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Investigations Of The Low Temperature Combustion Regions And Emissions Characteristics Of Aerospace F24 In A Constant Volume Combustion Chamber And A Common Rail Direct Injection Ci Engine, Richard C. Smith Iii

Electronic Theses and Dissertations

A study was conducted to investigate the low temperature combustion (LTC) regions of aerospace F24 and ULSD in the static setting of a CVCC and the dynamic setting of a CRDI research engine. This research is conducted to reduce in-cylinder emissions by understanding and implementing a technique to achieve an extended LTC. Emissions data for this study were collected during the operation of the CRDI research engine with a MKS 2030 FTIR and an AVL Microsoot 483. The parameters researched within the static setting of the CVCC included the determinations of the cool flames and NTC regions within the LTHR …

A Study Of Greenhouse Gas Emissions And Performance Of An Internal Combustion Engine Operating On Landfill Gas Blends As Fuel, Lauren T. Creadore

Dissertations and Theses

Landfill gas (LFG) is an abundant resource naturally occurring from the decomposition of municipal solid waste. It can be generated in U.S. landfills at a rate of 24.2 to 59.1 GNm³ per year.¹ LFG presents both a problem and solution with respect to global warming. Composed of carbon dioxide (CO₂, 30-40%) and methane (CH₄, 45-55%), as well as nitrogen (N₂, 10-15%), oxygen (O₂, 0-5%), and other trace gasses¹, LFG that is permitted release into the atmosphere will contribute to the greenhouse gas effect due to the presence of …

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 …

Numerical Investigation Of Effects Of Pressure And Chemistry On Characteristics Of Turbulent Premixed Flames, Jamie Bowers

Masters Theses and Doctoral Dissertations

Turbulent premixed flames are used in many energy conversion and propulsion devices. The efficiency and performance of these devices are affected by operating conditions, which also affect the highly nonlinear turbulence-chemistry interactions (TCIs). Previous fundamental studies characterize TCIs at atmospheric pressure, but relevant devices usually operate at higher pressures. This study investigates the effects of elevated pressure and finite-rate chemistry on methane/air turbulent premixed flames using direct numerical simulations performed at pressures of 1 atm and 10 atm and utilize an 8-species and 4-steps mechanism and a 13-species and 73-steps mechanism. The effects of pressure and chemistry on TCIs are …

Development Of Experimental And Numerical Methods For Investigations Of High-Octane Fuels In Heavy-Duty Applications, Jared James Zeman

Master's Theses (2009 -)

Increasingly stringent emissions regulations has threatened the existence of the internal combustion (IC) engine. In some transportation sectors, non-IC engine powertrains have the potential to be a logical solution. However, in the heavy-duty sector, the IC engine is predicted to remain the dominant propulsion method for the foreseeable future. With ever-increasing demand for heavy-duty power generation platforms, the primary focus for the development of the future heavy-duty IC engine needs to be on increasing engine efficiency and the adoption of lowlife-cycle carbon, clean burning fuels, e.g. methanol. The fuel ignition properties of these fuels, e.g. high octane, cause difficulties when …

Fluorine-Based Inorganic Oxidizers For Use In Metal-Based Reactive Materials, Siva Kumar Valluri

Dissertations

This work explores inorganic fluorides as oxidizers for fuel-rich reactive materials. A preliminary assessment of metal fluorides accounting for their enthalpy of formation points to bismuth (III) fluoride, BiF3 and cobalt (II) fluoride, CoF2 as oxidizers of interest. Initially, composite powders of aluminum with chosen fluorides at 50-50 wt. % are prepared by arrested reactive milling. Despite an increase in reactivity and lowtemperature ignition, the prepared composite powders are insensitive to initiation by electro-static discharge (ESD), making them attractive alternative to analogous thermites having very high ESD sensitivity. In air, the composite powder particles burn faster than reference aluminum particles …

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 …

Development And Testing Of A Rotating Detonation Rocket Engine With A Racetrack Combustor And Shear-Coaxial Injectors, Evan Colson Unruh

Theses

Rotating Detonation Engines (RDEs) have the potential to provide higher propulsive performance compared to conventional deflagrative combustors. The objective of this study is to compare liquid propane (LC3H8) and gaseous methane (GCH4) fuels in a laboratory-scale RDE. To accomplish this objective, a 4-inch, “racetrack” type RDE was developed that facilitates optical access to the combustion region. Fuels are injected, along with gaseous oxygen (GO2), using 50 discrete GO2-centered shear-coaxial injector elements. The design approach for the engine is discussed including combustor channel sizing, injector selection, ignition method, and instrumentation. Counter-propagating detonation waves were observed during testing with average wave velocities …

