Developed through the combination of two preexisting methods - a shock tube acting as an impulse heater and a flame speed measurement from a spherically expanding flame - the shock-tube flame speed method brought significant promise to enable fundamental laminar flame speed measurements at previously inaccessible temperature conditions. Nevertheless, early applications of the method, as originally devised, encountered challenges associated with flame stability and structure that limited its ability to fulfill its full potential. In this dissertation, a series of efforts undertaken to characterize and optimize the shock-tube flame speed method are reported; the newly refined methods are subsequently validated and applied to demonstrate flame speed measurements at extreme unburned-gas temperatures, up to and exceeding 1,000 K, for the first time. After introducing the fundamentals of shock tubes, spherically expanding flames, and their combination in the first-generation shock-tube flame speed method, three investigations extending the original methods are described. First, the development of a technique for performing side-wall emission imaging through a small diagnostic port allowed for the identification of axial flame distortion in shock tube experiments. Then, the side-wall imaging was again leveraged in the development of the [laser-induced] flame image velocimetry ([LI]FIV) technique as a seedless, single-point velocimetry method for combustion environments, which was used in the first systematic investigation of core-gas velocities in the post-reflected-shock environment. Finally, a meta-analysis to identify conditions producing stable flames was performed on a collection of ten groups of experiments performed using variations of the first-generation method. In the resulting binary-classifier model, the unburned-gas ratio of specific heats and the ignition location were found to most strongly affect stability, guiding the optimal selection of an oxygen-argon oxidizer mixture for future experiments and motivating the need for additional experimental flexibility. Inspired by the significant insight gained through the application of side-wall imaging to shock-tube flame experiments, and seeking to realize the flexibility required to perform optimized flame speed experiments, a novel side-wall imaging flame test section (SWIFT) was designed and procured. The SWIFT features first-of-their-kind side-wall windows designed as cemented-doublet cylindrical lenses in order to provide large field-of-view, schlieren-compatible optical access through the curved side walls of the shock tube. Together with an enhanced suite of instrumentation, the implementation of the SWIFT enabled what would become the second-generation of the shock-tube flame speed method through the studies that followed. Making use of the new schlieren capabilities, the effect of the axial position on the stability of flames was reevaluated, both using static experiments to quantify the effect of asymmetric end-wall confinement and through post-reflected-shock experiments performed near 650 K and 1 atm to observe the effect of the post-shock flow field, reaffirming the presence of significant axial distortion at a certain (6.4-cm) axial location. Then, based on the need for a model capable of extracting laminar flame data from experiments exhibiting aspherical flames, an area-averaged formulation of the linear-curvature extrapolation model (the AA-LC model) was derived for use in shock-tube flame experiments. Applied to the static and 650 K experiments at different ignition locations, the model was demonstrated to yield precise and repeatable measurements, even in cases in which flame distortion was observed. The SWIFT, side-wall schlieren, and AA-LC model were finally applied in laminar flame speed measurements of propane, norm-heptane, and iso-octane at highest-ever-reported unburned-gas temperatures, up to and exceeding 1,000 K.

