Download or read book Measurements of Soot Formation and Hydroxyl Concentration in Near Critical Equivalence Ratio Premixed Ethylene Flame written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-27 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: The testing and development of existing global and detailed chemical kinetic models for soot formation requires measurements of soot and radical concentrations in flames. A clearer understanding of soot particle inception relies upon the evaluation and refinement of these models in comparison with such measurements. We present measurements of soot formation and hydroxyl (OH) concentration in sequences of flat premixed atmospheric-pressure C2H4/O2/N2 flames and 80-torr C2H4/O2 flames for a unique range of equivalence ratios bracketting the critical equivalence ratio (phi(sub c)) and extending to more heavily sooting conditions. Soot volume fraction and number density profiles are measured using a laser scattering-extinction apparatus capable of resolving a 0.1 percent absorption. Hydroxyl number density profiles are measured using laser-induced fluorescence (LIF) with broadband detection. Temperature profiles are obtained from Rayleigh scattering measurements. The relative volume fraction and number density profiles of the richer sooting flames exhibit the expected trends in soot formation. In near-phi(sub c) visibility sooting flames, particle scattering and extinction are not detected, but an LIF signal due to polycyclic aromatic hydrocarbons (PAH's) can be detected upon excitation with an argon-ion laser. A linear correlation between the argon-ion LIF and the soot volume fraction implies a common mechanistic source for the growth of PAH's and soot particles. The peak OH number density in both the atmospheric and 80-torr flames declines with increasing equivalence ratio, but the profile shape remains unchanged in the transition to sooting, implying that the primary reaction pathways for OH remain unchanged over this transition. Chemical kinetic modeling is demonstrated by comparing predictions using two current reaction mechanisms with the atmospheric flame data. The measured and predicted OH number density profiles show good agreement. The predicted benzene number...
Download or read book Measurements of Soot Formation and Hydroxyl Concentration in Near Critical Equivalence Ratio Premixed Ethylene Flame written by Michael Andrew Inbody and published by . This book was released on 1993 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Temperature and Hydroxyl Concentration on Incipient Soot Formation in Premixed Flames written by Mark Miller Harris and published by . This book was released on 1985 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1994-03 with total page 1012 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Growth in Laminar Premixed Flames written by Fang Xu and published by . This book was released on 1999 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book China written by World Bank and published by World Bank Publications. This book was released on 1993 with total page 1422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Republic of Korea's industrial policy has directed that nation's economy through nearly three decades of spectacular growth. But the authors of this paper maintain that this policy is showing signs of being outmoded. The time has come, the authors argue, for the Korean government to stop managing the economy's structural development and to redefine the responsibilities of business and government. Under this proposed compact, the allocation of resources would shift from the government to the private industrial and financial sectors. The transformation of the government bureaucracy from an ad hoc policy role to one of a transparent and predictable regulator is a key to the success of this undertaking. These new directions would present the government with enormous challenges. Greater competitive discipline and regulatory oversight would be required. While dealing with the complexities of the transition, the government would have to maintain macroeconomic stability and the momentum of savings and investment. For comparison, the study examines the industrial economies of France, Germany, Japan, and the United States, which underwent similar shifts.
