Blowoff Characteristics In Interacting Premixed V Flames

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Blowoff Characteristics In Interacting Premixed V Flames

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Author : Joseph Crane
language : en
Publisher:
Release Date : 2015

Blowoff Characteristics In Interacting Premixed V Flames written by Joseph Crane 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.

Flame interaction is a common phenomenon in many common combustion applications thatcan have a leading order effect on flame stabilization. In particular, flame stabilization is a key performance metric in low-emissions gas turbine engines for both aircraft and power generation applications. In this study, we explore the impact flame interaction on blowoff characteristics and flame shape on three two-dimensional bluff-body stabilized flames by varying the spacing between the bluff bodies and the velocity of the incoming flow. Flame locations are extracted from particle image velocimetry (PIV) data to study the differences in blowoff limits between two different bluff-body spacing configurations all at the same entering bulk flow velocity. Increasing the flame spacing led to wider flamesand less interaction. Geometric and flow profile effects are discussed with respect to flame interaction and blowoff phenomena.

Blow Off Characteristics Of Conical Premixed Flames Subjected To Upstream Velocity Modulations

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Author : Andres Arturo Chaparro
language : en
Publisher:
Release Date : 2004

Blow Off Characteristics Of Conical Premixed Flames Subjected To Upstream Velocity Modulations written by Andres Arturo Chaparro and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

Blowoff Characteristics Of Partially Premixed Flames Of Prevaporized Blends Of Biofuels And Petroleum Fuels

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Author : Tonči Maleta
language : en
Publisher:
Release Date : 2017

Blowoff Characteristics Of Partially Premixed Flames Of Prevaporized Blends Of Biofuels And Petroleum Fuels written by Tonči Maleta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Biodiesel fuels 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.

Experimental Study Of Turbulent Premixed Combustion In V Shaped Flames

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Author : Sina Kheirkhah
language : en
Publisher:
Release Date : 2016

Experimental Study Of Turbulent Premixed Combustion In V Shaped Flames written by Sina Kheirkhah and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

Characteristics of turbulent premixed flames were investigated experimentally. The investigations were performed using Mie scattering, Particle Image Velocimetry, Rayleigh scattering, and broad-band luminosity imaging techniques. Methane-air flames associated with a relatively wide range of turbulence intensities, fuel-air equivalence ratios, and mean bulk flow velocities were investigated. For a relatively moderate value of turbulence intensity, a new concept is introduced and utilized to provide a detailed description associated with interaction of turbulent flow and flame front. The concept pertains to reactants velocity estimated at the vicinity of the flame front and is referred to as the edge velocity. Specifically, it is shown that fluctuations of the flame front position are induced by fluctuations of the edge velocity. For a relatively wide range of turbulence intensity, several characteristics of turbulent premixed flames, namely, front topology, brush thickness, surface density, and consumption speeds are investigated. For the first time, several flame front structures are identified and studied. It is shown that, due to formation of these front structures, the regime of turbulent premixed combustion transitions from the regime of counter-gradient diffusion to that of the gradient diffusion. In addition to these, a comprehensive study is performed to investigate influence of flame configuration on several flame front characteristics. It is obtained that, although changing the flame configuration influences several flame characteristics, the trends associated with the effects of governing parameters on the characteristics are nearly independent of the flame configuration.

Stabilization And Dynamic Of Premixed Swirling Flames

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Author : Paul Palies
language : en
Publisher: Academic Press
Release Date : 2020-07-03

Stabilization And Dynamic Of Premixed Swirling Flames written by Paul Palies and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-07-03 with Technology & Engineering categories.

Stabilization and Dynamic of Premixed Swirling Flames: Prevaporized, Stratified, Partially, and Fully Premixed Regimes focuses on swirling flames in various premixed modes (stratified, partially, fully, prevaporized) for the combustor, and development and design of current and future swirl-stabilized combustion systems. This includes predicting capabilities, modeling of turbulent combustion, liquid fuel modeling, and a complete overview of stabilization of these flames in aeroengines. The book also discusses the effects of the operating envelope on upstream fresh gases and the subsequent impact of flame speed, combustion, and mixing, the theoretical framework for flame stabilization, and fully lean premixed injector design. Specific attention is paid to ground gas turbine applications, and a comprehensive review of stabilization mechanisms for premixed, partially-premixed, and stratified premixed flames. The last chapter covers the design of a fully premixed injector for future jet engine applications. Features a complete view of the challenges at the intersection of swirling flame combustors, their requirements, and the physics of fluids at work Addresses the challenges of turbulent combustion modeling with numerical simulations Includes the presentation of the very latest numerical results and analyses of flashback, lean blowout, and combustion instabilities Covers the design of a fully premixed injector for future jet engine applications

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.

