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Author: N. V. Fedoseeva
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
The investigation of a system of burning droplets of liquid fuel is given. The droplet combustion velocity is determined as a function of the number of droplets and the distance between them. The results obtained are compared with the rate of combustion of a single drop of liquid fuel. It is established that the droplet combustion velocity does not vary monotonically as a function of the distance between the droplets. (Author).
Author: N. V. Fedoseeva
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
The investigation of a system of burning droplets of liquid fuel is given. The droplet combustion velocity is determined as a function of the number of droplets and the distance between them. The results obtained are compared with the rate of combustion of a single drop of liquid fuel. It is established that the droplet combustion velocity does not vary monotonically as a function of the distance between the droplets. (Author).
Author: Alan Williams
Publisher: Butterworth-Heinemann
ISBN: 1483101584
Category : Technology & Engineering
Languages : en
Pages : 300
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Book Description
Combustion of Liquid Fuel Sprays outlines the fundamentals of the combustion of sprays in a unified way which may be applied to any technological application. The book begins with a discussion of the general nature of spray combustion, the sources of liquid fuels used in spray combustion, biomass sources of liquid fuels, and the nature and properties of fuel oils. Subsequent chapters focus on the properties of sprays, the atomization of liquid fuels, and the theoretical modeling of the behavior of a spray flame in a combustion chamber. The nature and control of pollutants from spray combustion, the formation of deposits in oil-fired systems, and the combustion of sprays in furnaces and engines are elucidated as well. The text is intended for students undertaking courses or research in fuel, combustion, and energy studies.
Author: Saptarshi Basu
Publisher: Springer
ISBN: 9811074496
Category : Technology & Engineering
Languages : en
Pages : 433
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Book Description
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.
Author: W. A. Sirignano
Publisher: Cambridge University Press
ISBN: 0521884896
Category : Science
Languages : en
Pages : 481
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Book Description
This book discusses the theoretical foundations of spray and droplet applications relevant to the technology for active control of sprays applied to new products and applications, improved product performance, cost reductions, and improved environmental outcomes. It also covers theory related to power and propulsion; materials processing and manufacturing technologies including droplet-based net form processing, coating, and painting; medication; pesticides and insecticides; and other consumer uses.
Author: Forman A. Williams
Publisher: CRC Press
ISBN: 0429973683
Category : Science
Languages : en
Pages : 549
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Book Description
Combustion Theory delves deeper into the science of combustion than most other texts and gives insight into combustions from a molecular and a continuum point of view. The book presents derivations of the basic equations of combustion theory and contains appendices on the background of subjects of thermodynamics, chemical kinetics, fluid dynamics, and transport processes. Diffusion flames, reactions in flows with negligible transport and the theory of pre-mixed flames are treated, as are detonation phenomena, the combustion of solid propellents, and ignition, extinction, and flamibility pehnomena.
Author: Miguel Angel Plascencia Quiroz
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
These experiments examined the reactive processes involving nanoparicle laden liquid droplets, and turbulent jet flames as two separate sets of studies. The first part of this dissertation (Chapters 2 and 3) deals with the combustion of ethanol liquid droplets loaded with nano particulate additives using different droplet formation methods. For this study, an apparatus at the Energy and Propulsion Research Laboratory at UCLA was used to keep the droplet in a quiescent environment. Three different types of droplet combustion experiments were performed, involving: (I) the classic single droplet suspended from a quartz fiber, (II) a single droplet suspended from a quartz capillary, (III) a burning droplet that has continual fuel deliver to sustain the droplet for longer periods of time during the combustion process. Two alternative nanoparticles were explored to demonstrate the effect of energetic additives: reactive nano aluminum (nAl) and inert nano silicon dioxide (nSiO2), each having nominal average diameters of 80 nm. Simultaneous high speed visible and OH* chemiluminescence images were taken to determine the shape of the droplet over time and hence the burning rate constant (K), flame standoff distance, and mean OH* chemiluminescence intensity with varying particulate concentrations. Visible imaging showed particle/vapor ejections and jetting in continuously fed droplet experiments, while rod-suspended burning droplets showed limited particle ejection, usually towards the end of the droplet lifetime. The nSiO2-laden, rod-suspended droplets formed a porous, shell-like structure resembling the shape of a droplet at higher nSiO2 concentrations, in contrast to smaller residue structures left for nAl-laden droplets. A systematic increase in the burning rate constant was observed as the loading concentration of nAl was increased from 1wt%-6wt%. The droplet with continual fuel delivery had the greatest improvement in K of 13% over the pure fuel value. For nSiO2, the continuously fed droplet showed the greatest increase of 5% at 1 wt% loading concentrations, and no consistent trend was observed for nSiO2, likely due to the large shell-like residue structures in the latter stages of combustion. Transmission electron microscopy (TEM) images of particle residue revealed additional insights.The second part of this dissertation (Chapters 4 and 5) studied reacting gaseous turbulent jets in a newly constructed experiment at the Air Force Research Laboratory (AFRL/RQR) located at Edwards Air Force base. This experimental study aimed to characterize the coupling of an acoustic field with a turbulent gaseous methane nonpremixed flame under atmospheric pressure conditions. Two separate injection configurations were examined: one that involved a classic single methane jet surrounded by a minimal velocity oxidizer co-flow and a second coaxial jet configuration with annular oxidizer flow and the same low-velocity co-flow. The different jets were placed within an acoustic waveguide in which standing waves could be created using several speakers. The reacting jets could thus be situated at either a pressure node or a pressure anti-node location. High-speed Schlieren and OH* chemiluminescence images recorded the near field behavior of the flame under both unforced and acoustically forced conditions. High-speed imaging showed two different phenomena associated with these standing waves. When the flame was forced while situated at a pressure node, a sinuous