Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 61 for “"Lean-Premixed"”.
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Lean Premixed Prevaporised Combustion for Microturbines
… strategy to meet these requirements is the lean premixed prevaporised (LPP) concept. Thus, this thesis explores the fuel flexibility, flame stability, structures, gas emissions, and droplet behaviour in LPP combustion at conditions relevant for microturbines. The first part of the thesis …
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Fuel Droplet Optical Diagnostic Techniques for Lean Premixed Prevaporized Aeroengine Combustors
… counterparts. One promising solution is the lean prevaporized premixed (LPP) combustor design, which shows potential for lowering emissions at supersonic conditions. An LPP combustor is designed to premix and prevaporize the fuel before combustion. In reality, not all the fuel vaporizes, …
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Digital Fuel Control for a Lean Premixed Hydrogen-Fueled Gas Turbine Engine
Hydrogen-powered engines have been gaining increasing interest due to the global concerns of the effects of hydrocarbon combustion on climate change. Gas turbines are suitable for operation on hydrogen fuel. This thesis reports the results of investigations of the special requirements of the fuel …
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An Investigation of Lean Premixed Hydrogen Combustion in a Gas Turbine Engine
… fuels, hydrogen is gaining more attention as a clean alternative. The combustion of hydrogen in air produces no carbon emissions. However, hydrogen-air combustion does have the potential to produce oxides of nitrogen (NOx), which are harmful pollutants. The production of NOx can be significantly …
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Experimental Investigation of a Lean, Premixed Gas Turbine Combustor Using Advanced Laser Diagnostics
Flame structure and stabilization were studied using planar laser-induced fluorescence of the hydroxyl radical. Four operating conditions were examined---two equivalence ratios, 0.6 and 0.7, and two combustor pressure drops, 3% and 5%. Time-resolved images were acquired at two axial locations for …
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Effects of curvature and strain on a lean premixed methane-hydrogen-air flame
… stability and extend flammability limits of lean premixed combustion in a number of recent experiments. It is suggested that these trends may be explained by the impact of hydrogen on the flame response to stretch and curvature. The elemental flame model is used to simulate premixed …
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Laser Diagnostics Applied to Lean Premixed Swirling Flames - Simultaneous Flow Field and Scalar Measurements
… reported here includes experimental studies of lean premixed swirling flames. Various laser-based optical diagnostic techniques were used to collect information under different operational conditions. Combined flow- and scalar field measurements were performed at high repetition rates for …
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Fuel/air Mixing and Nitrogen Oxide Formation in a Lean Premixed Gas Turbine Combustor
… to predict engine-out NOx concentrations for lean premixed combustors. The CRM model only requires information regarding the reactor loading, the combustor inlet state, and the combustor geometry. Model improvements were obtained by including the effects of reactant unmixedness based on the …
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A Lean-Premixed Hydrogen Injector with Vane Driven Swirl for Application in Gas Turbines
… has a wide range of flammability limits, fuel lean combustion can take place at lower equivalence ratios than those with typical hydrocarbon fuels. Numerous efforts have been made to develop gas turbine fuel injectors that premix methane/natural gas and air in fuel lean proportions prior to the …
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Numerical Analysis of Flow and Heat Transfer through a Lean Premixed Swirl Stabilized Combustor Nozzle
… driven thermal NOX also needs to be addressed. Lean premixed combustion has been found as one of the solutions to these objectives. However, since less amount of air is available for backside cooling of liner walls, it becomes very important to characterize the convective heat transfer that …
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Design and Evaluation of a Lean-Premixed Hydrogen Injector with Tangential Entry in a Sector Combustor
Hydrogen use in a gas turbine engine has many benefits. Chief among these is the elimination of carbon based emissions. The only products and emissions from the combustion process are water vapor and oxides of nitrogen (NOx). However due to the lower flammability limit of hydrogen, it can be burned …
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Conversion of a Gas Turbine Engine to Operate on Lean-Premixed Hydrogen-Air: Design and Characterization
… The purpose of this research was to design a lean premixed hydrogen fuel system that could be readily retrofit into an existing gas turbine engine to provide a clean renewable energy solution to this growing problem. There were major hurdles that had to be overcome to develop a hydrogen fuel …
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Swirl-stabilized lean-premixed flame combustion dynamics: An experimental investigation of flame stabilization, flame dynamics and combustion instability control strategies
… challenges in the development of next generation lean premixed combustor technology. Combustion instability is the coupling between unsteady heat release and combustor acoustic modes where one amplifies the other in a feedback loop. This is a complex phenomenon which involves unsteady chemical …
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experimental investigation of a reacting transverse jet in a high pressure oscillating vitiated crossflow
… of the air and fuel are injected downstream of a lean premixed low NOx primary combustion zone. The gas residence time at elevated temperatures is decreased resulting in lower thermal NOx, and the reduced oxygen and high temperature vitiated primary zone flow further help to reduce pollutant …
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LARGE EDDY SIMULATION OF TURBULENT HYDROGEN FLAMES
… These issues are particularly critical in lean premixed conditions, which are commonly used to limit emissions but lead to complex turbulence-chemistry interactions. This dissertation investigates turbulent hydrogen combustion using large eddy simulation (LES) combined with advanced …
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Modelling of turbulent stratified flames
… are increasingly being designed to operate in a lean premixed mode. However, the reduction in emissions offered by lean premixed combustion can be offset by its susceptibility to instabilities and ignition and extinction problems. These instabilities, caused by the coupling of unsteady heat …
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Suppression of thermoacoustic instabilities in a swirl combustor through microjet air injection
… of combustion instability by designing non-premixed combustors around a fixed operating point. Increasing trends toward lower emissions and greater fuel flexibility have placed more emphasis on developing lean-premixed combustors that are stable over a range of operating conditions. This …
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Active Stabilization of Thermoacoustic Oscillation
… to micro turbines and aeroplane engines. Lean premixed combustion offers a potential to reduce the emission levels, but suffers from instability problems which can be overcome by the use of active control. This thesis addresses the problem of actively controlling thermoacoustic …
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Experimental investigation on traversing hot jet ignition of lean hydrocarbon-air mixtures in a constant volume combustor
… Indianapolis (IUPUI) was used for this study. Lean premixed combustible mixture in a rectangular cuboid constant-volume combustor is ignited by a hot-jet traversing at different fixed speeds. The hot jet is issued via a converging nozzle from a cylindrical pre-chamber where partially combusted …
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