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Multidimensional Transport-Coupled Numerical Investigation Of Non-Premixed Low-Temperature Flame In Atmospheric And High-Pressure Systems, Sudipta Saha

Theses and Dissertations

Gas-phase chemical reactions coupled with multidimensional fluid flow and heat and mass transport are found in various applications, i.e., from conventional engine applications to novel combustion techniques. With the goal of understanding such complex coupling in reacting flow systems, this dissertation work focuses on developing multi-physics simulation frameworks to investigate the effect of multidimensional transport on flame dynamics. This study primarily focuses on the modeling and simulation of low temperature flame formation in i) a canonical experimental setting with counterflow burners and ii) a supercritical water medium (i.e., hydrothermal flame).

In the first part of the dissertation, simulations of the …

Computational Tools For Modeling And Simulation Of Sooting Turbulent Non-Premixed Flames, Victoria B. Stephens

Theses and Dissertations

Turbulent combustion systems are physically complex processes that involve many interdependent phenomena---including turbulent fluid dynamics, multi-component mass transfer, convective and radiative heat transfer, and multiphase flow---that occur over a wide range of length and time scales. Modeling and simulation studies complement experimental work by implementing and validating models and providing predictive capabilities, but current software tools are often limited by a lack of standardization and best practices, non-robust implementation, or over-specialization. Some topics in combustion CFD research, notably radiative heat transfer and soot modeling, are critically underrepresented in simulation studies as a result of software limitations. This project establishes and …

Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao

Theses and Dissertations

This dissertation introduces a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of flame response under acoustic modulation. The model is built upon the kinematic flame model–G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and ii) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc models …

Completion And Initial Testing Of A Pressurized Oxy-Coal Reactor, Scott Hunsaker Gardner

Theses and Dissertations

Oxy-combustion is a process which removes nitrogen from air prior to combustion in order to produce a high concentration of CO2 in the exhaust. This enables CO2 liquefaction, transport, and storage to greatly reduce CO2 emissions to the atmosphere. Atmospheric oxy-coal combustion has been successfully demonstrated at industrial scales and could be retrofit in existing coal boilers, but thermodynamic efficiencies are low and therefore uneconomical. Pressurized oxy-coal combustion has the potential for higher efficiency and lower cost but requires new technologies related to the coal feed system, the burner, and ash management. This project describes work needed to complete the …

Development Of A Converging-Channel Drop Tower For Sphere Symmetric Isolated Single Droplet Combustion, Nicholas Alexander Demaio

Theses and Dissertations

The dawn of a new Space Age is upon us; Microgravity combustion of hydrocarbon fuels is a popular method of research and characterization. This allows for a one-dimensional analysis by suppressing the buoyancy forces produced by gravity and the large temperature differential between the flame boundary and the surrounding air. The current testing methods are expensive and require extensive preparation on the researchers behalf. There is a need to investigate an alternative method that is inexpensive, repeatable, and comparable to the other approaches that coincides with the literature.

A low-cost converging-channel drop tower was designed and fabricated for sphero-symmetric single …

Detailed Chemical Mechanism Generation Of Oxygenated Biofuel, Shrabanti Roy

Theses and Dissertations

With the increase of global temperature and decrease of fossil fuel sources, biofuels become an excellent alternative in present days. Because of its oxygenated nature, biofuels are found to be more environmentally friendly over fossil fuels. Therefore, in this study, initially two different biofuels: ethanol and 2,5 dimethyl furan (DMF) are considered as an additive to gasoline which shows a significant improvement in its combustion characteristics. Due to this promising result for further studies of these biofuel, details chemical kinetic study of biofuels is considered in this work through generating its mechanism for engine relevant conditions. Detail chemical mechanism PCRL-Mech1 …

Nonwovens Of Ceramic Decorated Cellulose Based Fine Fibers For Leaded Water Purification, Alejandro J. Castillo

Theses and Dissertations

Fine fibers of cellulose acetate were Forcespun and used to make nonwoven mats of cellulose. Nonwovens were activated using a solution combustion synthesis which deposited iron nitride onto fibers. Cellulose and cellulose composite mats were tested as adsorbents for lead ion in water. Cellulose showed slightly higher adsorption capacities (mg/g) up to 1300 mg/g lead loading. Adsorption data were further analyzed using several isotherms, of which the Dubinin-Raduskevich gave the best fits.

