Mechanical Engineering Commons^™

High Pressure Testing Of Composite Solid Rocket Propellant Mixtures: Burner Facility Characterization, Rodolphe Valentin Carro

Electronic Theses and Dissertations

Much Research on composite solid propellants has been performed over the past few decades and much progress has been made, yet many of the fundamental processes are still unknown, and the development of new propellants remains highly empirical. Ways to enhance the performance of solid propellants for rocket and other applications continue to be explored experimentally, including the effects of various additives and the impact of fuel and oxidizer particle sizes on burning behavior. One established method to measure the burning rate of composite propellant mixtures in a controlled laboratory setting is to use a constant-volume pressure vessel, or strand …

Characterization And Flow Physics Of Plasma Synthetic Jet Actuators, Arvind Santhanakrishnan

University of Kentucky Doctoral Dissertations

Plasma synthetic jet actuators are investigated experimentally, in which the geometrical design of single dielectric barrier discharge (SDBD) plasma actuators is modified to produce zero-mass flux jets similar to those created by mechanical devices. The SDBD plasma actuator consists of two rectangular electrodes oriented asymmetrically and separated by a layer of dielectric material. Under an input of high voltage, high frequency AC or pulsed DC, a region of plasma is created in the interfacial air gap on account of electrical breakdown of the ambient air. A coupling between the electric field in the plasma and the neutral air near the …

Diseño E Implementación De Un Controlador Automático Para La Tostación Del Café En Pequeña Y Media Producción, William Fernando Acero Morales

Ingeniería en Automatización

El café es un buen símbolo nacional y pilar fundamental de la economía del país; es así, que siendo conscientes de la necesidad de impulsar el desarrollo tecnológico se planteó el “DISEÑO E IMPLEMENTACIÓN DE UN CONTROLADOR AUTOMÁTICO PARA LA TOSTACIÓN DEL CAFÉ EN PEQUEÑA Y MEDIA PRODUCCIÓN”. Para el diseño y la posterior implementación se realizó el diagnóstico de la máquina tostadora de pequeña producción, el cual permitió identificar las actividades realizadas durante la tostación de café. Una vez analizadas, se determinó cuando era necesaria la aplicación de estrictos criterios de producción, los cuales a su vez garantizan la …

Rediseño Del Sistema Vibratorio De Una Máquina Secadora De Sal Por El Método De Lecho Fluidizado, Diego Alejandro Camargo Soler, Jorge Armando Conde Contento

Ingeniería en Automatización

En la industria de la producción de sal existen tres operaciones básicas para su tratamiento; lavado, refinado y envasado. En el refinado de sal se realiza la molienda, yodado, secado y cribado. En una parte del proceso de secado de sal se usa la máquina de lecho fluidizado, la cual es el objeto de estudio en este proyecto. El secado en lecho fluidizado es uno de los métodos mas eficientes y modernos de secado por tal razón se ha fomentado su uso en diversas industrias, especialmente en la industria de alimentos y farmacéutica. Estas máquinas a pesar de su correcto …

Automatización Del Sistema De Comunicación Entre Equipos De Proceso Y Llenado Uht/Uat Larga Vida En La Planta De Producción Algarra S.A, Andres Ricardo Pedraza Leguizamon

Ingeniería en Automatización

No abstract provided.

Caracterización, Implementación Y Puesta En Marcha Del Modulo De Ensamble Del Laboratorio De Robótica Y Sistemas Integrados De Manufactura, Mauricio Giovanny Garzon Ruiz, Martin Eduardo Rodriguez Rojas

Ingeniería en Automatización

La Universidad de La Salle dentro de su laboratorio de Robótica y Sistemas Integrados de Manufactura, posee un módulo de ensamble, el cual como su nombre lo indica tiene como función realizar el ensamble de las diferentes piezas mecanizadas dentro del Sistema Integrado de Manufactura. Dicho módulo se encontraba en condiciones no óptimas para su funcionamiento y por tal razón era necesario realizar un mantenimiento el cual lo restableciera a la labor para la cual fue diseñado. Las labores realizadas para la ejecución de este proyecto fueron: levantamiento de información, mantenimiento a cada uno de sus sistemas, obtención de la …

Diseño Y Simulación De Un Sistema Para Empaque, Pesado Y Sellado De Papa A La Francesa Precocida, Gustavo Guevara Pabon

Ingeniería en Automatización

No abstract provided.

