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Full-Text Articles in Engineering
Flow Induced Vibration In Corrugated Metal Flexhoses, Patrick Tran
Flow Induced Vibration In Corrugated Metal Flexhoses, Patrick Tran
Electronic Theses and Dissertations, 2020-
This study on flow-induced vibration provides valuable insights into the fundamental dynamics of fluid-structure interactions. The findings contribute to the development of predictive models and design guidelines for engineering systems susceptible to flow-induced vibration. By improving our understanding of this phenomenon, engineers can enhance the safety and reliability of various structures subjected to fluid flow, such as pipelines, flexhoses, and bellows. Flowinduced vibration is a phenomenon that occurs when fluid flow interacts with a structure, leading to oscillations and potentially causing mechanical damage. Understanding the underlying mechanisms and predicting the vibration characteristics is crucial for the design and safe operation …
A Study Of The Performance Of Wind Turbines Fitted With Sprayed Liquid Flaps, Alexander Spitzer
A Study Of The Performance Of Wind Turbines Fitted With Sprayed Liquid Flaps, Alexander Spitzer
Electronic Theses and Dissertations, 2020-
Lift generating technologies are often considered a potential solution to increased power generation and reliability within wind turbine design. The Sprayed Liquid Flap (SLF) is a novel active control method that has shown success in providing lift generation on aircraft wings, but its application in the context of rotating flows is unexplored. This research aims to understand the effects of the SLF on a wind turbine and provide a pathway for future exploration of its aerodynamic impacts on rotating flows. Computational Fluid Dynamics with an Euler-Euler multiphase approach is employed to assess the influence of the SLF on a wind …
A Study Of The Influence Of Heat Flux On Aerodynamics In Hypersonic Flow, Kristina Pionessa
A Study Of The Influence Of Heat Flux On Aerodynamics In Hypersonic Flow, Kristina Pionessa
Electronic Theses and Dissertations, 2020-
This study investigates the utilization of computational fluid dynamics (CFD) to simulate aerodynamic heating effects in support of research and design endeavors. The initial investigation demonstrates the effectiveness of a computational approach in analyzing different geometries and flow conditions. Specifically, CFD is employed to analyze the aerodynamics of a blunt cone, double cone, and hypersonic leading edge experiencing a changing heat source across the flow/body boundary. At the stagnation point, maximum thermal loading occurs as previously found; therefore, boundary layer thickness and shock standoff distance is measured at that position to compare the results of each case. Characteristics such as …
A High-Pressure Shock Tube Study Of Hydrogen And Ammonia Addition To Natural Gas For Reduced Carbon Emissions In Power Generation Gas Turbines, Michael Pierro
A High-Pressure Shock Tube Study Of Hydrogen And Ammonia Addition To Natural Gas For Reduced Carbon Emissions In Power Generation Gas Turbines, Michael Pierro
Electronic Theses and Dissertations, 2020-
Ignition delay times from undiluted mixtures of natural gas (NG)/H2/Air and NG/NH3/Air were measured using a high-pressure shock tube at the University of Central Florida. The combustion temperatures were experimentally tested between 1000-1500 K near a constant pressure of 25 bar. Mixtures were kept undiluted to replicate the same chemistry pathways seen in gas turbine combustion chambers. Recorded combustion pressures exceeded 200 bar due to the large energy release, hence why these were performed at the high-pressure shock tube facility. The data is compared to the predictions of the NUIGMech 1.1 mechanism for chemical kinetic model validation and refinement. An …
The Effects Of Microgravity On The Development Of Osteoporosis, Jackson Asiatico
The Effects Of Microgravity On The Development Of Osteoporosis, Jackson Asiatico
Electronic Theses and Dissertations, 2020-
Previous research has identified a potential link between microgravity conditions and the onset of osteoporosis, a connection that stems from altered fluidic pathways crucial in nutrient dispersion and cell stimulation. Specifically, the absence of mechanical loading in space environments reduces fluid shear stress, thereby disrupting the normal flow of interstitial fluid in trabecular bone. This disruption greatly impacts the functionality of osteoblasts and osteoclasts, the vital cells responsible for maintaining healthy bones. The focus of this study aims to explore the impact of microgravity on bone loss in astronauts, establishing the connection between the lack of mechanical loading and the …
