A Multi Dimensional Flamelet Model For Ignition In Multi Feed Combustion Systems
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A Multi Dimensional Flamelet Model For Ignition In Multi Feed Combustion Systems
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Author : Eric Michael Doran
language : en
Publisher: Stanford University
Release Date : 2011
A Multi Dimensional Flamelet Model For Ignition In Multi Feed Combustion Systems written by Eric Michael Doran and has been published by Stanford University this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
This work develops a computational framework for modeling turbulent combustion in multi-feed systems that can be applied to internal combustion engines with multiple injections. In the first part of this work, the laminar flamelet equations are extended to two dimensions to enable the representation of a three-feed system that can be characterized by two mixture fractions. A coupling between the resulting equations and the turbulent flow field that enables the use of this method in unsteady simulations is then introduced. Models are developed to describe the scalar dissipation rates of each mixture fraction, which are the parameters that determine the influence of turbulent mixing on the flame structure. Furthermore, a new understanding of the function of the joint dissipation rate of both mixture fractions is discussed. Next, the extended flamelet equations are validated using Direct Numerical Simulations (DNS) of multi-stream ignition that employ detailed finite-rate chemistry. The results demonstrate that the ignition of the overall mixture is influenced by heat and mass transfer between the fuel streams and that this interaction is manifested as a front propagation in two-dimensional mixture fraction space. The flamelet model is shown to capture this behavior well and is therefore able to accurately describe the ignition process of each mixture. To provide closure between the flamelet chemistry and the turbulent flow field, information about the joint statistics of the two mixture fractions is required. An investigation of the joint probability density function (PDF) was carried out using DNS of two scalars mixing in stationary isotropic turbulence. It was found that available models for the joint PDF lack the ability to conserve all second-order moments necessary for an adequate description of the mixing field. A new five parameter bivariate beta distribution was therefore developed and shown to describe the joint PDF more accurately throughout the entire mixing time and for a wide range of initial conditions. Finally, the proposed model framework is applied in the simulation of a split-injection diesel engine and compared with experimental results. A range of operating points and different injection strategies are investigated. Comparisons with the experimental pressure traces show that the model is able to predict the ignition delay of each injection and the overall combustion process with good accuracy. These results indicate that the model is applicable to the range of regimes found in diesel combustion.
A Multi Dimensional Flamelet Model For Ignition In Multi Feed Combustion Systems
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Author : Eric Michael Doran
language : en
Publisher:
Release Date : 2011
A Multi Dimensional Flamelet Model For Ignition In Multi Feed Combustion Systems written by Eric Michael Doran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
This work develops a computational framework for modeling turbulent combustion in multi-feed systems that can be applied to internal combustion engines with multiple injections. In the first part of this work, the laminar flamelet equations are extended to two dimensions to enable the representation of a three-feed system that can be characterized by two mixture fractions. A coupling between the resulting equations and the turbulent flow field that enables the use of this method in unsteady simulations is then introduced. Models are developed to describe the scalar dissipation rates of each mixture fraction, which are the parameters that determine the influence of turbulent mixing on the flame structure. Furthermore, a new understanding of the function of the joint dissipation rate of both mixture fractions is discussed. Next, the extended flamelet equations are validated using Direct Numerical Simulations (DNS) of multi-stream ignition that employ detailed finite-rate chemistry. The results demonstrate that the ignition of the overall mixture is influenced by heat and mass transfer between the fuel streams and that this interaction is manifested as a front propagation in two-dimensional mixture fraction space. The flamelet model is shown to capture this behavior well and is therefore able to accurately describe the ignition process of each mixture. To provide closure between the flamelet chemistry and the turbulent flow field, information about the joint statistics of the two mixture fractions is required. An investigation of the joint probability density function (PDF) was carried out using DNS of two scalars mixing in stationary isotropic turbulence. It was found that available models for the joint PDF lack the ability to conserve all second-order moments necessary for an adequate description of the mixing field. A new five parameter bivariate beta distribution was therefore developed and shown to describe the joint PDF more accurately throughout the entire mixing time and for a wide range of initial conditions. Finally, the proposed model framework is applied in the simulation of a split-injection diesel engine and compared with experimental results. A range of operating points and different injection strategies are investigated. Comparisons with the experimental pressure traces show that the model is able to predict the ignition delay of each injection and the overall combustion process with good accuracy. These results indicate that the model is applicable to the range of regimes found in diesel combustion.
