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Articles 1 - 23 of 23
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Droplet Impact On Liquid Pools: Secondary Droplets Formation From Rayleigh Jet Break-Up And Crown Splash, Eduardo Castillo Orozco
Droplet Impact On Liquid Pools: Secondary Droplets Formation From Rayleigh Jet Break-Up And Crown Splash, Eduardo Castillo Orozco
Electronic Theses and Dissertations
This work aims to study the impact of a droplet on liquid pools of the same fluid to understand the formation of secondary drops from the central jet and crown splash that occur after the impact. The impact of droplets on a deep pool has applications in cleaning up oil spill, spray cooling, painting, inkjet printing and forensic analysis, relying on the changes in properties such as viscosity, interfacial tension and density. Despite the exhaustive research on different aspects of droplet impact, it is not clear how liquid properties can affect the instabilities leading to the Rayleigh jet breakup and …
Thermally Induced Motion, Collision And Mixing Of Levitated Droplets, Ashkan Davanlou
Thermally Induced Motion, Collision And Mixing Of Levitated Droplets, Ashkan Davanlou
Electronic Theses and Dissertations
This dissertation investigates the motion of a levitated droplet experimentally and analytically against the Marangoni flow in an immiscible outer fluid at higher speeds than is possible currently. Based on our earlier experiments, when a droplet is released from a height of 1.5 – 4 times its diameter from the liquid surface, it can overcome the impact and stay levitated at the liquid-air interface due to the existence of an air gap between the droplet and the liquid film. In order to explain this behavior of droplet traveling against the counter-current motion, we propose a simple approach: first, the Marangoni …
Spray Deposition Modeling Of Carbon Nano-Inks, John Sparkman
Spray Deposition Modeling Of Carbon Nano-Inks, John Sparkman
Electronic Theses and Dissertations
Carbon nanopaper (CNP) exhibits qualities that are desirable for a number of applications such as flame retardancy, lightning protection, and flexible printed circuit boards. CNP has become a desired engineering material in many important sectors of industries such as space, automotive, aviation, and military. However the production of consistent thicknesses and dispersion remains a challenge for practical use. Most of the standard methods of production do not allow for continuous applications or digital fabrication of the CNP. In this work, CNP is produced two different ways that allows for continuous production and digital fabrication. The continuous CNP making technique uses …
Comparison Of Modeling Methods For Power Cycle Components Using Supercritical Carbon Dioxide As The Operating Fluid, Joshua Schmitt
Comparison Of Modeling Methods For Power Cycle Components Using Supercritical Carbon Dioxide As The Operating Fluid, Joshua Schmitt
Electronic Theses and Dissertations
Supercritical carbon dioxide as a working fluid in a Brayton power cycle has benefits but also faces unique challenges in implementation. With carbon dioxide, turbomachinery is much more compact and potentially more cost effective. The primary impediments to cycle component performance are the high pressures required to bring the fluid to a supercritical state and the wildly varying fluid properties near the critical point. Simple design models are often used as a quick starting point for modern turbomachinery and heat exchanger design. These models are reasonably accurate for design estimate, but often assume constant properties. Since supercritical carbon dioxide varies …
Analysis Of Steady State Micro-Droplet Evaporation To Enhance Heat Dissipation From Tiny Surfaces., Harish Voota
Analysis Of Steady State Micro-Droplet Evaporation To Enhance Heat Dissipation From Tiny Surfaces., Harish Voota
Electronic Theses and Dissertations
Experimental investigations and numerical predictions of steady state microdroplet evaporation experiments are presented. Steady state droplet evaporation experiments are conducted to understand (1) Droplet contact line influence on evaporation rate efficiency, (2) Droplet contact angle correlation to evaporation rate and (3) Substrate cooling. Experiments are performed on a polymer substrate with a moat like trench (laser patterned) to control droplet contact line dynamics. A bottom-up methodology is implemented for droplet formation on the patterned substrate. Droplet evaporation rates on substrate temperatures 22°C≤ ∆TSubstrate ≤75°C and contact angles 80°≤ Θ ≤110° are measured. For a pinned microdroplet (CCR), volumetric infuse rate …
Inverse-Consistent Determination Of Young's Modulus Of Human Lung, Behnaz Seyfi Noferest
Inverse-Consistent Determination Of Young's Modulus Of Human Lung, Behnaz Seyfi Noferest
Electronic Theses and Dissertations