The Performance Of A Liquid-Fueled High Pressure Igniter For Scramjets, Gerardo Rodriguez
The Performance Of A Liquid-Fueled High Pressure Igniter For Scramjets, Gerardo Rodriguez
Electronic Theses and Dissertations, 2020-
Ignition systems within scramjet combust ors remain a trending topic of research because of the essential role they play in the engine's operation. An alternative to currently researched ignition systems is investigated in this study with the main goal of u tilizing the same liquid fuel as the mai n combustion chamber for the ignition system itself. In this case, JetA fuel was injected in a liquid jet in crossflow configuration with air to atomize the fuel. To characterize this ignition system, metrics such as combustion chamber pressure rise, pulse frequency, and jet penetration were used to validate possible utilization …
Heat Release And Flame Scale Effects On Turbulence Dynamics In Confined Premixed Flows, Max Fortin
Heat Release And Flame Scale Effects On Turbulence Dynamics In Confined Premixed Flows, Max Fortin
Electronic Theses and Dissertations, 2020-
As industry transitions to a net-zero carbon future, turbulent premixed combustion will remain an integral process for power generating gas turbines and are also desired for aviation engines due to their ability to minimize pollutant emissions. However, accurately predicting the behavior of a turbulent reacting flow field remains a challenge. To better understand the dynamics of premixed reacting flows, this study experimentally investigates the evolution of turbulence in a high-speed bluff-body combustor. The combustor is operated across a range of equivalence ratios from 0.7-1 to quantify the role of heat release and flame scales on the evolution of turbulence as …
Rotorcraft Lander Fixed To A Descending Capsule Backshell, Corey Zucker
Rotorcraft Lander Fixed To A Descending Capsule Backshell, Corey Zucker
Electronic Theses and Dissertations, 2020-
NASA is financing a mission to study the surface of Titan, Saturn's largest moon, to investigate the terrain, chemical compositions, and potential for existent life. This mission is an exciting advancement from Mars Ingenuity, because the quadrotor lander, Dragonfly, will be the first of its kind with four coaxial rotors. Upon entry into Titan, and at near surface atmospheric conditions, Dragonfly will exit a parachute supported backshell that has shed its protective heatshield. The aerodynamics of this state are significant in comprehending the dynamics of the overall system for successful deployment into powered flight. The studies presented here examine the …
An Evaluation Of Thermocouple Reconstruction Techniques, Derek Brauneis
An Evaluation Of Thermocouple Reconstruction Techniques, Derek Brauneis
Electronic Theses and Dissertations, 2020-
Temperature measurements can be difficult to obtain across many different harsh environments such as engine combustion chambers, engine exhaust temperatures, and explosion fireballs. While there are alternate methods to measure fluid temperature such as laser measurements, acoustic measurements, and camera imaging techniques, these methods can often be expensive, difficult to implement, and not able to see within the environment. Thermocouples are popular sensors because they are cheap and easy to implement across a wide range of applications and can measure temperature in areas where other methods cannot reach or see. However, while these sensors are very popular and versatile, they …
The Development Of Computational Models For Melting-Solidification Applications Using The Volume-Of-Fluid Method, Brendon Cavainolo
The Development Of Computational Models For Melting-Solidification Applications Using The Volume-Of-Fluid Method, Brendon Cavainolo
Electronic Theses and Dissertations, 2020-
Fluids-related issues in the Aerospace industry are often multiphase in scope. Numerical modeling, such as computational fluid dynamics, is used to describe these problems, as they are difficult or impossible to describe analytically. This research uses computational fluid dynamics to describe multiphase problems related to melting-solidification and particle impingement. Firstly, a numerical model was established that uses the Volume-of-Fluid method to resolve a melting/solidifying particle. This model was verified against experiments and simplified analytical models, and a mesh independence study was done to ensure the results were independent of the mesh sizing. Next, the model was applied to two separate …