3d Cfd Simulation Der Gemischbildung Verbrennung Und Emissionsentstehung Eines Hochdruck Gas Diesel Brennverfahrens
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Author : Alexandros Hatzipanagiotou
language : de
Publisher: Logos Verlag Berlin GmbH
Release Date : 2018-09-15
3d Cfd Simulation Der Gemischbildung Verbrennung Und Emissionsentstehung Eines Hochdruck Gas Diesel Brennverfahrens written by Alexandros Hatzipanagiotou and has been published by Logos Verlag Berlin GmbH this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-15 with Technology & Engineering categories.
Die Arbeit behandelt die Gemischbildung, Verbrennung und Emissionsentstehung eines Hochdruck-Gas-Diesel-Brennverfahrens mittels der 3D-CFD-Simulation. Als Basis dient eine Prozesskette zur Simulation der dieselmotorischen Verbrennung, welche für die Simulation des Hochdruck-Gas-Diesel-Brennverfahrens erweitert wird. Hierbei wird die Einblasung von Erdgas unter Hochdruck in den Brennraum sowie die Zündung, Verbrennung und Rußbildung von parallel vorliegendem Diesel und Erdgas modelliert. Darüber hinaus erfolgt eine im Vergleich zum Stand der Technik detailliertere Beschreibung der Strahl-Wand-Interaktion, um die Gemischbildung nach Auftreten der Gasstrahlen auf die Brennraumwand besser abzubilden. Die entwickelte Modellkette wird durch einen Vergleich mit Einzylindermessungen thermodynamisch validiert. Darüber hinaus findet eine lokale Validierung durch Vergleich mit Aufnahmen an einem optisch zugänglichen Einzylinderaggregat statt. Es zeigt sich, dass die Zündorte sowie Zündzeitpunkte der Gasstrahlen durch die Simulation unter allen betrachteten motorischen Randbedingungen sehr gut wiedergegeben werden können. Insbesondere ist die Simulation in der Lage, den Einfluss des Abstands zwischen Dieselvoreinspritzung und Gaseinblasung auf die Zündverzugszeit abzubilden. Darüber hinaus wird die Wirkung der Zündverzugszeit auf die Intensität der Vormischverbrennung für alle betrachteten Betriebspunkte gut vorhergesagt. Mit der entwickelten und validierten Simulationsmethodik kann kann die hohe Anzahl der Freiheitsgrade bei der Entwicklung des Hochdruck-Gas-Diesel-Brennverfahrens für minimalen Verbrauch und geringste Emission in einem sehr frühen Entwicklungsstadium optimiert werden.
Technical Literature Abstracts
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Author : Society of Automotive Engineers
language : en
Publisher:
Release Date : 1996
Technical Literature Abstracts written by Society of Automotive Engineers and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Technical literature categories.
Cumulative Index Of The Sae Papers
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Author : Society of Automotive Engineers
language : en
Publisher:
Release Date : 1965
Cumulative Index Of The Sae Papers written by Society of Automotive Engineers and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1965 with Engineering categories.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 1995
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Dissertations, Academic categories.
Turbulent Combustion
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Author : Norbert Peters
language : en
Publisher: Cambridge University Press
Release Date : 2000-08-15
Turbulent Combustion written by Norbert Peters and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000-08-15 with Science categories.
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.
International Aerospace Abstracts
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Author :
language : en
Publisher:
Release Date : 1998
International Aerospace Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Aeronautics categories.
Computational Fluid Dynamics 94
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Author : Siegfried Wagner
language : en
Publisher:
Release Date : 1994
Computational Fluid Dynamics 94 written by Siegfried Wagner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Engineering mathematics categories.
Chemical Abstracts
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Author :
language : en
Publisher:
Release Date : 2002
Chemical Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Chemistry categories.