Download or read book Experimental Studies on Flow Field and Flame Stabilization of a Premixed Reacting Jet in Vitiated Crossflow written by Jason Allen Wagner and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Studies on Flow Field and Flame Stabilization of a Premixed Reacting Jet in Vitiated Crossflow written by Jason Allen Wagner and published by . This book was released on 2016 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Field and Mixing Characteristics of Multiple Reacting Jets in Vitiated Crossflow written by George M. Lapaan and published by . This book was released on 2014 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unsteady Combustor Physics written by Tim C. Lieuwen and published by Cambridge University Press. This book was released on 2021-10-21 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Characterization of the Reacting Jet of a High pressure Axially Staged Combustor written by Tommy Genova (Jr.) and published by . This book was released on 2020 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emissions, flame behavior, and flow-field characteristics of a high-pressure reacting jet-in-crossflow are experimentally studied at industry-relevant conditions. An experimental facility consisting of a headend burner, optically accessible test section, and converging exit nozzle is designed, manufactured, and operated over a wide range of conditions for the study. The axial stage consists of an injector that can be modified into three configurations: fully premixed, partially premixed, and non-premixed. Particle image velocimetry (PIV) is used to obtain flow-field dynamics, high-speed CH* chemiluminescence is leveraged to analyze flame characteristics, and emission measurements are made at the exit of the facility to quantify nitrogen oxides (NO[subscript x]), and carbon monoxide (CO) emissions. These measurement techniques provide insight into flame-flow field interaction, the effects of injector geometry on flame liftoff and stabilization, jet trajectories in the presence of heat release, and how flame stabilization mechanisms affect emissions. The results show for a non-premixed configuration, the flame is lifted further downstream and burns at its core compared to the fully premixed configuration. The results also demonstrate these highly lifted flames provide a significant improvement in NO[subscript x] formation of the axial stage. For conditions where the flame ignites near the jet exit, the jet centerline is pushed further into the crossflow compared to jets where the flame is lifted further downstream. A jet trajectory correlation that accounts for pressure and heat release is proposed.

Download or read book Flame and Emissions Characteristics of a High pressure Reacting Jet in Vitiated Crossflow written by Michelle Otero and published by . This book was released on 2020 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this work was to provide more insight in the jet in crossflow interaction at relevant operating conditions found in a gas turbine. The first part of this work focus on understanding the influence of pressure on the jet in crossflow mechanism as well as and the effect on NOx levels. Jet conditions such equivalence ratio and momentum flux ratios were held constant throughout the study with the pressure of the system ranging from 1atm to 5atm. The flow structure and flame stabilization of the jets at different pressures were characterized using particle image velocimetry (PIV) and CH* chemiluminescence.

Download or read book Stabilization and Dynamic of Premixed Swirling Flames written by Paul Palies and published by Academic Press. This book was released on 2020-07-03 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book The Effects of Fiscal Policies when Incomes are Uncertain written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unsteady Combustor Physics written by Tim C. Lieuwen and published by Cambridge University Press. This book was released on 2012-08-27 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book An Experimental Study of Flame Stabilization Mechanisms in Turbulent Non premixed Jet Flames Under Autoignitive Conditions written by Aravind Ramachandran and published by . This book was released on 2019 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure of Hydrogen rich Transverse Jets in a Vitiated Turbulent Flow written by and published by . This book was released on 2014 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our paper reports the results of a joint experimental and numerical study of the flow characteristics and flame structure of a hydrogen rich jet injected normal to a turbulent, vitiated crossflow of lean methane combustion products. Simultaneous high-speed stereoscopic PIV and OH PLIF measurements were obtained and analyzed alongside three-dimensional direct numerical simulations of inert and reacting JICF with detailed H2/COH2/CO chemistry. Both the experiment and the simulation reveal that, contrary to most previous studies of reacting JICF stabilized in low-to-moderate temperature air crossflow, the present conditions lead to a burner-attached flame that initiates uniformly around the burner edge. Significant asymmetry is observed, however, between the reaction zones located on the windward and leeward sides of the jet, due to the substantially different scalar dissipation rates. The windward reaction zone is much thinner in the near field, while also exhibiting significantly higher local and global heat release than the much broader reaction zone found on the leeward side of the jet. The unsteady dynamics of the windward shear layer, which largely control the important jet/crossflow mixing processes in that region, are explored in order to elucidate the important flow stability implications arising in the inert and reacting JICF. The paper concludes with an analysis of the ignition, flame characteristics, and global structure of the burner-attached flame. FurthermoreChemical explosive mode analysis (CEMA) shows that the entire windward shear layer, and a large region on the leeward side of the jet, are highly explosive prior to ignition and are dominated by non-premixed flame structures after ignition. The predominantly mixing limited nature of the flow after ignition is examined by computing the Takeno flame index, which shows that ~70% of the heat release occurs in non-premixed regions.

