Interactions of Premixed Flames with Surfaces

Interactions of Premixed Flames with Surfaces PDF Author: Preeti Aghalayam
Publisher:
ISBN:
Category : Flame
Languages : en
Pages : 544

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Interactions of Premixed Flames with Surfaces

Interactions of Premixed Flames with Surfaces PDF Author: Preeti Aghalayam
Publisher:
ISBN:
Category : Flame
Languages : en
Pages : 544

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A Theoretical and Experimental Study of Preferential-diffusion/stretch Interactions of Laminar Premixed Flames

A Theoretical and Experimental Study of Preferential-diffusion/stretch Interactions of Laminar Premixed Flames PDF Author: Oh Chae Kwon
Publisher:
ISBN:
Category :
Languages : en
Pages : 536

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Turbulent Premixed Flames

Turbulent Premixed Flames PDF Author: Nedunchezhian Swaminathan
Publisher: Cambridge University Press
ISBN: 1139498584
Category : Technology & Engineering
Languages : en
Pages : 447

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Book Description
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.

Preferential-diffusion/stretch Interactions of Laminar Premixed Hydrogen/oxygen/nitrogen Flames

Preferential-diffusion/stretch Interactions of Laminar Premixed Hydrogen/oxygen/nitrogen Flames PDF Author: Kyaw Than Aung
Publisher:
ISBN:
Category :
Languages : en
Pages : 632

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Dynamics of Interacting Turbulent Flames

Dynamics of Interacting Turbulent Flames PDF Author: Ankit Tyagi
Publisher:
ISBN:
Category :
Languages : en
Pages :

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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.

Fundamentals of Premixed Turbulent Combustion

Fundamentals of Premixed Turbulent Combustion PDF Author: Andrei Lipatnikov
Publisher: CRC Press
ISBN: 1466510250
Category : Science
Languages : en
Pages : 548

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Book Description
Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine combustors. Yet researchers face several challenges in dealing with premixed turbulent combustion, from its nonlinear multiscale nature and the impact of local phenomena to the multitude of competing models. Filling

Unsteady Combustor Physics

Unsteady Combustor Physics PDF Author: Tim C. Lieuwen
Publisher: Cambridge University Press
ISBN: 1108841317
Category : Science
Languages : en
Pages : 533

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Book Description
Explore a unified treatment of the dynamics of combustor systems, including acoustics, fluid mechanics, and combustion in a single rigorous text. This updated new edition features an expansion of data and experimental material, updates the coverage of flow stability, and enhanced treatment of flame dynamics. Addresses system dynamics of clean energy and propulsion systems used in low emissions systems. Synthesizing the fields of fluid mechanics and combustion into a coherent understanding of the intrinsically unsteady processes in combustors. This is a perfect reference for engineers and researchers in fluid mechanics, combustion, and clean energy.

Joint Meeting of the U.S. Sections of the Combustion Institute, Western States, Central States, Eastern States

Joint Meeting of the U.S. Sections of the Combustion Institute, Western States, Central States, Eastern States PDF Author:
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 954

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Turbulence and Interactions

Turbulence and Interactions PDF Author: Michel Deville
Publisher: Springer Science & Business Media
ISBN: 3642002625
Category : Technology & Engineering
Languages : en
Pages : 166

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Book Description
Contains seven keynote lectures of the TI 2006 conference that was held in Porquerolles, May 29-June 2, 2006. This book offers a view on theory, experiments and numerical simulations in the field of turbulence.

A study of the interaction of flames and surfaces

A study of the interaction of flames and surfaces PDF Author: Gyan Prakash Tewari
Publisher:
ISBN:
Category :
Languages : en
Pages :

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