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Full-Text Articles in Aerospace 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 …
Trajectory Design Optimization Using Coupled Radial Basis Functions (Crbfs), Kyler Roy
Trajectory Design Optimization Using Coupled Radial Basis Functions (Crbfs), Kyler Roy
Electronic Theses and Dissertations, 2020-
Optimal trajectory design has been extensively studied across multiple disciplines adopting different techniques for implementation and execution. It has been utilized in past space trajectory missions to either optimize the amount of fuel spent or minimize the time of flight to meet mission requirements. Coupled Radial Basis Functions (CRBFs) are a new way to solve these optimal control problems, and this thesis applies CRBFs to spacecraft trajectory optimization design problems. CRBFs are real-valued radial basis functions (RBFs) that utilize a conical spline while also not being affected by the value of the shape parameter. The CRBF approach is applied to …
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 …
Determination Of Damage Initiation Mechanisms In Aerospace Alloys Due To Stress Corrosion Cracking Via In-Situ Microscale Characterization Techniques, Remelisa Esteves
Determination Of Damage Initiation Mechanisms In Aerospace Alloys Due To Stress Corrosion Cracking Via In-Situ Microscale Characterization Techniques, Remelisa Esteves
Electronic Theses and Dissertations, 2020-
Aluminum alloys are used on aerospace vehicles due to their high strength-to-weight ratio, formability and machinability. However, they become vulnerable to stress corrosion cracking (SCC) during their service life. SCC is primarily caused by the material's stress condition, a suitable corrosive environment and material susceptibility. It is also influenced by a mixture of electrochemical, mechanical, and chemical factors. Due to the complexity of SCC, tools with better resolution and sensitivity are needed to better understand the impact and interaction of the contributing factors. A vast amount of research has been done to study SCC behavior, but the scale of characterization …
Characterizing Air Plasma Sprayed Aluminum Oxide Coatings For The Protection Of Structures In Lunar Environments, Perla Latorre Suarez
Characterizing Air Plasma Sprayed Aluminum Oxide Coatings For The Protection Of Structures In Lunar Environments, Perla Latorre Suarez
Electronic Theses and Dissertations, 2020-
Wear-resistant ceramic and ceramic composite coatings are significant to provide durability and support long-duration missions to the moon's surface for rovers, landers, robotic systems, habitats, and many other components. On the Lunar surface, structural components are continuously exposed to lunar dust projectiles that can cause protective coating delamination around the affected area, of protective coatings and this may not be physically visible. Ceramic coatings, composed of alumina, present excellent resistance to different types of wear due to their high strength and hardness as well as the ability to protect structural components from regolith impacts, wear, and abrasive damage. Air Plasma …
The Effect Of Wing Shape And Ground Proximity On Unsteady Fluid Dynamics During The Perching Maneuver., Dibya Raj Adhikari
The Effect Of Wing Shape And Ground Proximity On Unsteady Fluid Dynamics During The Perching Maneuver., Dibya Raj Adhikari
Electronic Theses and Dissertations, 2020-
While landing, birds often perform a perching maneuver, which involves pitching their wings upwards while decelerating to a complete stop. By performing this perching maneuver, the birds can continue generating higher lift and drag force while slowing down, resulting in a smooth landing. The present study is motivated by the perching maneuver and aims to investigate two critical aspects of it. First, we want to explore how the proximity of the ground affects the unsteady forces and the flow field during the perching flight; and second, we want to analyze how a wing sweep influences a perching maneuver. To explore …
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 …
Polyelectrolyte Functionalized Forward Osmosis For Water Reclamation From Synthetic Spacecraft Wastewater, Alina Ripp
Polyelectrolyte Functionalized Forward Osmosis For Water Reclamation From Synthetic Spacecraft Wastewater, Alina Ripp
Electronic Theses and Dissertations, 2020-
