Application Of Direct Simulation Monte Carlo Method To Computation Of Rf Signal Degradation During Hypersonic Flight,
2023
Washington University in St. Louis
Application Of Direct Simulation Monte Carlo Method To Computation Of Rf Signal Degradation During Hypersonic Flight, Andrew Derubertis
McKelvey School of Engineering Graduate Student Theses & Dissertations
In order to further understand the hypersonic blackout problem, the first step is to investigate models to quantify signal degradation and begin implementing these models to representative plasma sheath and flow data. This research is the first attempt at implementing a model to predict RF signal degradation through the plasma sheath surrounding the hypersonic air vehicle. The investigation is performed using a Direct Simulation Monte Carlo (DSMC) based flow solver. The dsmcFoam solver in the OpenFoam library is used to simulate the flow around hypersonic bodies to obtain flow field properties, most importantly the electron number density profile, to aid …
Investigation Of Hypersonic Near-Wake Relaminarization Over A 7 Degree Half-Angle Cone,
2023
Air Force Institute of Technology
Investigation Of Hypersonic Near-Wake Relaminarization Over A 7 Degree Half-Angle Cone, Jesse L. Roberts
Theses and Dissertations
To investigate the potential for relaminarization in the near-wake of a 7-degree half-angle cone, a series of hypersonic wake experiments were conducted in the Air Force Research Laboratory Mach 6.1 Ludwieg tube. Relaminarization is a spatial phenomenon that occurs when a turbulent flow reverts to a laminar-like state at a downstream location, where turbulent fluctuations negligibly contribute to average flow properties. Although relaminarization has been documented in subsonic and supersonic flows, the current body of knowledge related to the occurrence of, and mechanisms that drive, relaminarization at hypersonic speeds is sparse. Measurements were obtained across a range of freestream unit …
Numerical Study Of Owls’ Leading-Edge Serrations,
2023
Coastal Carolina University
Numerical Study Of Owls’ Leading-Edge Serrations, Asif Shahriar Nafi
Electronic Theses and Dissertations
The silent flight ability of owls is often attributed to their unique wing morphology and its interaction with their wingbeat kinematics. Among these distinctive morphological features, leading-edge serrations stand out – these are rigid, miniature, hook-like patterns located at the leading edge of the primary feathers of their wings. It had been hypothesized that these leading-edge serrations serve as a passive flow control mechanism, influencing the aerodynamic performance and potentially affecting the boundary layer development over the wing, subsequently influencing wake flow dynamics. Despite being the subject of research spanning multiple decades, a consensus regarding the aerodynamic mechanisms underpinning owls’ …
The Numerical Study Of Aeroacoustics Performance Of Wings With Different Wavelength Leading-Edge Tubercles,
2023
University of Central Florida
The Numerical Study Of Aeroacoustics Performance Of Wings With Different Wavelength Leading-Edge Tubercles, Youjie Zhang
Honors Undergraduate Theses
The leading-edge tubercle is a type of airfoil modification that inspired by the humpback whale. It was found that the aerodynamic performance of the wing would increase compared to the wing without tubercles. In the past several years, a lot of numerical and experimental studies have been accomplished to explore this leading-edge modification. Besides the aerodynamic performance change, this research explores the aeroacoustics behavior of airfoils with leading-edge tubercles. A numerical study based on Computational Fluid Dynamics (CFD) is established, and simulations using Star CCM are accomplished based on reasonable set-ups. The airfoil chosen to create the wing is NACA …
Design Considerations And Imaging Setup For Liquid Fuel Droplet Detonation Wave Experiments,
2023
University of Central Florida
Design Considerations And Imaging Setup For Liquid Fuel Droplet Detonation Wave Experiments, Nicolas Berube
Electronic Theses and Dissertations, 2020-2023
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 …
An Evaluation Of Thermocouple Reconstruction Techniques,
2023
University of Central Florida
An Evaluation Of Thermocouple Reconstruction Techniques, Derek Brauneis
Electronic Theses and Dissertations, 2020-2023
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 …
Mitigation Of Aeroacoustic Noise Of A Fixed Wing Using Passive Flow Control,
2023
Georgia Southern University
Mitigation Of Aeroacoustic Noise Of A Fixed Wing Using Passive Flow Control, Cameron L. Perry
College of Graduate Studies: Theses & Dissertations
As the world becomes more environmentally conscious, noise pollution is of increasing concern. In this study, shallow dimples are applied to a NACA 0012 airfoil at multiple angles of attack (AoA) with the intent of reducing aeroacoustic noise emissions. Both Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models are used for aerodynamic and aeroacoustic investigations, respectively, at a fixed Reynolds number of 4.8 x 105. Altering the dimple depth to diameter ratio (d/D) from 2.5% to 15% is first investigated, with a d/D of 5% or lower resulting in the least aerodynamic impact. The transition from …
