Engineering Commons^™

Analysis Of Wingtip Vortex Structure Generated By Bio-Inspired Winglets, D'Zahn A. Smith

Doctoral Dissertations and Master's Theses

Bio-inspired winglets were studied with the goal of better understanding the structure of the wingtip vortices they generate. Measurements of the tip vortex were previously carried out using stereoscopic particle image velocimetry (sPIV). The bio-inspired winglet was tested on a rectangular NACA 0012 wing section at a 5-degree angle of attack and at a chord Reynolds number of 900,000. Velocity field measurements were recorded at 0.7 and 2 chord lengths aft of the wing’s trailing edge. Compared to the wing with no attachment and a traditional blended winglet, the bio-inspired winglet’s vortex exhibited significantly less intense flow field properties. These …

Modeling Of Rotor Wake Vortex Dynamics And Interactions In Non-Homogenous Vertiport Environments, Garrison P. Shaw

Doctoral Dissertations and Master's Theses

The current research serves to analyze and study the effects ground forces can have on the thrust performance of a propeller in multiple different configurations. The current research utilizes an open source Computational Fluid Dynamics (CFD) software known as OpenFOAM to generate calculate and visualize these runs. The model used for this experiment is a hybrid model that employs both a Unsteady Reynolds-Averaged Navier-Stokes (URANS) and a detached eddy simulation using a hybrid Large Eddy Simulation (LES) via a KomegaSSTDDES model. This model serves to save computational time as well as allow for accurate results. The three cases run are …

Characterization And Analysis Of Supersonic Flow Through De Laval Nozzles At Varied Design Conditions, Sarah Baird

Doctoral Dissertations and Master's Theses

A combined numerical and experimental investigation of supersonic planar nozzles under different design conditions has been conducted. Supersonic planar nozzles are common geometries observed in supersonic wind tunnels and aircraft or rocket engines. For the important role they play in wind tunnel testing and aircraft propulsion, it is important to conduct a thorough numerical and experimental study to characterize their performance at different operating conditions. In this study, a de Laval nozzle was scanned to extract its contours and subsequently modeled to compare analytical and numerical performance expectations under design and off-design conditions. The nozzle was then installed in a …

Machine Learning-Based Gps Jamming And Spoofing Detection, Alberto Squatrito

Doctoral Dissertations and Master's Theses

The increasing reliance on Global Positioning System (GPS) technology across various sectors has exposed vulnerabilities to malicious attacks, particularly GPS jamming and spoofing. This thesis presents an analysis into detection and mitigation strategies for enhancing the resilience of GPS receivers against jamming and spoofing attacks. The research entails the development of a simulated GPS signal and a receiver model to accurately decode and extract information from simulated GPS signals. The study implements the generation of jammed and spoofed signals to emulate potential threats faced by GPS receivers in practical settings. The core innovation lies in the integration of machine learning …

Development Of Eagle3d Solver For Wall Modeled Les Of Transonic Flows, Spencer Moore

Doctoral Dissertations and Master's Theses

Wall modeled Large Eddy Simulation (LES) is an area of interest due to its ability to lower computational costs of LES simulation. Even with the application of wall models, LES still proves to have practicality issues when it comes to use in industry, due to the expertise, time, and computational resources required to get results. A case described by an axisymmetric transonic bump is explored utilizing the Embry-Riddle Aeronautical Universities in house unstructured finite volume multi-element CFD code, Eagle3D. Eagle3D, has been brought to the state of the art and validated against current research using this transonic bump case as …

Adaptive Control Of An Aeroelastic System For Active Flutter Suppression And Disturbance Rejection, Patrick Sterling Downs

Doctoral Dissertations and Master's Theses

The future of aircraft design strives for lighter weight, more aerodynamically efficient structures. These improvements may come with the drawback of increased structural flexibility and elevated aeroelastic effects, often resulting in a lower flutter speed. This motivates the implementation of advanced control methods to control aeroelastic systems over a range of flight conditions, suppress and delay the onset of flutter, and compensate for disturbances, actuator dynamics, and unmodeled nonlinear dynamics.

This dissertation first develops a novel method for constructing time-domain simulation models of two and three-dimensional aeroelastic systems, resulting in models that are suitable for the implementation of state-space control …

Starfish: A Compact, Biomimetic, And Adaptive Shape Memory Alloy Orbital Debris Remover, Katelyn Branaman

Doctoral Dissertations and Master's Theses

This thesis aims to turn the tides on the orbital debris issue through the fabrication and demonstration of a compact, biomimetic, and adaptive shape memory alloy actuated orbital debris remover. The design, referred to as Starfish, is discussed in detail along with its fabrication process and object capture ability. A hard skeleton crafted from PETG was combined with shape memory alloy wires and extension springs to create a biomimetic structure that operates similar to the human hand, capable of gripping a wide range of objects. Relevant simulations were performed and discussed, the iterative fabrication process used to create each component …

State Omniscience For Cooperative Local Catalog Maintenance Of Close Proximity Satellite Systems, Chris Hays

