Mechanical Engineering Commons^™

Engineering The Surface Chemistry And Surface Conditions To Optimize The Heat Removal Rate Of Various Surfaces, Thomas Germain

Electronic Theses and Dissertations, 2020-2023

As the demand for more powerful and smaller electronics rise, the need for creative cooling solutions to prevent burnout becomes increasingly paramount. In response to recent cooling needs, new cooling techniques, such as jet impingement cooling, spray cooling, and heat pipes, have risen in popularity for their simple design and efficiency in thermal transport. This interest has risen in both industry and academia, where research has been conducted to optimize the heat transfer performance for these systems and how these systems can be implemented in new technologies. One method that has risen in interest is affecting the surface, through physical …

Contact Mechanics Of Fish Scale Inspired Exoskeletal Components On A Nonlinear Elastic Substrate, Jeremy Stephen

Electronic Theses and Dissertations, 2020-2023

The contact mechanics of structures with exoskeletal components deviate significantly from classical Hertzian and non-linear models. In the case of fish scale inspired samples under blunt indentation loading these factors are inherently tied to both the size of the indenter and the scales' distribution and orientation. Control of these geometric parameters provides a pathway to tailor the properties of surfaces for better grip, damage mitigation and controlled deformation. This study explores the response of a substrate with stiff scales protruding from its surface, which is comprised of a soft elastomeric material with properties typical of those in soft robotics applications. …

High-Speed Imaging Of Reflected Shockwave-Initiated Combustion, Erik Ninnemann

Electronic Theses and Dissertations, 2020-2023

Shock tubes are considered ideal reactors and are used extensively to provide valuable chemical kinetic measurements, such as ignition delay times and in-situ species time-histories. However, due to nonideal affects the combustion of fuel inside shock tubes can become nonhomogeneous, particularly at low temperatures, which complicates the acquired data. In this work, the combustion of practical fuels used by society are investigated with high-speed imaging. First, high-speed images were captured through the end wall of the shock tube for two hydrogen-oxygen systems. The combustion process was found to initiate in two modes, one that is homogeneous across the fluid medium …

Rotational And Shower Head Cooling Hole Effects On Leading-Edge Jet Impingement Heat Transfer, Weston Olson

Electronic Theses and Dissertations, 2020-2023

Jet Impingement and shower head cooling are critical cooling techniques used to maintain turbine blades at operational temperatures. Jet impingement is extremely effective at removing large amounts of heat flux from the target surface, the inner blade wall, through stagnation point heat transfer. Shower head cooling produces a cooling film around the exterior of the blade, in return reducing external heat flux. The current work consisted of investigating the jet impingement effectiveness with rotational effects for two different cooling schemes. The analysis was conducted numerically using STAR CCM+ with two different turbulence models, the three equation Lag Elliptic Blending K …

Experimental Investigation Of The Laminar Burning Velocities Of High-Performance Co-Optima Biofuels, Gihun Kim

Electronic Theses and Dissertations, 2020-2023

Co-Optimization of Fuels and Engines (Co-Optima) initiative of the U.S Department of Energy (DOE) started research on biofuel and biodiesel to replace the gasoline (petrol) and diesel for over the road internal combustion engines. From an initial list of thousands of fuels, selected bio-fuels and biodiesels were investigated for further combustion studies following the implementation of screening, which consisted of biodegrading, toxicity, flash point, research octane number, motor octane numbers, cetane number, and economic effect, etc. Experimental measurements of laminar burning velocity (LBV) are key parameters to understand fuel performance and applicability in engines. Furthermore, knowledge of LBV is required …

Virtual Experiments For Engineering Education, Amy P. Lebanoff

Honors Undergraduate Theses

In-person engineering instruction relies on the availability of equipment and space. Cost, safety, and scheduling may pose barriers to conducting in-person labs. Virtual experiments may be used to enhance the student experience by, for example, incorporating pre-labs for in-person experiments and providing access to equipment that cannot be safely used in-person. Virtual learning is used in many fields, but there remain questions as to how it should be employed in engineering, an area largely reliant on in-person lab and classroom setups. Earlier studies reviewed the advantages of virtual labs such as demonstrating hard-to-observe phenomena and allowing unlimited trials. This project …