oscillatory response of the flame was observed, in addition to transverse oscillations of the center fuel jet, which shortened the intact fuel core length. The flame "flattened" into an ellipsoidal shape in the direction of the acoustic waves. Conversely, at a pressure anti-node, the coupling of the acoustics and flame gave rise to an axisymmetric response (puff-like oscillations), which prompted the flame to become unstable at the anchoring region. This could lead to periodic liftoff or permanent flame liftoff. A receptivity study for a methane jet at Reynolds number of 5,300 and an ambient oxygen concentration of 40\% showed that the reacting jet was able to respond at the frequency of the unsteady acoustic field for a range of frequencies, but with a diminishing response of the flame for both the pressure node and the pressure anti-node under high frequency excitation. Proper Orthogonal Decomposition (POD) analysis was able to extract mode shapes and frequencies based on pixel intensity fluctuations. For the cases of pressure node forcing, this analysis method illustrated the different modes of flame oscillation, in many cases which were similar to corresponding low Reynolds number fuel jet experiments with pressure node excitation conducted at UCLA. A forcing susceptibility diagram was created to map the three different anchoring stability regimes the flame experienced under pressure anti-node forcing, demonstrating the need for higher amplitude excitation required for the flame to lift off when forced at higher frequency pressure anti-node conditions. As an extension to the single jet, the shear coaxial jet configuration kept the center fuel and surrounding oxidizer co-flow constant. Only the outer annular oxidizer flowrate was varied, with annulus-to-inner jet velocity ratios ranging from R = 0.05 to 0.3, to investigate its impact on the flame's ability to respond to the acoustics. In the absence of acoustic excitation, the coaxial jet did demonstrate natural shear layer/wake like instabilities at higher annular-to-jet velocity ratios, for R = 0.17 and 0.3. The dynamical response of the coaxial jet to pressure node excitation exhibited similar characteristics to that of the single jet for a range of forcing frequencies. But when forced at a pressure anti-node, a notable difference between the two configurations was found. The shear coaxial jet was more responsive to the acoustic forcing at higher forcing frequencies, for example, than the single fuel jet. The susceptibility diagrams for the full range of annular-to-inner jet velocity ratios demonstrated opposite trends when compared to the single jet, that is, that the coaxial jet was more responsive to excitation at a given excitation amplitude when the forcing frequency was higher, and thus closer to the natural coaxial jet instability frequency. Hence evidence suggests that the natural instabilities of the coaxial jet shear layer may be causing the difference in susceptibility diagrams. Both sets of experimental studies here, the nanofuel droplet combustion studies and the acoustically-coupled turbulent fuel jet combustion experiments, provide useful advances to our understanding of reactive flows relevant to liquid rocket engine systems. Enhancement in burning rates with nanoparticulate additives show potential benefits for rocket fuels, and attendant benefits are documented in the presence of acoustic disturbances, studied separately [1]. AFRL-based acoustically coupled turbulent fuel jet studies reveal different dynamical characteristics, depending on the injection system and the acoustic frequency and amplitude range. Different characteristic signatures extracted via POD analysis are both relevant in understanding combustion instabilities and in developing reduced order models underlying control of such instabilities. The present studies contribute to these goals in important ways.
Author: David T. Harrje
Publisher:
ISBN:
Category : Liquid propellant rockets
Languages : en
Pages : 668
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Book Description
The solution of problems of combustion instability for more effective communication between the various workers in this field is considered. The extent of combustion instability problems in liquid propellant rocket engines and recommendations for their solution are discussed. The most significant developments, both theoretical and experimental, are presented, with emphasis on fundamental principles and relationships between alternative approaches.
Author: Irvin Glassman
Publisher: Academic Press
ISBN: 0124115551
Category : Technology & Engineering
Languages : en
Pages : 775
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Book Description
Throughout its previous four editions, Combustion has made a very complex subject both enjoyable and understandable to its student readers and a pleasure for instructors to teach. With its clearly articulated physical and chemical processes of flame combustion and smooth, logical transitions to engineering applications, this new edition continues that tradition. Greatly expanded end-of-chapter problem sets and new areas of combustion engineering applications make it even easier for students to grasp the significance of combustion to a wide range of engineering practice, from transportation to energy generation to environmental impacts. Combustion engineering is the study of rapid energy and mass transfer usually through the common physical phenomena of flame oxidation. It covers the physics and chemistry of this process and the engineering applications—including power generation in internal combustion automobile engines and gas turbine engines. Renewed concerns about energy efficiency and fuel costs, along with continued concerns over toxic and particulate emissions, make this a crucial area of engineering. - New chapter on new combustion concepts and technologies, including discussion on nanotechnology as related to combustion, as well as microgravity combustion, microcombustion, and catalytic combustion—all interrelated and discussed by considering scaling issues (e.g., length and time scales) - New information on sensitivity analysis of reaction mechanisms and generation and application of reduced mechanisms - Expanded coverage of turbulent reactive flows to better illustrate real-world applications - Important new sections on stabilization of diffusion flames—for the first time, the concept of triple flames will be introduced and discussed in the context of diffusion flame stabilization
Author:
Publisher:
ISBN:
Category : Space vehicles
Languages : en
Pages : 668
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Book Description
Author: Sara McAllister
Publisher: Springer Science & Business Media
ISBN: 1441979433
Category : Science
Languages : en
Pages : 315
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Book Description
Fundamentals of Combustion Processes is designed as a textbook for an upper-division undergraduate and graduate level combustion course in mechanical engineering. The authors focus on the fundamental theory of combustion and provide a simplified discussion of basic combustion parameters and processes such as thermodynamics, chemical kinetics, ignition, diffusion and pre-mixed flames. The text includes exploration of applications, example exercises, suggested homework problems and videos of laboratory demonstrations
