Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 14 of 14
Full-Text Articles in Engineering
Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan
Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan
Electronic Theses and Dissertations
In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep …
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
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 …
Experimental Setup Of A Rapid Compression Machine For Spark Ignition Studies, Daniel Llaguno
Experimental Setup Of A Rapid Compression Machine For Spark Ignition Studies, Daniel Llaguno
Electronic Theses and Dissertations
The main objective of this thesis is to document the design and development of a rapid compression machine (RCM). A series of tests were performed to verify the operation of the system using the compression of air. Finally, an experiment was conducted to validate the auto-ignition temperature of DME under HCCI mode. Based on the first version of the RCM, improvements were made to speed up the compression process, and to create the conditions required for the auto-ignition of a DME-air mixture. The inlet diameter of the pneumatic actuation cylinder was increased to reduce the choking effect of the air …
Analysis Of Combustion In Plasma Electrolytic Oxidation (Peo) Coatings Of The Piston Surface In Spark Ignition Engines, Brendon Bain
Analysis Of Combustion In Plasma Electrolytic Oxidation (Peo) Coatings Of The Piston Surface In Spark Ignition Engines, Brendon Bain
Electronic Theses and Dissertations
With the global effort to “green” the transportation industry, the internal combustion engine (ICE) is required to reduce its carbon footprint and can do so by increasing efficiency. Plasma Electrolytic Oxidation (PEO) coatings confer properties of high wear and corrosion resistance, high hardness, excellent adhesion and a superior thermal barrier to their substrate, suggesting that coating of ICE components has the potential to greatly improve the combustion efficiency. The primary objective of this thesis is to analyze the effects of PEO coating on the surface of pistons in a spark ignition ICE, with the goal of increasing efficiency, to address …
Simulation Of An Ethylene Flame With Turbulence, Soot And Radiation Modeling, Santu Golder
Simulation Of An Ethylene Flame With Turbulence, Soot And Radiation Modeling, Santu Golder
Electronic Theses and Dissertations
This thesis will investigate soot models that are available in commercial codes. We will look at the effect of turbulence models, gravity, soot models and radiation. Simulations will be compared to Coppalle and Joyeux [1]. The flame is an ethylene air diffusion flame at a Reynolds number of 5700. Simulations show the SST turbulence model, one-step soot model and Rosseland radiation model including gravity agree well with experimental data (temperature and soot). Flamelet soot modeling from Carbonell et al. [2] and flamelet radiation modeling from Doom [3] has been incorporated and compared as well.
Investigation Of The Performance And Emissions Characteristics Of Dual Fuel Combustion In A Single Cylinder Idi Diesel Engine, Johnnie L. Williams Jr
Investigation Of The Performance And Emissions Characteristics Of Dual Fuel Combustion In A Single Cylinder Idi Diesel Engine, Johnnie L. Williams Jr
Electronic Theses and Dissertations
Restrictions in the allowable exhaust gas emissions of diesel engines has become a driving factor in the design, development, and implementation of internal combustion (IC) engines. A dual fuel research engine concept was developed and implemented in an indirect injected engine in order to research combustion characteristics and emissions for non-road applications. The experimental engine was operated at a constant speed and load 2400 rpm and 5.5 bar indicated mean effective pressure (IMEP). n-Butanol was port fuel injected at 10%, 20%, 30%, and 40% by mass fraction with neat ultra-low sulfur diesel (ULSD#2). Peak pressure, maximum pressure rise rates, and …
Combustion Kinetics Of Advanced Biofuels, Ghazal Barari
Combustion Kinetics Of Advanced Biofuels, Ghazal Barari
Electronic Theses and Dissertations
Use of biofuels, especially in automotive applications, is a growing trend due to their potential to lower greenhouse gas emissions from combustion. Ketones are a class of biofuel candidates which are produced from cellulose. However, ketones received rather scarce attention from the combustion community compared to other classes such as, alcohols, esters, and ethers. There is little knowledge on their combustion performance and pollutant generation. Hence their combustion chemistry needs to be investigated in detail. Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. A detailed understanding of the combustion kinetics of the oxidation …
Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace
Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace
Electronic Theses and Dissertations
Water injection has been used in internal combustion engines for many years. It has been used to cool combustion temperatures, reduce emissions, and in some instances clean carbon buildup from the cylinder. Research has shown that the water to fuel mass ratio is most effective between 20-30%, so the upper and lower limit were used for simulations in Converge CFD. To validate the CFD model, a case without water injection was compared to experimental data from Sandia National Laboratory. The predicted in-cylinder pressure and heat release rate showed good agreement with the experimental data. Cases were run with the injection …
Design And Development Of Heterogenous Combustion Systems For Lean Burn Applications, Anthony Terracciano
Design And Development Of Heterogenous Combustion Systems For Lean Burn Applications, Anthony Terracciano
Electronic Theses and Dissertations
Combustion with a high surface area continuous solid immersed within the flame, referred to as combustion in porous media, is an innovative approach to combustion as the solid within the flame acts as an internal regenerator distributing heat from the combustion byproducts to the upstream reactants. By including the solid structure, radiative energy extraction becomes viable, while the solid enables a vast extension of flammability limits compared to conventional flames, while offering dramatically reduced emissions of NOx and CO, and dramatically increased burning velocities. Efforts documented within are used for the development of a streamlined set of design principles, and …
Perovskite Catalysts Enhanced Combustion On Porous Media And Thermoelectric Power Conversion, Manuel Robayo
