Aerospace Engineering Commons^™

Multi-Parametric And Multi-Objective Optimization Of Heatsinks For Forced And Natural Convection Based Single-Phase Immersion Cooling Of Server, Tushar Rohidas Wagh

Mechanical and Aerospace Engineering Theses - Archive

An increase in utility of internet-based services, cloud computing and greater performance demands due to rising AI and ML applications have led to a steep growth in GPU and CPU thermal design power. Efficient thermal management of these processors has become a bottleneck in performance enhancement and corresponding power densification of these components. Furthermore, increased pressure on data center owners to reduce power demands and move towards green computing has exacerbated the data center cooling challenges. Single-phase immersion cooling allows data center owners to not only dissipate the increasing heat fluxes efficiently but can also potentially improve equipment reliability as …

Airframe And Systems Design, Analysis, And Testing Of The Horizon Morphing-Wing Aircraft, Sabrina A. Snow

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Morphing trailing edge technology can provide the ability to dynamically alter the twist distribution, and therefore lift distribution, of an aircraft during flight. There are certain optimal lift distributions which can be chosen to create proverse yawing effects and eliminate the need for vertical control surfaces. The purpose of this project is to support the design and testing of a morphing, crescent flying wing airframe which will be used to evaluate yaw control in an aircraft without vertical control surfaces. There are three main objectives of this project, which are to perform static and dynamic analysis on the crescent wing …

On Mode Transition Phenomenon And Operating Conditions In Rotating Detonation Rocket Engines, Taha Rezzag-Lebza

Electronic Theses and Dissertations, 2020-2023

The work presented herein consist of first studying the instantaneous properties of the detonation waves in a rotating detonation rocket engine by tracking each individual wave and recording its position, velocity, and peak intensity as it travels around the annulus. Results for a steady portion of a test performed on a rotating detonation rocket engine show that the wave properties exhibit oscillatory behavior. Results obtained from the rotating detonation rocket engine show that the properties are highly dependent on the azimuthal position. In an attempt to understanding the cause of such a behavior, similar investigations were performed on an air-breathing …

Small Satellite Development And Mission Design For Low Earth Orbit And Geostationary Transfer Orbit Missions, Ashiqur Rahman

Open Access Theses & Dissertations

Aerospace Center formerly known as cSETR at UTEP is a NASA funded center of excellence in aerospace and exploration, focusing on strategic capability development in propulsion and robotic lander, lunar surface exploration, and small spacecraft technologies. To support the center’s mission for space exploration and to demonstrate advancements in small satellite technologies, the Aerospace Center at The University of Texas at El Paso is on track to develop and launch several CubeSats in next few years. A CubeSat is a small satellite that has become popular in recent years due to their low cost, low complexity and short development timeline. …

On The Mobility Of Small Aperture Telescopes For Initial Orbit Determination And Apparent Magnitude Derivation Of Low Earth Satellites, Jonathan Ian Hernandez

Master's Theses

Maintaining Space Domain Awareness (SDA) of satellites in low Earth orbit (LEO) requires effective methods of tracking and characterization. Optical measurements of these objects are generally sparse due to limited access intervals and high angular rates. Light pollution and geographic obstructions may also preclude consistent observations. However, a mobile small aperture telescope grants the ability to minimize such environmental effects, thereby increasing capture likelihoods for objects within this regime. By enhancing LEO satellite visibility in this way, extensive orbital and visual data are obtainable.

An 8-inch Meade LX200GPS telescope equipped with a Lumenera SKYnyx2-0M CCD camera comprises the system that …

Developing A Light Curve Simulation Tool For Ground And Space-Based Observations Of Spacecraft And Debris, Andrew T. Ochoa

Master's Theses

A light curve is a plot of brightness versus time of an object. Light curves are dependent on orbit, attitude, surface area, size, and shape of the observed object. Using light curve data, several analysis methods have been developed to derive these parameters. These parameters can be used for tracking orbital debris, monitoring satellite health, and determining the mission of an unknown spacecraft.

