Download or read book Numerical Simulation of Combustion of Single Component and Multicomponent Unsupported and Fiber supported Droplets in Micro gravity written by Narugopal Ghata and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed computational study of evaporation and combustion phenomena of unsupported and fiber-supported single and multi-component droplets is presented. The current study consists of a total of five parts: (a) study the effects of support fibers on the vaporization of single component n-heptane droplets, (b) study the effects of the Marangoni stress in single component n-heptane droplet combustion, (c) study the effects of support fibers in single component n-heptane droplet combustion, (d) study soot shell formation for single component n-heptane droplet, and (e) study multi-component n-heptane/n-hexadecane droplet evaporation and combustion. The volume-of-fluid (VOF) method is employed in the studies to capture the liquid-gas interface for transient two-phase multidimensional flows. The calculations also include variable thermo-physical properties of the liquid and gas phases as well as Marangoni stresses. In the first part of the study, a detailed numerical investigation of the effects of support fibers on the vaporization of a fiber-supported n-heptane droplet in reduced gravity is presented. This part of the study also investigated the effects of the thickness of fiber, ambient pressure, and ambient temperature on droplet evaporation. The computational results were validated with experimental results. In the second part of the droplet combustion study, a detailed numerical investigation of the Marangoni effects for fiber supported n-heptane droplet combustion in reduced gravity is presented. A 21-step n-heptane reaction mechanism proposed by Machrafi et al. (2009) is incorporated to model the combustion with both low and high temperature chemistry. Predicted burning rates and flame diameters have been validated with data from drop tower experiments. The present computational results agree well with the experimental results. The primary focus in the third part of the study is on the effects of support fibers on the droplet burning rates and flame structure. A 21-step n-heptane reaction mechanism consisting of 20 species proposed by Zhang et al. (2013) is employed to model the combustion chemistry. Computed burning rates and flame stand-off ratios are compared with the experimental results of Jackson and Avedisian (1993). Predicted flame structures are also validated with the experimental results of Mikami et al. (1994). The present computational results agree well with the experimental results. The results indicate that the support fibers can have significant impact on droplet burning rates and flame structures. In the fourth part of the study, a detailed numerical investigation of unsupported and fiber supported n-heptane droplet combustion in reduced gravity is done to explore some important information i.e., the location of pyrolysis and soot shell using a complex multidimensional computational fluid dynamic (CFD) analysis with a detailed reaction mechanism. A 25-step n-heptane mechanism consisting of 21 species is incorporated to model the combustion. The reaction mechanism is validated for the ignition delay time. Computed burning rates and flame stand-off ratios for both unsupported and fiber-supported droplets have been validated with prior computational and experimental studies. The computed soot shell stand-off ratios are validated by comparisons with experimental and computational results. The present computational results agree well with the experimental results.In the fifth and final part, a numerical study of vaporization and combustion of unsupported and fiber-supported multi-component n-heptane/n-hexadecane droplet is presented.

Download or read book Droplet Interactions During Combustion of Unsupported Droplet Clusters in Microgravity written by Irina N. Ciobanescu Husanu and published by . This book was released on 2005 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Isolated Droplet Combustion Under Microgravity Conditions written by Kenneth G. Kroenlein and published by . This book was released on 2007 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new numerical model for the simulation of liquid fuel droplet vaporization and combustion time-histories under conditions of no body forces or bulk fluid flow is developed. Assuming spherosymmetry, the model applies finite volume methods combined with high-order implicit time integration to the system of interest. Molecular transport, thermal radiation, thermophysical properties, and chemical kinetic behaviors are represented in rigorous detail. Specifically, this effort represents the first implementation of a Stefan-Maxwellian transport formulation and of a spectrally-resolved radiant thermal transport formulation to this physical configuration. Particular effort has been applied toward computational efficiency so that the interactive complexities of these phenomena can be represented with substantial detail. Liquid fuels, consisting of n-heptane, n-nonane, n-hexadecane and methanol, under a variety of ambient conditions were simulated yielding generally good agreement with experiment and highlighting areas for future model development where discrepancies do exist. In particular, the highly modular design allows for the inclusion and comparison of differing chemical, thermodynamic and transport representations, aiding in the validation of simplified representations, highlighting the impact of more detailed ones and making the inclusion of new phenomena such as soot production or radiative penetration of the liquid phase dependent only on developing the appropriate submodel.

Download or read book Droplets and Sprays written by Saptarshi Basu and published by Springer. This book was released on 2017-12-11 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on droplets and sprays relevant to combustion and propulsion applications. The book includes fundamental studies on the heating, evaporation and combustion of individual droplets and basic mechanisms of spray formation. The contents also extend to the latest analytical, numerical and experimental techniques for investigating the behavior of sprays in devices like combustion engines and gas turbines. In addition, the book explores several emerging areas like interactions between sprays and flames and the dynamic characteristics of spray combustion systems on the fundamental side, as well as the development of novel fuel injectors for specific devices on the application side. Given its breadth of coverage, the book will benefit researchers and professionals alike.

