Download or read book Radical Concentration and Temperature Measurements in Sooting Flames by Cavity Ring down Spectroscopy and Laser induced Fluorescence written by Yuxuan Hu and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sooting laminar flames at atmospheric pressure present a very complex chemical environment with numerous sources of interference for optical measurement techniques. Absolute concentration profiles of 1CH2 and HCO have been measured under a range of flame conditions in a sooting laminar premixed C2H4-air flat-flame by Cavity-Ring Down Spectroscopy performed at wavelengths in the range 615 to 625 nm. Also, concentration profiles of the OH radical have been detected via the band of A2 ∑(v' = 0) ← X2 ∏(v'' = 0) system by Laser-Induced Fluorescence and quantitatively calibrated by Cavity-Ring Down Spectroscopy. In situ measurements of these radicals in sooting flames have hitherto been lacking and are essential for validation of chemical kinetic models of aromatic hydrocarbon and soot formation in flames. The experimental results are compared to simulated concentration profiles generated using the Appel-Bockhorn-Frenklach mechanism. Temperature profiles obtained using OH LIF thermometry are used in interpreting the CRDS data and as input for flame simulation. Additionally, weak broadband absorption is observed by CRDS in the region between the reaction zone and the onset of soot formation; this may be attributable to low concentrations of large aromatic species.
Download or read book Cavity Ring Down Spectroscopy written by Giel Berden and published by John Wiley & Sons. This book was released on 2009-08-11 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cavity Ring-Down Spectroscopy: Techniques and Applications provides a practical overview of this valuable analytical tool, explaining the fundamental concepts and experimental methods, and illustrating important applications. Designed as both an introductory text and a reference source, this book is relevant for scientists unfamiliar with CRDS who are interested in using the technique in their research, as well as experienced users.
Download or read book Applied Combustion Diagnostics written by KoHse-HoingHaus and published by Taylor & Francis US. This book was released on 2002-04-26 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt: The editors have assembled a world-class group of contributors who address the questions the combustion diagnostic community faces. They are chemists who identify the species to be measured and the interfering substances that may be present; physicists, who push the limits of laser spectroscopy and laser devices and who conceive suitable measurement schemes; and engineers, who know combustion systems and processes. This book assists in providing guidance for the planning of combustion experiments, in judging research strategies and in conceiving new ideas for combustion research. It provides a snapshot of the available diagnostic methods and thier typical applications from the perspective of leading experts in the field.
Download or read book Combustion Phenomena written by Jozef Jarosinski and published by CRC Press. This book was released on 2009-02-12 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensively using experimental and numerical illustrations, CombustionPhenomena: Selected Mechanisms of Flame Formation, Propagation, and Extinction provides a comprehensive survey of the fundamental processes of flame formation, propagation, and extinction. Taking you through the stages of combustion, leading experts visually display, mathematically explain, and clearly theorize on important physical topics of combustion. After a historical introduction to the field, they discuss combustion chemistry, flammability limits, and spark ignition. They also study counterflow twin-flame configuration, flame in a vortex core, the propagation characteristics of edge flames, instabilities, and tulip flames. In addition, the book describes flame extinction in narrow channels, global quenching of premixed flames by turbulence, counterflow premixed flame extinction limits, the interaction of flames with fluids in rotating vessels, and turbulent flames. The final chapter explores diffusion flames as well as combustion in spark- and compression-ignition engines. It also examines the transition from deflagration to detonation, along with the detonation wave structure. With downloadable resources of images that beautifully illustrate a range of combustion phenomena, this book facilitates a practical understanding of the processes occurring in the conception, spread, and extinguishment of a flame. It will help you on your way to finding solutions to real issues encountered in transportation, power generation, industrial processes, chemical engineering, and fire and explosion hazards.