This study investigated the application of a polyelectrolyte (PE)-assisted metallic iron nanoparticle-integrated forward osmosis (FO) membrane to treat synthetic spacecraft wastewater comprising urea, ammonium carbonate, and linear alkylbenzene sulfonate (LAS). The draw solution (MgSO4) diluted via the FO operation was further treated using a nanofiltration (NF) membrane aimed at producing potable quality water by the FO-NF hybrid process. A cellulose triacetate FO membrane was functionalized by layer-by-layer deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) followed by incorporating zero valent iron nanoparticles (ZVINP) within the "bilayers". It required 14 bilayers to ensure a uniform coating as demonstrated via scanning …
Adaptive Analytic Continuation For The State Transition Tensors Of The Two-Body Problem, Tahsinul Haque Tasif
Adaptive Analytic Continuation For The State Transition Tensors Of The Two-Body Problem, Tahsinul Haque Tasif
Electronic Theses and Dissertations, 2020-
In the past few decades, Kessler syndrome (named after Donald J. Kessler) has become a point of concern in the field of Space Situational Awareness and the future of space missions. It refers to a scenario, where space debris in Earth's orbits collides and creates an exponential increase in space debris numbers leading to more collisions and more debris. In order to handle the resulting challenges like conjunction analysis, tracking, and probability of collisions, the State Transition Matrix (STM) and Tensors (STTs) of the orbit problem play a significant role. In addition, STM and STTs are ubiquitous in spaceflight dynamics, …
A Unified Tool For Adaptive Collocation Techniques Applied To Solving Optimal Control Problems, Bethany Kelly
A Unified Tool For Adaptive Collocation Techniques Applied To Solving Optimal Control Problems, Bethany Kelly
Electronic Theses and Dissertations, 2020-
In this work, a user-friendly MATLAB tool is introduced to solve nonlinear optimal control problems by applying collocation techniques using Coupled Radial Basis Functions (CRBFs). CRBFs are a new class of Radial Basis Functions combined with a conical spline r^5, which provides the advantage of insensitivity to the shape parameter while maintaining accuracy and robustness. To solve optimal control problems, software tools are often employed to implement numerical methods and apply advanced techniques to solving differential equations. Although several commercial software tools exist for solving optimal control problems, such as ICLOCS2, GPOPS, and DIDO, there are no options available that …
Broadband Investigation Of The Pyrolysis Of Propane Using A Mir Optical Parametric Oscillator, Robert Greene
Broadband Investigation Of The Pyrolysis Of Propane Using A Mir Optical Parametric Oscillator, Robert Greene
Electronic Theses and Dissertations, 2020-
The chemistry of propane continues to play a pivotal role in today's power production technologies. As reliance on natural gas expands as greener cleaner fuels are sought throughout the world, especially as countries are attempting to transition away from traditional coal and crude-oil fired plants towards solar, wind, and hydro-electric sources. Natural gas, often seen as a bridge fuel between these two competing ends, has been in the recent past and for the foreseeable future will continue to play an important role in the energy sector. Among the components of natural gas, propane plays a key role in the chemistry …
Influence Of Nonlinear Multiaxial Matrix Viscoelasticity On Piezoresistivity Of Carbon Nanotube Polymer Composites, Wolfgang Klimm
Influence Of Nonlinear Multiaxial Matrix Viscoelasticity On Piezoresistivity Of Carbon Nanotube Polymer Composites, Wolfgang Klimm
Electronic Theses and Dissertations, 2020-
Nanocomposites are prominent candidates to extend the capabilities in areas of established fiber reinforced composites. Carbon nanotubes (CNT) with their outstanding mechanical, electrical, and thermal properties are of particular interest. Especially polymers profit from the addition of CNTs, and can be rendered significantly stiffer, stronger, and even electrically conductive. The resulting electrical conductance is deformation-sensitive, known as piezoresistivity, and is utilized in strain sensing applications. However, the polymer matrix introduces time- and temperature-dependency into the mechanical behavior, known as viscoelasticity, and thus affects the relationship between deformation and electrical conductivity over time. Although piezoresistivity and polymer viscoelasticity have been studied …
Design And Mechanical Characterization Of Functionally Graded Sandwich Beams Fabricated Via Additive Manufacturing, Timothy Grondin
Design And Mechanical Characterization Of Functionally Graded Sandwich Beams Fabricated Via Additive Manufacturing, Timothy Grondin
