Download or read book Soot Morphology in Unsteady Counterflow Diffusion written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the resulting reduction of efficiency, providing an IR source for tracking and targeting, and its harmful effects on human health, soot emission from diesel engines continues to be of interest to the US Army. The broad focus of this three-year project has been to better understand the soot formation processes occurring in diesel engines though experimentation in simple unsteady counterflow diffusion flames. Specifically, we have developed a planar diagnostic technique to measure the morphology (fractal dimension, primary spherule diameter, number if spherules per aggregate, etc) of soot in a plane using optical techniques, measured soot volume fraction in high pressure jet diffusion flames (up to 30 atmospheres), and measured a range of PAR (three different size classes) in an unsteady counterflow diffusion flame.
Download or read book Soot Morphology in Unsteady Counterflow Diffusion Flames written by William Roberts and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Diesel engines consume the majority of the injected fuel in diffusion controlled combustion processes compared to the relatively short initial premixed phase, and diffusion flames have a greater propensity to form soot, particulate matter emission from Diesel engines can considerable. These particles have a much stronger thermal signature compared to gas phase products, water and carbon dioxide, and render Diesel-powered vehicles susceptible to tracking and targeting via IR sensors. This IR signature will decay with time as the particles cool, and this temporal profile is a function of the morphology of the soot. Therefore, it is important to understand, and eventually control, not only the soot volume fraction of the particulate matter, but also its morphology.
Download or read book Effect of Flow Unsteadiness on Soot Morphology written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The morphology of combustion-generated soot is of fundamental interest, but is difficult to measure. A new planar diagnostic technique was developed for morphology measurements in simple laminar flames. Additionally, Polycyclic Aromatic Hydrocarbons, (PAH) the precursors to soot formation, were measured non-intrusively in an unsteady laminar flame to determine the characteristic time scales of their formation. An existing point-wise laser scattering technique to determine soot morphology was extended to a planar technique and applied to a laminar ethylene air co-flow flame. An Nd:YAG laser (532 nm) was used to illuminate the soot particles and the resulting scattered light was collected over a wide range of angles. A low power laser was used to eliminate fluorescence and incandescence interferences. Simultaneous laser induced incandescence measurements were used to determine the soot volume fraction. Six morphological parameters, including primary spherule size and mass fractal dimension, were derived using this new planar measurement technique based on RDG/PFA theory. The results clearly show the soot formation processes, including inception, agglomeration, and oxidization. A two-angle approximate method was also demonstrated and shown to be applicable for instantaneous measurements in unsteady flames. The approximate method can provide limited soot morphology information including primary particle size and number of primary particles per aggregate, when the fractal dimension and distribution are assumed. The approximate method was not suitable over the entire region of this flame because the fractal dimension varies significantly from the assumed value of 1.8, particularly in the soot inception zone. Three different size classes of PAH were measured qualitatively via laser induced fluorescence by detecting fluorescence in different spectral regions. The relative concentrations of these PAH were measured in counterflow diffusion flames subjected to both steady and.
Download or read book The Effects of Unsteady Hydrodynamics on Soot Formation in a Counterflow Diffusion Flame written by Michele Elaine Riggen-DeCroix and published by . This book was released on 1998 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Morphology in a Laminar Co flow Diffusion Flame written by Jidong Xiao and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Evolution of Soot Morphology in Laminar Co Flow Diffusion Flames of the Surrogates for Jet A 1 and a Synthetic Kerosene written by Mohammad Reza Kholghy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Temperature and OH Measurements in a Unsteady Counterflow Diffusion Flame written by William Roberts and published by . This book was released on 1998 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research project was to increase the current level of understanding of the interaction between an unsteady hydrodynamic field and the chemical kinetics in a laminar diffusion flamelet. A steady counterflow diffusion flame burner has been modified to allow periodic oscillations of the input velocity. Laser diagnostics were used to quantitatively measure soot volume fraction in an unsteady propane-air counterflow diffusion flame. The instantaneous strain rate at global flame extinction for a propane-air flame has been measured as a function of steady strain and both amplitude and frequency of the unsteady component Two component LDV was used to measure the velocities allowing determination of the true strain rate. The phase lag between velocity and strain rate was quantified. Low frequency oscillations in the reactant flow rates increased net soot production by as much as 6 times over the steady flame. At low initial strain rates, high frequency oscillations reduce the maximum soot volume fraction by as much as 90% of the steady flame soot concentration. At high initial strain rates, soot production was insensitive to high frequency oscillations.
