Mechanical Engineering Commons^™

Experimental And Numerical Investigation Of Air-Cooled Heat Sinks, Ethan Weems

Mechanical Engineering Undergraduate Honors Theses

Lightweight and affordable cooling capabilities are critical as the physical scale of electronics continues to decrease. Air-cooled heat sinks that dissipate heat from electronic components to the surrounding air are excellent candidates to fill this role. While plate-fin and pin-fin heat sinks have been implemented extensively for electronic cooling, recent advances in additive manufacturing enable the fabrication of more complex structures. In this undergraduate Honors thesis, a means by which to generate novel heat sink geometries is presented. To that end, an experimental characterization facility is developed to evaluate existing traditional heat sinks. The heat transfer performance of the heat …

Aerodynamic Design And Analysis Of A Modified 2006 Mazda Miata, William N. Recher

Honors College Theses

Aerodynamic forces developed by automobiles have destabilizing effects at high speed. These forces tend to skew toward a vehicle’s rear which can present safety concerns, especially for rear-wheel-drive automobiles like the Mazda Miata. To address oversteer and high-speed instability, a vehicle’s design can be tailored to bring about aerodynamic balance and improve traction. LiDAR was used to bring the physical automobile into the digital space. Then, a splitter and diffuser were added to reduce the magnitude of the destabilizing forces. Next, the size and shape of the rear-wing required to balance the vehicle was calculated using a combination of parameters …

Rans-Dns Simulations For Uncertainty Quantification In Dns Data Of Turbulent Mixing Layer, Mohamed Abuhegazy

Mechanical Engineering ETDs

Mixing layer flow is one of the canonical free shear flows in fluid dynamics. Such a flow is formed when two fluid streams move along one another with different velocities. Investigation of this flow development has been an active topic of research for many decades not only due to a wide range of environmental and technological applications where this flow may be observed, but also because of large discrepancies in the results obtained experimentally and numerically regardless this flow simple geometry. In this dissertation, the quality and uncertainty of extracted turbulent statistics of mixing layer flow are analyzed by applying …

Numerical Investigation Of Subglottal Stenosis Effects On Human Voice Production, Dariush Bodaghi

Electronic Theses and Dissertations

This dissertation aimed to advance knowledge of how subglottal stenosis impacts voice production physiology. An in-house fluid-structure-acoustic interaction approach based on the hydrodynamic/acoustic splitting technique was employed. This technique was rigorously verified for simulating phonation by matching the acoustic behavior to a compressible flow solver for phonation-relevant geometries. Simulations of an idealized 2D vocal tract model demonstrated the effects of supraglottal acoustic resonance on vocal fold kinematics and glottal flow waveform. Results showed that the acoustic coupling between higher harmonics and formats generated pressure oscillations, modifying vocal fold dynamics and glottal flow rate.

A major novelty was the incorporation and …

Development Of Alternative Air Filtration Materials And Methods Of Analysis, Ivan Philip Beckman

Theses and Dissertations

Clean air is a global health concern. Each year more than seven million people across the globe perish from breathing poor quality air. Development of high efficiency particulate air (HEPA) filters demonstrate an effort to mitigate dangerous aerosol hazards at the point of production. The nuclear power industry installs HEPA filters as a final line of containment of hazardous particles. Advancement air filtration technology is paramount to achieving global clean air. An exploration of analytical, experimental, computational, and machine learning models is presented in this dissertation to advance the science of air filtration technology. This dissertation studies, develops, and analyzes …

Computational Modelling Of Resin Infiltration And Curing In High Pressure Resin Transfer Molding, Anthony Paul Rexford Sherratt

Electronic Thesis and Dissertation Repository

Increased pressure on automotive manufactures to reduce overall greenhouse gas emissions from their vehicles has driven research into replacing conventional steel components with carbon fiber reinforced plastics (CFRP). This is due to their high weight specific properties and design freedom. High pressure resin transfer molding (HP-RTM), a derivative of resin transfer molding, is a manufacturing process for CFRP’s that offers high automation potential and low cycle times; critical properties of a manufacturing process for the automotive sector.