Download or read book Near Field Mixing Characteristics of a Variable Density Non Reacting Jet in a Hot Vitiated Crossflow written by Kyle T Linevitch (Jr) and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mixing characteristics in the "extreme" near field of a non-reacting jet in crossflow were experimentally investigated in an environment relevant to gas turbine combustors. A turbulent jet was injected into a hot vitiated crossflow of combustion products at 1500K. Different jet-to-crossflow momentum flux ratios and jet-to-crossflow density ratios were studied using three different jet exit velocity profiles; a fully developed turbulent pipe flow with 4% turbulence intensity (TI), a top-hat flow with 8% TI, and a turbulent pipe-like flow with 40% TI. Center-plane scalar mixing of the jet and crossflow were investigated using measured temperature fields from planar laser Rayleigh scattering. Jet trajectory, centerline concentration decay, scalar dissipation and mixing time scales were determined as a function of the above-mentioned jet parameters to characterize the jet-crossflow mixing characteristics. The observed center-plane mixing metrics indicated that better near field mixing was exhibited for lower values of the momentum flux ratio and larger values of density ratio. As the momentum flux ratio increased, windward and leeward mixing decreased. The magnitude of scalar dissipation in the windward region decreased as the momentum flux increased, while the leeward dissipation region increased in size and magnitude as momentum flux ratio increased. When the density ratio was decreased, both the windward and leeward dissipation regions reduced in size and magnitude. The top-hat and turbulent pipe jet exit velocity profiles displayed similar mixing characteristics while the 40% TI profile exhibited deeper jet penetration, slower centerline concentration decay rates, and lower scalar dissipation.

Download or read book Reacting Flow Studies in a Dump Combustor written by Alison Anne Behrens and published by . This book was released on 2007 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Acoustically Forced Non premixed Jet Flames in Crossflow written by Kevin Chek-Shing Marr and published by . This book was released on 2011 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented here discusses the effects of strong acoustic forcing on jet flames in crossflow (JFICF) and the physical mechanisms behind theses effects. For forced non-premixed JFICF, the jet fuel flow is modulated using an acoustic speaker system, which results in a drastic decrease in flame length and soot luminosity. Forced JFICF are characterized by periodic ejections of high-momentum, deeply penetrating vortical structures, which draws air into the jet nozzle and enhances mixing in the nearfield region of the jet. Mixture fraction images of the non-reacting forced jet in crossflow are obtained from acetone planar laser-induced fluorescence and show that the ejected jet fluid is effectively partially premixed. Flame luminosity images and exhaust gas measurements show that forced non-premixed JFICF exhibit similar characteristics to unforced partially-premixed JFICF. Both strong forcing and air dilution result in net reductions in NOx, but increases in CO and unburned hydrocarbons. NOx scaling analysis is presented for both forced non-premixed and unforced partially-premixed flames. Using flame volume arguments, EINOx scales with amplitude ratio for forced non- premixed flames, but does not scale with air dilution for unforced partially-premixed flames. The difference in scaling behavior is attributed to differences in flame structure. The effect of forcing on the flowfield dynamics of non-premixed JFICF is investigated using high-speed stereoscopic particle image velocimetry and luminosity imaging. The frequency spectra of the windward and lee-side flame base motions obtained from luminosity movies of the forced JFICF show a peak at the forcing frequency in the lee-side spectrum, but not on the windward-side spectrum. The lee-side flame base responds to the forcing frequency because the lee-side flame base stabilizes closer to the jet exit. The windward-side flame base does not respond to the forcing frequency because the integrated effect of the incident crossflow and vortical ejections leads to extinction of the flame base. From the PIV measurements, flowfield statistics are conditioned at the flame base. The local gas velocity at the flame base did not collapse for forced and unforced JFICF and was found to exceed 3SL. The flame propagation velocity was determined from the motion of the flame base, which is inferred from regions of evaporated seed particles in the time-resolved PIV images. The flame propagation velocity collapses for forced and unforced JFICF, which implies that the flame base is an edge flame; however, the most probable propagation velocity, approximately 2-3SL, is larger than propagation velocity predicted by edge flame theories. A possible explanation is that the flame propagation is enhanced by turbulent intensities and flame curvature.

Download or read book An Experimental Investigation of Jet Diffusion Flames written by Ho-Nam Bang and published by . This book was released on 1996 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flame Stabilization of a Premixed Jet in Vitiated Coflow written by Tyler Cameron Owens and published by . This book was released on 2020 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Stabilization of Hydrogen rich Transverse written by and published by . This book was released on 2014 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper reports the results of a joint experimental and numerical study of the ow characteristics and flame stabilization of a hydrogen rich jet injected normal to a turbulent, vitiated cross ow of lean methane combustion products. Simultaneous high-speed stereoscopic PIV and OH PLIF measurements were obtained and analyzed alongside three-dimensional direct numerical simulations of inert and reacting JICF with detailed H2/CO chemistry. Both the experiment and the simulation reveal that, contrary to most previous studies of reacting JICF stabilized in low-to-moderate temperature air cross ow, the present conditions lead to an autoigniting, burner-attached flame that initiates uniformly around the burner edge. Significant asymmetry is observed, however, between the reaction zones located on the windward and leeward sides of the jet, due to the substantially different scalar dissipation rates. The windward reaction zone is much thinner in the near field, while also exhibiting significantly higher local and global heat release than the much broader reaction zone found on the leeward side of the jet. The unsteady dynamics of the windward shear layer, which largely control the important jet/cross flow mixing processes in that region, are explored in order to elucidate the important flow stability implications arising in the reacting JICF. Vorticity spectra extracted from the windward shear layer reveal that the reacting jet is globally unstable and features two high frequency peaks, including a fundamental mode whose Strouhal number of ~0.7 agrees well with previous non-reacting JICF stability studies. The paper concludes with an analysis of the ignition, ame stabilization, and global structure of the burner-attached flame. Chemical explosive mode analysis (CEMA) shows that the entire windward shear layer, and a large region on the leeward side of the jet, are highly explosive prior to ignition and are dominated by non-premixed flame structures after ignition. The predominantly mixing limited nature of the flow after ignition is confirmed by computing the Takeno flame index, which shows that ~70% of the heat release occurs in non-premixed regions.