Doctoral Dissertations and Master's Theses

Resiliency in multi-agent system navigation is reliant on the inherent ability of the system to withstand, overcome, or recover from adverse conditions and disturbances. In large part, resiliency is achieved through reducing the impact of critical failure points to the success and/or performance of the system. In this view, decentralized multi-agent architectures have become an attractive solution for multi-agent navigation, but decentralized architectures place the burden of information acquisition directly on the agents themselves. In fact, the design of distributed estimators has been a growing interest to enable complex multi-sensor/multi-agent tasks. In such scenarios, it is important that each local …

Implementation Of Path Planning Methods To Detect And Avoid Gps Signal Degradation In Urban Environments, Ayush Raminedi

Doctoral Dissertations and Master's Theses

In the modern world, various missions are being carried out under the assistance of autonomous flight vehicles due to their ability to operate in a wide range of flight conditions. Regardless, these autonomous vehicles are prone to GPS signal loss in urban environments due to obstructions that cause scintillation, multi-path, and shadowing. These effects that decrease the GPS functionality can deteriorate the accuracy of GPS positioning causing losses in signal tracking leading to a decrease in navigation performance. These effects are modeled into the simulation environment and are used as part of the path planning algorithm to provide better navigation …

Development Of Eagle3d Solver For Wall Modeled Les Of Transonic Flows, Spencer Moore

Doctoral Dissertations and Master's Theses

Wall modeled Large Eddy Simulation (LES) is an area of interest due to its ability to lower computational costs of LES simulation. Even with the application of wall models, LES still proves to have practicality issues when it comes to use in industry, due to the expertise, time, and computational resources required to get results. A case described by an axisymmetric transonic bump is explored utilizing the Embry-Riddle Aeronautical Universities in house unstructured finite volume multi-element CFD code, Eagle3D. Eagle3D, has been brought to the state of the art and validated against current research using this transonic bump case as …

Damage Control Measures In Composites: Focus On Damage Tolerance Of Aerospace Structures, Kais Jribi

Doctoral Dissertations and Master's Theses

Barely Visible Impact Damage (BVID) in composite materials presents a stealthy yet significant risk to structural integrity, particularly challenging due to its elusive nature. The approach adopted here diverges from traditional methodologies, focusing on the novel application of Digital Image Correlation (DIC) to map surface area changes during in-situ Compression After Impact (CAI) tests. This technique allows for an in-depth analysis of planar strains along the x and y axes, shedding light on the material's behavior under stress.

A pivotal advancement lies in developing a method for precisely identifying when BVID-induced delamination recommences. By meticulously analyzing strain pattern deviations along …

Ti Nano Powder Speckle Pattern Creation And Use In Dic Of Zno Modified Single Carbon Fibers, James Matthew Harris

Doctoral Dissertations and Master's Theses

As the use of composites continues to grow across aerospace, naval, automotive, construction, 3D printing, and other countless industries, so does the desire to continuously improve their mechanical properties. Improving the adherence of the fiber-matrix interface is one important step for amplifying the capabilities of composites. Work has been performed in modifying carbon fibers by growing zinc oxide (ZnO) nanorods in the fiber surface using a hydrothermal approach, increasing interfacial area and fiber-matrix friction. Macroscale evaluation has shown that the interfacial modification decreases the inter-ply movement and reduces the processing strains and residual stresses. To fully understand the mechanism taking …

Numerical Study In Wind Energy Extraction From Controlled Limit-Cycle Oscillations In Modified Glauert Airfoil, Ethan L. Deweese

Doctoral Dissertations and Master's Theses

Typically, wind energy harvesting technology employs wind turbines. Towards the goal of meeting increasing energy needs with renewable energy sources a novel wind energy harvesting scheme is considered, utilizing a modified Glauert (MG) airfoil experiencing aeroelastic limit cycle oscillation (LCO) from which energy may be extracted. Synthetic jet actuators (SJA)s are used along with the unique geometry of the MG airfoil to control flow separation and amplify the LCO and energy generation potential of the system. The discussed wind energy harvesting scheme could provide flexibility in allowing installations previously unsuitable to wind turbines due to geometric or low wind velocity …

Benchmarking Of A Sco2 Heat Exchanger Flow Loop, David Velasco

Doctoral Dissertations and Master's Theses

Heat transfer of supercritical carbon dioxide (sCO2) was studied experimentally by commissioning a sCO2 flow loop featuring a horizontal tube-in-tube counterflow heat exchanger with a circular cross section. The main objective was to establish experimental heat transfer research capabilities for sCO2 at Embry-Riddle Aeronautical University’s (ERAU) Thermal Science Lab. sCO2 experiences a drastic change in thermophysical properties near its critical point that results in unique heat transfer characteristics. The high pressures at which sCO2 exists make the large gradients in thermophysical and transport properties difficult to study, experimentally and numerically. However, understanding the heat transfer characteristics and thermophysical behavior of …

Mitigating Engine Unstart In Scramjets With Porous Bleeders, Ryan Lindley

Doctoral Dissertations and Master's Theses

The effectiveness of porous bleeders in mitigating unstart phenomena and enhancing isolator effectiveness in a hypersonic scramjet was investigated. Through computational fluid dynamics simulations, the impact of porous bleeder design parameters such as pressure jump coefficient and bleeder size on isolator effectiveness and unstart prevention was evaluated. Results indicated that porous bleeders delayed flow separation and reduced adverse pressure gradients, thereby enhancing isolator performance. Additionally, porous bleeders demonstrated promising capabilities in preventing full unstart events and mitigating oscillatory unstart phenomena.

