Stratified combustion, combustion of fuel/air mixtures with temperature and/or mixture-composition stratification, is present in many combustion-related phenomena and applications such as forest wildfires, mining explosions, vessel ruptures, gas turbines, and reciprocating engines to name a few. A new generation of highly efficient internal combustion (IC) engines capable of satisfying stringent emission requirements, including modern direct-injection gasoline engines and gas turbines with lean premixed pre-vaporized (LPP) combustors, requires more comprehensive understanding and control of stratified combustion. Fundamentally, stratification of temperature or mixture composition affects a wide range of combustion characteristics such as flame speed, flammability, mode of combustion, instability, and others. This dissertation aims to identify, analyze and evaluate fundamental processes in the combustion of stratified mixtures, using theoretical analysis and advanced numerical simulation tools. ASURF-Parallel, a transient numerical solver of compressible reacting flow, is developed on the basis of the original A-SURF and exploited for stratified combustion simulations. A domain-decomposition parallelization scheme using Message Passing Interface (MPI) is developed and implemented in ASURF-Parallel to speed up the otherwise time-consuming numerical simulations. A significant speedup with the speed-up factor up to 10 is achieved on lab-scale servers. Effects of stratification on flame speeds, lean flammability limit, and modes of combustion are numerically investigated and studied. For flame speeds, laminar flame speeds of stratified flames propagating from rich mixtures to lean mixtures are generally faster than those of the corresponding homogeneous flames, primarily due to the preferential diffusion of lighter species and radicals such as H2, H and OH, i.e., the chemical effect. The degree of enhancement in flame speeds can be correlated to the degree of stratification, leading to the development of a transient local stratification level (LSL) model which is able to determine the stratified flame speeds incorporating both chemical effect and memory effect. For lean flammability limits, the extension introduced by stratification is very weak due to reduced overall reactivity and reduced degree of stratification. For modes of combustion, different modes can be realized by specific reactivity gradients, regardless of the sources of such gradients. Pressure waves introduced by ignition in a closed chamber can also lead to different modes of reaction front propagation and end-gas combustion. A transient reactivity gradient method is proposed to identify the onset of detonation.

Fundamentals of Combustion Processes is designed as a textbook for an upper-division undergraduate and graduate level combustion course in mechanical engineering. The authors focus on the fundamental theory of combustion and provide a simplified discussion of basic combustion parameters and processes such as thermodynamics, chemical kinetics, ignition, diffusion and pre-mixed flames. The text includes exploration of applications, example exercises, suggested homework problems and videos of laboratory demonstrations

Combustion is an old technology which presently provides about 90% of our worldwide energy support. The authors include combustion specific topics of chemistry and fluid mechanics while describing tools for the simulation of the combustion process. This revised and updated edition provides a detailed and rigorous treatment of the coupling of chemical reactions and fluid flow.

The book begins with an introduction to the general problems of making measurements in high temperature and a presentation of chemically reacting flow systems. It describes each instrument with the various diagnostic techniques and discusses measurements that have been made in furnaces, flames, and rocket engines. The detailed measurement techniques described in this book cover a wide spectrum of applications in combustion systems, including gas turbine, rocket measurement techniques that were developed in laboratories. Information obtained on detailed temperature, velocity, particle size, and gas concentration distribution is leading to improve understanding of the chemical combustion process and to design imporvements in combustors.

Combustion under sufficiently fuel-lean conditions can have the desirable attributes of high efficiency and low emissions, this being particularly important in light of recent and rapid increases in the cost of fossil fuels and concerns over the links between combustion and global climate change. Lean Combustion is an eminently authoritative, reference work on the latest advances in lean combustion technology and systems. It will offer engineers working on combustion equipment and systems both the fundamentals and the latest developments in more efficient fuel usage and in much-sought-after reductions of undesirable emissions, while still achieving desired power output and performance. This volume brings together research and design of lean combustion systems across the technology spectrum in order to explore the state-of-the-art in lean combustion and its role in meeting current and future demands on combustion systems. Readers will learn about advances in the understanding of ultra lean fuel mixtures and how new types of burners and approaches to managing heat flow can reduce problems often found with lean combustion such as slow, difficult ignition and frequent flame extinction. The book will also offer abundant references and examples of recent real-world applications. - Covers all major recent developments in lean combustion science and technology, with new applications in both traditional combustion schemes as well as such novel uses as highly preheated and hydrogen-fueled systems - Offers techniques for overcoming difficult ignition problems and flame extinction with lean fuel mixtures - Covers new developments in lean combustion using high levels of pre-heat and heat re-circulating burners, as well as the active control of lean combustion instabilities

This book presents the papers from the Internal Combustion Engines: Performance, fuel economy and emissions held in London, UK. This popular international conference from the Institution of Mechanical Engineers provides a forum for IC engine experts looking closely at developments for personal transport applications, though many of the drivers of change apply to light and heavy duty, on and off highway, transport and other sectors. These are exciting times to be working in the IC engine field. With the move towards downsizing, advances in FIE and alternative fuels, new engine architectures and the introduction of Euro 6 in 2014, there are plenty of challenges. The aim remains to reduce both CO2 emissions and the dependence on oil-derivate fossil fuels whilst meeting the future, more stringent constraints on gaseous and particulate material emissions as set by EU, North American and Japanese regulations. How will technology developments enhance performance and shape the next generation of designs? The book introduces compression and internal combustion engines' applications, followed by chapters on the challenges faced by alternative fuels and fuel delivery. The remaining chapters explore current improvements in combustion, pollution prevention strategies and data comparisons. - Presents the latest requirements and challenges for personal transport applications - Gives an insight into the technical advances and research going on in the IC Engines field - Provides the latest developments in compression and spark ignition engines for light and heavy-duty applications, automotive and other markets