Diseño E Implementación De Un Sistema De Monitoreo De Variables Para Los Circuitos Hidráulicos Y De Lubricación Instalados En El Tren De Laminación Morgan En La Empresa Acerías Paz Del Río S.A, Jaime Andrés Zambrano Perilla

Ingeniería en Automatización

No abstract provided.

Construcción De Un Prototipo Final De Pie Para Prótesis Transfemoral, Aide Mercedes Espejo Mora

Ingeniería en Automatización

No abstract provided.

Non-Intrusive Pressure Measurement In Microchannels, Derek Fultz

Dissertations, Master's Theses and Master's Reports - Open

A non-intrusive interferometric measurement technique has been successfully developed to measure fluid compressibility in both gas and liquid phases via refractive index (RI) changes. The technique, consisting of an unfocused laser beam impinging a glass channel, can be used to separate and quantify cell deflection, fluid flow rates, and pressure variations in microchannels. Currently in fields such as microfluidics, pressure and flow rate measurement devices are orders of magnitude larger than the channel cross-sections making direct pressure and fluid flow rate measurements impossible. Due to the non-intrusive nature of this technique, such measurements are now possible, opening the door for …

Effect Of Segmented Anodes On The Performance And Plume Of A Hall Thruster, Alexander W. Kieckhafer

Dissertations, Master's Theses and Master's Reports - Open

Development of alternative propellants for Hall thruster operation is an active area of research. Xenon is the current propellant of choice for Hall thrusters, but can be costly in large thrusters and for extended test periods. Condensible propellants may offer an alternative to xenon, as they will not require costly active pumping to remove from a test facility, and may be less expensive to purchase. A method has been developed which uses segmented electrodes in the discharge channel of a Hall thruster to divert discharge current to and from the main anode and thus control the anode temperature. By placing …

Meso-Machining Of Miniature Space System Components, Carlos Ramirez

Open Access Theses & Dissertations

Many industries in engineering and science are focusing more on producing mechanisms and system components of magnitudes smaller than existing products. One of the major technologies associated with these demands is the development of meso scale precision manufacturing systems. Meso scale fabrication involves the scaling down of conventional machining to incorporate the use of familiar materials, such as aluminum, steel, and even titanium for machining miniature components. New techniques in meso scale fabrication allow for the machining of miniature space system components in an efficient manner to meet certain specifications. A description of the processes used to accurately machine a …

Performance Characteristics Of An Innovative Wind Power System, David James Kerze

ETD Archive

This project entails a study of a wind energy recovery system that utilizes a unique three-dimensional spiral structure to amplify wind speed and direct it toward pluralities of turbines. The system is comprised of an outer spiral shell, internal support structure, turbines, and mechanisms for positioning the turbines to face the prevailing wind. Computational Fluid Dynamics (CFD) analyses were conducted to determine the wind speed amplification factors as a result of a simulated wind flow around the spiral structure. To ensure accuracy of the results, state of the art CFD techniques were applied using Gambit 2.2.30 and Fluent 6.2.16. Specifically, …

Flow Of Sub-Cooled Cryogens Through A Joule-Thomson Device: Investigation Of Metastability Conditions, John M. Jurns

ETD Archive

Cryogenic fluid systems are fundamental to space flight architecture. Due to the unique properties of cryogenic fluids and the environments in which they operate for space flight, cryogenic fluid management systems must be developed to maintain these fluids at conditions in which they can be utilized. Liquid oxygen boils at 90 K, and liquid hydrogen boils at 20 K. Significant care must be taken to provide a thermal management system that prevents heat entering these fluids with consequential adverse effects on the performance of the cryogenic fluid systems. One critical component of a cryogenic thermal management system is a Joule-Thomson …

Thermal Shock Fracture Behaviors Of Functionally Graded Ceramics, Wenjin Luo

Electronic Theses and Dissertations

This thesis uses a thermal fracture mechanics model to study the thermal shock fracture behavior of functionally graded ceramics (FGC). The specimen used in this study is a FGC strip with an edge crack on one surface. A severe thermal shock is applied on the cracked surface. The temperature field in a thermally shocked FGC strip is evaluated first using a closed form solution. Thermal stresses, thermal stress intensity factors (TSIF) and critical thermal shocks are evaluated using a thermomechanics and fracture mechanics approach. The effective thermal properties of the FGC specimens are estimated using micromechanics models for conventional composites. …

Manufacturing And Characterization Of Soy-Based Pultruded Polyurethane Composites, Rama Bhadra Raju Vuppalapati

Masters Theses

"In the recent past, composites have been finding various applications in civil infrastructure, marine, transportation, automotive and non-automotive applications by replacing metals in structural components. Pultrusion is considered to be a cost effective method for manufacturing composite materials.

