Investigation Of Blowoff Mechanism And Forced Response Of Bluff Body Stabilized Turbulent Premixed Flames
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Investigation Of Blowoff Mechanism And Forced Response Of Bluff Body Stabilized Turbulent Premixed Flames
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Author : Swetaprovo Chaudhuri
language : en
Publisher:
Release Date : 2010
Investigation Of Blowoff Mechanism And Forced Response Of Bluff Body Stabilized Turbulent Premixed Flames written by Swetaprovo Chaudhuri and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Experimental Investigation Of The Dynamics And Blowoff Characteristics Of Bluff Body Stabilized 2d V Shaped Turbulent Premixed Flames With Different Gaseous Hydrocarbon Fuels
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Author : Rishi Roy
language : en
Publisher:
Release Date : 2018
Experimental Investigation Of The Dynamics And Blowoff Characteristics Of Bluff Body Stabilized 2d V Shaped Turbulent Premixed Flames With Different Gaseous Hydrocarbon Fuels written by Rishi Roy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Electronic dissertations categories.
Phase Resolved Characterization Of Conical Turbulent Premixed Flames
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Author : Sayan Biswas
language : en
Publisher:
Release Date : 2012
Phase Resolved Characterization Of Conical Turbulent Premixed Flames written by Sayan Biswas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Experimental Investigation On The Effects Of Free Stream Turbulence And Fuel Type On Structure And Blowoff Characteristics Of Turbulent Premixed Bluff Body Stabilized Flames
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Author : Bikram Roy Chowdhury
language : en
Publisher:
Release Date : 2017
Experimental Investigation On The Effects Of Free Stream Turbulence And Fuel Type On Structure And Blowoff Characteristics Of Turbulent Premixed Bluff Body Stabilized Flames written by Bikram Roy Chowdhury and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Electronic dissertations categories.
An experimental investigation on the effect of different levels of turbulence intensity and properties of the fuel/air mixture on the structure and characteristics of lean flames stabilized on an axisymmetric bluff body is described in this thesis. Simultaneous imaging of hydroxyl (OH) and formaldehyde (CH2O) by planar laser induced fluorescence and particle image velocimetry (PIV) were used to study the interaction between the flame and the flow field. CH2O fluorescence and the pixel-by-pixel multiplication of OH and CH2O fluorescence signals were utilized to mark preheat and heat release regions respectively. In addition, high-speed chemiluminescence imaging was performed to understand the time resolved characteristics of the flame. The first part of the thesis focuses on the characteristics of stably burning lean methane/-, propane/- and ethylene/air flames when subjected to low (4 %), moderate (14 %) and intense (24 and 30%) levels of free stream turbulence. The flame front structure was observed to be strongly dependent on the free stream turbulence level of the incoming fuel/air mixture as well on the properties of the fuel/air mixture. Formation of cusps and unburnt mixture fingers were observed as the turbulence intensity was increased from 4 to 14 % but, the heat release region remained continuous. Under intense turbulence conditions, methane/- and ethylene/air (f = 0.85) flames exhibited localized extinctions along the flame sheet and flamelet merging events which created isolated pockets of reactants in the flame envelope. In addition to these features, propane/- and ethylene/air (f=0.655) flames exhibited the occurrence of flame fragmentation events and the general shape of these flames were observed to intermittently switch from a symmetric (varicose) to asymmetric (sinuous) mode. Several properties were measured to characterize the effects of turbulence – flame interaction which includes the average preheat and reaction zone thicknesses, strain rates and curvature along the flame front, burning fraction, flame brush thickness, flame surface density, area ratio and turbulent flame speed. The next part of the thesis focuses on blowoff dynamics of lean methane/-, propane/- and ethylene/air flames for mean velocities of 5, 10 and 15 m/s and subjected to free stream turbulence levels from 4 to 30%. Apart from the propane/air flames at an apporach velcoity of 5 m/s and turbulence intensity of 30 %, increasing turbulence intensity was found to reduce the flame stability. The blowoff equivalence ratios of propane/air flames was observed to be higher than methane/- and ethylene/air flames. As blowoff was approached, the flame front and shear layer vortices entangled inducing high local strain rates on the flame front that exceed the extinction strain rate resulting in significant breaks along the reaction zone. At conditions near blowoff, significant increase in the frequency of breaks along the reaction zone was observed for low and moderate turbulence conditions. For the higher turbulence conditions, fragmentation of the flame along with the presence of sinuous wakes was observed which aided in the penetration of reactants into the recirculation zone. Velocity vectors near the flame holes indicate the penetration of the reactants into the recirculation zone. Mostly similar sequence of events was observed for methane/-, propane/- and ethylene/air flames near blowoff. Several properties weremeasured to characterize the near blowoff flames which include the strain rate and curvature statistics along the flame front, burning fraction, asymmetric index and the average duration of the blowoff event. Based on the observation from the experiments, turbulent flame speed was attributed to be the primary factor in governing the blowoff equivalence ratio. This point of view was examined by comparing the mean strain rate of methane/- and ethylene/air flames at the equivalence ratio corresponding to near blowoff for propane/air flames.