The goal of the present work is to increase the accuracy and reduce the computational overhead of current RTM infiltration and curing models. …

Fuel Injector Design Of A Hypersonic Jet Engine Using Computational Fluid Dynamics, Melissa Rose Mercado

UNLV Theses, Dissertations, Professional Papers, and Capstones

The development of hypersonic airbreathing engines, such as a supersonic combustion ramjet, or scramjet, are implemented for flight Mach numbers over 5 where combustion must occur in supersonic conditions. The advancement of scramjet propulsion has led to favored usage over rocket propulsion systems for in atmosphere applications due to their lighter weight, higher specific impulse, and greater maneuverability [1]. The combustor section of a scramjet engine houses the fuel injectors. Fuel is injected into the supersonic flow with the main objective of achieving rapid and thorough fuel-air mixing because the residence time in the combustion chamber has a timescale of …

A Study Of Asymmetric Supersonic Wind Tunnel Nozzle Design, Brittany A. Davis

Mechanical & Aerospace Engineering Theses & Dissertations

Achieving higher Mach numbers for private and commercial flight is a growing interest in the aerospace community. To qualify vehicles prior to flight, tests must be run in wind tunnels. Asymmetric wind tunnel nozzles are of continuing interest to the aerospace community due to their ability to change throat geometry, allowing for a range of Mach numbers to be achieved that encompasses all of the supersonic regime. The sliding block wind tunnel at Old Dominion University (ODU) is designed for a range of Mach numbers from about 1.8 to 3.5 but is limited to an upper limit of 2.8 by …

Structural And Hemodynamic Analysis Of Transcatheter Aortic Valves, Dong Qiu

Electronic Theses and Dissertations

The transcatheter aortic valve replacement (TAVR) procedure has become a well-established procedure for high, intermediate-risk, and low-risk patients. However, there is limited clinical data on the TAV's long-term durability, unlike SAV devices. Computational simulations can be an alternative way to evaluate the TAV devices. This dissertation aims to conduct structural and hemodynamic analyses on the TAV devices under different conditions using computational simulation approaches.

Initially, the impact of the bicuspid aortic valve on the TAV devices was evaluated. The result indicated that the CoreValve-like supra-annular self-expandable device was likely to have increased stress and strain on the leaflet when it …

A Computational Fluid Dynamics Analysis Of The Temperature And Impurity Profiles In The Protodune-Sp Neutrino Detector, Jenna Harrison

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) models of the ProtoDUNE single-phase detector were developed, refined, and analyzed. The ProtoDUNE single-phase detector is a prototype detector that is part of the Deep Underground Neutrino Experiment, an international research collaboration aimed at better understanding neutrinos and the role they play in our universe. The ProtoDUNE single-phase detector is used to gather data and inform design changes for the full-sized far detector prior to its construction. The effects of certain geometric features and heat sources on the thermal profiles within the liquid region of the detector were investigated in a set of parametric studies. The …

Simulating The Effects Of Floating Platforms, Tilted Rotors, And Breaking Waves For Offshore Wind Turbines, Hannah Johlas

Doctoral Dissertations

Offshore wind energy is a rapidly expanding source of renewable energy worldwide, but many aspects of offshore wind turbine behavior are still poorly understood and are not accurately captured by low-cost engineering models used in the design process. To help improve these models, computational fluid dynamics (CFD) can provide valuable insight into the complex fluid flows that affect offshore wind turbine power generation and structural loads. This research uses CFD simulations to examine three main topics important to future offshore wind development: how breaking waves affect structural loads for fixed-bottom wind turbines; how platform motions affect power generation, wake characteristics, …

Experimental And Computational Study Of Determining Mass Transport Parameters In Vanadium Redox Flow Batteries, Tugrul Y. Ertugrul

Doctoral Dissertations

Vanadium redox flow batteries are a promising large-scale energy storage technology, but a number of challenges must be overcome for commercial implementation. At the cell level, mass transport contributes significantly to performance losses, limiting VRFB performance. Therefore, understanding mass transport mechanisms in the electrode is a critical step to mitigating such losses and optimizing VRFBs.