Design Considerations And Imaging Setup For Liquid Fuel Droplet Detonation Wave Experiments, Nicolas Berube
Design Considerations And Imaging Setup For Liquid Fuel Droplet Detonation Wave Experiments, Nicolas Berube
Electronic Theses and Dissertations, 2020-
Initial results, design considerations, and experimental validation of a new detonation tube are presented to further improve detonation wave interaction research. The new structure consists of four independent portions: the deflagration to detonation initiation section, transition expansion section, operating test section, and dump section. The initiation, transition, and test sections are designed to operate within a temperature limit of 150°C and a maximum detonation pressure of 100 bar. The test section is comprised of interchangeable 155 cm stainless steel 316 plates assembled to create a 10x10 cm square hollow structure, sealed with longitudinal O-rings between plates and lateral O-rings between …
Detonability Of A Rotating Detonation Combustor Seeded With Carbon/Hydrocarbon Particles At Fringe Operating Conditions, Matthew Hopwood
Detonability Of A Rotating Detonation Combustor Seeded With Carbon/Hydrocarbon Particles At Fringe Operating Conditions, Matthew Hopwood
Electronic Theses and Dissertations, 2020-
The Rotating Detonation Combustor (RDC) has, in recent years, been a subject of great interest in the pressure-gain combustion research community. Researchers have been investigating the RDC as a potential improvement over current combustors in today's turbomachinery-based power generation systems. With the theoretical efficiency boost that detonations provide over deflagrating combustors, RDCs have the promise to be a next step in fuel/cost savings in the power generation industry. One mode of research to push an RDCs capabilities is the potential use of combustible carbon/hydrocarbon solid particles in addition to liquid or gaseous fuels. These particles are a source of high …
Flame-Generated Turbulence For Flame Acceleration And Detonation Transition, Rachel Hytovick
Flame-Generated Turbulence For Flame Acceleration And Detonation Transition, Rachel Hytovick
Electronic Theses and Dissertations, 2020-
Detonations are a supersonic mode of combustion witnessed in a variety of applications, from next-generation propulsion devices to catastrophic explosions and the formation of supernovas. Detonations are typically initiated through the deflagration to detonation transition (DDT), a detailed process where a subsonic flame undergoes rapid acceleration increasing compressibility until a hotspot forms on the flame front inciting a detonation wave to form. Due to the complex nature of the phenomena, DDT is commonly investigated in three stages – (i) preconditioning, (ii) detonation onset, and (iii) wave propagation and stability. The research presented explores each of these stages individually, with a …
Investigating The Effect Of Cmas Infiltration On Residual Stress Of High Temperature Ceramic Coatings For Turbine Engines Using 3d Confocal Raman Spectroscopy, Zachary Stein
Electronic Theses and Dissertations, 2020-
Calcium-magnesium-aluminosilicates (CMAS), such as sand or volcanic ash, are ingested by aircraft jet engines during operation. CMAS then becomes molten while traveling through the combustor of the engine before depositing onto turbine blades within the turbine section of the engine. The molten CMAS melt infiltrates and interacts with the high temperature ceramic coated turbine blades. This infiltration increases coating stiffness and promotes coating phase destabilization, encouraging micro-crack formation and increasing the risk of spallation. Thermomechanical effects from CMAS infiltration were mapped over time with confocal Raman spectroscopy. The residual stresses within infiltrated 7YSZ EB-PVD coatings were captured with microscale resolution. …
Interactions Of Aerosol Droplets With Ventilated Airflows In The Context Of Airborne Pathogen Transmission, Steven Schroeder
Interactions Of Aerosol Droplets With Ventilated Airflows In The Context Of Airborne Pathogen Transmission, Steven Schroeder
Electronic Theses and Dissertations, 2020-
This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with a crossflow of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how ventilation can alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and …