Thermoacoustic Combustion Instability Control
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Author : Dan Zhao
language : en
Publisher: Academic Press
Release Date : 2023-02-13
Thermoacoustic Combustion Instability Control written by Dan Zhao and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-02-13 with Technology & Engineering categories.
Thermoacoustic Combustion Instability Control: Engineering Applications and Computer Codes provides a unique opportunity for researchers, students and engineers to access recent developments from technical, theoretical and engineering perspectives. The book is a compendium of the most recent advances in theoretical and computational modeling and the thermoacoustic instability phenomena associated with multi-dimensional computing methods and recent developments in signal-processing techniques. These include, but are not restricted to a real-time observer, proper orthogonal decomposition (POD), dynamic mode decomposition, Galerkin expansion, empirical mode decomposition, the Lattice Boltzmann method, and associated numerical and analytical approaches. The fundamental physics of thermoacoustic instability occurs in both macro- and micro-scale combustors. Practical methods for alleviating common problems are presented in the book with an analytical approach to arm readers with the tools they need to apply in their own industrial or research setting. Readers will benefit from practicing the worked examples and the training provided on computer coding for combustion technology to achieve useful results and simulations that advance their knowledge and research. Focuses on applications of theoretical and numerical modes with computer codes relevant to combustion technology Includes the most recent modeling and analytical developments motivated by empirical experimental observations in a highly visual way Provides self-contained chapters that include a comprehensive, introductory section that ensures any readers new to this topic are equipped with required technical terms
Unsteady Combustor Physics
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Author : Tim C. Lieuwen
language : en
Publisher: Cambridge University Press
Release Date : 2012-08-27
Unsteady Combustor Physics written by Tim C. Lieuwen 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 2012-08-27 with Technology & Engineering categories.
Developing clean, sustainable energy systems is a pre-eminent issue of our time. Most projections indicate that combustion-based energy conversion systems will continue to be the predominant approach for the majority of our energy usage. Unsteady combustor issues present the key challenge associated with the development of clean, high-efficiency combustion systems such as those used for power generation, heating or propulsion applications. This comprehensive study is unique, treating the subject in a systematic manner. Although this book focuses on unsteady combusting flows, it places particular emphasis on the system dynamics that occur at the intersection of the combustion, fluid mechanics and acoustic disciplines. Individuals with a background in fluid mechanics and combustion will find this book to be an incomparable study that synthesises these fields into a coherent understanding of the intrinsically unsteady processes in combustors.
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.
Unsteady Combustor Physics
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Author : Tim C. Lieuwen
language : en
Publisher: Cambridge University Press
Release Date : 2012-08-27
Unsteady Combustor Physics written by Tim C. Lieuwen 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 2012-08-27 with Science categories.
This book deals with unsteady combustor issues, which have posed key challenges associated with development of clean, high-efficiency combustion systems.
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.
Stabilization Of An Unconfined Flame By A Bluff Body
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Author : Jean R. Hertzberg
language : en
Publisher:
Release Date : 1986
Stabilization Of An Unconfined Flame By A Bluff Body written by Jean R. Hertzberg and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with categories.