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.

Dynamics Of Interacting Turbulent Flames

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Author : Ankit Tyagi
language : en
Publisher:
Release Date : 2019

Dynamics Of Interacting Turbulent Flames written by Ankit Tyagi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.

This dissertation investigates the physics of interactions between turbulent premixed flames. It is known that multiple flame configurations provide better stability characteristics compared to a large single-flame. However, the advantages of multiple flames are limited by flame proximity as flame-flame interactions tend to reduce the burning efficiency of the reactant gases. Previous studies have shown that interactions between multiple flames directly impact the flame structure and its propagation, resulting in reduced burning efficiency. Previous experimental studies of interacting flames addressed flame-flame interactions investigating their effects on combustor stability and efficiency from a global perspective. However, the local flame-flame interaction physics was not addressed comprehensively, in part because these studies were limited to specific flow and flame configurations. In particular, these studies focused on swirling flames in bluff-body configurations typical of modern combustor geometries. Furthermore, these studies lacked flowfield measurements and were limited to flame structure and heat release rate measurements due to the complex nature of the experimental configurations. Much of the work to date on understanding the local physics of interactions comes from direct numerical simulations (DNS), but these studies treated idealized configurations of limited practical utility.To bridge these two gaps, an experimental investigation of flame-flame interactions was performed using a dual-burner rig, composed of two flames, built to facilitate precise variations in flame spacing. This rig was designed to operate in different configurations. These facilitated the focus on local interaction physics. In particular, the rig was built to study interacting V-flames and Bunsen flames. Moreover, the design of the dual-burners permitted conducting studies of nonreacting flow interactions with flames to better understand local physics of the flame. Direct flame and flow measurements were performed to characterize the mutual interaction of flame and the local flowfield. In particular, flame structure and flow were characterized using synchronized OH-planar laser-induced fluorescence (OH-PLIF) and stereoscopic-particle image velocimetry (s-PIV). These measurements were performed at a sampling rate of 10 kHz to obtain converged statistics on flame-flame interactions. A novel image processing technique was implemented for robust detection and characterization of flame-flame interaction events from OH-PLIF images.Using this experimental approach, the following studies were conducted: i) effects of flame spacing on flame structure of interacting V-flames, ii) effects of multiple flames on frequency, topology, and orientation of local flame-flame interactions, iii) effects of high mean-shear flow on flame-flame interactions, and iv) effects of pocket formation on flame dynamics. In the first study, flame spacing variations in V-flames were found to directly impact flame attachment. For smaller flame spacings, recirculation of hot combustion products near the bluff-bodies facilitated a secondary flame branch attachment in the shear layers in the interaction regions. For larger flame spacing, the secondary attachment became intermittent, indicating that closer flame spacing resulted in better attachment and stability characteristics for these flames. In the second study, the presence of adjacent flames was found to directly impact the frequencies of flame-flame interaction events. Dual-flames showed lower reactant-side interactions rates and higher product-side interactions rates when compared with single-flames. For dual-flames, comparisons between interaction orientation and local strain rate orientation showed that compressive forces led to flame front merging or pinch-off. The third study, which focused on how mean shear affects the local flame dynamics, found that high-mean shear flows entrained the flame away from the center of the burner. This entrainment directly reduced interaction event frequencies along the flame branch closest to the high mean-shear flow, while interaction event frequency in the other branch increased. Finally, flame pocket formation was investigated and results showed that a majority of the reactant pockets burned-out, while a majority of the product pockets merged with the flame surface. These results suggested that pocket behavior in turbulent flames can change local flame dynamics and it is important to capture these effects to accurately predict flame behavior. Additionally, limitations of planar high-speed imaging techniques were explored and a statistical framework, using probabilistic models, was presented in the context of reactant pocket propagation. The outcome of this work provided improved uncertainty estimation for planar measurements in three-dimensional flows.This experimental investigation provided deeper insights into the local physics of flame-flame interactions, in practical configurations, using detailed flame and flow measurements. The presence of adjacent flames influenced the attachment characteristics and local flame structure that directly impacted the stability of these multiple flame configurations. Local compressive forces facilitated the occurrence of these events, highlighting the importance of changes to the flowfield due to adjacent flames. Pocket formation, which directly affected reactant gas burning efficiency, was found to occur frequently. Taken together, these results provided comprehensive insights into the effects of flame-flame interactions that enhance our understanding of the nature of interacting flames.

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.