Human lung undergoes respiration-induced deformation due to sequential inhalation and exhalation. Accurate determination of lung deformation is crucial for tumor localization and targeted radiotherapy in patients with lung cancer. Numerical modeling of human lung dynamics based on underlying physics and physiology enables simulation and virtual visualization of lung deformation. Dynamical modeling is numerically complicated by the lack of information on lung elastic behavior, structural heterogeneity as well as boundary constrains. This study integrates physics-based modeling and image-based data acquisition to develop the patient-specific biomechanical model and consequently establish the first consistent Young's modulus (YM) of human lung. This dissertation has …
Theoretical And Experimental Investigation Of The Cascading Nature Of Pressure-Swirl Atomization, Pretam Choudhury
Theoretical And Experimental Investigation Of The Cascading Nature Of Pressure-Swirl Atomization, Pretam Choudhury
Electronic Theses and Dissertations
Pressure swirl atomizers are commonly used in IC, aero-engines, and liquid propellant rocket combustion. Understanding the atomization process is important in order to enhance vaporization, mitigate soot formation, design of combustion chambers, and improve overall combustion efficiency. This work utilizes non-invasive techniques such as ultra -speed imaging, and Phase Doppler Particle Anemometry (PDPA) in order to investigate the cascade atomization process of pressure-swirl atomizers by examining swirling liquid film dynamics and the localized droplet characteristics of the resulting hollow cone spray. Specifically, experiments were conducted to examine these effects for three different nozzles with orifice diameters .3mm, .5mm, and .97mm. …
Modeling Phase Change Heat Transfer Of Liquid/Vapor Systems In Free/Porous Media, James Wilson
Modeling Phase Change Heat Transfer Of Liquid/Vapor Systems In Free/Porous Media, James Wilson
Electronic Theses and Dissertations
Effective solvent extraction incorporating electromagnetic heating is a relatively new concept that relies on Radio Frequency heating and solvents to replace steam in current thermal processes for the purpose of extracting bitumen from oil rich sands. The work presented here will further the understanding of the near wellbore flow of this two phase system in order to better predict solvent vaporization dynamics and heat rates delivered to the pay zone. This numerical study details the aspects of phase change of immiscible, two component, liquid/vapor systems confined in porous media heated by electromagnetic radiation, approximated by a spatially dependent volumetric heat …
Thermodynamic Analysis And Optimization Of Supercritical Carbon Dioxide Brayton Cycles, Mahmood Mohagheghi
Thermodynamic Analysis And Optimization Of Supercritical Carbon Dioxide Brayton Cycles, Mahmood Mohagheghi
Electronic Theses and Dissertations
The power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power (CSP) and waste heat recovery (WHR) applications. With this regard, this dissertation is intended to perform thorough thermodynamic analyses and optimization of S-CO2 Brayton cycles for both of these applications. A modeling tool has been developed, which …
Mechanism Of Hip Dysplasia And Identification Of The Least Energy Path For Its Treatment By Using The Principle Of Stationary Potential Energy, Mohammed Abdulwahab M. Zwawi
Mechanism Of Hip Dysplasia And Identification Of The Least Energy Path For Its Treatment By Using The Principle Of Stationary Potential Energy, Mohammed Abdulwahab M. Zwawi
Electronic Theses and Dissertations
Developmental dysplasia of the hip (DDH) is a common newborn condition where the femoral head is not located in its natural position in the acetabulum (hip socket). Several treatment methods are being implemented worldwide to treat this abnormal condition. One of the most effective methods of treatment is the use of Pavlik Harness, which directs the femoral head toward the natural position inside the acetabulum. This dissertation presents a developed method for identifying the least energy path that the femoral head would follow during reduction. This is achieved by utilizing a validated computational biomechanical model that allows the determination of …
Development Of 3d Vision Testbed For Shape Memory Polymer Structure Applications, Kenneth Thompson
Development Of 3d Vision Testbed For Shape Memory Polymer Structure Applications, Kenneth Thompson
Electronic Theses and Dissertations
As applications for shape memory polymers (SMPs) become more advanced, it is necessary to have the ability to monitor both the actuation and thermal properties of structures made of such materials. In this paper, a method of using three stereo pairs of webcams and a single thermal camera is studied for the purposes of both tracking three dimensional motion of shape memory polymers, as well as the temperature of points of interest within the SMP structure. The method used includes a stereo camera calibration with integrated local minimum tracking algorithms to locate points of interest on the material and measure …