In this study, mass transport mechanisms (e.g. convection, diffusion) are investigated in a VRFB test bed using a strip cell architecture, having 1 cm² active area. It is found that diffusion-dominated cells have large current gradients; convection-dominated cells have relatively uniform current distribution from …

Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke

Mechanical & Aerospace Engineering Theses & Dissertations

Urban Air Mobility (UAM) is one of the most popular proposed solutions for alleviating traffic problems in populated areas. In this context, the proposed types of vehicles mainly consist of rotors and propellers powered by electric motors. However, those rotary-wing components can contribute excessively to noise generation. Therefore, a significant noise concern emerges due to urban air vehicles in or around residential areas. Reducing noise emitted by air vehicles is critically important to improve public acceptance of such vehicles for operations in densely populated areas.

Two main objectives of the present dissertation are: (1) to expand the multidisciplinary optimization to …

Validation Of A Two-Dimensional Clinostat Design To Provide Functional Weightlessness To Custom Gas Exchange Vessels, Collin R. Topolski

Doctoral Dissertations and Master's Theses

Understanding the impacts of microgravity on bacteria is vital for successful long duration space missions. In this environment, bacteria have been shown to become more virulent, more resistant to antibiotics and form more biofilms. To learn more about these phenomena, many experiments must be sent to the International Space Station, which is cost- and time prohibitive. Instead, the use of ground-based analogs is advantageous to define preliminary results that can later be verified with a space-based experiment. This research explored the development of an innovative 2D clinostat for simulating microgravity using bacteria. Computational fluid dynamics, standards established by previous literature …

Integrated Modelling Of Wastewater Treatment And Sewer Processes - Interactions Of Fluid Flow, Mass Transfer, And Biochemical Reactions, Ahmed Khalil

Electronic Thesis and Dissertation Repository

Numerical modelling of wastewater management systems is crucial for investigating alternative designs and developing strategies for operation and control that improve the performance of the treatment stage (such as improving the aeration systems in activated sludge systems). Modelling can also help operators to mitigate common problems that arise from unwanted biochemical conversions in the sewer networks (such as the production of sulfide and methane). Therefore, this work focuses on two major areas related to modelling wastewater management systems. First, it seeks to develop more accurate models for aeration systems in activated sludge reactors. Second, it seeks to study the mathematical …

A Theory-Supported Machine Learning Model For The Prediction Of Melt Pool Geometry And Optimal Process Window In Metal Additive Manufacturing, Sina Tayebati

Graduate Research Theses & Dissertations

Direct Energy Deposition (DED) is an additive manufacturing (AM) process capable of producing complicate-shaped or functionally graded components, and it is getting intense attention as a revolutionary technology to satisfy high demand in manufacturing process for the aerospace, automotive, and medical industries. However, the repeatability in geometries and properties of fabricated products is one of the most challenging issues for the DED process to be fully utilized, requiring comprehensive understanding of effect of processing conditions on the properties of fabricated parts, and development of relations among those conditions and properties. That is the motivation of this research. In this study, …

Development Of A Pediatric Cardiac Assist Maglev Pump For Use With A Universal Driver System., Landon Heath Tompkins

Electronic Theses and Dissertations

Heart failure (HF) remains the leading cause of death, affecting 26 million adults worldwide and 6.5 million adults in the United States. Pediatric HF patients have been a historically underserved population with few options for mechanical circulatory support (MCS) therapy, a leading treatment as an alternative to heart transplantation. To address this clinical need, the Inspired Universal MagLev System is being developed; a low cost, universal magnetically levitated extracorporeal MCS system with interchangeable single-use pumps that will ultimately provide adult and pediatric patients ventricular and respiratory assist therapies. The Inspired Pediatric VAD is the first single-use pump application for this …

Analytical And Computational Modelling Of The Ranque-Hilsch Vortex Tube, Nolan J. Dyck

Electronic Thesis and Dissertation Repository

The Ranque-Hilsch vortex tube (RHVT) is a simple mechanical device with no moving parts capable of separating a supply of compressed fluid into hot and cold streams through a process called temperature separation. The overall aim is to develop models which can be used to assess the temperature separation mechanisms in the RHVT, leading to a better overall understanding of the underlying physics. The introductory chapter contains a thermodynamic analysis and introduction to the flow physics, alongside three miniature literature reviews and critiques identifying research gaps.

