Direct Numerical Simulation Of Bluff Body Stabilized Flames
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Direct Numerical Simulation Of Bluff Body Stabilized Flames
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Author : Farzin Jalilalghadr
language : en
Publisher:
Release Date : 2007
Direct Numerical Simulation Of Bluff Body Stabilized Flames written by Farzin Jalilalghadr and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Direct numerical simulation (DNS) is used to study reacting and non-reacting bluff-body stabilized flows. Three fuel-to-air velocity ratios were considered. The results show that three types of flow fields can be identified. For the fuel-to-air velocity ratio of 0:84, the flow field is dominated by the reverse flow of the coflowing air. The jet does not penetrate through the reverse flow, and two stagnation points are formed on the centerline, where the jet and air stagnate. The downstream flow field is similar to a wake flow, and therefore this flow is referred to as a bluff-body dominant flow. For the fuel-to-air velocity ratio of 1:4, the flow field is neither dominated by the jet nor the coflowing air and is referred to as an intermittent flow. For the fuel-to-air velocity ratio of 2:8, the jet penetrates through the reverse flow and no stagnation point is formed. The flow field is similar to that of a pure jet, therefore this flow is referred to as a jet dominant flow. In all cases, the coflowing air converges towards the centerline and forms a recirculation zone that extends to approximately one bluff-body diameter downstream. For the reacting flow, the methane combustion is modeled via a global, 1-step kinetic mechanism. The main effects of combustion on the flow field are an increase in the length of the recirculation zone, and a decrease in the velocity fluctuations. Based on the three velocity ratios, three types of flames are produced. For the velocity ratio of 0:84, a short mushroom shaped flame is produced near the fuel stagnation point. For the velocity ratio of 1:4, a medium length flame is produced in the shear layer region between the fuel and air. The flame is anchored in the recirculation zone, and extends downstream of the bluff-body. For the velocity ratio of 2:8, a long flame is produced near the centerline and is also anchored in the recirculation zone. All three flames are stabilized between the coflowing air and the jet, where the strain-rates are low, and the mixture fraction is near the stoichiometric value for methane combustion.
Direct Numerical Simulation For Turbulent Reacting Flows
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Author : Thierry Baritaud
language : en
Publisher: Editions TECHNIP
Release Date : 1996
Direct Numerical Simulation For Turbulent Reacting Flows written by Thierry Baritaud and has been published by Editions TECHNIP this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Science categories.
Contents: Description of accurate boundary conditions for the simulation of reactive flows. Parallel direct numerical simulation of turbulent reactive flow. Flame-wall interaction and heat flux modelling in turbulent channel flow. A numerical study of laminar flame wall interaction with detailed chemistry: wall temperature effects. Modeling and simulation of turbulent flame kernel evolution. Experimental and theoretical analysis of flame surface density modelling for premixed turbulent combustion. Gradient and counter-gradient transport in turbulent premixed flames. Direct numerical simulation of turbulent flames with complex chemical kinetics. Effects of curvature and unsteadiness in diffusion flames. Implications for turbulent diffusion combustion. Numerical simulations of autoignition in turbulent mixing flows. Stabilization processes of diffusion flames. References.
Advances In Turbulent Combustion Dynamics Simulations In Bluff Body Stabilized Flames
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Author : Jonathan Michael Tovar
language : en
Publisher:
Release Date : 2015
Advances In Turbulent Combustion Dynamics Simulations In Bluff Body Stabilized Flames written by Jonathan Michael Tovar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
This work examines the three main aspects of bluff-body stabilized flames: stationary combustion, lean blow-out, and thermo-acoustic instabilities. For the cases of stationary combustion and lean blow-out, an improved version of the Linear Eddy Model approach is used, while in the case of thermo-acoustic instabilities, the effect of boundary conditions on the predictions are studied. The improved version couples the Linear Eddy Model with the full-set of resolved scale Large Eddy Simulation equations for continuity, momentum, energy, and species transport. In traditional implementations the species equations are generally solved using a Lagrangian method which has some significant limitations. The novelty in this work is that the Eulerian species concentration equations are solved at the resolved scale and the Linear Eddy Model is strictly used to close the species production term. In this work, the improved Linear Eddy Model approach is applied to predict the flame properties inside the Volvo rig and it is shown to over-predict the flame temperature and normalized velocity when compared to experimental data using a premixed single step global propane reaction with an equivalence ratio of 0.65. The model is also applied to predict lean blow-out and is shown to predict a stable flame at an equivalence ratio of 0.5 when experiments achieve flame extinction at an equivalence ratio of 0.55. The improved Linear Eddy Model is, however, shown to be closer to experimental data than a comparable reactive flow simulation that uses laminar closure of the species source terms. The thermo-acoustic analysis is performed on a combustor rig designed at the Air Force Research Laboratory. The analysis is performed using a premixed single step global methane reaction for laminar reactive flow and shows that imposing a non-physical boundary condition at the rig exhaust will result in the suppression of acoustic content inside the domain and can alter the temperature contours in non-physical ways. It can be concluded from this work that it is important to include the proper exhaust configuration for reacting thermo-acoustic calculations so that non-physical boundary conditions do not compromise the solution.