Download or read book Single and Multicomponent Liquid Droplet Combustion written by Anthony John Marchese and published by . This book was released on 1996 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theoretical and Experimental Studies on Evaporation and Combustion of Multicomponent Droplets in Reduced Gravity written by Israel Aharon and published by . This book was released on 1996 with total page 1186 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling Combustion of Multicomponent Fuel Droplets written by Kannan Vittilapuram Subramanian and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The quasi-steady, spherically symmetric combustion of multicomponent isolated fuel droplets has been modeled using modified Shvab-Zeldovich variable mechanism. Newly developed modified Shvab-Zeldovich equations have been used to describe the gas phase reactions. Vapor-liquid equilibrium model has been applied to describe the phase change at the droplet surface. Constant gas phase specific heats are assumed. The liquid phase is assumed to be of uniform composition and temperature. Radiative heat transfer between the droplet and surroundings is neglected. The results of evaporation of gasoline with discrete composition of hydrocarbons have been presented. The evaporation rates seem to follow the pattern of volatility differentials. The evaporation rate constant was obtained as 0.344mm2/sec which compared well with the unsteady results of Reitz et al. The total evaporation time of the droplet at an ambience of 1000K was estimated to be around 0.63 seconds. Next, the results of evaporation of representative diesel fuels have been compared with previously reported experimental data. The previous experiments showed sufficient liquid phase diffusional resistance in the droplet. Numerical results are consistent with the qualitative behavior of the experiments. The quantitative deviation during the vaporization process can be attributed to the diffusion time inside the droplet which is unaccounted for in the model. Transient evaporation results have also been presented for the representative diesel droplets. The droplet temperature profile indicates that the droplet temperature does not reach an instantaneous steady state as in the case of single-component evaporation. To perform similar combustion calculations for multicomponent fuel droplets, no simple model existed prior to this work. Accordingly, a new simplified approximate mechanism for multicomponent combustion of fuel droplets has been developed and validated against several independent data sets. The new mechanism is simple enough to be used for computational studies of multicomponent droplets. The new modified Shvab-Zeldovich mechanism for multicomponent droplet combustion has been used to model the combustion characteristics of a binary alcohol-alkane droplet and validated against experimental data. Burn rate for the binary droplet of octanol-undecane was estimated to be 1.17mm2/sec in good concurrence with the experimental value of 0.952mm2/sec obtained by Law and Law. The model has then been used to evaluate the combustion characteristics of diesel fuels assuming only gas phase reactions. Flame sheet approximation has been invoked in the formulation of the model.

Download or read book Numerical Simulation of Convective Fuel Droplet Vaporization and Combustion in a Low Pressure Zero gravity Environment written by Daniel N. Pope and published by . This book was released on 2001 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation of Microgravity Droplet Combustion in Quiescent Atmospheres and in Slow Flow written by Malissa Dawn Ackerman and published by . This book was released on 2003 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Droplet Combustion of Surrogate and Real Fuel Systems in a Low Convection Condition written by Yu-Cheng Liu and published by . This book was released on 2013 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: The droplet burning characteristics of aviation (Jet-A) and ground transportation (gasoline) fuels, a standard reference gasoline (indolene), three and four component surrogate fuels, several biodiesel surrogates (methyl butanoate (MB) and decanoate (MD)), and three single component fuels (heptane, octane and decane) were examined from the perspective of the spherically symmetric droplet flame promoted by a low gravity environment in the standard atmosphere. The parameters included the initial droplet diameter (Do) and the fuel composition. Access to the experimental times required to observe the complete droplet burning history was obtained by carrying out the experiments in a drop tower that provided about 1 s of experimental time (Do ~ 1 mm), and the orbiting International Space Station (ISS) using an experimental design on the ISS that could produce both freely-floating and fiber-supported droplets with essentially any Do and unlimited experimental times. For some of the results reported (those for n-heptane, n-octane, ndecane) Do was varied over the widest range ever reported (0.5 mm to 5 mm) across which radiative and sooting processes were considered to either influence burning (for Do ~ 1.5 mm) or have a minimal affect (for Do

Download or read book Numerical Study on Vaporization and Burning of Multi component Stationary Fuel Droplets and Single component Convective Fuel Droplets Both with Complex Configuration and Variable Properties written by Guang Wu and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computer Simulation of the Burning of a Multicomponent Droplet written by Elizabeth Katherine Flatbush and published by . This book was released on 1987 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Flame Synthesis Involving Multi component Aerosols written by Zhen Sun and published by . This book was released on 2002 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Numerical Simulation of a Multicomponent Droplet laden Mixing Layer written by Kishore K. Varanasi and published by . This book was released on 2001 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detailed Numerical Simulation of an Isolated Droplet particle Combustion with Applications to Combustion of Metals written by Abhijit Modak and published by . This book was released on 2003 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling of the Multicomponent Droplet Vaporization written by Virginel Bodoc and published by . This book was released on 2011 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this thesis was to study the vaporization of a multicomponent spray with both experimental and numerical approaches. To achieve this objective, the effort was guided in two directions. Firstly, an experimental database has been created using different optical measurement techniques. A special attention was focused onto the application of Global Rainbow Refractometry (GRR), used for the measurement of droplets temperature. Secondly, numerical simulations were performed for mono and bi-component sprays in evaporation. In the first part of this study, experimental and numerical tests were carried out on a polydisperse nonconfined and cooling spray. This configuration was adopted because it allows the study of the vaporization with a reduced influence from the gaseous phase. For a bi-component liquid, the effect of the composition variation on the GRR measurements was analysed within a coupling between the experimental technique and the numerical simulation. In the second part, experimental investigations and numerical simulation were performed for a more complex configuration that consists in a spray evolving in a heated and confined medium. The gaseous phase was computed with a LES approach while the dispersed phase, always mono-component, was solved with a Lagrangian tracking approach . The unsteady nature of the flow was demonstrated and the interest of the GRR technique for the droplets temperature measurement was proved.

Download or read book Numerical Simulation of Combustion Phenomena written by Roland Glowinski and published by . This book was released on 1985 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: