Mechanical Engineering Commons^™

Experimental Investigation Of Two-Phase (Gas/Liquid) Flow In Intermediate Sized, Horizontal And Inclined Pipes, Noble C. Anumbe

Theses and Dissertations

Multiphase flow models and correlations are indispensable tools for the design and operation of vital flow systems that power various industries. The development, validation and tuning of these flow models & correlations depend on the availability of reliable and accurate data. This dissertation reports on an experimental campaign that not only generated crucial two-phase flow data but also evaluated the effect of inclination angle on several flow parameters of interest. The report details the experimental investigation of upward, adiabatic, co-current two-phase (gas/liquid) flow through a 101.6 mm inner diameter (ID) pipe. Experimental data for the investigation were acquired using an …

Topological Conduction And Investigation On Multi Occurrence Of Dirac Cone, Mustahseen Mobashwer Indaleeb

Theses and Dissertations

The unique phenomena in acoustic metamaterial at the Dirac-like cone, and at the exceptional spawning ring could transform the field of engineering with multiple new applications that were never possible before. Localized conical dispersion called Dirac cone at the Brillouin Zone boundaries are the well-known phenomena demonstrated by photonics and phononic metamaterials. However, Dirac cone-like dispersion at the center of the Brillouin zone (where wave number, k = 0) [1] is rare and only happens due to accidental degeneracy at finite frequencies in two-dimensional periodic crystals (PCs), with or without microarchitectures. Accidental degeneracies are generally the ‘sweet spots’ where the …

Ultrasonic Analysis And Tools For Quantitative Material State Awarness Of Engineered Materials, Subir Patra

Theses and Dissertations

The objective of this research is to devise new methods and tools to generate real time awareness of the material state of composite and metallic structures through ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) at its very early stage of failure. To device new methodology it is also important to verify the method through virtual experiments and hence computational NDE is getting popular in the recent years. In this thesis, while experimental methodology is developed to understand the material state at its early stage of failure, a new peridynamic based Peri-Elastodynamic (PED) computational method is also developed for …

System Optimization And Material Development Of Solid Oxide Cells For Energy Conversion And Storage, Libin Lei

Theses and Dissertations

Solid oxide cells (SOCs) can convert chemical energy to electricity in the fuel cell mode and store electricity to chemicals in the electrolysis mode. However, there are still critical barriers, such as energy efficiency and durability, for the development and commercialization of SOCs. The objective of this dissertation is to apply system optimization and materials design to address the critical barriers for solid oxide cells in energy conversion and energy storage applications. One major focus of the dissertation is related to improve energy efficiency, enhance the cell performance and achieve multifunctionality in solid oxide electrolysis cells (SOECs). In addition, development …

Characterization Of Evaporation/Condensation During Pool Boiling And Flow Boiling, Mostafa Mobli

Theses and Dissertations

Present dissertation has investigated pool and flow boiling and their characteristics via numerical means. A code was developed to investigate and enhance heat transfer performance during different modes of phase change phenomena. Multiphase heat transfer has proven to be one of the most effective means of heat transfer in different industries, therefore, there have been numerous experimental and numerical studies on the subject of phase change phenomena in a wide range of conditions and setups; yet there are complex bubble dynamics and heat transfer characteristics that remain unresolved. To have a more detailed look at and a better understanding of …

Structural Health Monitoring Using Ultrasonic Guided Waves And Piezoelectric Wafer Active Sensors, Faisal Haider Mohammad

Theses and Dissertations

This dissertation is organized in three major parts covering ardent and challenging research topics in structural health monitoring (SHM). Part I focuses on the theoretical and numerical analysis of acoustic emission (AE) guided waves in both Cartesian coordinates (2D) and cylindrical coordinates (3D) system using energy approach, which, to the best of our knowledge, has not been yet reported elsewhere. AE guided waves appear due to sudden energy release during incremental crack propagation in a plate. The Helmholtz decomposition approach is applied to the inhomogeneous elastodynamic Navier-Lame equation for both the displacement field and body forces. For the displacement field, …

Manufacturing Feature Recognition With 2d Convolutional Neural Networks, Yang Shi

Theses and Dissertations

Feature recognition is a critical sub-discipline of CAD/CAM that focuses on the design and implementation of algorithms for automated identification of manufacturing features. The development of feature recognition methods has been active for more than two decades for academic research. However, in this domain, there are still many drawbacks that hinder its practical applications, such as lack of robustness, inability to learn, limited domain of features, and computational complexity. The most critical one is the difficulty of recognizing interacting features, which arises from the fact that feature interactions change the boundaries that are indispensable for characterizing a feature. This research …

Analysis Of Pellet-Cladding Mechanical Interaction On U3si2 Fuel With A Multi-Layer Sic Cladding Using Bison, Ray A. Freeman

Theses and Dissertations

U3Si2 is currently being considered as a possible replacement for the current light water reactor fuel, UO2. U3Si2’s high melting temperature, high uranium density, and high thermal conductivity are favorable in accident conditions, such as a loss of coolant accident. Improved accident performance is further expected when paired with a SiC/SiC cladding, since it provides relatively high strength and a high oxidation resistance.