Vibrations Of Rotationally Periodic Structures: A Metric For Mistuning Characterization And Vibration Localization, Andres Rodriguez
Vibrations Of Rotationally Periodic Structures: A Metric For Mistuning Characterization And Vibration Localization, Andres Rodriguez
Electronic Theses and Dissertations, 2020-
Blisk components are an integral part of jet engines and power generation systems. Composed of a single monolithic structure, integral blisks combine the blade-and-disk portion of primary components such as the fan, compressor stage, or turbine stage. This design modification increases the aerodynamic performance while decreasing the cost and eliminating time of assembly. However, these benefits come with the loss of blade-disk connection interfaces, which greatly reduces the structure's damping and its ability to attenuate unwanted structural vibrations. Blisk dynamics are impacted by mistuning, which is a disruption of the periodic symmetry of otherwise identical bladed sections. This disruption degrades …
Autoignition Delay Time Measurements And Chemical Kinetic Modeling Of Hydrogen/Ammonia/Natural Gas Mixtures, Jessica Baker
Autoignition Delay Time Measurements And Chemical Kinetic Modeling Of Hydrogen/Ammonia/Natural Gas Mixtures, Jessica Baker
Electronic Theses and Dissertations, 2020-
In recent years, hydrogen-carrying compounds have accrued interest as an alternative to traditional fossil fuels due to their function as zero-emission fuels. As such, there is interest in investigating hydrogen-carrying compounds to improve understanding of the fuels' characteristics for use in high pressure systems. In the current study, the oxidation of ammonia/natural gas/hydrogen mixtures was carried out to study CO formation profiles as well as the ignition delay times behind reflected shock waves in order to refine chemical kinetic models. Experiments were carried out in the University of Central Florida's shock tube facility by utilizing chemiluminescence to obtain OH* emission …
The Breakup Of Rp-2 Liquid Fuel Droplets In A Detonation Field, Daniel Dyson
The Breakup Of Rp-2 Liquid Fuel Droplets In A Detonation Field, Daniel Dyson
Electronic Theses and Dissertations, 2020-
Experimentally obtained droplet breakup patterns are presented for RP-2 liquid fuel droplets in the environment behind a detonation wave. To the best of our knowledge, this data is the first of its kind to examine the fundamental interactions between detonation waves and an individual fuel droplet. The experiments presented here are expected to support the ongoing effort of creating accurate models of droplet breakup in a variety of environments, which in turn will lead to enhanced predictions of rotating detonation engine performance, improved safety considerations for facilities operating in hazardous conditions, and new knowledge in energetics, hypersonics, and explosion dynamics …
Energy Based Diagnostics Of Cfd: Revealing New Insights To Complex Aerodynamics, George Loubimov
Energy Based Diagnostics Of Cfd: Revealing New Insights To Complex Aerodynamics, George Loubimov
Electronic Theses and Dissertations, 2020-
This thesis documents a new approach to assess the aerodynamics of complex fluid dynamic systems using modern assessment methods associated with computational fluid dynamics (CFD). The method is developed to extract novel and additional insight in the context of a higher-fidelity modeling tool. Although the methods are based on classical control volume techniques balancing fluid momentum and energy, the approach uses the detailed data provided by CFD to expand on it. Classical methods typically use a fixing control volume defined at simple control surfaces, whereas this assessment method utilizes CFD to provide complex integrals on the control surfaces and uses …
A Study Of Microgravity On Fluid Transport Through Porous Structures In Microfluidic Devices, Sylvain Le Henaff
A Study Of Microgravity On Fluid Transport Through Porous Structures In Microfluidic Devices, Sylvain Le Henaff
Electronic Theses and Dissertations, 2020-
The objective of this study is to refine the understanding of micro-fluidics subject to micro-gravity in an attempt to support future space exploration efforts. A combination of experimental and numerical approaches were utilized to build a validated assessment approach. A quasi-pore geometry, inspired by CT scans of rat bones, was used in lieu of human bone structures. A quasi-1D assessment of the conservation of momentum was used to identify the dominant forces acting on the fluid at the operating length-scales. The dominant forces were surface tension, gravity, and shear stress. Experiments were conducted to visualize the flow moving through the …