Experimental And Numerical Investigations Of Flames Stabilized By Swirl Flow And Bluff Body
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Author : Yiheng Tong
language : en
Publisher:
Release Date : 2017
Experimental And Numerical Investigations Of Flames Stabilized By Swirl Flow And Bluff Body written by Yiheng Tong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Modeling And Simulation Of Turbulent Combustion
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Author : Santanu De
language : en
Publisher: Springer
Release Date : 2017-12-12
Modeling And Simulation Of Turbulent Combustion written by Santanu De and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-12-12 with Science categories.
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.
Direct Numerical Simulations Of Strained Laminar And Turbulent Nonpremixed Flames
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Author : Chunsang Yoo
language : en
Publisher:
Release Date : 2005
Direct Numerical Simulations Of Strained Laminar And Turbulent Nonpremixed Flames written by Chunsang Yoo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Turbulent Premixed Flames
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Author : Nedunchezhian Swaminathan
language : en
Publisher: Cambridge University Press
Release Date : 2011-04-25
Turbulent Premixed Flames written by Nedunchezhian Swaminathan 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 2011-04-25 with Technology & Engineering categories.
A work on turbulent premixed combustion is important because of increased concern about the environmental impact of combustion and the search for new combustion concepts and technologies. An improved understanding of lean fuel turbulent premixed flames must play a central role in the fundamental science of these new concepts. Lean premixed flames have the potential to offer ultra-low emission levels, but they are notoriously susceptible to combustion oscillations. Thus, sophisticated control measures are inevitably required. The editors' intent is to set out the modeling aspects in the field of turbulent premixed combustion. Good progress has been made on this topic, and this cohesive volume contains contributions from international experts on various subtopics of the lean premixed flame problem.
Numerical Calculation Of The Cold Flow Characteristics Of A Bluff Body Flame Stabilizer
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Author : J. O. Ilegbusi
language : en
Publisher:
Release Date : 1984
Numerical Calculation Of The Cold Flow Characteristics Of A Bluff Body Flame Stabilizer written by J. O. Ilegbusi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1984 with Fluid mechanics categories.
A Detailed Investigation Of Bluff Body Stabilized Flames Postprint
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Author :
language : en
Publisher:
Release Date : 2007
A Detailed Investigation Of Bluff Body Stabilized Flames Postprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Reduced Order Models (ROMs) and Computational Fluid Dynamics (CFD) codes are tools used to predict the extinction of flames behind bluff bodies. Accurate prediction of these models and codes is predicated on their validation with experimental data. This paper describes detailed experiments to obtain validation data for bluff body stabilized flames over a wide range of conditions. Included are non-reacting data from CFD and LDV, lean blowout and high speed images for three different flame holders. In our previous paper (Kiel 2006) it was asserted that the large vortices were a major driver of extinction. Those assertions are further supported here. It is concluded that the vortex dynamics and not geometry is the dominant mechanism for bluff body flame extinction. This conclusion is supported by the lean blowout data, by the high speed images and reference data from NACA.
Coarse Grained Simulation And Turbulent Mixing
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Author : Fenando F. Grinstein
language : en
Publisher: Cambridge University Press
Release Date : 2016-06-30
Coarse Grained Simulation And Turbulent Mixing written by Fenando F. Grinstein 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 2016-06-30 with Science categories.
Reviews our current understanding of the subject. For graduate students and researchers in computational fluid dynamics and turbulence.