The body of the thesis contains three articles. The first article studies the flow …

A Numerical Investigation Of Microgravity Evaporation, Daniel Peter Ringle

Dissertations and Theses

Evaporation is important to myriad engineering processes such as cooling, distillation, thin film deposition, and others. In fact, NASA has renewed interest in using cabin air pressure evaporation as a means to recycle waste water in space. As one example, NASA recently conducted experiments aboard the International Space Station (ISS) to measure evaporation rates in microgravity and to determine the impacts of porous structure on the process. It has long been assumed that differences in evaporation rates between 1-g₀ and microgravity are small. However, discrepancies by as much as 40% have been observed in practice. The assumption now …

Computational Analysis And Design Optimization Of Convective Pcr Devices, Jung Il Shu

Mechanical & Aerospace Engineering Theses & Dissertations

Polymerase Chain Reaction (PCR) is a relatively novel technique to amplify a few copies of DNA to a detectable level. PCR has already become common in biomedical research, criminal forensics, molecular archaeology, and so on. Many have attempted to develop PCR devices in numerous types for the purpose of the lab-on-chip (LOC) or point-of-care (POC). To use PCR devices for POC lab testing, the price must be lower, and the performance should be comparable to the lab devices. For current practices with the existing methods, the price is pushed up higher partially due to too much dependence on numerous developmental …

Aerodynamic Design Optimization Of A Locomotive Nose Fairing For Reducing Drag, Chad Lamar Stucki

Theses and Dissertations

Rising fuel cost has motivated increased fuel efficiency for freight trains. At cruising speed,the largest contributing factor to the fuel consumption is aerodynamic drag. As a result of stagnationand flow separation on and around lead and trailing cars, the first and last railcars experiencegreater drag than intermediate cars. Accordingly, this work focused on reducing drag on lead locomotivesby designing and optimizing an add-on nose fairing that is feasible for industrial operation.The fairing shape design was performed via computational fluid dynamic (CFD) software.The simulations consisted of two in-line freight locomotives, a stretch of rails on a raised subgrade,a computational domain, and …

Flow Fields Past Grain Bins As It Relates To Vertical Axis Wind Turbine Placement Optimization, Jon Richter

All Graduate Theses, Dissertations, and Other Capstone Projects

This thesis studies the 3D flow field of grain bins as it relates to Vertical Axis Wind Turbine (VAWT) placement. Numerical CFD simulations using ANSYS FLUENT were created and validated with the Minnesota State University, Mankato water channel. It was found that the best speed-up regions were on the outer most sides of the models, closest to the walls of the water channel. The model that is furthest upwind in the group has the best speed-up velocity. As the models become closer together, an asymmetric flow field develops. VAWT placement between the models for any case researched is not recommended. …

Using Cfd To Improve Off-Design Throughflow Analysis, Troy J. Lanchman

Browse all Theses and Dissertations

In turbomachinery design, complex internal flows give rise to significant losses and blockage whose effects are difficult to properly analyze without detailed computational fluid dynamics (CFD) methods or experiments. In a typical design method, CFD is used in conjunction with simpler throughflow or cascade codes to hasten the process. However, the lesser physical accuracy of the design codes demands the inclusion of models to improve the accuracy of the throughflow codes. This thesis aims to use CFD data to generate improved loss and blockage models for a 2D compressor throughflow code by matching throughflow data to CFD data using optimizations. …

Blade Design And Analysis Of Horizontal-Axis Wind Turbine: Cfd And Experimental Investigation Of Blades Design, Relwinde Fabrice Zongo

Electronic Theses and Dissertations

The present thesis focuses on the investigations of the computational fluid dynamics analysis and the experimental study of small scales Horizontal Axis Wind Turbine (HAWT) blades. The initial steps are taken; in the process of this research were the selection of the airfoil type to be used in each blade design and the creation of a blade design with high efficiency operating in a low wind speed zone. For the mentioned blade design process, the following airfoils were selected respectively NACA 0010, NACA 0012, NACA 1412, NACA 2412, NACA 2414, NACA 4412 and NACA 6412. This selection intends to provide …

