Author : Dirk Großschmidt
Publisher :
Page : 163 pages
File Size : 20,83 MB
Release : 2007
Category : Combustion
ISBN : 9783183555062
Author :
Publisher :
Page : 0 pages
File Size : 15,6 MB
Release : 1998
Category :
ISBN :
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.
Author : Santanu De
Publisher : Springer
Page : 663 pages
File Size : 37,16 MB
Release : 2017-12-12
Category : Science
ISBN : 9811074100
This book presents a comprehensive review of state-of-the-art models for turbulent combustion, with special emphasis on the theory, development and applications of combustion models in practical combustion systems. It simplifies the complex multi-scale and nonlinear interaction between chemistry and turbulence to allow a broader audience to understand the modeling and numerical simulations of turbulent combustion, which remains at the forefront of research due to its industrial relevance. Further, the book provides a holistic view by covering a diverse range of basic and advanced topics—from the fundamentals of turbulence–chemistry interactions, role of high-performance computing in combustion simulations, and optimization and reduction techniques for chemical kinetics, to state-of-the-art modeling strategies for turbulent premixed and nonpremixed combustion and their applications in engineering contexts.
Author : Massimiliano Di Domenico
Publisher :
Page : 0 pages
File Size : 21,42 MB
Release : 2008
Category :
ISBN :
Author : Norbert Peters
Publisher : Cambridge University Press
Page : 322 pages
File Size : 38,59 MB
Release : 2000-08-15
Category : Science
ISBN : 1139428063
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.
Author : Henning Bockhorn
Publisher : Springer Science & Business Media
Page : 595 pages
File Size : 35,72 MB
Release : 2013-03-08
Category : Science
ISBN : 3642851673
Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:
Author : J. Lahaye
Publisher : Springer Science & Business Media
Page : 429 pages
File Size : 25,73 MB
Release : 2013-04-17
Category : Science
ISBN : 1468444638
Our interest in Mulhouse for carbon black and soot began some 30 years ago when J.B. Donnet developed the concept of surface chemistry of carbon and its involvement in interactions with gas, liquid and solid phases. In the late sixties, we began to study soot formation in pyrolytic systems and later on in flames. The idea of organ1z1ng a meeting on soot formation originated some four or five years ago, through discussions among Professor J.B. Howard, Dr. A. D'Alessio and ourselves. At that time the scientific community was becoming aware of the necessity to strictly control soot formation and emission. Being involved in the study of surface properties of carbon black as well as of formation of soot, we realized that the combustion community was not always fully aware of the progress made by the physical-chemists on carbon black. Reciprocally, the carbon specialists were often ignoring the research carried out on soot in flames. One objective of this workshop was to stimulate discussions between these two scientific communities. During the preparation of the meeting, and especially during the review process by the Material Science Committee of the Scientific Affairs Division of N.A.T.O. the toxicological aspect emerged as being an important component to be addressed during the workshop. To reflect these preoccupations we invited biologists, physical chemists and engineers, all leaders in their field. The final programme is a compromise of the different aspects of the subject and was divided in five sessions.
Author : Marc Hendrikus Franciscus Woolderink
Publisher :
Page : 147 pages
File Size : 45,13 MB
Release : 2014
Category :
ISBN : 9789036537117
Author : Paul A. Libby
Publisher :
Page : 12 pages
File Size : 45,51 MB
Release : 1995
Category : Combustion
ISBN :
Author : Lu-Yin Wang
Publisher :
Page : 0 pages
File Size : 14,77 MB
Release : 2019
Category :
ISBN :
Soot formation and evolution in relation with the flow fields were investigated experimentally in turbulent swirl-stabilized non-premixed flames using three different fuels: methane, ethanol and aviation Jet A-1. The studied flames were confined and stabilized in a model gas turbine combustor with a swirl number of ~0.55. Soot volume fraction, fv, and primary soot particle size, dp, were measured using auto-compensating laser-induced incandescence, and planar three-component velocity fields were measured using stereoscopic particle image velocimetry. Measurements of planar laser-induced fluorescence of OH and OH* chemiluminescence were also made for methane and ethanol flames. The OH* field was further Abel-inverted to qualitatively locate the heat release zone. The flow field for all flames featured pronounced inner and outer recirculation zones (IRZ, ORZ), each bounded by their corresponding inner and outer shear layers (ISL, OSL). Abel-inverted OH* intensity maps showed that primary reaction zones occurred in the vicinity of ISL. The central fuel jet penetrating into the IRZ accompanied by a stagnation zone was observed in all methane flames. Soot measurements showed that the overall dp for methane and Jet A-1 flames ranged between 30 nm and 60 nm without discernible trends. In methane flames, peak time-averaged fv occurred between the central jet penetration and the ISL. The decrease and the final disappearance of time-averaged fv were strongly correlated with elevated OH, demonstrating a dominant oxidative attack of OH on soot. With a ~7% increase in air flow rate, the level of soot volume fraction dropped by nearly threefold due to enhanced turbulence intermittency. The appearance of ethanol spray flames, which lacked a bright yellow color, largely differed from others. The absence of soot was confirmed in the laser-induced incandescence measurements. The isothermal flow field of ethanol flames exhibited a large-scale structure of precessing vortex core which was then suppressed under reacting conditions. In Jet A-1 flames, spray pattern changed from V-shaped hollow cone to semi-solid cone when air flow rate increased by 20%, resulting in a 60% reduction in peak time-averaged fv. In contrast to results obtained from the methane flame, soot was found primarily outside the ISL where fuel existed in abundance.