Experimental Study Of A Liquid Fuel Bluff Body Flame At Elevated Pressures, Karam Paul

Honors Undergraduate Theses

The purpose of this research was to operate a bluff body flame holder with the objective of stabilizing a flame at elevated pressures over a range of equivalence ratios. The ability to have a ground-based test rig capable of maintaining stable flames at high pressures and temperatures is critical in understanding flames present in modern jet engines and gas turbine technologies. The facility was reconfigured multiple times and the resultant flame was imaged within the optical test section. A converging nozzle was utilized to choke the flow and vary the operating pressures up to 5 atm. By regulating mass flow …

Investigation Of Various Jet Configurations On Jet-In Crossflow Flame Characteristics At Elevated Pressures, Max K. Fortin

Honors Undergraduate Theses

The goal of this study is to investigate how varying the configuration of an axially staged combustion test facility affects the resultant flame and its relevant characteristics. Such relevant characteristics are the jet liftoff and the centerline jet trajectory. The configurations that are primarily being investigated are varied jet configuration diameters, 4mm and 12.7mm, preheated and non-preheated fuel, and different fuels. The testing facility is located at the University of Central Florida in the PERL (Propulsion and Energy Research Lab) facility. The facility allows for modeling an industrial turbine combustor, specifically an axial staged combustor with a Jet-In-Crossflow …

Combustion Phasing Modeling For Control Of Spark-Assisted Compression Ignition Engines, Dennis Robertson

All Dissertations

Substantial fuel economy improvements for light-duty automotive engines demand novel combustion strategies. Low temperature combustion (LTC) demonstrates potential for significant fuel efficiency improvement; however, control complexity is an impediment for real-world transient operation. Spark-assisted compression ignition (SACI) is an LTC strategy that applies a deflagration flame to generate sufficient energy to trigger autoignition in the remaining charge. For other LTC strategies, control of autoignition timing is difficult as there is no direct actuator for combustion phasing. SACI addresses this challenge by using a spark plug to initiate a flame that then triggers autoignition in a significant portion of the charge. …

An Investigative Study Of Combustion And Emissions With Noise And Vibrations Of Synthetic Fuels Within An Aero-Gas Turbine, Camille J. Phillips

Honors College Theses

The pollution from the aerospace transportation is rapidly becoming the largest source of greenhouse gas (GHG) emissions. The FAA expects aviation emissions to almost triple by 2050, making the aerospace industry responsible for the release of approximately 25% of the global carbon dioxide budget. These aviation emissions, including CO2 and NOx, as well as other GHGs, contribute to the destruction of ozone layer. Carbon dioxide emissions have a particularly negative effect on humans, leading to airway diseases especially in children and elderly. To combat the addition of further GHG emissions into the atmosphere, it is necessary to minimize the usage …

High Pressure Combustor Flame And Wall Conjugate Radiative Heat Transfer, Andressa Johnson

Master's Theses

Efficient aeronautical engines operate at higher pressure ratios and temperature, creating challenges due to higher heat loads. Thermal radiation in aviation has conventionally been treated as correction factors or scaled from experimental data. The complexity of the radiative transfer equation (RTE) leads to computational costly solutions resulting in simplified treatment. The goal of this work is to extend knowledge of non-gray gas radiation modeling to gas-turbine combustor simulations under high-pressure conditions. A one-dimensional temperature solver for combustor liners with thermal barrier coating is developed first, and a non-gray wide-band spectral model for high-pressure conditions is constructed subsequently. Both retrieve spectral …

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.

Portable Calorimeter For Fire Experiments, Kayla Collins, Kara Hewson, Christopher Chen, Joel Keddie

Mechanical Engineering

Executive Summary

An oxygen consumption calorimeter works by measuring the heat release rate of a burning substance. This value is calculated by measuring the oxygen and byproducts in smoke from afire.In order to get these values two types of sensors were used. A non-dispersive infrared sensor (NDIR) that measured CO and CO2 and a zirconium O2 sensor were used to find their respective gas concentrations.The design to calculate the heat release rate is focused on maximizing sensor accuracy and portability while simplifying the manufacturing by using off-the-shelf components. The goal included making the system simple to recreate and package in …

Reinitiation Mode Study Of Highly Irregular Detonation, Nandakumar Vijayakumar

Mechanical and Aerospace Engineering Dissertations

The propagation of detonation waves is governed by their stability characteristics. Interest in highly unstable detonation grew when early experiments revealed limits of operation to be directly proportional to the stability of detonation. This research focuses on reinitiation pathways of highly irregular self-sustaining detonation. This is an important aspect of stability which is not yet fully understood, while many possible mechanisms have been proposed in the literature. First, a one-dimensional instability model simulation was performed using a global one-step chemistry mechanism to understand the different unstable modes by increasing the activation energy of a mixture of hydrogen and oxygen. The …