Maximizing Bass Reflex System Performance Through Optimization Of Port Geometry, Bryce Doll

Honors Undergraduate Theses

A bass-reflex system is a type of loudspeaker design that uses a port or a vent to improve low-frequency performance. The port acts as a Helmholtz resonator which extends the bass response of the system. However, at high drive levels, the air inside the port can become turbulent and cause distortion, noise, and compression. From previous works, it is known that the geometry of the port plays a crucial role in reducing these unwanted effects. This paper serves to provide more insight into optimal port shape by performing several objective tests on a group of 5 different prototype port shapes …

High-Speed Interferometry And Visible Videography For Meniscus Curvature Analysis During Anisotropic Hemiwicking, John Bal

Electronic Theses and Dissertations, 2020-2023

Recent advancements in microelectronics have increased the need for thermal management systems capable of high heat flux dissipation within significant spatial constraints. One method of increasing local heat fluxes is the fabrication of superhydrophilic materials via micro/nanostructuring of the surface. Superhydrophilic surfaces act in a self-pumping capacity, spreading fluid beyond its intrinsic meniscus length to form thin-films, a process known as "hemiwicking", with practical applications in evaporative cooling, as well as flow, pool, and thin-film boiling. Of particular interest is anisotropic hemiwicking via asymmetric microstructuring. The microscopic asymmetricity of the design induces a macroscopically preferred direction of wicking, which has …

A Shock Tube Chemical Kinetic Study Of Ethanol Oxidation At Elevated Pressures, Andrew Laich

Electronic Theses and Dissertations, 2020-2023

Understanding the combustion chemistry of ethanol is critical for continued proliferation and use in future internal combustion engines (ICEs) that will operate in a downsized, turbo-charged, high compression configuration. Detailed chemical kinetic reaction mechanisms already exist for ethanol, which have been validated over a range of operating conditions; however, capturing the conditions that may be seen in future ICEs requires extension of these conditions, namely at elevated pressure. Investigating the kinetics of ethanol existing in a combustion system first involve, for example, understanding a key global metric like ignition delay time (IDT) and measuring major or minor species in a …

Study On Comprehensive Mechanical Properties Of Metallic Matrix Cnt Nano-Composites, Shutao Song

Electronic Theses and Dissertations, 2020-2023

Carbon nanotubes (CNT) have excellent mechanical strengths, electrical conductivity, and thermal conductivity. CNT reinforced metallic nano-composites are viewed as a great candidate to replace traditional alloy materials. It has been shown that CNTs can greatly enhance the strength, thermal conductivity, and electrical conductivity of composites. However, the ductility of composites would deteriorate due to the addition of CNTs if the fabrication or/and processing methods are not improved or well designed. This dissertation investigated (1) the strengthening mechanisms of CNT on metallic matrix, such as mechanical strength and thermal conductivity, and (2) analytical modeling on the strength-ductility trade-off of CNT reinforced …

Seismocardiographic Signal Variability And Pulmonary Phase Detection In Adults, Md Khurshidul Azad

Electronic Theses and Dissertations, 2020-2023

Cardiovascular disease is one of the leading causes of mortality in the world. Early detection and intervention can significantly improve disease management and patient quality of life. Current methods of evaluating cardiac function often involve history and physical examination (including stethoscope auscultation), electrocardiograms (ECG), echocardiogram imaging, computed tomography, and various blood tests. Seismocardiographic signals (SCG) are the chest surface vibrations resulting from cardiomechanical activity. SCG may be recorded using accelerometers and can be used for monitoring and predicting cardiac health. SCG's potential utility may be impeded by its spatial, postural, respiratory, and longitudinal variability. In this dissertation, the SCG variability …

Applied Laser Absorption Spectroscopy For Sensing In Detonative Flows, Kyle Thurmond

Electronic Theses and Dissertations, 2020-2023

A great deal of interest lies in detonative combustion due to its destructive potential and the theoretical thermodynamic advantages over traditional deflagration devices used for propulsion and energy. High energy materials and explosives combustion products and temperature must be characterized to gain greater insight into the energy release mechanisms, allowing for more tailored deployment. Predictive models for detonations employ various types of state equations, and temperature can be used as a check on the equation validity. However, the extreme environment of explosives is incredibly challenging to evaluate temperature. Additionally, these reactions are extremely fast, taking place over microseconds, and have …