Download or read book Absolute CH Radical Concentrations in Rich Low pressure Methane oxygen argon Flames Via Cavity Ringdown Spectroscopy of the A Transition written by and published by . This book was released on 1999 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: We measure cavity ringdown spectra of the A2?-X2II transition of the methylidyne (CH) radical in a series of rich low-pressure methane-oxygen-argon flames and demonstrate that the technique is sensitive, quantitative, and straightforward in its implementation and interpretation. As a line-of-sight technique, it complements imaging techniques, such as planar laser-induced fluorescence. Our results generally agree with chemical kinetic models for methane oxidation that have appeared in the literature, but suggest some refinements are necessary. Additional examination of the CH + O2 reaction rate as a function of temperature is advised. Our results are consistent with those of Derzy et al. using the C2?-X2II transition for stoichiometric, low-pressure flames which include nitrogen. Our results for rich flames, as with earlier experiments for singlet methylene, suggest that flame chemical kinetic models need to be adjusted to account for flame chemistry for stoichiometries richer than? = 1.5.
Download or read book Springer Handbook of Experimental Fluid Mechanics written by Cameron Tropea and published by Springer Science & Business Media. This book was released on 2007-10-09 with total page 1570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accompanying DVD-ROM contains ... "all chapters of the Springer Handbook."--Page 3 of cover.
Download or read book Investigation of Premixed Sooting Flames by Combined Laser Induced Incandescence and Laser Induced Fluorescence written by Jaclyn Dunn and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study applies the techniques of laser induced incandescence (LII) and laser induced fluorescence (LIF) to investigate laminar sooting flames of premixed ethylene air. The approach involves using three different excitation wavelengths, together with temporally and spectrally resolved detection, generating a rich dataset concerning the formation of soot and polycyclic aromatic hydrocarbons (PAHs). Both prompt and delayed detection are used to perform LII when exciting with short wavelengths, both with issues involved. Delayed detection gives an underestimation of soot volume fraction at low heights in the flame, as a result of particle size effects. Prompt detection gives overestimation of soot volume fraction due to fluorescence in the measurement volume. It is shown that care must be taken with either method and through evaluation of the associated errors this study shows delayed detection provides a more accurate measure of soot volume fraction. The ability to obtain the fluorescence signals over a range of heights above burner and stoichiometries is demonstrated. The approach relies on heating the soot particles equivalently with three excitation wavelengths so the LII contribution to the signals can be subtracted, leaving only fluorescence. Fluorescence profiles obtained show similar features to those seen in the literature for invasive measurements, including a reduction in the fluorescence signal generated by 283 nm excitation at intermediate heights above the burner surface followed by a re-increase. Although the data do not allow species-selective measurements of PAHs, these in-situ measurements allow inferences to be drawn about changing concentration of different size classes of these precursors to soot formation. Finally the method of obtaining subtracting the LII contribution to signals was used to obtain fluorescence spectra both for 283 nm and 532 nm excitation. This showed the possibility that fluorescence can yield useful information that it is otherwise impossible to obtain in-situ under sooting conditions.
Download or read book The Spectroscopy of Flames written by Alfred Gordon Gaydon and published by Chapman & Hall. This book was released on 1974 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Instantaneous Temperature Imaging in Sooty Flames written by Qing N. Chan and published by . This book was released on 2011 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation reports on the single-shot temperature imaging in sooty flames, based on the development of two-line atomic fluorescence (TLAF), with neutral Indium atom as seeded thermometry species. The TLAF technique in the linear excitation regime has previously been demonstrated to be feasible in sooty environments but single-shot imaging, which requires a higher signal-to-noise ratio (SNR), has been elusive. The previous TLAF theory has been extended from the linear excitation into the nonlinear excitation fluence regime. Nonlinear regime two-line atomic fluorescence (NTLAF) provides superior signal, and improves single-shot precision from ~250 K for the linear TLAF to ~100 K for the NTLAF. The NTLAF technique is shown to resolve the temperature profiles across a range of equivalence ratios for natural gas, hydrogen, and ethylene laminar premixed flames, with deviation from radiation-corrected thermocouple measurements not exceeding 100 K, and typically ~30 K. Measurements in lightly sooty flames demonstrate good capacity of the NTLAF technique