Development Of Velocity Profile Generating Screens For Gas Turbine Components, Joseph Tate
Development Of Velocity Profile Generating Screens For Gas Turbine Components, Joseph Tate
Electronic Theses and Dissertations
Laboratory experiments on components of complex systems such as gas turbines require many conditions to be met. Requirements to be met in order to simulate real world conditions include inlet flow conditions such as velocity profile, Reynold's number, and temperature. The methodology to be introduced designs a velocity profile generating screen to match real world conditions through the use of perforated plates. The velocity profile generating screen is an array of jets arranged in a manner to produce sections of different solidities, a ratio of area that obstructs fluid flow compared to that of the total area. In an effort …
Experimental And Numerical Study Of Endwall Film Cooling, Srikrishna Mahadevan
Experimental And Numerical Study Of Endwall Film Cooling, Srikrishna Mahadevan
Electronic Theses and Dissertations
This research work investigates the thermal performance of a film-cooled gas turbine endwall under two different mainstream flow conditions. In the first part of the research investigation, the effect of unsteady passing wakes on a film-cooled pitchwise-curved surface (representing an endwall without airfoils) was experimentally studied for heat transfer characteristics on a time-averaged basis. The temperature sensitive paint technique was used to obtain the local temperatures on the test surface. The required heat flux input was provided using foil heaters. Discrete film injection was implemented on the test surface using cylindrical holes with a streamwise inclination angle of 35? and …
Large Eddy Simulations With A Tabulated Conditional Moment Closure Moment Closure Model For Turbulent Premixed Combustion With Heat Loss, Carlos Velez
Electronic Theses and Dissertations
The Tabulated Premixed Conditional Moment Closure (T-PCMC) method has been shown to provide the capability to predict turbulent, premixed methane flames with detailed chemistry and reasonable run times in a RANS/URANS adiabatic environment. Here the premixed T-PCMC method is extended in a Large Eddy Simulation (LES) framework for non-adiabatic premixed flames, allowing heat loss to occur in the mixture before, during and after combustion. It is proposed that the LES framework is a more suitable representation for both chemical and turbulent scales in premixed combustion. By resolving the high energy turbulent scales and modeling the small scale turbulence, it is …
A Full Coverage Film Cooling Study: The Effect Of An Alternating Compound Angle, Justin Hodges
A Full Coverage Film Cooling Study: The Effect Of An Alternating Compound Angle, Justin Hodges
Electronic Theses and Dissertations
This thesis is an experimental and numerical full-coverage film cooling study. The objective of this work is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for two full-coverage film cooling geometries. Experimental data was acquired with a scientific grade CCD camera, where images are taken over the heat transfer surface, which is painted with a temperature sensitive paint. The CFD component of this study served to evaluate how well the v2-f turbulence model predicted film cooling effectiveness throughout the array, as compared with experimental data. The two staggered arrays tested are different from one another through …
Biomechanics Of Developmental Dysplasia Of The Hip - An Engineering Study Of Closed Reduction Utilizing The Pavlik Harness For A Range Of Subtle To Severe Dislocations In Infants., Victor Huayamave
Electronic Theses and Dissertations
Developmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult life. To this day several non-surgical treatments involving the use of harnesses and braces have been proposed to treat DDH in infants, …
A Multi-Scale Cfd Analysis Of Patient-Specific Geometries To Tailor Lvad Cannula Implantation Under Pulsatile Flow Conditions: An Investigation Aimed At Reducing Stroke Incidence In Lvads, Ray Prather
Electronic Theses and Dissertations
A Left Ventricular Assist Device (LVAD) is a mechanical pump that provides temporary circulatory support when used as bridge-to-transplantation and relieves workload demand placed on a failing heart allowing for myocardia recovery when used as destination therapy. Stroke is the most devastating complication after ventricular assist device (VAD) implantation, with an incidence of 14-47% over 3-6 months. This complication due to thrombus formation and subsequent transport through the vasculature to cerebral vessels continues to limit the widespread implementation of VAD therapy. Patient-specific computational fluid dynamics (CFD) analysis may elucidate ways to reduce this risk. We employed a multi-scale model of …