Supercritical Co2 Heat Transfer Study Near Critical Point In A Heated Circular Pipe, Akshay Khadse

Electronic Theses and Dissertations, 2020-2023

Supercritical CO2 (sCO2) power cycle is an up-and-coming technology to produce electricity from various heat sources. Apart from power cycles, sCO2 can also be used as coolant in centralized cooling system and stand-alone cooling device. However, lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge behind fundamental heat transfer processes can hinder its practical realization in key energy and cooling systems. The overall objective of the study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO2 power cycle. The emphasis here is investigation of heat transfer effects …

Additive Manufacturing Of Elastomeric Lung Phantoms In Radiation Oncology, Jonathan Sookdeo

Electronic Theses and Dissertations, 2020-2023

Cancer is a particularly difficult disease to manage and treat, with cancer of the lung being a notably complex disease to treat with radiation therapy. In this study, a stereolithography-based 3D printing process was developed to fabricate human lung phantoms with identical mechanical and physical properties of human lungs in order to assist with targeted radiation therapy. A highly flexible UV photopolymer material with an elastic modulus of approximately 350 KPa was formulated for use in a custom-built stereolithography-based 3D printing apparatus. The printer built for 3D printing of the photopolymer features a large build volume with off-shelf components with …

Detailed Study Of Flow And Surface Heat Transfer Enhancement Mechanism In The Presence Of Dimples And/Or Protrusions, Gaurav Gupta

Electronic Theses and Dissertations, 2020-2023

Recent advancements in material technology have led to the development of non-porous negative Poisson's ratio (NPR) materials (also called auxetic structures) by making spherical inline dimples on both sides of an elastic sheet. Manufacturing technologies such as 3-D printing and additive manufacturing paved the way to realize the complex shapes needed to achieve NPR behavior. These materials are desirable in many engineering applications, especially in the gas turbines hot-gas-path, due to their unique properties. In the current study, an effort is made to understand the flow physics and surface heat transfer mechanism for channel flow having one wall with spherical …

Tip Clearance Effect On Convective Heat Transfer In Micro Scale Pin Fins, Hanieh Tabkhivayghan

Electronic Theses and Dissertations, 2020-2023

Fluid flow and local heat transfer in a microchannel with single and array of pin fins have been studied. For the single pin fin case, a microchannel with a 150-µm diameter pin fin with a tip clearance was experimentally and numerically studied for three Reynolds numbers in laminar regime. Tip clearances of 0, 30, 45 and 100 µm in a 200-µm high microchannel. Experimental and numerical local temperatures and the corresponding Nusselt numbers along the centerline of the pin fin were presented and discussed. Local temperatures were measured on top of the heater surface and downstream the pin fin through …

Seismocardiography - Genesis, And Utilization Of Machine Learning For Variability Reduction And Improved Cardiac Health Monitoring, Peshala Thibbotuwawa Gamage

Electronic Theses and Dissertations, 2020-2023

Seismocardiography (SCG) is the measured chest surface vibrations resulting from cardiac activity. Although SCG can contain information that correlate with cardiac health, its utility may be limited by lack of understanding of the signal genesis and a variability that can mask subtle SCG changes. The current research utilized medical imaging reconstruction and finite element method (FEM) to simulate SCG by modeling the propagation of myocardial movements to the chest surface. FEM analysis provided a link between myocardial movements and the SCG signals measured at the chest surface and suggested that myocardial movement is a primary source of SCG. Increased understanding …

City Of New Smyrna Beach Solar Feasibility Assessment, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

At the request of the City of New Smyrna Beach, the Florida Solar Energy Center (FSEC) assessed rooftop solar and building energy efficiency improvement potential for 17 city-owned facilities. The intent has been to assist City leaders in identifying opportunities to reduce the City's overall electricity consumption and increase its use of renewable energy.