Perovskite Catalysts Enhanced Combustion On Porous Media And Thermoelectric Power Conversion, Manuel Robayo
Electronic Theses and Dissertations
A combustion chamber incorporating a high temperature porous matrix was design and tested. The effects and merits of combining combustion on porous media and catalytic enhancement were explored, in addition to the proof of concept of integrating these technologies with simple heat engines, such as thermoelectric generators, to generate efficient and reliable power. The direct observation of the flame during the combustion becomes possible due to a specially designed stainless steel chamber incorporating a quartz window where the initiation and propagation of the combustion reaction/flame was directly visible. The simple design of the combustion chamber allowed for a series of …
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond
Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond
Electronic Theses and Dissertations
During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles …
Combustion Synthesis And Characterization Of Porous Niti Intermetallic For Structural Application, Jessica Vanterpool
Combustion Synthesis And Characterization Of Porous Niti Intermetallic For Structural Application, Jessica Vanterpool
Electronic Theses and Dissertations
This thesis describes experimental investigation of thermal and combustion phenomena as well as structure for self- propagating combustion synthesis of porous Ni - Ti intermetallic aimed for structural biomedical application. The control parameters for the porosity distribution have been investigated experimentally through varying the preheat temperature, initial porosity, initial elemental particle size, and applied pressure during the fabrication process. Ni and Ti elemental powders are mixed using a 1:1 ratio. The mixture is compressed using several different compression forces to produce cylindrical samples of 1.1 cm diameter and 2-3cm length, with initial porosity ranging from 30% to 40%. The samples …
A Study Of Syngas Oxidation At High Pressures And Low Temperatures, Danielle Marie Kalitan
A Study Of Syngas Oxidation At High Pressures And Low Temperatures, Danielle Marie Kalitan
Electronic Theses and Dissertations
Ignition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825 < T < 1400 K) for a wide range of pressures (1 < P < 45 atm). Results of this study provide the first undiluted fuel-air ignition delay time experiments to cover such a wide range of syngas mixture compositions over the stated temperature range. Emission in the form of chemiluminescence from the hydroxyl radical (OH*) transition near 307 nm and the pressure behind the reflected shock wave were used to monitor reaction progress from which ignition delay times were determined. In addition to the experimental analysis, chemical kinetics calculations were completed to compare several chemical kinetics mechanisms to the new experimental results. Overall, the models were in good agreement with the shock-tube data, especially at higher temperatures and lower pressures, yet there were some differences between the models at higher pressures and the lowest temperatures, in some cases by as much as a factor of five. In order to discern additional information from the chemical kinetics mechanisms regarding their response to a wide range of experimental conditions, ignition delay time and reaction rate sensitivity analyses were completed at higher and lower temperatures and higher and lower pressures. These two sensitivity analyses allow for the identification of the key reactions responsible for ignition. The results of the sensitivity analysis indicate that the ignition-enhancing reaction H + O2 = O + OH and hydrogen oxidation kinetics in general were most important regardless of mixture composition, temperature or pressure. However, lower-temperature, higher-pressure ignition delay time results indicate additional influence from HO2- and CO- containing reactions, particularly the well-known H + O + M = HO2 + M reaction and also the CO + O + M = CO2 + M and CO + HO2 = CO2 + OH reactions. Differences in the rates of the CO-related reactions are shown to be the cause of some of the discrepancies amongst the various models at elevated pressures. However, the deviation between the models and the experimental data at the lowest temperatures could not be entirely explained by discrepancies in the current rates of the reactions contained within the mechanisms. Additional calculations were therefore performed to gain further understanding regarding the opposing ignition behavior for calculated and measured ignition delay time results. Impurities, friction induced ionization, static charge accumulation, boundary layer effects, wall reaction effects, and revised chemical kinetics were all considered to be possible mechanisms for the model and measured data disparity. For the case of wall-reaction effects, additional shock-tube experiments were conducted. For the remaining effects listed above, only detailed calculations were conducted. Results from this preliminary anomaly study are at this time inconclusive, but likely avenues for future study were identified. Additional kinetics calculations showed that the large difference between the experimental data and the chemical kinetics models predictions at low temperatures can be explained by at least one missing reaction relevant to low-temperature and high-pressure experimental conditions involving the formation of H2O2, although further study beyond the scope of this thesis is required to prove this hypothesis both theoretically and experimentally.
Design And Implementation Of An Emission Spectroscopy Diagnostic In A High-Pressure Strand Burner For The Study Of Solid Propell, Jason Arvanetes
Design And Implementation Of An Emission Spectroscopy Diagnostic In A High-Pressure Strand Burner For The Study Of Solid Propell, Jason Arvanetes
Electronic Theses and Dissertations
The application of emission spectroscopy to monitor combustion products of solid rocket propellant combustion can potentially yield valuable data about reactions occurring within the volatile environment of a strand burner. This information can be applied in the solid rocket propellant industry. The current study details the implementation of a compact spectrometer and fiber optic cable to investigate the visible emission generated from three variations of solid propellants. The grating was blazed for a wavelength range from 200 to 800 nm, and the spectrometer system provides time resolutions on the order of 1 millisecond. One propellant formula contained a fine aluminum …