This paper discusses the development, verification, and utilization of a tool that simulates light curve data. This tool models ground-based observations, space-based observations, self-shadowing geometry, tumbling debris, and controlled spacecraft. The main output from the tool is …

Accelerated Performance Degradation Of Single-Phase Cold Plates For Direct-To-Chip Liquid Cooled Data Centers, Lochan Sai Reddy Chinthaparthy

Mechanical and Aerospace Engineering Theses - Archive

Expanding demands for cloud-based computing and storage, the Internet of Things, and AI-based applications have escalated thermal loads in high-density data centers which necessitated the utilization of more efficient cooling technologies. Direct-to-chip liquid cooling using cold plates has proven to be one of the most efficient methods to dissipate the high heat fluxes of modern high-power CPUs and GPUs. While the published literature has well-documented research on the thermal aspects of direct liquid cooling, a detailed account of reliability degradation is missing. The present investigation provides an in-depth analysis of the reliability degradation of copper cold plates used in high-power …

Creasing Of Polyimide Thin Film For Use In Solar Sails, Andrew Allen

Electronic Theses and Dissertations, 2020-2023

Polymer thin membranes are used in a variety of deployable structures that require large areas and compact stowage. Packaging membrane structures often involves creasing the membrane along predefined fold lines to enforce the desired kinematics under folding action. Inducing permanent deformation by folding to a high curvature is a common method to create creases, particularly in the design of solar sails. The distinct mechanical characteristics at the crease regions have a profound effect on the subsequent deployment and tensioning of the membrane structures. The mechanical and geometric properties at the crease are related to the crease formation process, but the …

Autonomous Guidance Of Unmanned Combat Air Vehicles In Basic Fighter Maneuvering, Jeffery G. Dean

Mechanical and Aerospace Engineering Dissertations - Archive

Basic fighter maneuvering, or BFM, is the dynamic engagement of two or more aircraft in close-range air combat. The relatively recent introduction of advanced unmanned combat air vehicles (UCAVs) has opened the possibility for automated systems to be players in this arena of air-to-air combat, which has thus far been limited to manned aircraft. In order to design an unmanned system that could fight and win a BFM engagement, the system must include an advanced system for guidance. This dissertation leverages techniques from gain scheduling and incorporates adjustable aimpoint guidance, in order to address the capability for UCAVs to execute …

Trajectory Generation For A Multibody Robotic System: Modern Methods Based On Product Of Exponentials, Aryslan Malik

Doctoral Dissertations and Master's Theses

This work presents several trajectory generation algorithms for multibody robotic systems based on the Product of Exponentials (PoE) formulation, also known as screw theory. A PoE formulation is first developed to model the kinematics and dynamics of a multibody robotic manipulator (Sawyer Robot) with 7 revolute joints and an end-effector.

In the first method, an Inverse Kinematics (IK) algorithm based on the Newton-Raphson iterative method is applied to generate constrained joint-space trajectories corresponding to straight-line and curvilinear motions of the end effector in Cartesian space with finite jerk. The second approach describes Constant Screw Axis (CSA) trajectories which are generated …

Airspace Integration Of New Entrants And Safety Risk Management Models, Fadjimata Issoufou Anaroua

Doctoral Dissertations and Master's Theses

In recent years, the demand for airspace access of Unmanned Aerial Systems (UAS) increased significantly and is continuously increasing for different altitude-types UAS. A similar evolution is expected from Commercial Space Operations (CSO) in the next years. These aviation/aerospace systems will need to be seamlessly integrated into the National Airspace System (NAS), at their operational altitude levels, and accounted for from all perspectives, including proactively addressing their safety hazards. This thesis captures the requirements for the new entrants’ integration, and then identifies and analyzes the safety risks added to the NAS operations by its new entrants, the future omnipresent UAS …

Fabrication & Mechanical Properties Of Hastelloy-X Matrix Ceramic Composite, Sultan Stewart