Design And Analysis Of A Compact Combustor For Integration With A Jetcat P90 Rxi, Daniel Holobeny

Theses and Dissertations

Ultra Compact Combustors are a novel approach to modern gas turbine combustor designs that look to reduce the overall combustor length and weight. A previous study integrated an Ultra Compact Combustor into a JetCat P90 RXi turbine engine and achieved self-sustained operation with a length savings of 33% relative to the stock combustor. However, that combustor could not operate across the full stock engine performance range due to flameout at increased mass ow rates as reactions were pushed out of the primary zone. To ensure reactions stayed in the primary zone, a new design with a larger combustor volume was …

Detonation Confinement In A Radial Rotating Detonation Engine, Kavi Muraleetharan

Theses and Dissertations

Radial Rotating Detonation Engines (RRDE) have provided an opportunity for use of a pressure-gain combustor in a more compact form compared to an axial RDE. A successfully tested RRDE has operated over a wide range of test conditions and produced detonation modes with one, two, and three waves. The presence of multiple waves located the detonation waves to the outer radius, while one wave modes operated closer to the inner radius. Locating the detonation wave closer to the inner diameter resulted in less time for combustion prior to the radial turbine. Subsequently, this tended to decrease efficiency. To attempt to …

Burner Design For A Pressurized Oxy-Coal Reactor, William Cody Carpenter

Theses and Dissertations

The need for electric power across the globe is ever increasing, as is the need to produce electricity in a sustainable method that does not emit CO2 into the atmosphere. A proposed technology for efficiently capturing CO2 while producing electricity is pressurized oxy-combustion (POC). The objective of this work is to design, build, and demonstrate a burner for a 20 atmosphere oxy-coal combustor. Additionally, working engineering drawings for the main pressure vessel and floor plan drawings for the main pressure vessel, exhaust, and fuel feed systems were produced. The POC reactor enables the development of three key POC technologies: a …

Design, Fabrication And Testing Of A Pressurized Oxy-Coal Reactor Exhaust System, Aaron Bradley Skousen

Theses and Dissertations

One of the challenges facing engineers is to provide clean, sustainable, affordable and reliable electricity. One of the major pollutants associated with coal combustion is CO2. A proposed technology for efficiently capturing CO2 while producing electricity is pressurized oxy-combustion (POC). The first objective of this work is to design, build and demonstrate an exhaust system for a 20 atmosphere oxy-coal combustor. The second objective of this work is to design and build mounts for a two-color laser extinction method in the POC. The POC reactor enables the development of three key technologies: a coal dry-feed system, a high pressure burner, …

Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller

Theses and Dissertations

Recent progress has been made in demonstrating Radial Rotating Detonation Engine (RRDE) technology for use in a compact Auxiliary Power Unit with a rapid response time. Investigation of RRDEs also suggests an increase in stable operating range, which is hypothesized to be due to the additional degree of freedom in the radial direction which the detonation wave can propagate. This investigation seeks to determine if the detonation wave is in fact changing its radial location. High speed photography was used to capture chemiluminescence of the detonation wave within the channel to examine its radial location, which was found to vary …

Examination Of Flow Dynamics And Passive Cooling In An Ultra Compact Combustor, Tylor C. Rathsack

Theses and Dissertations

The Ultra Compact Combustor (UCC) promises to greatly reduce the size of a gas turbine engine’s combustor by altering the manner in which fuel is burnt. Differing from the common axial flow combustor, the UCC utilizes a rotating flow, coaxial to the engine’s primary axis, in an outboard circumferential cavity as the primary combustion zone. The present study investigates two key UCC facets required to further this combustor design. The first area of investigation is cooling of the Hybrid Guide Vane (HGV). This UCC specific hardware acts as a combustor center body that alters the exit flow angle and acts …