Modeling of U3Si2 and SiC/SiC in reactor is currently very important since much of their behavior is still unknown. By implementing models that describe the properties of U3Si2 and SiC/SiC into INL’s fuel performance code BISON, performance …

Physics-Based Approaches For Structural Health Monitoring And Nondestructive Evaluation With Ultrasonic Guided Waves, Md Yeasin Bhuiyan

Theses and Dissertations

The engineering infrastructures have a growing demand for damage monitoring systems to avoid any potential risk of failure. Proper damage monitoring solutions are of a great interest to this growing demand. The structural health monitoring (SHM) and nondestructive evaluation (NDE) offer appropriate online and offline damage monitoring solutions for a variety of mechanical and civil infrastructures that includes unmanned aerial vehicles (UAV), spaceships, commercial aircraft, ground transportation, wind turbines, nuclear spent fuel storage tanks, bridges, naval ships, and submarines. The fundamentals of the ultrasonic SHM and NDE consist of multi-disciplinary fields. The dissertation addresses SHM and NDE using ultrasonic guided …

Effect Of Weak Adhesion Interface On Mechanical And Dielectric Properties Of Composite Materials, Prashant Katiyar

Theses and Dissertations

Interfaces are often the most critical part of the heterogeneous materials and their structures. Such interfaces appear a multiple length scales and significantly affect bulk properties in different material systems. Fiber reinforced composite materials are one such example of heterogeneous materials with interfaces at constituent scale (fiber-matrix interface and interphase) to laminate scale (secondary adhesive joints). Manufacturing induced defects and subsequent in-service damage at these interfaces can severely affect the durability of fiber reinforced laminated composite materials and their joints. In addition to lamination process, defects can also form during secondary joining process (e.g., adhesive bonding and repair) which can …

High Temperature Compression Creep Of U3si2, Emil Angelo Cahanap Mercado

Theses and Dissertations

As a result of the Fukushima Daiichi Nuclear Disaster in 2011, a push for increasing the safety of nuclear power plants was made through research grants funded through the United States Department of Energy via the Accident Tolerant Fuels (ATF) campaign. One of the focuses of the campaign is improving the accident tolerance of nuclear fuel during a loss of coolant accident.

A promising set of being researched from the ATF is Silicon Carbide (SiC) composite cladding and Uranium Silicide (U3Si2) fuel pellets. Under high temperatures, stresses, and times the creep deformation can play an important factor in pellet to …

Combustion Behavior Of Sub-Millimeter Sized Oxygenated And N-Alkane Fuel Droplets, Mohammad Fahd Ebna Alam

Theses and Dissertations

The primary scientific explorations of this thesis work are to better understand (a) microgravity fire-suppression of untested extinguisher, (b) combustion kinetic model refinement of renewable fuel butanol (C4H9OH) isomers, and (c) directly induced cool flame dynamics of higher n-alkane fuels from an isolated small droplet combustion perspective employing computational fluid dynamics with comprehensive chemical kinetics. The chronological development of the research direction shifts from a relatively small fuel like methanol (CH3OH) to heavier straight paraffinic fuel n-decane (n-C10H22). The first installment of the thesis is directed towards answering the feasibility of thennewly considered fire suppressant xenon (Xe) for microgravity space …

The Mechanical Properties And Deformation Behavior Of Heat Treated Versus As-Received Inconel X-750, Christopher Marsh

Theses and Dissertations

X-750 is a nickel-chromium based super alloy of usefulness in a wide variety of applications such as gas turbines, rocket engines, nuclear reactors, pressure vessels, tooling, and aircraft structures. Its good mechanical properties are due to the strengthening from precipitation of γ′ particles upon prior ageing heat treatment. In this work, the effect of such heat treatment on the mechanical properties, tensile behavior, and fracture mechanisms of X-750 was studied at various temperatures by comparing it with a non-aged, solution annealed X-750. Tensile tests were conducted from room temperatures up to 900 °C at three separate strain rates (10-3, 10-4, …

Fundamentals Of Srcoo3 Based Oxygen-Deficient Perovskites As Cathodes For Solid Oxide Fuel Cells, Tianrang Yang