Doctoral Dissertations and Master's Theses

In the aerospace industry, there is a desire for increased thermal and mechanical properties of sealing materials. In this thesis, porous Hastelloy-X alloy scaffolds with 80% porosity, currently used for fabricating seals in turbine applications, were used as the base material. The microstructure of the porous Hastelloy-X scaffolds was infiltrated using a room temperature curing silicate colloid (trade name -Dichtol HTWG Hydro #2506) and a novel zirconia based colloid to fabricate the metal matrix composites. Various fabrication processes, some using vacuum and pressure to assist the flow were utilized to infiltrate the scaffolds. The green composites were then cured at …

Satellite Deceleration Using Gravity Assist From Asteroid, Nicolas M. Prulhiere

Doctoral Dissertations and Master's Theses

Satellites have used gravity assists to increase their speed when exploring the solar system. This same maneuver can be done but with the objective to slow down the satellites. This has been theorized to slow down asteroids using the moon to capture them in earth’s orbit. My goal is to determine if asteroids can be used to provide a change in speed great enough to the point that after multiple of these maneuvers the satellite can come to a stop. By being able to slow down and stop a satellite without having to use thrusters will allow the mass allocated …

High Fidelity Studies In Closed-Loop Control Of Unsteady Aerodynamics, Miriam Theobald-Deschine

Doctoral Dissertations and Master's Theses

We implement and explore the success of a nonlinear, closed loop flow control strategy based on POD-ROM focusing on boundary-layer transitional flow in high-fidelity computational studies involving FDL3DI ILES code. Controlling the boundary-layer transition from laminar to turbulent allows the laminar boundary-layer to be lengthened, decreasing skin-friction drag on an airfoil. Analyses are conducted on a flat plate with an elliptical leading edge, later to be implemented in future studies with real airfoil geometry. The feedback control design employs strategically placed synthetic-jet micro actuators and pressure sensors. The efficiency of the closed-loop flow control strategies is examined in comparison with …

The Effect Of Part Curvature On The Formation Of Residual Stresses In Carbon Fiber Prepreg Laminates, Bradley Rogan

Doctoral Dissertations and Master's Theses

The formation of residual stresses during the processing of composite parts can lead to undesired defects such as delamination which can reduce the overall strength of a completed component. Furthermore, the addition of curvature to the part geometry tends to result in wrinkle formation which leads to stress concentrations developing throughout the curing process in the areas near these wrinkles. In this work, Digital Image Correlation (DIC) will be used to monitor the development of stresses throughout the cure cycle of carbon fiber prepreg in several different lay-ups and across tool plates with varying curvatures to determine what effect the …

Break The Ice Challenge, Peter Karkos, Alex Lewis, Eva Kouyate, Vy Han

Mechanical Engineering

The report documents and justifies team LEGION’s senior design project, from research and ideation to prototype manufacturing and testing. It begins by providing some background on the project and outlining the mission scenario given by NASA. This is followed by related literature on excavation of icy regolith on the moon, water transportation, lunar environment, and space law. Next, research is performed into existing products, such as patents and various designs from previous related NASA competitions.

After providing the relevant background information, focused objectives are outlined, with a problem statement, boundary sketch, and engineering specifications. The wants & needs of NASA …

Design, Development, And Testing Of Embedded Computing On Afit's Control & Autonomy Space Proximity Robot (Caspr), Collin A. Gwaltney

Theses and Dissertations

This thesis reviews RPO algorithm testbeds and discusses the development of the Control and Autonomy Space proximity Robot (CASpR) kinematic testbed housed at the Air Force Institute of Technology (AFIT). CASpR operates on a rail system to propagate the trajectories of two satellites using the Hill-Clohessy-Wiltshire (HCW) Equations of Motion (EOMs). In this study, the implementation of a Jetson TX2i as an onboard flight computer is discussed and accomplished. Each hardware component used in the process of adding embedded computing as well as the software and paths of communication are all discussed in detail. Tests are conducted to assess the …

Investigation Of Mirror Satellite Concept To Augment Natural Lighting Conditions On Orbit, Daniel M. Dombrowski