The FSEC team conducted Level 1 energy audit activities and site assessments including:

On-site assessment

• Solar feasibility measurements and characterization including orientation, roof shading (adjacent structures, encroaching trees, etc.), available roof area, system output, annualized savings
• HVAC characterization
• Lighting survey
• Occupancy density, schedule, thermostat settings

Post …

Environmental And Economic Implications Of Energy Efficiency In New Residential Buildings: A Multi-Criteria Selection Approach, Florida Solar Energy Center, Delia D'Agostino

FSEC Energy Research Center®

The choice of the most appropriate technologies in buildings is often a challenge at the design stage, especially when many different criteria are taken into account. Consequently, the decision process relies often on one criterion only, such as costs or energy savings. We propose a multi-criteria approach based on multi-attribute utility theory to assess alternative energy efficiency measures, explicitly considering both environmental and economic criteria. We apply it to the design of a new residential building in Milan (Italy), with the aim to maximize CO₂ emission savings related to electricity and gas consumption, and to minimize embodied energy and …

How Will Climate Alter Efficiency Objectives? Simulated Impact Of Using Recent Versus Historic European Weather Data For The Cost-Optimal Design Of Nearly Zero Energy Buildings (Nzebs), Florida Solar Energy Center, Delia D'Agostino

FSEC Energy Research Center®

Achieving "nearly zero energy buildings" (NZEB) has been established as a vital objective over the next decade within the European Union (EU) [1, 2]. Previous work has shown that a series of very cost-effective thermal efficiency measures, equipment, appliance and renewable energy choices are available across climates to reach the NZEB objective. Resulting detailed energy and economic optimization findings have been obtained and published. One area that has just begun to be explored, however, is how selection of weather files and their application against coming climate change can influence outcomes from energy optimization procedures.

Presented at: CLIMA 2019, REHVA 13th …

Maximizing The Effectiveness Of Ductless Heat Pumps In Existing Homes By Demonstrating Integrated Controls: Measurement And Verification Plan, Florida Solar Energy Center, Eric Martin

FSEC Energy Research Center®

There is a trend for homeowners to install efficient ductless air-source heat pumps (ASHP) as a supplement to less efficient existing space conditioning systems, with most homeowners adding one unit in a central living area. Because of the potential for ASHPs to save energy by providing a large portion of the space conditioning, utilities have incentivized this strategy. However, post installation evaluations suggest ASHPs are not reaching their full potential because the existing heating system continues to operate more than necessary. This report describes a measurement and verifications strategy for a research project that aims to maximize savings from supplemental …

City Of New Smyrna Beach Solar Feasibility Assessment - City Hall Annex, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This review and solar assessment is organized by component with brief description of intended details, challenges and recommendations.

Building: City of New Smyrna Beach, City Hall Annex (Renovation of a portion of the Historic First Baptist Church of New Smyrna Beach) Year of Construction: 1920's[1] Building Use: Renovation will create spaces for City workers and a new City Council Chambers Conditioned area: 1^st floor = 7856 ft² 2^nd floor = 3,967 ft² Total = 11,823 ft²[2]

[1] New Smyrna Beach Property Appraiser's website states 1920, historic marker states circa 1929. [2] New Smyrna …

Residential Attic Performance Comparison Research, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This research project evaluated cooling energy and moisture-related impacts between conventional attic venting and sealed attic vents in a lab home located in central Florida. All tests had R30 insulation on the ceiling and the roof deck uninsulated. A total of four different test configurations were tested. The four tested configurations were: Attic Vented with Attic Ducts, Attic Vents Sealed with Attic Ducts, Attic Vented with Indoor Ducts, and Attic Vents Sealed with Indoor Ducts. On average the impact from sealing attic vents will increase annual cooling energy use in a Florida home between 5%-10%. For a 1620 square foot …

Further Investigation Of Energy And Performance Impacts Of Whole-House Dehumidifier Duct Configurations, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This research project evaluated the energy impacts and dehumidification performance related to how ducted dehumidifiers (DHU) ducts were configured. Lab controlled testing over a variety of weather and latent loads evaluated five-different ducted DHU configurations as follows: Test 1 DHU air ducted from/to the central main body of building. Test 2 DHU air ducted from/to return side of central air conditioner (AC). Test 3 DHU air ducted from/to supply side of AC. Test 4 DHU air ducted from central main body and ducted to supply side of AC. Test 5 DHU air ducted from outdoors and indoors mixed before DHU …

