Download or read book Experimental and numerical studies of solid fuel combustion in an opposed flow configuration written by Barbara Ellen Johnson and published by . This book was released on 1990 with total page 270 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 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Modeling of Flame Spread Over Spherical Solid Fuel Under Low Speed Flow in Microgravity written by Makoto Endo and published by . This book was released on 2015 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flame spread over solid fuel presents distinctive characteristics in reduced gravity, especially when the forced flow velocity is low. The lack of buoyancy allows a blue, dim flame to sustain where the induced velocity would otherwise blow it off. At such low velocities, a quenching limit exists where the soot content is low and the effect of radiative heat loss becomes important. The objective of this study is to establish a high fidelity numerical model to simulate the growth and extinction of flame on solid fuels in a reduced gravity environment. The great importance of the spectral dependency of the gas phase absorption and emission were discovered through the model development and therefore, Statistical Narrow-Band Correlated-k (SNB-CK) spectral model was implemented.The model is applied to an experimental configuration from the recent space experiment, Burning And Suppression of Solids (BASS) project conducted aboard the International Space Station. A poly(methyl methacrylate) (PMMA) sphere (initial diameter of 2cm) was placed in a small wind tunnel (7.6cm x 7.6cm x 17cm) within the Microgravity Science Glovebox where flow speed and oxygen concentration were varied.Data analysis of the BASS experiment is also an important aspect of this research, especially because this is the first space experiment that used thermally thick spherical samples. In addition to the parameters influencing the flammability of thin solids, the degree of interior heat-up becomes an important parameter for thick solids. For spherical samples, not only is the degree of internal heating constantly changing, but also the existence of stagnation point, shoulder, and wake regions resulting in a different local flow pattern, hence a different flame-solid interaction.Parametric studies using the numerical model were performed against (1) chemical reaction parameters, (2) forced flow velocity, (3) oxygen concentration and (4) amount of preheating (bulk temperature of the solid fuel). Flame Spread Rate (FSR) was used to evaluate the transient effect and maximum flame temperature, standoff distance and radiative loss ratio were used to evaluate the spontaneous response of the gas phase to understand the overall response of the burning solid fuel. After evaluating the individual effect of each parameter, the efficacy of each parameter was compared. Selected results of this research are:[1]Experimental data from BASS and numerical simulation both showed that within the time periodbetween ignition until the flame tip reaches the shoulder of the sample, the flame length and timehave almost a linear relation.[2]Decreasing forced flow velocity increases the radiative loss ratio whereas decreasing oxygen molefraction decreases the radiative loss ratio. This finding must be considered in the effort to replicatethe behavior of flame spread over thick solid fuels in microgravity on earth.[3]Although the standoff distance will increase when the forced flow velocity is decreased as well aswhen the oxygen mole fraction is decreased, the forced flow velocity has a much stronger effect onthe standoff distance than the oxygen mole fraction.[4]Unlike the previous two comparisons, the effect of forced flow velocity and oxygen mole fraction onthe maximum flame temperature was at similar level, reduction of either parameter would result inlowering the maximum flame temperature.[5]The effect of preheating on the flame spread rate becomes stronger when either the oxygen flowrate or forced flow velocity becomes larger. Depending on which element is more important, we candistinguish oxygen flow rate driven flame spread from preheating driven flame spread.Findings of this research are being utilized in the design of the upcoming space experiment, Growth and Extinction Limits of solid fuel (GEL) project. This research is supported by the National Aeronautics and Space Administration (NASA). This work made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Case Western Reserve University and the Ohio Supercomputer Center.

Download or read book Forced Opposed Flow Flame Spread Over Flat Solid Fuels in the Thermal Near Quiescent and Chemical Kinetic Regimes written by Jeffrey S. West and published by . This book was released on 1998 with total page 842 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed numerical model of opposed-flow flame spread over solid fuels is developed. The model is used to study flame spread in three regimes of flame spread; the Thermal, Chemical Kinetic and Near Quiescent Regimes. Simplifying assumptions that have been historically applied to this problem are investigated and their effect on the flame spread rate and flame structure are quantified in each regime. A semi-empirical flame spread formula for thermally thick fuels is developed from knowledge of the dominant simplifying assumptions in this regime. Spread rate predictions compare well to experimental and computed results. This semi-empirical model provides field variables which previous theories are unable to predict. Mechanisms of heat transfer ahead of the flame are studied in each regime. Forward heat transfer though the solid fuel becomes more important in the Chemical Kinetic and Near Quiescent Regimes, a previously unknown result. The rate and path of forward heat transfer is found to depend strongly on simplifying assumptions and the flame anchor location. These results explain the relationship between previous analytical and experimental forward heat transfer results. A dimensionless criterion predicting the fuel thickness at which transition from thermally thick to thermally thin is developed which compares well with experimental and computed results. Finite-rate gas-phase chemical kinetics are found to be the cause of the super-thin regime of flame spread. A formula for the limiting flame spread rate in this regime is developed. Correlation of computed spread rates with the Damkohler number is revisited. Uncertainty in residence time due to uncertainties in characteristic velocity and gas-phase properties is found to be the cause of spread in the correlation. The Damkohler number alone explains variations in many parameters although it alone cannot explain changes in gas-phase activation energy. The boundary between the Near Quiescent and Thermal Regime is quantified using a dimensionless radiation number. A new extinction limit for thick fuels in the Near Quiescent Regime is discovered. Radiative losses cause the flame to grow small and spread so slowly that sufficient oxygen is not available to sustain the flame. Recent experimental results confirm this conclusion.