Theses and Dissertations

A method of augmenting on-orbit lighting conditions for rendezvous and proximity operations through the novel use of solar reflectors is presented. Natural lighting conditions on-orbit pose extreme challenges to these already complex missions. This research summarizes and applies the historical basis of solar reflectors to the proximity operations issues encountered today. Building on this past research, a simulation has been created to test the efficacy of a solar reflector constellation in facilitating less complex servicing/inspection missions. Initial testing has shown promising results for low mass membrane mirrors in augmenting illumination conditions with particular benefit in the geosynchronous orbital regime. Through …

The Effect Of Shot Dependency On Composite Materials Subject To Ballistic Testing, Clayton C. Hankins

Theses and Dissertations

Ballistic analysis was performed on four common composite armor materials: 3k standard modulus plain weave carbon fiber, 8HS satin weave S-glass fiber, plain weave Kevlar® KM2 600 Denier fiber, and Spectra Shield® 4232 ultra-high molecular weight polyethylene to determine shot dependency based upon shot-to-shot impact distance, degree of penetration from the initial impacts, and the delamination effects from the initial impact. The primary measure of ballistic performance was the projectile velocity which represents a 50% probability of penetration, V₅₀. This velocity was determined using a three-phase optimal design test method with an average of twelve shots per test. …

Design And Performance Characterization Of A Water Propellant Resistojet Thruster, Sean M. Weathersby

Theses and Dissertations

Secondary payloads, such as CubeSats, are being increasingly used by the US Department of Defense in the role of defense capability enhancement, and these increasingly complex defense missions can require extended lifespans that result in the need for a thruster. While many thruster options exist, characteristics such as propellant toxicity, complexity, and low performance limit many viable solutions. However, a potential answer that satisfies these thruster limitations is found in electrothermals, specifically the resistojet. The research presented here represents the first attempt to construct a 1U water-propellant resistojet thruster design and establish an initial characterization through evaluation of various performance …

Injection Studies On A Small-Scale Rotating Detonation Engine With Improved Flow Control, Jonathan J. Wyatt

Theses and Dissertations

The Rotating Detonation Engine (RDE) has gained increasing attention in recent years for its potential advantages over typical deflagration combustion. A Micro-RDE design with an outer diameter of 28mm operating on Nitrous Oxide and Ethylene was recently developed, which stretched the limits of small-scale detonation engines. The testing on this rig has shown a stable one wave mode detonation with frequencies reaching 16.8 kHz. Key parameters that influence the detonation wave mode are cell size, fill height, and wave speed, which are heavily influence d by injection schemes. Previous testing utilized a partially premixed jets in crossflow (JIC) injection scheme, …

Estimating Smart Wi-Fi Thermostat-Enabled Thermal Comfort Control Savings For Any Residence, Abdulelah D. Alhamayani, Qiancheng Sun, Kevin Hallinan

Mechanical and Aerospace Engineering Faculty Publications

Nowadays, most indoor cooling control strategies are based solely on the dry-bulb temperature, which is not close to a guarantee of thermal comfort of occupants. Prior research has shown cooling energy savings from use of a thermal comfort control methodology ranging from 10 to 85%. The present research advances prior research to enable thermal comfort control in residential buildings using a smart Wi-Fi thermostat. "Fanger's Predicted Mean Vote model" is used to define thermal comfort. A machine learning model leveraging historical smart Wi-Fi thermostat data and outdoor temperature is trained to predict indoor temperature. A Long Short-Term-Memory neural network algorithm …

Post-Processing And Characterization Of Additive Manufactured Carbon Fiber Reinforced Semi-Crystalline Polymers, Patricia Revolinsky

Mechanical & Aerospace Engineering Theses & Dissertations

The aim of this work is to study the effect of post-processing on additive manufactured (AM) continuous carbon fiber reinforced plastics (CFRPs) performance. As-printed AM CFRPs do not perform as well as conventionally manufactured CFRPs with the same composition. Possible improvements to AM CFRP performance include annealing and applying uniaxial pressure with elevated temperature. Samples were subjected to pressure and temperature treatments and annealing at a constant temperature. Treated materials were subjected to three-point bending tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) to characterize and assess sample performance. Results were assessed for flexural strength, …

2021 Summer-Fall Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for summer and fall 2021. Includes photographs, upcoming events, recent publications, and student profiles.