Electronic Theses and Dissertations, 2020-
Lightweight aerospace structures have been sought after since humans took flight in 1903, making major strides in NASA's pursuit of the moon with the development of sandwich panel composites. Sandwich structures typically consist of two stiff phases (i.e., face sheets) separated by a lightweight phase (i.e., core), which are stacked together through adhesive layers. Such a structural arrangement provides a high stiffness-to-weight ratio and is often used in applications where weight saving is critical. Functionally Graded Materials (FGMs), refer to multifunctional materials, which contain a spatial variation of composition and/or microstructure for the specific purpose of altering thermal and structural …
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. …
Characteristics Of Rotating Detonation Engines For Propulsion And Power Generation, Robert Burke
Characteristics Of Rotating Detonation Engines For Propulsion And Power Generation, Robert Burke
Electronic Theses and Dissertations, 2020-
Conventional engines are limited by the efficiency of their combustion mode. Compared to present constant pressure deflagration-based engines, detonation-based systems can realize a higher thermodynamic cycle efficiency, making them an attractive candidate for next generation propulsion systems that will take humanity to hypersonic speeds and even to Mars. For all its performance gains, detonation engines are still far off from implementation. One system, the rotating detonation engine (RDE) is promising as a detonation-based engine concept for its stability, simplicity, and versatility. For these reasons, RDEs have been the subject of studies internationally in efforts to understand their operation and integration …
Studying The Electrostatic Effects On The Dynamics Of Charged Lunar Dust Via Discrete Element Method, Hao Wang
Studying The Electrostatic Effects On The Dynamics Of Charged Lunar Dust Via Discrete Element Method, Hao Wang
Electronic Theses and Dissertations, 2020-
Dust problems raise significant concerns in planetary surface exploration. The unusual behavior of the dust particles that surround the vehicle after engine cutoff has the potential to have more of an influence on surface systems than the high velocity lunar rocket plume ejecta in the landing process. A prevailing hypothesis attributes the levitation and transport of dust particles on the surface of airless bodies to the electrostatic effects and electric field. However, there is no accurate model considering the inter-particle electrostatic interactions, especially when the particles are charged by plume. This dissertation aims to understand the behavior of charged lunar …
Shape Parameter & Nodal Distribution Insensitive Radial Basis Functions For Nonlinear Optimal Control Problems, Ahmed Elsadek Ahmed Elshafee Seleit
Shape Parameter & Nodal Distribution Insensitive Radial Basis Functions For Nonlinear Optimal Control Problems, Ahmed Elsadek Ahmed Elshafee Seleit
Electronic Theses and Dissertations, 2020-
Computational optimal control relies mainly on pseudospectral methods. The use of Chebyshev and Legendre polynomials is ubiquitous in the literature. This family of methods has good accuracy characteristics but constraints the nodal distribution to a certain grid that is denser at the boundaries. In this work, a set of novel Coupled Radial Basis Functions (CRBFs) is introduced as an approximation means for the nonlinear optimal control problem. CRBFs are real-valued Radial Basis Functions (RBFs) augmented with a conical spline. They do not require a specific nodal distribution. A plethora of research articles were published on the optimization of the shape …
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 …
Exploration Of Shock-Droplet Ignition And Combustion, John Patten
Exploration Of Shock-Droplet Ignition And Combustion, John Patten
Electronic Theses and Dissertations, 2020-
Liquid fuels are desirable in aerospace applications due to their higher energy density when compared to gaseous fuels. With the advent of detonation-based engines, it is necessary to characterize and analyze how liquid fuel interacts with detonation waves as well as shocks to ignite. While liquid fuel sprays have been proven to successfully aid and sustain detonations, the physical mechanism by which the individual liquid droplets accomplish this is yet to be understood. Such knowledge allows for more predictable detonation properties, which in turn can let detonation-based engines be sustained more easily. This research seeks to quantify and characterize interactions …