to exclude interferences that hamper most two-dimensional laser-based thermometry techniques. The developed technique has been further assessed in a laminar nonpremixed flame. The results show the expediency of the technique in the study of the reaction zone, and reveal interesting findings about the Indium formation process. The temperature profile across the reaction zone shows good agreement with laminar flame calculations. Indium fluorescence is observed to be strongest at the flame front, where the temperature exceeds 1000 K. Indium has been typically seeded into flame as Indium Chloride dissolved in distilled water. The feasibility to improve on the signal quality of the developed technique, through the substitution of distilled water with an organic solvent (namely acetone, isopropanol, methanol, and ethanol) as the seeding solution, has been examined. Acetone and methanol are shown to enhance the fluorescence signal intensity the most (approximately threefold to fivefold at stoichiometric flame condition) when used. Acetone and methanol are also shown to improve the fluorescence emission across a range of equivalence ratios, most significantly in the rich combustion region, as well as a twofold enhancement in the SNR. The use of acetone or methanol, has the potential to reduce the precisoin of the measurements down to ~60 K. The use of the NTLAF technique for measurements in flames with high soot loadings was assessed. In particular, the interferences from soot or its precursors on the fluorescence measurements have been evaluated. The findings indicate that interferences, such as spurious scattering and laser-induced incandescence (LII), from soot are not significant. However, interferences from soot precursors, predominantly condensed species (CS) and perhaps polycyclic aromatic hydrocarbons (PAH), are substantial. Potential detection schemes to correct or circumvent these interferences have been identified. The technical feasibility of the NTLAF technique to be used concurrently with the LII technique to provide simultaneous single-shot imaging of temperature and soot concentration has been demonstrated. The joint NTLAF-LII method has been applied to laminar premixed and nonpremixed flames, as well as a wrinkled nonpremixed flame. No significant interference of the two measurement techniques on each other is observed, for the detection and timing schemes employed. The images also reveal that, whilst NTLAF has a limited operating range, this range is sufficient to span all regions with soot. This observation demonstrates the applicability of the joint NTLAF-LII method in assessing the coupled dependency of temperature and soot in flame.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cavity ringdown Spectroscopy written by Kenneth W. Busch and published by . This book was released on 1999 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cavity-ringdown spectroscopy is an emerging method for making high sensitivity absorption measurements with gas-phase samples. This volume, the first devoted to the method, covers the history, theory, and numerous applications. Written by leaders in the field, it is a comprehensive guide to current methods and ongoing research.
Download or read book Cavity Ringdown Spectroscopy of Atmospherically Important Radicals written by Andrei Deev and published by . This book was released on 2005 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applications of Cavity Ring down Spectroscopy in Environmental Physics written by Yangzhuoran Liu and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic Measurement of Flame Temperature written by R. D. Cutting and published by . This book was released on 1974 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pulsed Cavity Ring down Spectroscopy in Combustion Environments written by Rogier Evertsen and published by . This book was released on 2002 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Cavity Ring down Spectroscopy Setup and Validation with Carbon hydrogen Radical Measurements in an Argon and Acetylene Direct Currentb Low pressure Glow Discharge Plasma written by Alexandre Ouimet-Storrs and published by . This book was released on 2006 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Cavity ring-down spectroscopy (CRDS) is a novel, accurate, sensitive and non-intrusive laser-based technique using multiple-paths molecular absorption to measure weak absolute concentrations of atoms or molecules (ppm range or better). In CRDS, a laser pulse is coupled into an optical cavity equipped of highly reflective mirrors mounted at both ends and containing the absorbing medium. The laser pulse experiences numerous round trips inside the cavity thus considerably increasing the absorption path. The decay of the laser pulse intensity leaking out of one of the cavity mirrors is monitored in real-time and the concentration of the species is obtained by fitting a Beer-Lambert's decay to the measured signal. The resulting signal is an exponentially decaying function with a 1/e cavity ring-down (tau), proportional to the absolute concentration of the absorbing species." --
Download or read book Cavity Ringdown Spectroscopy of the Nitrate and Peroxy Radicals written by Kana Takematsu and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