Download or read book Experimental and Numerical Studies in Premixed Combustion written by Kumaresan Sivapalan and published by . This book was released on 2012 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Turbomachinery written by and published by . This book was released on 1994 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microgravity Combustion written by Howard D. Ross and published by Elsevier. This book was released on 2001-09-03 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to understanding combustion, the burning of a substance that produces heat and often light, in microgravity environments-i.e., environments with very low gravity such as outer space. Readers are presented with a compilation of worldwide findings from fifteen years of research and experimental tests in various low-gravity environments, including drop towers, aircraft, and space.Microgravity Combustion is unique in that no other book reviews low- gravity combustion research in such a comprehensive manner. It provides an excellent introduction for those researching in the fields of combustion, aerospace, and fluid and thermal sciences.* An introduction to the progress made in understanding combustion in a microgravity environment* Experimental, theoretical and computational findings of current combustion research* Tutorial concepts, such as scaling analysis* Worldwide microgravity research findings

Download or read book Experiments and Numerical Simulations of Turbulent Combustion of Diluted Sprays written by Bart Merci and published by Springer Science & Business Media. This book was released on 2014-03-27 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reflects the results of the 2nd and 3rd International Workshops on Turbulent Spray Combustion. The focus is on progress in experiments and numerical simulations for two-phase flows, with emphasis on spray combustion. Knowledge of the dominant phenomena and their interactions allows development of predictive models and their use in combustor and gas turbine design. Experts and young researchers present the state-of-the-art results, report on the latest developments and exchange ideas in the areas of experiments, modelling and simulation of reactive multiphase flows. The first chapter reflects on flame structure, auto-ignition and atomization with reference to well-characterized burners, to be implemented by modellers with relative ease. The second chapter presents an overview of first simulation results on target test cases, developed at the occasion of the 1st International Workshop on Turbulent Spray Combustion. In the third chapter, evaporation rate modelling aspects are covered, while the fourth chapter deals with evaporation effects in the context of flamelet models. In chapter five, LES simulation results are discussed for variable fuel and mass loading. The final chapter discusses PDF modelling of turbulent spray combustion. In short, the contributions in this book are highly valuable for the research community in this field, providing in-depth insight into some of the many aspects of dilute turbulent spray combustion.

Download or read book Paper written by and published by . This book was released on 1992 with total page 952 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 2001 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical and Experimental Investigations of Liquid Fuel Combustion in a Counterflow Configuration written by Paolo Berta and published by . This book was released on 2005 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Numerical Model of Opposed Flow Flame Spread Over Thin Solid Fuels written by Amit Kumar (Ph. D.) and published by . This book was released on 2004 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ASME Technical Papers written by and published by . This book was released on with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solid Fuels Combustion and Gasification written by Marcio L. de Souza-Santos and published by CRC Press. This book was released on 2004-06-07 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridging the gap between theory and application, this reference demonstrates the operational mechanisms, modeling, and simulation of equipment for the combustion and gasification of solid fuels. Solid Fuels Combustion and Gasification: Modeling, Simulation, and Equipment Operation clearly illustrates procedures to improve and optimize the de

Download or read book Numerical Combustion written by Alain Dervieux and published by . This book was released on 1989 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interest in numerical combustion is growing among applied mathematicians, physicists, chemists, engine manufacturers and many industrialists. This proceedings volume contains nine invited lectures and twenty seven contributions carefully selected by the editors. The major themes are numerical simulation of transsonic and supersonic combustion phenomena, the study of supersonic reacting mixing layers, and turbulent combustion. Emphasis is laid on hyperbolic models and on numerical simulations of hydrocarbon planes with a complete set of chemical reactions carried out in two-dimensional geometries as well as on complex reactive flow simulations.