Rotorcraft Lander Fixed To A Descending Capsule Backshell,
2023
University of Central Florida
Rotorcraft Lander Fixed To A Descending Capsule Backshell, Corey Zucker
Electronic Theses and Dissertations, 2020-2023
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 …
Hypersonic Aero-Optic Measurements In A High-Pressure Shock Tube,
2023
University of Central Florida
Hypersonic Aero-Optic Measurements In A High-Pressure Shock Tube, Jonathan P. Mcgaunn
Graduate Thesis and Dissertation 2023-2024
The high-pressure shock tube facility (HiPER-STAR) at the University of Central Florida (UCF) is analyzed experimentally to demonstrate the practicality of hypersonic aero-optical testing in an impulse facility without the use of an expansion nozzle or acceleration tube. The investigation analyses driver gas blending with helium and hydrogen to raise the speed of sound ratio in an attempt to increase the Mach number for aero-optics testing. HiPER-STAR has a unique ability to withstand pressures up to 1000 atm and run in a double diaphragm configuration allowing for a significant pressure differential to be created between the driver and driven sections. …
Thermal Management Strategies For Hypersonic Flight: Supercritical Co2 Jet Impingement Cooling Investigation For Leading Edge,
2023
University of Central Florida
Thermal Management Strategies For Hypersonic Flight: Supercritical Co2 Jet Impingement Cooling Investigation For Leading Edge, Manoj Prabakar Sargunaraj
Graduate Thesis and Dissertation 2023-2024
This study addresses the critical need for effective thermal management in hypersonic vehicles facing intense heat at their leading edge due to high enthalpy flow. The objective is to propose an active impingement cooling system that ensures the structural stability and performance of these vehicles. This dissertation presents an in-depth exploration of the numerical simulations conducted on the hypersonic leading edge, focusing on a 3mm radius with active cooling utilizing supercritical carbon dioxide (sCO2) as the coolant. The research incorporates conjugate simulations that merge external hypersonic flow and sCO2 active cooling. Utilizing a thermodynamic non-equilibrium two-temperature model and various chemical …
Topologically Optimized Electrodes For Electroosmotic Actuation,
2023
Old Dominion University
Topologically Optimized Electrodes For Electroosmotic Actuation, Jianwen Sun, Jianyu Zhang, Ce Guan, Teng Zhou, Shizhi Qian, Yongbo Deng
Mechanical & Aerospace Engineering Faculty Publications
Electroosmosis is one of the most used actuation mechanisms for the microfluidics in the current active lab-on-chip devices. It is generated on the induced charged microchannel walls in contact with an electrolyte solution. Electrode distribution plays the key role on providing the external electric field for electroosmosis, and determines the performance of electroosmotic microfluidics. Therefore, this paper proposes a topology optimization approach for the electrodes of electroosmotic microfluidics, where the electrode layout on the microchannel wall can be determined to achieve designer desired microfluidic performance. This topology optimization is carried out by implementing the interpolation of electric insulation and electric …
Initial Procedure For Small-Scale Extraction Of Subsurface Martian Ice,
2023
South Dakota State University
Initial Procedure For Small-Scale Extraction Of Subsurface Martian Ice, Evan Steers
Electronic Theses and Dissertations
For decades, NASA has been surveying the surface of Mars with plans for human exploration. Due to recent advancements, there is strong evidence to believe that frozen aquifers beneath the Martian surface hold great amounts of usable H2O. Since the discovery of water on Mars, NASA has expressed key interest in harvesting this valuable resource. The presence of usable H2O on Mars could reduce the launching mass of future missions by giving astronauts the capability to harvest water once they have landed on Mars. This research focuses on the optimization of a current design to extract Martian water and the …
Heat Release And Flame Scale Effects On Turbulence Dynamics In Confined Premixed Flows,
2023
University of Central Florida
Heat Release And Flame Scale Effects On Turbulence Dynamics In Confined Premixed Flows, Max Fortin
Electronic Theses and Dissertations, 2020-2023
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 …
An Optimization Study Of Small-Scale Propeller Blade,
2023
University of Central Florida
An Optimization Study Of Small-Scale Propeller Blade, Fahad M. Nabid
Honors Undergraduate Theses