Quantification Of The Aerodynamic Drivers Of A Deployable Propeller, David Malyszek
Quantification Of The Aerodynamic Drivers Of A Deployable Propeller, David Malyszek
Electronic Theses and Dissertations, 2020-
With the use deployable drones becoming more common research into their improvement is necessary. Deployable drones that are launched from tubes have size limits on the diameter of the propeller during launch and storage. The purpose of this research is to develop deployable propeller blades for practical uses, such as tube launched propeller driven drones and easier to transport wind turbine blades. A deployable propeller will allow for the utilization of larger propellers when a large non-deployable blade isn't an option. Because deployable propellers need to fold, the deployable propeller blades were designed to be hollow and with a slit …
Sensitivity Of Combustion Liner Contour To Sand Ingestion Clogging, Nelson Padilla
Sensitivity Of Combustion Liner Contour To Sand Ingestion Clogging, Nelson Padilla
Electronic Theses and Dissertations, 2020-
This currently presented work is an evaluation of the characteristics of different cooling hole geometries to particulate ingestion clogging. Experimentation was conducted using a premixed bluff body flame combustor facility to generate high temperature combustor flow conditions. Sand ingestion along the cooling path of the combustion liner was reproduced using an air-assisted seeder providing consistent sand ingestion. Mass flow rate of cooling air was controlled using a sonic orifice downstream of a pressure regulator so that the mass flow rate of the air and sand mixture is independent of the clogging state. Pressure data upstream of a small section of …
Shock Tube And Gas Dynamic Design Considerations And Implementation For Extended Test Times, Jacklyn Higgs
Shock Tube And Gas Dynamic Design Considerations And Implementation For Extended Test Times, Jacklyn Higgs
Electronic Theses and Dissertations, 2020-
A new shock tube test section has been designed and manufactured for the purpose of increasing the test time and expanding the applications of the shock tube for a multitude of ongoing and future projects. One purpose for the test section extension is to allow for flow visualization of droplets impacted by a shock wave for the interaction of hypersonic vehicles and atmospheric disturbances. Another purpose is to measure behind the incident shock to capture the chemical kinetics for a high-altitude environment and low-pressure, high-temperature space applications. This new test section contains 24 round optical ports for laser spectroscopy for …
Aerodynamic Characterization Of An Elliptical Fairing In The Wake Of A Bluff Body, Luis Amaya
Aerodynamic Characterization Of An Elliptical Fairing In The Wake Of A Bluff Body, Luis Amaya
Electronic Theses and Dissertations, 2020-
Aerodynamic optimization is a key step in designing planes, cars, and even buildings. Numerical modeling is used to automate the optimization process and can use different methods to iterate through designs. In this process, consideration of the starting design is paramount as a poor choice can use up computational time and effort. Often, these designs are made with the intention of being out in the open, for which studies on shape variations in freestream situations abound. However, for the case where an object must be placed in the wake of another, there is little research. The study presented here aims …
Investigation Into Wedge Turbulator Effects In High Aspect Ratio Cooling Channels, Daniel Garcia
Investigation Into Wedge Turbulator Effects In High Aspect Ratio Cooling Channels, Daniel Garcia
Electronic Theses and Dissertations, 2020-
With reusability being a novel design parameter for liquid rocket engines (LRE), the need to lower internal wall temperatures for an increased engine longevity is a desired outcome. One of the mechanisms that has been effectively implemented is the use of high aspect ratio cooling channels (HARCC) to promote fin-like effects from internal cooling channel sidewalls. In the gas turbine industry, the use of wedge turbulators has gained recognition for its heat augmentation properties with relatively low pressure drop penalty. In an ideal case, LRE's could adopt the wedge turbulator cooling technique to enhance the benefits of HARCC with minimal …
Optimization Of A Wing Supporting A Coaxial Rotor For Multiple Flight Conditions, Tadd Yeager