Meshless Direct Numerical Simulation Of Turbulent Incompressible Flows, Andres Vidal Urbina
Meshless Direct Numerical Simulation Of Turbulent Incompressible Flows, Andres Vidal Urbina
Electronic Theses and Dissertations
A meshless direct pressure-velocity coupling procedure is presented to perform Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) of turbulent incompressible flows in regular and irregular geometries. The proposed method is a combination of several efficient techniques found in different Computational Fluid Dynamic (CFD) procedures and it is a major improvement of the algorithm published in 2007 by this author. This new procedure has very low numerical diffusion and some preliminary calculations with 2D steady state flows show that viscous effects become negligible faster that ever predicted numerically. The fundamental idea of this proposal lays on several important inconsistencies …
Zrb2-Sic Based Ultra High Temperature Ceramic Composites: Mechanical Performance And Measurement And Design Of Thermal Residual Stresses For Hypersonic Vehicle Applications, Richard Stadelmann
Zrb2-Sic Based Ultra High Temperature Ceramic Composites: Mechanical Performance And Measurement And Design Of Thermal Residual Stresses For Hypersonic Vehicle Applications, Richard Stadelmann
Electronic Theses and Dissertations
Ultra-high temperature ceramics (UHTCs), such as ZrB2-based ceramic composites, have been identified as next generation candidate materials for leading edges and nose cones in hypersonic air breathing vehicles. Mechanical performance of ceramic composites play an important role in the ultra-high temperature applications, therefore SiC is added to ZrB2 as a strengthening phase to enhance its mechanical performance. The high melting temperatures of both ZrB2 and SiC, as well as the ability of SiC to form SiO2 refractory oxide layers upon oxidation make ZrB2-SiC ceramics very suitable for aerospace applications. Thermal residual stresses appearing during processing are unavoidable in sintered ZrB2-SiC …
Pressurized Metal Bellows Shock Absorber For Space Applications., John Trautwein
Pressurized Metal Bellows Shock Absorber For Space Applications., John Trautwein
Electronic Theses and Dissertations
Numerous spacecraft designs exist for exploring the surfaces of planetary bodies and each have their own advantages and disadvantages. All successful landings have been made by stationary landers or wheeled rovers that rely on one-time use mechanisms, such as crushable aluminum honeycomb shock absorbers or inflatable airbags, to reduce shock loading to the spacecraft during landing. The stationary lander is the simplest type of lander, but can only take data from one location. Wheeled rovers add complexity in exchange for mobility to explore different locations. Rovers are limited by the terrain they can traverse; rovers becoming stuck have ended missions. …
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 …
Coordinated Optimal Power Planning Of Wind Turbines In A Wind Farm, Puneet Vishwakarma
Coordinated Optimal Power Planning Of Wind Turbines In A Wind Farm, Puneet Vishwakarma
Electronic Theses and Dissertations
Wind energy is on an upswing due to climate concerns and increasing energy demands on conventional sources. Wind energy is attractive and has the potential to dramatically reduce the dependency on non-renewable energy resources. With the increase in wind farms there is a need to improve the efficiency in power allocation and power generation among wind turbines. Wake interferences among wind turbines can lower the overall efficiency considerably, while offshore conditions pose increased loading on wind turbines. In wind farms, wind turbines* wake affects each other depending on their positions and operation modes. Therefore it becomes essential to optimize the …
Multi-Row Film Cooling Boundary Layers, Greg Natsui
Multi-Row Film Cooling Boundary Layers, Greg Natsui
Electronic Theses and Dissertations
High fidelity measurements are necessary to validate existing and future turbulence models for the purpose of producing the next generation of more efficient gas turbines. The objective of the present study is to conduct several different measurements of multi-row film cooling arrays in order to better understand the physics involved with injection of coolant through multiple rows of discrete holes into a flat plate turbulent boundary layer. Adiabatic effectiveness distributions are measured for several multi-row film cooling geometries. The geometries are designed with two different hole spacings and two different hole types to yield four total geometries. One of the …