Experimental And Numerical Characterization Of Multiphase Subsurface Oil Release, Feng Gao

Dissertations

Subsurface oil release is commonly encountered in the natural environment and engineering applications and has received the substantial attention of researchers after the disastrous Deepwater Horizon Blowout oil spill in 2009. The main focus on the present research is to systematically study the hydrodynamics of underwater oil jet under a variety of conditions, including the effect of dispersant and different gas to oil ratios (GOR) by using experimental measurement as well as a Computational Fluid Dynamics (CFD) approach, from which the measured turbulent characteristics (e.g., velocity, turbulent kinetic energy, turbulence dissipation rate, etc.) of underwater oil jet are thoroughly examined …

Electric-Field Assisted Manipulation And Self-Assembly Of Particle Suspensions, Edison Chijioke Amah

Dissertations

The aim of this dissertation is to model the processes by which particles suspended in liquids and at liquid surfaces self-assemble when they are subjected to uniform and non-uniform electric fields. To understand the role of electric forces, three related problems were studied numerically and experimentally.

In the first problem, particles are assumed to be suspended inside a liquid and a nonuniform electric field is applied using electrodes mounted in the domain walls which causes positively polarized particles to collect in the regions where the electric field intensity is locally maximal and the negatively polarized particles collect in the regions …

Simplified, Alternative Formulation Of Numerical Simulation Of Proton Exchange Membrane Fuel Cell, Russell L. Edwards

Mechanical & Aerospace Engineering Theses & Dissertations

Three-Dimensional proton exchange fuel cell (PEMFC) operation in steady-state is simulated with computational fluid dynamics / multiphysics software that is based upon the finite-element method. PEMFC operation involves the simultaneous simulation of multiple, interconnected physics involving fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts have varied by how they treat the physics occurring within and adjacent to the membrane-electrode assembly (MEA). Several approaches treat the MEA as part of the computational domain, solving multiple, and coupled conservation equations via the CFD approach within the 3 regions of the MEA. The thickness dimensions of the …

Computational Investigation Using Bleed As A Method Of Shock Stabilization, Dayle L. Chang

Theses and Dissertations

Shock-wave/boundary layer interactions (SWBLI) produce undesirable dynamic loads and separated unsteady flows, adversely impacting the performance and structural integrity of supersonic vehicles. Computational fluid dynamics (CFD) is a successful tool in experimental planning and shows promise as a critical tool in understanding and mitigating negative effects of SWBLI. The goal of this research is to demonstrate the effect of bleed holes on shock stability using the OVERFLOW CFD solver to inform the planning of an Air Force Research Laboratory (AFRL) SWBLI wind tunnel experiment. First, a two-dimensional, flat plate, single-hole configuration was developed. Massflow discrepancies of 14.8% were initially observed …

Uncertainty In Combustion Reaction Rates And Its Effects On Combustion Simulations, Joshua Piehl

Wayne State University Theses

This work investigates the uncertainties in reaction rates of an n-dodecane model on turbulent spray combustion simulations. Six major reactions were found to significantly impact the ignition delay of the mechanism in a 0-D batch reactor model. These reactions’ rates were independently modified and placed into individual mechanisms. These newly developed mechanisms were simulated in a 3-D turbulent spray simulation and a 0-D batch reactor at a pressure of 60 bar and temperatures from 900 to 1100 K. The combustion characteristics (e.g. ignition delays, flame lift-off length, liquid and vapor penetration) of the modified mechanisms were compared to those produced …

Optimization Of Microfluidic Particle Separator Geometry Using Computational Fluid Dynamics, Joseph Petersen

Electronic Theses and Dissertations

Computational fluid dynamics software was used to simulate the motion of circulating tumor cells in a variety of microfluidic cell isolation devices. Design of several novel microfluidic cell isolation devices was aided by viewing streamlines of fluid in devices in simulation. Devices that performed best in simulation used 5-micrometer wide guiding channels to guide cells to the capture location in the device. While these devices performed better than other devices in simulation and captured all particles regardless of position along inlet, experimental results differ from simulation.