Mechanical Interfacial Locking And Multiscale Modeling Of Reinforced Thermoplastic Composites For Structural Applications, Anmol Kothari

All Dissertations

The ever-growing pressure of reducing the adverse impact of transportation systems on environment has pushed industries towards fuel-efficient and sustainable solutions. While several approaches have been used to improve fuel efficiency, the light-weighting of structural components has proven broadly effective. In this regard, reinforced thermoplastic composites (RTPC), owing to their high recyclability, higher impact strength and fast cycle times, have become competitive candidates at an industrial scale. However, to implement RTPC toward large scale structural applications several challenges pertaining to material design and manufacturing effects need to be addressed. To this end, a computational study is carried out to address …

Optimal Sizing And Control Of Hybrid Rocket Vehicles, Srija Ryakam

Doctoral Dissertations and Master's Theses

In the present work, a genetic algorithm is used to optimize a hybrid rocket engine in order to minimize the propellant required for a specific mission. In a hybrid rocket engine, the mass flow rate of the oxidizer can be throttled to enhance the performance of the rocket. First, an analysis of the internal ballistics and the ascent trajectory has been carried out for different mass flow rates of the oxidizer as a function of time, for a fixed amount of oxidizer, in order to study the effect of throttling. Two equivalent problems are considered: in the first problem the …

Second-Order Reliability Methods: A Review And Comparative Study, Zhangli Hu, Rami Mansour, Mårten Olsson, Xiaoping Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Second-order reliability methods are commonly used for the computation of reliability, defined as the probability of satisfying an intended function in the presence of uncertainties. These methods can achieve highly accurate reliability predictions owing to a second-order approximation of the limit-state function around the Most Probable Point of failure. Although numerous formulations have been developed, the lack of full-scale comparative studies has led to a dubiety regarding the selection of a suitable method for a specific reliability analysis problem. In this study, the performance of commonly used second-order reliability methods is assessed based on the problem scale, curvatures at the …

Impact Of Surface And Pore Characteristics On Fatigue Life Of Laser Powder Bed Fusion Ti–6al–4v Alloy Described By Neural Network Models, Seunghyun Moon, Ruimin Ma, Ross Attardo, Charles Tomonto, Mark Nordin, Paul Wheelock, Michael Glavicic, Maxwell Layman, Richard Billo, Tengfei Luo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, the effects of surface roughness and pore characteristics on fatigue lives of laser powder bed fusion (LPBF) Ti–6Al–4V parts were investigated. The 197 fatigue bars were printed using the same laser power but with varied scanning speeds. These actions led to variations in the geometries of microscale pores, and such variations were characterized using micro-computed tomography. To generate differences in surface roughness in fatigue bars, half of the samples were grit-blasted and the other half were machined. Fatigue behaviors were analyzed with respect to surface roughness and statistics of the pores. For the grit-blasted samples, the contour …

Computational Sodium Heat Pipe Simulation In Three Dimensions For Transient Nuclear Reactor Analysis With Variable Surface Heat Flux, Valerie Jean Lawdensky

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heat pipes are used to transfer heat through phase change in a liquid/vapor contained in a metal tube. They are passive devices that require no pumps to circulate the fluid and can transfer heat far more efficiently than a solid copper rod of the same diameter. They are commonly used in laptop computers where copper heat pipes filled with water take heat away from the CPU and transfer the heat to air through a heat exchanger. Heat pipes were also used in the Kilopower nuclear reactor where higher temperatures required sodium as the working fluid with stainless steel tubes. Computer …

Tradespace Exploration Of A Uav Conceptual Design Using Model-Based Systems Engineering, Ayan Srivastava

All Theses

The objective of this research is to apply model-based systems engineering approaches to the conceptual design of unmanned aerial vehicles. This is accomplished by evaluating the models of aircraft performance, extracting input and output parameters from the models, creating chains of models, and implementing the models in the MATLAB programming language. By following this process, it is possible to identify the global parameters that remain constant across models, the shared input parameters, the dependencies between models, and the feedback loops with the systems models.

The models are currently implemented in two files using Microsoft MS Excel, one is focused on …