Download or read book Soot Formation In Turbulent Combusting Flows written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of soot formation in turbulent jet flames burning ethylene in air were studied for Reynolds numbers ranging from 4,000 to 23,000. Laser-based techniques were used to measure the soot volume fraction, particle size and number density as well as the temperature and relative concentration of hydroxyl radicals and polycyclic aromatic hydrocarbons. Measurements of the characteristics length scales for the soot and hydroxyl radical fields throughout the turbulent flames were obtained. The maximum soot eddy size was observed to be 7 mm or about three times the size of the diameter of the fuel jet (d= 2.18 mm). The soot eddy size increased linearly along the centerline of the turbulent flame until the mid-point, where it leveled off and finally decreased in the oxidation zone. In contrast, the hydroxyl radical eddy size always increased along the flame with a maximum eddy size of 12 mm for the higher Reynolds number flames. Analysis of the radial dependence of the eddy size was also determined. Relatively little radial dependence in the eddy size was observed for the soot particles indicating that the soot eddies moved off the axis very fast as compared to the mixing rate. However for the hydroxyl radicals, the eddy size was always larger off the axis of the flame except near the flame tip. With respect to the temperature field, temperature probability density functions indicated bimodality at all axially locations. With respect to soot formation, the highest soot formation location and the peak mean temperature were observed on the fuel-rich side of the stoichiometric flame location while the peak hydroxyl radical concentration was on the fuel-lean side.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Preliminary Analysis of the Effects of Mixing on Soot Formation written by Kevin L. Hoag and published by . This book was released on 1982 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fossil Energy Update written by and published by . This book was released on 1986 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1986 with total page 1066 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 American Doctoral Dissertations written by and published by . This book was released on 1992 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot and Pah Formation in Counterflow Non premixed Flames Atmospheric Butane and Butanol Isomers and Elevated pressure Ethylene written by Pradeep K Singh and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the complexity of the fluid dynamics and non-linear reactions in the combustion zone, a simplified approach to study this process is required. Given these complexities, it is practically very challenging to take measurements in very high temperature and pressure zones in practical combustion systems, and if by any means those measurements can be made, it is equally challenging to analyze those measurements. Hence, in order to more comprehensively understand these processes, the problem needs to be resolved into the smaller and controllable sub-category of experiments, by creating laminar flamelets. One approach used in creating these flamelets is by establishing simplified non-premixed flames in the counterflow configuration. Alongwith all the fundamental properties of combustion, it is important to study the health hazard and environmentally detrimental emissions, such as soot and polycyclic aromatic hydrocarbons (PAHs). Such combustion studies need to be carried out using the non-intrusive in-situ optical diagnostics measurement techniques, such as the Laser Induced Incandescence (LII), Planar Laser Induced Fluorescence (PLIF) and Light Extinction (LE). These measurements for renewable biofuels aid in better understanding of the soot formation process, as well as in developing the fuel specific knowledge to bring them into commercial use. Furthermore since the most practical combustion systems operate at elevated pressures, it is also important to understand the soot formation process under elevated pressure conditions. Considering these, in the current study, the soot and PAH formation processes for butane and butanol isomers (C4 fuels) at atmospheric pressure; and for ethylene at elevated pressure have been experimentally investigated and compared in a counterflow non-premixed flame configuration. Under the investigated conditions, butane isomers were observed to form more soot than butanol isomers, thereby showing the effect of the hydroxyl group. The effects of isomeric structural differences on sooting propensity were also observed within the butane and butanol isomers. In addition, while soot volume fraction was seen to increase with increasing fuel mole fraction, the ranking of sooting propensity for these C4 fuels remained unchanged. For the conditions studied, the sooting tendency ranking generally follows n-butane > iso-butane > tert-butanol > n-butanol > iso-butanol > sec-butanol. . The counterflow non-premixed flames were also simulated using the gas-phase chemical kinetic models, USC Mech II [1], Sarathy et al. [2] and Merchant et al. [3] available in the literature to compute the spatially-resolved profiles of soot precursors, including acetylene and propargyl. For these C4 fuels, the PAHs of various aromatic ring size groups (2, 3, 4, and larger aromatic rings) have been characterized and compared in non-premixed combustion configuration. In particular, the formation and growth of the PAHs of different aromatic ring sizes in these counterflow flames was examined by tracking the PAH-PLIF signals at various detection wavelengths. PAH-PLIF experiments were conducted, by blending each of the branched-chain isomers with the baseline straight-chain isomer, in order to study the synergistic effects. The fuel structure effects on the PAH formation and growth processes were also analyzed by comparing the PAH growth pathways for these C4 fuels. A chemical kinetic model, POLIMI mechanism [4-7], available in the literature that includes both the fuel oxidation and the PAH chemistry was also used to simulate and compare the PAH species up to A4 rings. Counterflow non-premixed sooting ethylene‒air flames with fuel mole fractions of 0.20‒0.40 in the pressure range of 1‒6 atm were investigated experimentally with the laser diagnostic techniques of LII, PLIF and LE. A better understating of the quantitative soot formation process has been developed for ethylene counterflow flames under elevated pressure conditions. The effect of pressure on the formation of PAHs with different aromatic ring sizes has also been determined qualitatively. With increase in pressure, the increase in soot volume fraction and PAH-PLIF signals were observed. A chemical kinetic model available in the literature, that includes both the fuel oxidation and the PAH chemistry, was also used to simulate and compare the PAH species up to A4 rings. At the incipient stage of the PAH formation, the simulated results exhibited similar behavior to the experimental observations. A chemical kinetic model, WF-PAH mechanism [8], available in the literature was also used to compute the PAHs up to four aromatic rings. This chemical kinetic model predicted enhancing PAHs formation with an increase in pressure, consistent with the experimental trend.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1995 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