Development Of A Single Sensor Approach For Capturing Three-Dimensional, Time Resolved Flame And Velocity Information, Jonathan Reyes

Electronic Theses and Dissertations

Performing non-intrusive measurements is the key to acquiring accurate information representative of what is being observed. The act of measuring often changes the environment being observed altering the information that is being obtained. Due to this, the community of fluid scientists have gravitated towards using laser-based measurements to observe the phenomena occurring in their experiments. The study of fluids has advanced since this point, utilizing techniques such as planar laser induced florescence (PLIF), particle image velocimetry (PIV), laser doppler velocimetry (LDV), particle doppler anemometry (PDA), etc. to acquire chemical species information and velocity information. These techniques, though, are inherently two-dimensional …

Decentralized Consensus-Based Control Allocation For Some Dynamical Systems, August Mark

Electronic Theses and Dissertations

In this dissertation, three separate studies, wherein techniques from graph theory and consensus control are used to address control allocation problems, are presented. In the first study, a decentralized allocator is presented for synthetic jet actuators and control surfaces onboard a small unmanned aerial vehicle to cooperatively generate desired aerodynamic moments. First order linear dynamics are assumed for both the synthetic jet actuators and control surfaces. A weighted consensus algorithm with limited feedback is used for the aerodynamic moment contribution allocator considering constraints. In the second study, the same allocation problem as in the first study is considered, but the …

Mechanical Properties Of Brittle Ceramics: Case Study Of Boron Rich Ceramics And Acropora Cervicornis Coral Skeleton, Alejandro Carrasco-Pena

Electronic Theses and Dissertations

Ceramics are ubiquitous in man-made and natural structures. Their mechanical properties highly depend on their composition, microstructure and level of defects in the bulk of the material, the latter affecting the integrity of the components; such is the case of boron-rich ceramics where large agglomerates create high stressed regions, or coral skeleton where porosity determines their strength against hydrodynamic forces present in the ocean tides. Therefore, studying the properties of ceramic materials using invasive and non-invasive methods helps in the understanding of the link between the properties and the performance of the structures. The aim of this research was to …

Variable Fluid Flow Regimes Alter Endothelial Adherens Junctions And Tight Junctions, Dilshan Ranadewa

Electronic Theses and Dissertations

Variable blood flow regimes influence a range of cellular properties ranging from cell orientation, shape, and permeability: all of which are dependent on endothelial cell-cell junctions. In fact, cell-cell junctions have shown to be an integral part of vascular homeostasis through the endothelium by allowing intercellular signaling and passage control through tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). It was our objective to determine the structural response of both AJs and TJs under steady and oscillatory flow. Human brain microvascular endothelial cells (HBMECs) were cultured in a parallel plate flow chamber and exposed to separate trails of …

Dynamic Behavior And Performance Of Different Types Of Multi-Effect Desalination Plants, Mohamed Abdelkareem

Electronic Theses and Dissertations

Water and energy are two of the most vital resources for the socio-economic development and sustenance of humanity on earth. Desalination of seawater has been practiced for some decades and is a well-established means of water supply. However, this process consumes large amounts of energy and the global energy supply is also faced with some challenges. In this research, multi-effect desalination (MED) has been selected due to lower cost, lower operating temperature and efficient in terms of primary energy and electricity consumption compared to other thermal desalination systems. The motivation for this research is to address thermo-economics and dynamic behavior …

Vibration Reduction Of Mistuned Bladed Disks Via Piezoelectric-Based Resonance Frequency Detuning, Garrett Lopp

Electronic Theses and Dissertations

Recent trends in turbomachinery blade technology have led to increased use of monolithically constructed bladed disks (blisks). Although offering a wealth of performance benefits, this construction removes the blade-attachment interface present in the conventional design, thus unintentionally removing a source of friction-based damping needed to counteract large vibrations during resonance passages. This issue is further exacerbated in the presence of blade mistuning that arises from small imperfections from otherwise identical blades and are unavoidable as they originate from manufacturing tolerances and operational wear over the lifespan of the engine. Mistuning is known to induce vibration localization with large vibration amplitudes …