Download or read book A Gallery of Combustion and Fire written by Charles E. Baukal, Jr. and published by Cambridge University Press. This book was released on 2020-09-03 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Gallery of Combustion and Fire is the first book to provide a graphical perspective of the extremely visual phenomenon of combustion in full color. It is designed primarily to be used in parallel with, and supplement existing combustion textbooks that are usually in black and white, making it a challenge to visualize such a graphic phenomenon. Each image includes a description of how it was generated, which is detailed enough for the expert but simple enough for the novice. Processes range from small scale academic flames up to full scale industrial flames under a wide range of conditions such as low and normal gravity, atmospheric to high pressures, actual and simulated flames, and controlled and uncontrolled flames. Containing over 500 color images, with over 230 contributors from over 75 organizations, this volume is a valuable asset for experts and novices alike.

Download or read book Experimental Studies on Nonpremixed Combustion at Atmospheric and Elevated Pressures written by Ryan Kyle Gehmlich and published by . This book was released on 2015 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and numerical studies are carried out employing the counterflow configuration to advance understanding of nonpremixed combustion of hydrocarbon fuels. The motivation for performing these studies is to increase the knowledge and accuracy of the parameters associated with the transport and chemical-kinetic rate processes of combustion. The counterflow configuration is a very useful tool in elucidating and inferring these parameters for using in numeric or analytical models of real combustion systems. First, a new counterflow burner was constructed for carrying out experiments on high molecular weight hydrocarbon fuels and jet fuels, in particular JP-8, at elevated pressures up to 2.5 MPa. Many of these fuels are liquids at room temperature and pressure. Previously, the U.S. Army Research Office (ARO) funded the design and construction of a High Pressure Combustion Experimental Facility (HPCEF) at the University of California, San Diego. The main pressure chamber with optical access from that project is used, and this new burner is placed inside the chamber. The "extinction top'", or the apparatus used to inject an oxidizing stream onto the fuel surface is also used from the previous work. The new burner is used to measure critical conditions of extinction for hydrocarbon fuels at elevated pressures. In the research previously supported by ARO, experiments were performed at elevated pressures on fuels that are gases at room temperature. Construction of the new liquid pool counterflow burner has extended the scope and quality of that research because it is now possible to characterize combustion of fuels that are liquids at room temperature and atmospheric pressure. An experimental study of nonpremixed combustion of a number of hydrocarbon fuels under moderate pressures is carried out. Fuels and blends used in this study include n-heptane, cyclo-hexane, n-octane, iso-octane, JP-8, Jet-A, and two surrogate blends. Next, experiments and numerical computations are completed to characterize mixtures of dimethyl ether and n-heptane at atmospheric pressures. Dimethyl ether is being studied as an oxygen-rich fuel additive or replacement for diesel fuel in compression-ignition engines due to its high cetane number, negligible global warming potential, it's ability to be produced from multiple sources, and it's high well-to-wheel efficiency. The research focuses on combining the well-validated and detailed LLNL DME mechanism with other hydrocarbon mechanisms to study blends of these fuels. Critical limits of extinction and autoignition of various blends are reported. Using a combined mechanism developed at RWTH Aachen, the extinction limits are very well predicted numerically. A formulation for calculating reactant mass fractions fixing stoichiometric mixture fraction and adiabatic flame temperature is described, which can be easily adapated for two-component blends of fuels with non-unity, unequal Lewis numbers. Experiments and computations both show that dimethyl ether enhances reactivity of blends of dimethyl ether and heptane. Ignition limits for blends are also reported, with numerical predictions overpredicting experimental ignition temperature by approximately 50-70 K, but otherwise predicting ignition temperatures well. Finally, in order to understand the gas-phase combustion characteristics of nitramine monopropellants, a number of subsystems of reactions among the major intermediate products are studied. This work considers the effect of the intermediate product nitrous oxide (N2O) on the autoignition temperature of ethane (C2H6). An improved understanding of the combustion taking place in this subsystem is required to model the combustion of nitramines. Here an experimental and computational study is carried out to determine the autoignition temperature of nonpremixed ethane flames with added (N2O). The oxidizer stream is a mixture of oxygen (O2), nitrogen (N2), and (N2O). Increasing the mass fraction of nitrous oxide in the oxidizer stream of an ethane diffusion flame has a tendency to first enhance combustion and produce lower ignition temperatures, then as the fraction increases, combustion is inhibited compared to ethane/air only diffusion flames.