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 …

Mechanically Activated Combustion Synthesis Of Niobium Silicide Based Composites, Reina Trevino

Open Access Theses & Dissertations

Niobium silicide-based composites are promising materials for high-temperature structural applications, such as gas turbines, but their implementation is hindered by the lack of effective processing methods. Self-propagating high-temperature synThesis (SHS) is an attractive method for fabrication of advanced materials. However, it is difficult to perform SHS of niobium silicides because the melting point of Nb is higher than the combustion temperature, which greatly inhibits Nb-Si reaction. To ignite an Nb/Si mixture and obtain Nb5Si3, the desired phase in niobium silicides, either preheating or mechanical activation of the mixture is necessary. This problem becomes even more critical in the SHS of …

Pulse Power Effects On Transient Plasma Ignition For Combustion, David Wayne Alderman Ii

Electrical & Computer Engineering Theses & Dissertations

Transient plasma ignition (TPI) uses highly non-equilibrium plasmas, driven by less than 100 nanosecond, high-voltage pulses, to initiate combustion. The effects of pulse repetition frequency (PRF) and ultrashort nanosecond rise times on TPI are investigated in this work using lean, stoichiometric, and rich air-fuel mixtures at atmospheric pressure. Experimental data show the transient plasmas driven by ultrashort rise time, high voltage pulses at high PRF’s enhance the combustion of lean or stoichiometric air-methane mixtures in a static chamber. In particular, increasing PRF enhances the combustion performance by means of reduced delay times independent of the equivalence ratio of the air-fuel …

Improving Boron For Combustion Applications, Kerri-Lee Annique Chintersingh

Dissertations

Boron has received much attention as a potential additive to explosives and propellants due to its high theoretical gravimetric and volumetric heating values. The challenge, however, is that boron particles tend to agglomerate, have lengthy ignition delays and very low combustion rates. Prior research indicates that boron’s long ignition delays are due to its inhibiting naturally occurring oxide layer, impeding the diffusion of reactants for oxidation. For combustion, current studies report that boron particles have two consecutive stages, but the actual reaction mechanism is poorly understood. Despite many years of relevant research, quantitative combustion data on micron-sized boron particles are …

Modeling And Simulation Of High-Density Spray Combustion, Chenwei Zheng

Dissertations - ALL

High-efficiencies and low-emissions can be realized in combustion engines that operate at high-pressures and low-temperatures conditions (high densities). The design of such engines relies on accurate models of the physical processes involved. Three areas of concern are multi-phase phenomena, the equation of state for the gas phase and cost-effective chemical kinetic modeling. Fuel injected as liquid must break up into droplets, evaporate, and mix with air before combusting. Models for these processes have been developed and need to be tested against experiments. As for the gas phases, the ideal gas model fails to capture thermodynamic relations at high-density combustion. A …

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, …

Reconstruction Of Attenuated Hybrid Rocket Motor Chamber Pressure Signals Using Maximum Likelihood Estimation And Optimal Deconvolution, Evan M. Zelesnik

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Chamber pressure, as it develops during rocket combustion, strongly correlates with many of the internal motor ballistics, including combustion stability, fuel regression rate, and mass flow. Chamber pressure is also an essential measurement for calculating achieved thrust coefficient and characteristic velocity. Due to the combustion environment hostility, sensing chamber pressure with high-fidelity presents a difficult measurement problem, especially for solid and hybrid rocket systems where combustion by-products contain high amounts of carbon and other sooty materials. These contaminants tend to deposit within the pneumatic tubing used to transmit pressure oscillations from the thrust chamber to the sensing transducer. Partially clogged …

Design And Development Of Hybrid Rocket For Spaceport America Cup, Benjamin Barnhill, Sean Darling, Austin Springer, Adam Todd, Stewart Whaley

Chancellor’s Honors Program Projects

No abstract provided.

Development Of A Quasi-Monte Carlo Method For Thermal Radiation, Joseph Farmer

Master's Theses (2009 -)

Radiative heat transfer in participating media is among the most challenging computational engineering problems due to the complex nonlinear, nonlocal nature of radiation transport. Many approximate methods have been developed in order to resolve radiative heat transfer in participating media; but approximate methods, by the nature of their approximations, suffer from various shortcomings both in terms of accuracy and robustness. The only methods that can resolve radiative transfer accurately in all configurations are the statistical Monte Carlo-based methods. While the Monte Carlo (MC) method is the most accurate method for resolving radiative heat transfer, it is also notoriously computationally prohibitive …

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 …

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 …