Thermochemical Conversion Of Biomass: Detailed Gasification And Near-Burner Co-Firing Measurements, Jacob B. Beutler

Theses and Dissertations

An increasing emphasis on mitigating global climate change (global warming) over the last few decades has created interest in a broad range of sustainable or alternative energy systems to replace fossil fuel combustion. Biomass, when harvested responsibly, is a renewable fuel with many uses in replacing fossil fuels. Cofiring biomass with coal in traditional large-scale coal power plants represents one of the lowest risk, least costly, near-term methods of CO₂ mitigation. Simultaneously, it is one of the most efficient and inexpensive uses of biomass. Alternatively, biomass can be transformed into useful products through gasification to produce clean syngas for …

Reconstruction Of The 3d Temperature And Species Concentration Spatial Distribution Of A Jet Engine Exhaust Plume Using An Infrared Fourier Transform Spectrometer Hyperspectral Imager, Mason D. Paulec

Theses and Dissertations

The measurement of combustion byproducts is useful for determining pollution of any fuel burning application, efficiency of combustion, and determining detectability of aircraft exhausts. Both intrusive and non-intrusive techniques have been utilized to measure these quantities. For the majority of the non-intrusive techniques, the absorption and emission spectra of the gases are utilized for measurements. For this research, the use of the Telops Infrared Fourier Transform Spectrometer (IFTS) Hyperspectral Imager (HSI) was explored within the scope of combustion diagnostic methods, as an option for remote measurements of a jet turbine to determine concentration of species and temperature of the combustion …

Combustion Dynamics And Heat Transfer In An Ultra Compact Combustor, Brian T. Bohan

Theses and Dissertations

The Ultra Compact Combustor (UCC) is an innovative combustion system alternative to a traditional turbine engine burner with the potential to improve engine efficiency with a reduced combustor volume. The UCC shortens the axial length of the combustor, and therefore reduces engine weight, by burning in an annulus and swirling the reactants in the circumferential direction. These length and weight improvements can directly lead to an increased thrust-to-weight rating of the engine. The present research included five objectives which advanced the UCC concept on four fronts; cooling UCC turbine vanes, advanced computational modeling of UCC systems, system air split control …

Microwave Plasma Assisted Ignition And Combustion Diagnostics, Che Amungwa Fuh

Theses and Dissertations

Plasmas when coupled to the oxidation process of various fuels have been shown to influence the process positively by improving upon flameholding, reduction in ignition delay time, reduced pollutant emission, etc. Despite all this positive effects being known to the science community, the mechanisms through which the plasmas effects all these enhancements are poorly understood. This is often due to the absence of accurate experimental data to validate theoretical mechanisms and the availability of a myriad sources of plasmas having different chemistries. The goal of this thesis is to further narrow the knowledge gap in the understanding of plasma assisted …

Alkyne Combustion: Experimental And Computational Studies Of Formyl Radical Production, Matthew Charles Drummer

Theses and Dissertations

The United States consumed a total of 97.4 trillion BTUs of energy in 2016 with over 80% of that energy consumption source being fossil fuel combustion. Before a combustion reactions reaches its end products, a number of intermediate products form and may react with other abundant atmospheric species to form aerosol particles and acid rain, both of which have potentially negative impacts on both human-made structures and the natural environment.

In an effort to counteract the consequences of fossil fuel combustion, scientists are interested in understanding the reaction mechanisms of hydrocarbon combustion reactions to understand which intermediate products form and …

Nox Formation In Syngas/Air Combustion, Nazli Asgari

Theses and Dissertations

Syngas is a reliable energy source derived from the gasification of coal and other solid fuels. The feedstock type and the production process of syngas can affect the composition of syngas. Gas turbines utilizing high hydrogen content (HHC) fuels like syngas for power generation applications need to meet stringent pollutant emission standards, particularly with respect to nitrogen oxides (NOx). For gas turbine conditions, reliable experimental data, especially at high-pressure, is necessary for both generating accurate NOx prediction models and improving reaction pathways regarding the NOx chemistry. In this study, NOx formation in post-flame gases of syngas combustion at different conditions …