Polyurethane resin systems form a good alternative to the conventional styrene based systems in pultrusion due to their better physical, chemical and mechanical properties. Polyols derived from soybean oil along with isocyanates produce polyurethanes that can match in many aspects with one derived from the petrochemical polyols. Even though, polyurethanes have good properties there are lots of challenges like designing unique material …

On-Line Inspection And Thermal Properties Comparison For Laser Deposition Process, Yu Yang

Masters Theses

"This thesis is focused on comparing the laser deposition cladding with intended design model and comparing the effect of laser deposition process on thermal properties with traditional welding process. It is research on two aspects of laser deposition cladding. The first part of the thesis is aimed at solving the geometric inspection of laser deposition cladding, and the second part is for comparing the thermal properties of laser deposition cladding to samples of conventional welding process"--Introduction, page 1.

Reactive Multilayer Foils And Their Applications In Joining, Xiaotun Qiu

LSU Master's Theses

In this study, Ni/Al multilayer foils were fabricated by a cold rolling method. A two-stage reaction process was observed in the reaction-ignition experiment. The phase formation process in the cold rolled foils was studied. The first reaction stage with a slow reaction velocity was the lateral growth of Al3Ni phase at isolated nucleation sites and the subsequent coalescence into a continuous layer. The second reaction stage with a fast reaction velocity was the growth of the Al3Ni layers in the direction normal to the Ni/Al interface until all Al was consumed. Afterwards, Al3Ni reacted with the remaining Ni to form …

Structural Behavior Of Pvc Pipe Liners Subjected To Seasonal Groundwater Loading, Qing Cai

Doctoral Dissertations

Thin-walled polymeric liners are routinely used to rehabilitate deteriorated underground pipe lines that are structurally sound but have lost their hydraulic integrity. These host pipes are said to be "partially deteriorated" since they can support soil and surface loading. For this case, the pipe liners must only be designed to withstand the pressure of the groundwater that seeps through openings in the host pipe and migrates through the small annular gap between the liner and the host pipe. This external pressure will cause the polymeric liner to slowly deform inward toward the center of the pipe, and the compressive hoop …

Analysis And Prediction Of Effectiveness For Residential Hvac Ductwork, Jinson J. Erinjeri

Doctoral Dissertations

An analysis of residential HVAC ductwork has been performed. Ductwork in 55 homes in Northern Louisiana was tested to determine duct leakage by means of using various measurement techniques to determine the differences between the existing methods as well as the revised method developed in this project referred to as Generalized Subtraction Correction Algorithm (GSCA). A protocol to measure and estimate return leaks at operating pressure was developed. The weighted average return leakage for the homes sampled was determined to be 115 cfm at operating pressure whereas the weighted average duct leakage was determined to be 348 cfm at 25 …

Mechanical Integrity And Behavior Of Thin Films And Their Applications In Mems, Gang Duan

Doctoral Dissertations

"Electric actuated thin films are widely used in micro-electromechanical systems (MEMS) such as radio frequency switches (RF-switches), micro-pumps and valves, and electrostatic actuators. This dissertation will focus on the operation of a MEMS-RF-switch. In a typical MEMS-RF-switch, a mechanically suspended 1-D rectangular or 2-D axisymmetric thin film is pulled by an electrostatic voltage (V₀) applied to an electrode-pad directly underneath. When V₀ exceeds a certain "pull-in" threshold, V₀*, the thin film makes direct contact with the pad so that either an "on" or "off" signal is induced, and when the voltage is removed, the thin film resumes its original undeformed …

E-Design Tools For Friction Stir Welding: Cost Estimation Tool, Pradeep Kumar Tipaji

Masters Theses

"A cost model is an important tool for product design and material selection. An efficient and effective cost estimation tool is necessary for early design evaluation. In this paper, cost estimation models that estimate the production cost for Metal Inert Gas (MIG), Friction Stir (FS), and Friction Stir Spot (FSS) welded joints are presented. These models determine the cost incurred to fabricate each joint along with a detailed explanation of each cost component. Each cost component has been closely analyzed and major cost components have been included in the cost model"--Abstract, page iv.