Download or read book Army Research Office and Air Force Office of Scientific Research 2002 Contractors Meeting in Chemical Propulsion written by David M. Mann and published by . This book was released on 2002 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstracts are given for 6.1 basic research in chemical propulsion sponsored by the Army Research Office and the Air Force Office of Scientific Research.
Download or read book An Experimental Study of Soot Formation and Oxidation in Axisymmetric Counterflow Diffusion Flames written by Keunchul Lee and published by . This book was released on 1991 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Fundamental Study of Soot Formation in Diffusion Flames written by Richard L. Axelbaum and published by . This book was released on 1988 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Morphology of Soot Particles in a Diffusion Flame Using the Discrete Dipole Approximation written by Amar Mahadeviah and published by . This book was released on 1991 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Pressure on Soot Morphology in Laminar Diffusion Flames written by Ben Gigone and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of pressure on soot aggregate morphology in laminar diffusion flames, specifically pertaining to primary soot particle size and soot aggregate fractal parameters, was investigated in methane-air and nitrogen-diluted ethylene flames. Soot aggregate samples were collected by thermophoretic sampling within a high-pressure combusting chamber. Soot samples were imaged via transmission electron microscopy followed by an automated imaging detection method. The experiments covered pressures from 7 to 30 bar at vertical flame heights of 3, 6, and 8 mm in methane-air flames, and 3 to 6 bar at heights of 2, 5, 10, and 15 mm in nitrogen-diluted ethylene flames. It was observed that mean primary soot particle size increased with increasing pressure for both fuel types at virtually all flame locations. The fractal dimension was found to vary with pressure for both fuel cases, suggesting that a universal soot aggregate fractal value may not be justified in high-pressure flames.
Download or read book Soot Formation in the Buoyancy dominated Ethene Diffusion Flame written by Haran Subramaniasivam and published by . This book was released on 1992 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intense particle inception region, characterized by a large concentration of liquid-like microdroplets, is contained within the low part of the flame. These microdroplets form on the fuel side of the flame front where the temperature is the highest. Above the inception region aggregates of increasing size are observed, i. e., increasing the number of primary particles, while the primary particles ceases to exist above the vortex region of the flame, i. e., above Z=15 cm. Since there is very little evidence of oxidation taking place within this buoyancy-dominated flame, it is concluded that most of the soot formed in this flame is released into the surroundings. Observations being made here have been compared to similar soot morphology studies previously made on laminar ethene diffusion flames, both non-sooting, and laser diagnostic tests.
Download or read book Effect of Flow Unsteadiness on Soot Morphology written by Jidong Xiao and published by . This book was released on 2004 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: PAH PLIF, soot morphology, LII, Laser scattering.
Download or read book A Study of the Fuel Oxygen Effect on Soot Formation in Counterflow Diffusion Flames written by Harjit Singh Hura and published by . This book was released on 1988 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fuel Structure and Pressure Effects on the Formation of Soot Particles in Diffusion Flames written by Robert J. Santoro and published by . This book was released on 1990 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies emphasizing the effects of fuel concentration and operating pressure on the formation of soot particles have been conducted in a series of laminar diffusion flames. These experiments have shown that fuel concentration has a measurable effect on the amount of soot formed in the flame. However, a simple, constant proportionality between the fuel concentration and soot volume fraction has not been found to apply for the range of flow conditions studied. This observation is believed to be a result of flame residence time and diffusion effects which mitigate the consequences of reduced initial fuel concentration. Comparisons with simple laminar diffusion flame models are currently being used to investigate the relationship between initial fuel concentration and local flame concentration fields. Similar studies of soot formation in laminar diffusion flames as a function of operating pressure have also been completed for ethene, ethane and propene fuel species. Keywords: Soot formation, Soot particles, Diffusion flames. (JES).
Download or read book Soot Fformation in Co flow and Counterflow Laminar Diffusion Flames of Fuel Mixtures written by Ahmet Emre Karatas and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the formation process of soot in the flames of even-carbon-numbered fuels, acetylene and its derivatives are suspected to be dominant. The addition of an odd-carbon-numbered fuel into these flames introduces methyl radicals and/or C3 chemistries, which are believed to (de)activate certain chemical pathways towards the production of soot. The resultant soot formation rate of the mixture could be higher than the sum of the respective rates of the mixture components, i.e., synergistic eff ect. In this work, the mixtures of butane isomers, ethylene-butane isomers, and propane-butane isomers were studied on a co-flow and a counterflow burner. Chemical effects were isolated from those of thermal and dilution by mixing isomers and comparing the mixtures including one isomer to those including the counterpart. Line of sight attenuation (LOSA) and laser-light extinction techniques were used for measuring soot volume fraction. The results provide information on synergistic effects in soot formation for the fuels used.