Pollutant Formation In Oxy-Coal Combustion, Nujhat Choudhury

Theses and Dissertations

With the increasing levels of carbon dioxide (CO2) in the atmosphere, researchers are driven to seek cleaner combustion techniques to burn coal for power generation. Oxy-coal combustion is a promising technique to cut down CO2 emissions. This technology requires the introduction of a pure oxygen (O2) stream and a recycled flue gas stream into the boiler instead of air. Flue gas stream generated from the system will be low in volume and highly concentrated in CO2. Thus, the capture and sequestration process will be facilitated. But, one of the concerns of adopting this technology is the altered chemistry of pollutants …

Optical And Laser Spectroscopic Study Of Microwave Plasma-Assisted Combustion, Wei Wu

Theses and Dissertations

Nonthermal plasma-assisted combustion (PAC) has been demonstrated to be a promising potential method to enhance combustion performance and reduce the pollutant emissions. To better understand the mechanism in PAC, we have conducted a series of studies on the combustion enhancement by plasma using a home-developed PAC platform which employs a nonthermal microwave argon plasma and a suit of optical diagnostic tools including optical imaging, optical emission spectroscopy, and cavity ringdown spectroscopy. A new PAC system in which a continuous atmospheric argon microwave plasma jet is employed to enhance combustion of methane/air mixtures was reported. Reactive species in PAC were characterized …

Injection Timing Effects Of Diesel-Ignited Methane Dual Fuel Combustion In A Single Cylinder Research Engine, Edward Scott Guerry

Theses and Dissertations

Diesel-ignited methane dual fuel combustion experiments were performed in a single cylinder research engine (SCRE). Methane was fumigated into the intake manifold and injection of diesel was used to initiate combustion. The engine was operated at a constant speed of 1500 rev/min, and diesel rail pressure was maintained at 500 bar. Diesel injection timing (SOI) was varied to quantify its impact on engine performance and engine-out ISNOx, ISHC, ISCO, and smoke emissions. The SOI sweeps were performed at different net indicated mean effective pressures (IMEPs) of 4.1, 6.5, 9.5, and 12.1 bar. Intake manifold pressure was maintained at 1.5 bar …

Development And Characterization Of A High Speed Mid-Ir Tunable Diode Laser Absorption Spectrometer For Co And Co2 Detection In Detonation Events, Stephen D. Wakefield

Theses and Dissertations

A tunable diode laser absorption spectroscopy system, capable of collecting data at a 10 kHz repetition rate near 4.5 microns. This system was made feasible in recent years due to the development of quantum cascade lasers active in the 4.5 microns region of the spectrum. Reaching into the mid-IR region of the electromagnetic spectrum allowed for an analysis of the fundamental absorption bands for both CO and CO₂. The spectral absorption was measured for ethylene, methane, ethane, and propane across a variety of equivalence ratios, at various heights above a Hencken Burner surface. For each fuel, the concentration …

An Experimental Investigation Of Diesel-Ignited Gasoline And Diesel-Ignited Methane Dual Fuel Concepts In A Single Cylinder Research Engine, Umang Dwivedi

Theses and Dissertations

Diesel-ignited gasoline and diesel-ignited methane dual fuel combustion experiments were performed in a single-cylinder research engine (SCRE), outfitted with a common-rail diesel injection system and a stand-alone engine controller. Gasoline was injected in the intake port using a portuel injector, whereas methane was fumigated into the intake manifold. The engine was operated at a constant speed of 1500 rev/min, a constant load of 5.2 bar IMEP, and a constant gasoline/methane energy substitution of 80%. Parameters such as diesel injection timing (SOI), diesel injection pressure, and boost pressure were varied to quantify their impact on engine performance and engineout ISNOx, ISHC, …

Spectral Stability Of Weak Detonations In The Majda Model, Jeffrey James Hendricks