This dissertation focuses on the development of two experimental approaches for the study of low-temperature combustion kinetics in a shock tube: a combined laser absorption spectroscopy-gas chromatography (LAS-GC), fast-sampling speciation diagnostic, and a method for measuring laminar flame speeds in a shock tube at previously unexplored temperature conditions. The combined LAS-GC speciation technique was developed in three stages. First, an endwall sampling system was developed to provide species yield measurements in conventional shock tube experiments. The diagnostic was paired with an in situ ethylene laser absorption diagnostic and used to study ethylene pyrolysis at conditions ranging from 1200-2000 K at 5 atm. A methodology for accurately comparing species-yield sampling results with laser and model results is also presented. In the second stage of GC fast-sampling technique development, the endwall sampling system was used to study low-temperature n-heptane oxidation. Quasi-time-resolved endwall samples were extracted and used to quantify intermediate species present between first- and second-stage n-heptane ignition. Three laser diagnostics were simultaneously employed to measure temperature, carbon dioxide, water, and ethylene. Laser-measured ignition delay times indicate an overestimation of three primary RO2 isomerization reactions in the kinetic model used for comparison. In the third stage of technique development, long test-time shock tube experiments were conducted to allow for three consecutive, 10-ms samples to be extracted from the reacting shock tube gas before the arrival of the expansion fan. This time-resolved, fast-sampling technique was applied to the study of cyclohexene pyrolysis (980-1150 K, 7.3 atm) and ethane pyrolysis (1060-1153 K, 6.9 atm). A time-resolved ethylene laser diagnostic was simultaneously used to provide truly time-resolved, in situ results. A discrepancy between late-time GC and laser/model results was found to be caused by endwall thermal boundary layer growth. In addition to the combined LAS-GC experimental approach, a new shock tube technique was developed for measuring high-temperature (> 500 K) laminar flame speeds. Shock-heated gas mixtures are ignited via laser-induced spark-ignition and high-speed, endwall emission imaging is used to capture flame propagation in time. The technique was validated by measuring stoichiometric methane/air and propane/air flame speeds at 1 atm and unburned gas temperatures below 600 K. Stoichiometric, 1-atm, propane/modified-air flame speeds were then recorded at unburned gas temperatures exceeding 750 K, representing the highest-temperature propane laminar flame speed data available to date. Next, single line-of-sight laser absorption diagnostics were deployed in the flame speed experiments, allowing for the simultaneous measurement of laminar flame speed, temperature, species, and pressure in high-temperature, spherically expanding ethane/air flames (449-537 K, 1 atm). The burned gas, equilibrium temperature and species measurements, as well as the flame speed measurements, show close agreement with model results.

Shock tubes are considered ideal reactors and are used extensively to provide valuable chemical kinetic measurements, such as ignition delay times and in-situ species time-histories. However, due to nonideal affects the combustion of fuel inside shock tubes can become nonhomogeneous, particularly at low temperatures, which complicates the acquired data. In this work, the combustion of practical fuels used by society are investigated with high-speed imaging. First, high-speed images were captured through the end wall of the shock tube for two hydrogen-oxygen systems. The combustion process was found to initiate in two modes, one that is homogeneous across the fluid medium and one that proceeds through a deflagration to detonation channel. In the second part of this work, the shock tube test section was redesigned to promote optical access from the end and side walls of the shock tube test section. Two high-speed cameras were used to capture perpendicular views of the combustion of iso-octane and n-heptane, two primary reference fuels. A homogeneous and nonhomogeneous combustion process were seen for these fuels as well. Using the side view images, the impact of the sporadic ignition process was evaluated on commonly used diagnostics in shock tubes. Based on these results, it is recommended that shock tube diagnostics be confined to the homogeneous ignition modes of fuels. This is found to strongly correlate with the temperature of the combustion process, where high temperatures promote a homogeneous ignition event.

This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2019. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.

The development of new technologies in the fields of photonics, digital systems and computers has resulted in many exciting innovations in high speed photography (HSP) and its commercial, industrial and military applications. This book forms a definitive work on the subject and was written to fill a hitherto uncovered gap in the available literature on this topic. Compiled by a leading team of international experts and written with the cooperation of the Association for High Speed Photography (AHSP) under the Editorship of Sidney F. Ray, this is the most authoritative work on the subject to date. The book forms an introduction to high speed photography, principally for those who wish to investigate its almost limitless potential as a tool for instrumentation, measurement and analysis in both research and development work. It will also interest those who are mainly concerned with standard photographic and digital imaging procedures but need to know more about high speed recording. As a university textbook it is ideally suited to those undertaking postgraduate research, as well as to undergraduates on courses that include film production, biomedical imaging, scientific photography and applied imaging. The material in the book follows progressively from an introduction to and development of HSP, to details of illumination and image capture systems, data extraction and necessary image processing in experimental procedures. Both major and specialist applications of HSP are detailed, including ballistics, the natural world, detonics, the properties of materials and aircraft engineering, combustion processes, motor vehicle safety and holography. A large number of diagrams and photographs illustrate and supplement the text while tables of data provide easy access to numerical information. Will appeal to newcomers as well as professionals in the topic Endorsed by the Association for High Speed Photography Major topics covered in one independent source