An Analysis Of The Study Of Mechanical Properties And Microstructural Relationship Of Hsla Steels Used In Ship Hulls, Htay Aung

World Maritime University Dissertations

No abstract provided.

Photocatalytic Oxidation Of Carbon Monoxide Using Sputter Deposited Molybdenum Oxide Thin Films On A Silicon Dioxide Substrate, Donald Bragg

Electronic Theses and Dissertations

CO contamination is common in hydrogen extraction processes. Proton exchange membrane fuel cells need a source of hydrogen containing less than 10ppm of CO to avoid the irreversible poisoning of the fuel cell’s platinum anode. Platinum metal is commonly used as a catalyst for the purification of hydrogen gas. An effort has been put forth to replace the expensive platinum catalyst with a less expensive alternative. Photocatalytically active metal oxide semiconductors have shown promise as less expensive alternatives to platinum for redox reactions such as the oxidation of CO. This research studies a MoO3 sputter deposited thin film on a …

Wall Heat Transfer Effects In The Endwall Region Behind A Reflected Shock Wave At Long Test Times, Corey Frazier

Electronic Theses and Dissertations

Shock-tube experiments are typically performed at high temperatures (≥1200K) due to test-time constraints. These test times are usually ~1 ms in duration and the source of this short, test-time constraint is loss of temperature due to heat transfer. At short test times, there is very little appreciable heat transfer between the hot gas and the cold walls of the shock tube and a high test temperature can be maintained. However, some experiments are using lower temperatures (approx. 800K) to achieve ignition and require much longer test times (up to 15 ms) to fully study the chemical kinetics and combustion chemistry …

Methods Of Extrapolating Low Cycle Fatigue Data To High Stress Amplitudes, David Charles Radonovich

Electronic Theses and Dissertations

Modern gas turbine component design applies much effort into prediction and avoidance of fatigue. Advances in the prediction of low-cycle fatigue (LCF) cracks will reduce repair and replacement costs of turbine components. These cracks have the potential to cause component failure. Regression modeling of low-cycle fatigue (LCF)test data is typically restricted for use over the range of the test data. It is often difficult to characterize the plastic strain curve fit constants when the plastic strain is a small fraction of the total strain acquired. This is often the case with high strength, moderate ductility Ni-base superalloys. The intent of …

Liquid Crystal Thermography Studies In Water Pool Boiling At Subatmospheric Pressures, Kiran Talari

Electronic Theses and Dissertations

A pool boiling experimental facility has been designed and built to investigate nucleate pool boiling in water under sub atmospheric pressure. Liquid crystal thermography, a non intrusive technique, is used for the determination of surface temperature distributions. This technique uses encapsulated liquid crystals that reflect definite colors at specific temperatures and viewing angle. Design of the test section is important in this experimental study. Since a new TLC is required for every new set of test conditions, a permanently sealed test section is not an option. The real challenge is to design a leak proof test section which is flexible …

An Interactive Framework For Meshless Methods Analysis In Computational Mechanics And Thermofluids, Salvadore Anthony Gerace

Electronic Theses and Dissertations

In recent history, the area of physics-based engineering simulation has seen rapid increases in both computer workstation performance as well as common model complexity, both driven largely in part by advances in memory density and availability of clusters and multi-core processors. While the increase in computation time due to model complexity has been largely offset by the increased performance of modern workstations, the increase in model setup time due to model complexity has continued to rise. As such, the major time requirement for solving an engineering model has transitioned from computation time to problem setup time. This is due to …

Lattice Boltzmann Simulation To Study Single And Multi Bubble Dynamics, Amit Gupta

Electronic Theses and Dissertations

In recent years, the lattice Boltzmann method (LBM) has emerged as a powerful tool that has replaced conventional macroscopic techniques like Computational Fluid Dynamics (CFD) in many applications. The LBM starts from meso- and microscopic Boltzmann's kinetic equation to determine macroscopic fluid dynamics. The origins of LBM can be drawn back to lattice gas cellular automata (LGCA); however it lacks Galilean invariance and creates statistical noise in the system. LBM on the other hand does away from these drawbacks of LGCA, and is easy to implement in complex geometries and can be used to study microscopic flow behavior in complex …

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.