Theses and Dissertations

Using analytical and numerical Evans-function techniques, we examine the spectral stability of weak-detonation-wave solutions of Majda's scalar model for a reacting gas mixture. We provide a proof of monotonicity of solutions. Using monotonicity we obtain a bound on possible unstable eigenvalues for weak-detonation-wave solutions that improves on the more general bound given by Humpherys, Lyng, and Zumbrun. We use a numerical approximation of the Evans function to search for possible unstable eigenvalues in the bounded region obtained by the energy estimate. For the parameter values tested, our results combined with the result of Lyng, Raoofi, Texier, and Zumbrun demonstrate that …

Application Of One Dimensional Turbulence (Odt) To Model Fire Spread Through Biomass Fuel Bed, Abinash Paudel

Theses and Dissertations

Each year fires destroy millions of acres of woodland, lives, and property, and significantly contribute to air pollution. Increased knowledge of the physics and properties of the flame propagation is necessary to broaden the fundamental understanding and modeling capabilities of fires. Modeling flame propagation in fires is challenging because of the various modes of heat transfer with diverse fuels, multi-scale turbulence, and complex chemical kinetics. Standard physical models of turbulence like RANS and LES have been used to understand the flame behavior, but these models are limited by computational cost and their inability to resolve sub-grid scales. Application of several …

Detailed Characterization Of Conventional And Low Temperature Dual Fuel Combustion In Compression Ignition Engines, Andrew C. Polk

Theses and Dissertations

The goal of this study is to assess conventional and low temperature dual fuel combustion in light- and heavy-duty multi-cylinder compression ignition engines in terms of combustion characterization, performance, and emissions. First, a light-duty compression ignition engine is converted to a dual fuel engine and instrumented for in-cylinder pressure measurements. The primary fuels, methane and propane, are each introduced into the system by means of fumigation before the turbocharger, ensuring the airuel composition is well-mixed. Experiments are performed at 2.5, 5, 7.5, and 10 bar BMEP at an engine speed of 1800 RPM. Heat release analyses reveal that the ignition …

Application Of Fuel Element Combustion Properties To A Semi-Empirical Flame Propagation Model For Live Wildland Utah Shrubs, Chen Shen

Theses and Dissertations

Current field models for wildfire prediction are mostly based on dry or low-moisture fuel combustion research. To better study live fuel combustion behavior and develop the current semi-empirical bush combustion model, a laminar flow flat-flame burner was used to provide a convection heating source to ignite individual live fuel samples. In this research project, four Utah species were studied: Gambel oak (Quercus gambelii), canyon maple (Acer grandidentatum), big sagebrush (Artemisia tridentata) and Utah juniper (Juniperus osteosperma). Leaf geometrical parameters and time-dependent combustion behavior were recorded. Qualitative results included various combustion phenomena like bursting, brand formation and bending. Quantitative results included …

Optical And Laser Spectroscopic Diagnostics For Energy Applications, Markandey Mani Tripathi

Theses and Dissertations

The continuing need for greater energy security and energy independence has motivated researchers to develop new energy technologies for better energy resource management and efficient energy usage. The focus of this dissertation is the development of optical (spectroscopic) sensing methodologies for various fuels, and energy applications. A fiber-optic NIR sensing methodology was developed for predicting water content in bio-oil. The feasibility of using the designed near infrared (NIR) system for estimating water content in bio-oil was tested by applying multivariate analysis to NIR spectral data. The calibration results demonstrated that the spectral information can successfully predict the bio-oil water content …

A Phenomenological Investigation Of Ignition And Combustion In Alternative-Fueled Engines, Saroj Kumar Jha

Theses and Dissertations

Current diesel technologies involve a broad spectrum of combustion regimes. Previous diesel combustion models either lack the universality across various combustion regimes or suffer computational cost. This dissertation discusses the development of a phenomenological framework to identify and understand key in-cylinder processes that influence the overall performance of a compression ignition engine. The first part of this research is focused on understanding the ignition delay (ID) of diesel fuel in a pilot-ignited partially premixed, low temperature natural gas (NG) combustion engine. Lean premixed low temperature NG combustion is achieved by using small pilot diesel sprays (2-3% of total fuel energy) …