Download or read book Carbon Monoxide and Turbulence Chemistry Interactions Blowoff and Extinction of Turbulent Jet Diffusion Flames written by S. M. Correa and published by . This book was released on 1988 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence chemistry interactions have been studied experimentally and theoretically in the context of turbulent diffusion flames. The goal is a quantitative understanding of these interactions under a wide range of conditions. These range from low Reynolds number conditions ('weak' interactions, affecting primarily the levels of intermediate species, pollutants and combustion efficiency) to high Reynolds number conditions, where the flame can be extinguished by intense turbulent straining. Jet flames in coflowing air have been emphasized, with a coannular pilot burner used where necessary for stabilization at the burner lip. Fuels have consisted of carbon dioxide/H2 mixtures with the fraction of hydrogen successively reduced to promote extinction. Reynolds numbers have been increased to the point of blowoff. Major species and temperature have been measured by Raman scattering, and velocity and turbulence have been measured by laser velocimetry. These experiments have provided a comprehensive set of data on CO/H2 flames, extending to conditions conducive to localized extinction. The data show significant temperature decrements due to finite-rate chemistry but no evidence of localized extinction. Keywords: Turbulence, Chemistry interactions, Extinction, Turbulent diffusion flames, Superequilibrium, Laser diagnostics. (MJM).
Download or read book Carbon Monoxide and Turbulence Chemistry Interactions Blowoff and Extinction of Turbulent Diffusion Flames written by S. M. Correa and published by . This book was released on 1987 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this program is to understand turbulence chemistry interactions in combustion up to and including localized extinction. Experimentally, pilot stabilized non premixed turbulent jet flames of selected mixtures are being studied under conditions conducive to strain-induced local extinction. Laser based techniques such as Raman scattering and Rayleigh scattering are employed. Analytically, models based on the asymptotically thin flamelet concept and on distributed reaction zone concepts are being assessed. A significant finding is that the popular contemporary view of a turbulent flame as an ensemble of asymptotically thin flamelets seems incorrect. Alternative mechanisms based on thick flamelets are proposed. The results include: (1) A complete re evaluation of Raman data showing significant corrections due to high temperature effects. Keywords: Turbulence chemistry interactions, Extinction, Blowoff, turbulent diffusion flames, Superequilibrium, Laser diagnostics.
Download or read book Carbon Monoxide and Turbulence Chemistry Interactions Measurements and Modeling of Turbulent Jet Diffusion Flames written by S. M. Correa and published by . This book was released on 1986 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of a fundamental understanding of turbulence-chemistry interactions remains one of the most important and challenging problems in turbulent reacting flows. This program couples laser based measurements and computer modeling of well-characterized laboratory-scale jet diffusion flames to study the effects of finite-rate chemistry and localized extinction in turbulent combustion. The long-range goal is to use this fundamental understanding for control of lean and high-altitude blow out in gas-turbine engines. The results of the first year of this program include: 1) improving the data base for CO/H2/N2 turbulent jet diffusion flames by analyzing direct measurements of CO2 concentrations from Strokes vibrational Raman intensities and by comparing two independent methods of determining temperatures from the Raman data; 2) testing of the stretched laminar flamelet concept in turbulent diffusion flames by comparison of instantaneous and conditionally averaged Raman measurements in turbulent H2 and CO/H2/N2 jet diffusion flame calculations and measurements; and 3) testing of a diffusion flame pilot for stabilization of turbulent jet flames at high Reynolds number.
Download or read book Local Extinction Mechanisms in Non premixed Turbulent Combustion written by S. M. Correa and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex flame Interactions and the Local Extinction of Turbulent Jet Diffusion Flames written by Fumiaki Takahashi and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theories of Turbulent Combustion in High Speed Flows written by Paul A. Libby and published by . This book was released on 1995 with total page 12 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 1989 with total page 984 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1989 with total page 1116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Model Based Closure Approach for Turbulent Combustion Using the One Dimensional Turbulence Model written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new model-based closure approach for turbulent combustion using the One-Dimensional turbulence model (ODT) is developed and validated in context to a turbulent jet diffusion flame. The interaction of turbulence and chemistry provides interesting finite rate chemistry effects including the phenomena of extinction and re-ignition. The ODT model resolves both spatially and temporally all the scales in a turbulent reaction flow problem, thus, combining the accuracy of a DNS like solver with efficiency by reduction in the number of dimensions. The closure approach is based on identifying the mechanisms responsible for the above mentioned effects and parameterizing the ODT results with a minimum set of scalars transported in the coarse grained solvers like the Reynolds-Averaged Navier-Stokes (RANS) or Large Eddy Simulation (LES). Thus, the closure from ODT is based on a "one-way" coupling between the coarse grained solvers and ODT. Two approaches for closure are developed in the present work with respect to a RANS solver; however, they can be easily extended to LES. The first approach relies on ODT to provide the history effects associated with the geometry, which represent the interactions of turbulence and chemistry, by tabulating scalar statistics (first and second moments) on two parameters measuring, the extent of mixing, the radial mean mixture fraction, and the extent of entrainment, the centerline mean mixture fraction. However, based on the above parameterization, the approach is limited to jet diffusion flame geometry. Furthermore, the closure requires a one to one correspondence between the flames simulated in the coarse grained solver and ODT. As a second approach, the results from ODT are parameterized based on general representative scalars; mixture fraction, which specifies the mixedness of the mixture and temperature, which specifies the reactedness of the mixture. The history effects associated with the flow geometry are provided by the RANS solver in t.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1985 with total page 1052 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the Engineering Technology Conference on Energy written by and published by . This book was released on 2001 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1988 with total page 1600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Finite rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non homogeneous Autoigntion Using the One dimensional Turbulence Model written by Sha Zhang and published by . This book was released on 2003 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: autoignition, ODT, turbulent combustion.
Download or read book Theories of Turbulent Combustion in High Speed Flows written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational and asymptotic analyses were completed for the structures of wet carbon monoxide flames. Both premixed flames and diffusion flames were considered. It was established that hydrogen containing species affect burning velocities and extinction limits of these flames down to hydrogen concentrations of about one part per million. Reduced chemistry was derived for these flames in the vicinity of this limit as well as above and below it. In particular, useful one-step descriptions were obtained. The results can be applied to determining flammability limits and to predicting influences of water hydrogen addition to dry carbon monoxide systems.
Download or read book Simulation of Flame Stabilization of Lifted Turbulent Jet Diffusion Flames written by Ming Chen and published by . This book was released on 2000 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