This research paper aims to investigate the optimization of smaller propeller blades to achieve maximum efficiency by studying the effect of the twist angle on reducing drag, increasing thrust, and preventing rapid wear on the blade. Inefficient propellers consume a significant amount of energy, particularly during low-speed flights. The low Reynolds number regime challenges aviation engineers to design propellers with the highest possible efficiency to minimize energy losses. The primary objective of this thesis is to optimize smaller propeller blade shapes to enable them to produce maximum efficiency. The advanced ratio of a propeller blade heavily influences the blade's performance …
The Development Of Computational Models For Melting-Solidification Applications Using The Volume-Of-Fluid Method,
2023
University of Central Florida
The Development Of Computational Models For Melting-Solidification Applications Using The Volume-Of-Fluid Method, Brendon Cavainolo
Electronic Theses and Dissertations, 2020-2023
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 …
A Computational Fluid Dynamic Analysis Of Oxyacetylene Combustion Flow For Use In Material Response Boundary Conditions,
2023
University of Kentucky
A Computational Fluid Dynamic Analysis Of Oxyacetylene Combustion Flow For Use In Material Response Boundary Conditions, Craig Meade
Theses and Dissertations--Mechanical and Aerospace Engineering
Oxyacetylene torches are used in the aerospace industry and research to test thermal protection system materials (TPS) due to their high flame temperatures and high heat flux capabilities. The purpose of this work is to determine a combustion model to accurately simulate the high temperature flow of an oxyacetylene torch. The flow conditions around a sample material can then be used as boundary conditions when modeling TPS material response. Two separate combustion models with equilibrium chemistry were investigated using ANSYS Fluent™; the Eddy-Dissipation Model, and the Partially Premixed model.The results of this study are compared to existing experiments for validation.
Stratospheric Glider Measurements Of Atmospheric Parameters,
2023
University of Kentucky
Stratospheric Glider Measurements Of Atmospheric Parameters, Anisa Haghighi
Theses and Dissertations--Mechanical and Aerospace Engineering
In June 2021 a series of high altitude flights were conducted in Spaceport America, NM, using a balloon launched Uncrewed Aircraft System (UAS) to assess its capability to conduct measurements of various atmospheric properties and study turbulence in the troposphere and lower stratosphere. This UAS descends using an automated flight trajectory. The instruments aboard included a NASA-developed infrasonic microphone to evaluate its remote turbulence detection capabilities and a five-hole probe capable of measuring the in situ wind vector. Also on board were temperature, humidity and wind profile sensors. This document focuses on the atmospheric properties measured at high altitudes, the …
Impact Of Spallation And Internal Radiation On Fibrous Ablative Materials,
2023
University of Kentucky, Lexington
Impact Of Spallation And Internal Radiation On Fibrous Ablative Materials, Raghava Sai Chaitanya Davuluri
Theses and Dissertations--Mechanical and Aerospace Engineering
Space vehicles are equipped with Thermal Protection Systems (TPS) that encounter high heat rates and protect the payload while entering a planetary atmosphere. For most missions that interest NASA, ablative materials are used as TPS. These materials undergo several mass and energy transfer mechanisms to absorb intense heat. The size and construction of the TPS are based on the composition of the planetary atmosphere and the impact of various ablative mechanisms on the flow field and the material. Therefore, it is essential to quantify the rates of different ablative phenomena to model TPS accurately. In this work, the impact of …
Precision Meteorological Prediction Employing A Data-Driven, Adaptive, Real-Time (Dart) Approach,
2023
University of Kentucky
Precision Meteorological Prediction Employing A Data-Driven, Adaptive, Real-Time (Dart) Approach, Sujit Sinha
Theses and Dissertations--Mechanical and Aerospace Engineering
The objective of this research is to improve precision meteorological prediction, benefiting both uncrewed aerial vehicle (UAV) operations by avoiding hazardous flight conditions and tracking contaminant or toxic clouds caused by incidents, accidents, or fires. The operational concept is to collect meteorological observations from instruments mounted on a swarm of UAVs, telemeter the data to a weather simulation model, revise the predicted solution by adapting the flow field to the observations, and then transmit the updated forecast to appropriate personnel as well as to the guidance system of UAVs for repositioning to the next set of most beneficial measurements. While …
Detonability Of A Rotating Detonation Combustor Seeded With Carbon/Hydrocarbon Particles At Fringe Operating Conditions,
2023
University of Central Florida
Detonability Of A Rotating Detonation Combustor Seeded With Carbon/Hydrocarbon Particles At Fringe Operating Conditions, Matthew Hopwood
Electronic Theses and Dissertations, 2020-2023
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 …