Optimization Of A Wing Supporting A Coaxial Rotor For Multiple Flight Conditions, Tadd Yeager
Electronic Theses and Dissertations, 2020-
Rotor-powered drones continue to grow in popularity in private and government sectors. The use of these drones in challenging environments and in high stakes applications calls for a certain level of robustness and redundancy. Often, these drones are equipped with sets of paired coaxial rotors, which not only improve the performance of the vehicle, but also ensure that a failure of one motor does not constitute the failure of the whole vehicle. Some applications such as extraterrestrial exploration, which use these coaxial rotors, can benefit from a wing shaped rotor arm to reduce drag and increase lift, extending mission lifetime. …
Numerical Modeling Of Shockwave Initiated Combustion Of A Hydrogen-Oxygen Mixture Within A Shock Tube, Reed Forehand
Numerical Modeling Of Shockwave Initiated Combustion Of A Hydrogen-Oxygen Mixture Within A Shock Tube, Reed Forehand
Electronic Theses and Dissertations, 2020-
Shock tubes are as close to an ideal reactor as most modern experiments can attain to examine chemical kinetics. As reaction temperatures drop, homogeneous combustion within a shock tube begins to exhibit inhomogeneous modes, which in a typical Hydrogen-Oxygen system are ex- pressed as deflagration to detonation transition. Experimental results of such a system in the Uni- versity of Central Florida's low-pressure shock tube have been collected through end and side-wall imaging to analyze flame structure and chemical kinetics. The purpose of this work is to con- duct a baselining of these results using both chemical and computational fluid dynamics …
Computational Studies For Extending Understanding Of Complex Droplet Breakup Mechanisms, Caroline Anderson
Computational Studies For Extending Understanding Of Complex Droplet Breakup Mechanisms, Caroline Anderson
Electronic Theses and Dissertations, 2020-
Conventional methods of classifying droplet breakup are evaluated in the context of unique variation in environmental and droplet fluid conditions. Most characterization is developed for subsonic speeds and Newtonian fluids, so this study extends understanding on how these forms change to a span of applications outside these conditions. Presented examples include the impact effects on hypersonic vehicles travelling through precipitation, where even smallest of rain drops at such speeds can cause damage. Before the droplet even reaches the vehicle, it interacts with the detached bow shock that leads it. Another example of exceptional recent concern is risk of viral transmission …
A Study Into Validating A Coupled Method Of Characteristics And Direct Simulation Monte Carlo Method Against Empirical Data, Andrew Brown
A Study Into Validating A Coupled Method Of Characteristics And Direct Simulation Monte Carlo Method Against Empirical Data, Andrew Brown
Electronic Theses and Dissertations, 2020-
The following will outline the methodology and results of validating a coupled Method of Characteristics (MOC) and Direct Simulation Monte Carlo (DSMC) method. This research focused specifically on modeling plume impingement, induced by Reaction Control System (RCS) thrusters that flew on the National Aeronautics and Space Administration's (NASA's) space shuttle Discovery. For each simulation, the continuum portion of the RCS thruster was simulated using MOC for solving hyperbolic Partial Differential Equations (PDEs) and computed with the NASA code, Reacting and Multi-phase Program (RAMP). The solution was then implemented as a starting condition into the NASA DSMC code, Direct Simulation and …
Study Of Non-Ideal Effects On Shock Wave Propagation, Cory Kinney
Study Of Non-Ideal Effects On Shock Wave Propagation, Cory Kinney
Electronic Theses and Dissertations, 2020-
Shock tube experiments provide insightful data on combustion, emissions, and ablation characterization for a wide variety of defense and energy sector research topics. Accurate characterization of shock tube facilities is essential to verifying the accuracy of research data. Non-ideal effects, such as boundary layer growth, introduce uncertainty into pressure and temperature conditions, the primary independent variables of interest for shock tube research results. The effect of boundary layer growth on shock tube experiments was investigated by conducting simulations for University of Central Florida's two geometrically different shock tube using StanShock, a quasi-one-dimensional, reacting, compressible flow solver. The characteristic quantities considered …