelling vision of a postcapitalist society” and shows how left-wing politics can be rebuilt for the 21st century (Mark Fisher, author of Capitalist Realism) Neoliberalism isn’t working. Austerity is forcing millions into poverty and many more into precarious work, while the left remains trapped in stagnant political practices that offer no respite. Inventing the Future is a bold new manifesto for life after capitalism. Against the confused understanding of our high-tech world by both the right and the left, this book claims that the emancipatory and future-oriented possibilities of our society can be reclaimed. Instead of running from a complex future, Nick Srnicek and Alex Williams demand a postcapitalist economy capable of advancing standards, liberating humanity from work and developing technologies that expand our freedoms. This new edition includes a new chapter where they respond to their various critics.
Download or read book Engines written by John L. Lumley and published by Cambridge University Press. This book was released on 1999-06-28 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Innovative text focusing on engine design and fluid dynamics, with numerous illustrations and a web-based software tool.
Download or read book Good Strategy Bad Strategy written by Richard Rumelt and published by Currency. This book was released on 2011-07-19 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good Strategy/Bad Strategy clarifies the muddled thinking underlying too many strategies and provides a clear way to create and implement a powerful action-oriented strategy for the real world. Developing and implementing a strategy is the central task of a leader. A good strategy is a specific and coherent response to—and approach for—overcoming the obstacles to progress. A good strategy works by harnessing and applying power where it will have the greatest effect. Yet, Rumelt shows that there has been a growing and unfortunate tendency to equate Mom-and-apple-pie values, fluffy packages of buzzwords, motivational slogans, and financial goals with “strategy.” In Good Strategy/Bad Strategy, he debunks these elements of “bad strategy” and awakens an understanding of the power of a “good strategy.” He introduces nine sources of power—ranging from using leverage to effectively focusing on growth—that are eye-opening yet pragmatic tools that can easily be put to work on Monday morning, and uses fascinating examples from business, nonprofit, and military affairs to bring its original and pragmatic ideas to life. The detailed examples range from Apple to General Motors, from the two Iraq wars to Afghanistan, from a small local market to Wal-Mart, from Nvidia to Silicon Graphics, from the Getty Trust to the Los Angeles Unified School District, from Cisco Systems to Paccar, and from Global Crossing to the 2007–08 financial crisis. Reflecting an astonishing grasp and integration of economics, finance, technology, history, and the brilliance and foibles of the human character, Good Strategy/Bad Strategy stems from Rumelt’s decades of digging beyond the superficial to address hard questions with honesty and integrity.
Download or read book The Last Utopia written by Samuel Moyn and published by Harvard University Press. This book was released on 2012-03-05 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human rights offer a vision of international justice that today’s idealistic millions hold dear. Yet the very concept on which the movement is based became familiar only a few decades ago when it profoundly reshaped our hopes for an improved humanity. In this pioneering book, Samuel Moyn elevates that extraordinary transformation to center stage and asks what it reveals about the ideal’s troubled present and uncertain future. For some, human rights stretch back to the dawn of Western civilization, the age of the American and French Revolutions, or the post–World War II moment when the Universal Declaration of Human Rights was framed. Revisiting these episodes in a dramatic tour of humanity’s moral history, The Last Utopia shows that it was in the decade after 1968 that human rights began to make sense to broad communities of people as the proper cause of justice. Across eastern and western Europe, as well as throughout the United States and Latin America, human rights crystallized in a few short years as social activism and political rhetoric moved it from the hallways of the United Nations to the global forefront. It was on the ruins of earlier political utopias, Moyn argues, that human rights achieved contemporary prominence. The morality of individual rights substituted for the soiled political dreams of revolutionary communism and nationalism as international law became an alternative to popular struggle and bloody violence. But as the ideal of human rights enters into rival political agendas, it requires more vigilance and scrutiny than when it became the watchword of our hopes.
Download or read book MILD Combustion Modelling Challenges Experimental Configurations and Diagnostic Tools written by Alessandro Parente and published by Frontiers Media SA. This book was released on 2021-11-26 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combustion Theory written by Forman A. Williams and published by CRC Press. This book was released on 2018-03-05 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion Theory delves deeper into the science of combustion than most other texts and gives insight into combustions from a molecular and a continuum point of view. The book presents derivations of the basic equations of combustion theory and contains appendices on the background of subjects of thermodynamics, chemical kinetics, fluid dynamics, and transport processes. Diffusion flames, reactions in flows with negligible transport and the theory of pre-mixed flames are treated, as are detonation phenomena, the combustion of solid propellents, and ignition, extinction, and flamibility pehnomena.