Theses and Dissertations

The local structure and oxygen stoichiometry in oxide systems have a profound impact on oxygen electrocatalysis encountered in metal-air batteries and solid oxide fuel cells (SOFCs). However, this knowledge is often obtained under conditions different from the real working conditions of the material, resulting in misinterpretation and misunderstanding. This PhD dissertation aims to obtain the structure and oxygen stoichiometry information of a class of perovskite oxides under their real working conditions in solid oxide fuel cells. Several perovskite oxides were selected for the study: Sr0.9Y0.1CoO3- (SYC10), Sr0.9Y0.3CoO3- (SYC30), SrCo0.9Nb0.1O3- (SCN10) and SrCo0.9Ta0.1O3- (SCT10). The local crystal structure and oxygen stoichiometry …

Monitoring The Progress Of Damage In A Sicf-Sicm Composite Nuclear Fuel Cladding Under Internal Pressure Using Acoustic Emission, Luis H. Alva

Theses and Dissertations

The relation between the progress of damage and the acoustic emission (AE) activity of a nuclear grade Sif-SiCm composite tubing under internal pressure was studied. The nuclear grade Sif-SiCm composite tubing is manufactured by the company General Atomics (GA) and made of nuclear grade HI Nicalon type S fiber preforms following a chemical vapor infiltration (CVI) technique. Sif-SiCm composites are good candidates to replace current nuclear fuel cladding materials because of the good chemical stability and strength at high temperatures. In this work, a Sif-SiCm composite tubing was tested under internal pressure at room temperature (RT) to study the damage …

Enhance Flow Boiling In Microchannels By Regulating Two-Phase Transport Patterns, Wenming Li

Theses and Dissertations

Flow boiling in microchannels is one of the most promising cooling techniques for microelectronics. Using latent heat by vaporization can significantly improve heat dissipation of high power density electronic devices. Most of the failure of electronic devices is induced by the occurrence of critical heat flux (CHF), which defines the maximum operating conditions. However, the vigorous rapid generation of vapor through phase change leads to chaotic two-phase flows in microchannels, resulting in flowinstability in terms of severe flow, temperature and pressure drop fluctuations. Particularly, the very well-known bubble confinement exacerbates the two-phase flow instabilities and greatly deteriorates heat transfer performance …

Effect Of Material Orientation On The Impact Response Of Graded Cellular Materials, Abigail Wohlford

Theses and Dissertations

In this study, the effect of layer stacking on the energy absorption characteristics of density-graded cellular polymers subjected to high velocity impact is investigated experimentally. The focus in the present work is to characterize the constitutive response and deformation mechanisms of these Functionally Graded Foam Materials (FGFM) using full-field measurements. Uniform foam Quasi-static and dynamic testing of uniform foam specimens are completed for each nominal density used in the layered foam samples. The low strain-rate experiments are performed in order to determine the mechanical properties of foam specimens. The high-rate experiments for homogenous foam specimens were completed to further characterize …

Acousto-Ultrasonic Shm/Nde Methods Toward Field Application, Stephen Harris Howden

Theses and Dissertations

Acousto-ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) methods offers solutions in damage detection, material properties evaluation and more. These ultrasonic waves can propagate through solids and interact with structural features and discontinuities. In this thesis use of several acousto-ultrasonics NDE/SHM methods were explored to evaluate their sensing and detection capabilities toward damage detection field applications in nuclear and aerospace industries.

For nuclear applications, passive sensing using piezoelectric sensors and acoustic emission (AE) techniques were explored on the spent fuel dry storage casks. Dry storage casks are used in the nuclear industry to transport or store spent nuclear fuel …

Multiscale Deformation And Failure Behavior Of Polymer Bonded Explosives Subjected To High Rate Loading, Suraj Muthiramalil Ravindran

Theses and Dissertations

Polymer bonded explosives (PBX) are heterogeneous granular composites with a high-volume fraction of solid. Typically, they contain 80-95% explosive crystals and 5- 20% soft polymer binder. These materials are subjected to different loading conditions during their service life. The main function of the soft binder is to reduce shock sensitivity to prevent an accidental explosion. However, there have been inadvertent detonations in these materials during transportation and handling. The reason for such unintentional explosion is not well understood. It is commonly accepted that the formation of local hightemperature regions, called ‘hot spots’, is the primary cause. Hotspot formation is associated …

Development Of Advanced Mixed Electronic And Carbonate Ion Conducting Membranes And Reactors For Combined Co2 Capture And Conversion, Jie Fang

Theses and Dissertations

Global warming and climate change resulted from CO2 emissions have been increasingly observed to impact our daily life and damage our economy in recent human history. To deal with this grand challenge, carbon capture and storage (CCS) has been established as a key technology to curb CO2 emission from fossil-fueled power plants. The core of the CCS technology is to capture CO2 at emission sources and geologically bury it for permanent storage or enhanced oil recovery (OER). As the first step of CCS, carbon capture technologies are currently being developed for three power-generation related combustion processes that are responsible for …