Conceptual Design Methodology For The Fan-In-Wing Vtol Aircraft, Brock Steinfeldt

Doctoral Dissertations and Master's Theses

The Fan-In-Wing (FIW) aircraft concept is one of the most compelling solutions for missions demanding jet-like cruise speeds and Vertical TakeOff and Landing (VTOL) capability. However, despite years of interest and documented improvements in lift-fan technology, there exists little in the way of an adequate theory for conceptual design of a fan-in-wing aircraft. To address this issue, a general conceptual design methodology has been developed as a source of guidance for the FIW designer. Through this work, the top-level requirements ranking the fan-in-wing concept above other VTOL aircraft have been defined, while a cross-comparison between the FIW concept and conventional …

A Comparison Of Beamforming Characteristics In Isotropic And Composite Plate Structures For Use In Structural Health Monitoring, Sarah Ketchersid

Doctoral Dissertations and Master's Theses

Structural health monitoring in plate-like simple structures using phased array beamsteering of guided Lamb waves is useful in damage detection and evaluation efforts. Lamb waves can be effectively used for beamsteering using a linear array. The experimentation primarily focuses on beamsteering in the aluminum panel, which involves developing a simulation based on extracted data to visualize the dispersion of waves across the panel. By evaluating parameters such as slowness, velocity, and amplitude direction and variation for a specific metallic plate, the wavefront generated by a single wave source can be represented as a function of propagation angle and distance from …

Artificial Intelligence-Assisted Inertial Geomagnetic Passive Navigation, Andrei Cuenca

Doctoral Dissertations and Master's Theses

In recent years, the integration of machine learning techniques into navigation systems has garnered significant interest due to their potential to improve estimation accuracy and system robustness. This doctoral dissertation investigates the use of Deep Learning combined with a Rao-Blackwellized Particle Filter for enhancing geomagnetic navigation in airborne simulated missions.

A simulation framework is developed to facilitate the evaluation of the proposed navigation system. This framework includes a detailed aircraft model, a mathematical representation of the Earth's magnetic field, and the incorporation of real-world magnetic field data obtained from online databases. The setup allows an accurate assessment of the performance …

Deep-Learning Based Multiple-Model Bayesian Architecture For Spacecraft Fault Estimation, Rocio Jado Puente

Doctoral Dissertations and Master's Theses

This thesis presents recent findings regarding the performance of an intelligent architecture designed for spacecraft fault estimation. The approach incorporates a collection of systematically organized autoencoders within a Bayesian framework, enabling early detection and classification of various spacecraft faults such as reaction-wheel damage, sensor faults, and power system degradation.

To assess the effectiveness of this architecture, a range of performance metrics is employed. Through extensive numerical simulations and in-lab experimental testing utilizing a dedicated spacecraft testbed, the capabilities and accuracy of the proposed intelligent architecture are analyzed. These evaluations provide valuable insights into the architecture's ability to detect and classify …

Verification And Validation Of Robot Manipulator Adaptive Control With Actuator Deficiency, Sebastian Comeaux

Doctoral Dissertations and Master's Theses

This work addresses the joint tracking problem of robotic manipulators with uncertain dynamical parameters and actuator deficiencies, in the form of an uncertain control effectiveness matrix, through adaptive control design, simulation, and experimentation. Specifically, two novel adaptive controller formulations are implemented and tested via simulation and experimentation. The proposed adaptive control formulations are designed to compensate for uncertainties in the dynamical system parameters as well as uncertainties in the control effectiveness matrix that pre-multiplies the control input. The uncertainty compensation of the dynamical parameters is achieved via the use of the desired model compensation–based adaptation, while the uncertainties related to …

Stochastic Point Process Modeling For Engineering Applications, Samarth Motagi

Doctoral Dissertations and Master's Theses

Hawkes model or self-exciting point process model is a branching point process model. The model classifies the dataset of discrete events to background and offspring events. It has been used to study interconnected events in many fields, but relatively little work exists in applying these concepts to engineering problems. In our research, we use a self-exciting point process model for two engineering applications: (a) To identify secondary crashes from a given traffic data and (b) To quantify the agglomeration state and size of nanoparticles from computationally generated carbon nanotube microstructure using stochastic percolation model and experimentally generated titanium nanoparticle microstructures. …

Comparative Evaluation Of Propulsive Power Transmission Technologies For High-Speed Vertical Takeoff And Landing (Hsvtol) Cargo Aircraft, Xinyu Yang

Doctoral Dissertations and Master's Theses

Designing High-Speed Vertical Takeoff and Landing (HSVTOL) cargo aircraft capable of both low downwash velocity hovering and high subsonic speed cruising presents a significant engineering challenge. This challenge, stemming from conflicting design requirements, has been substantially influenced by recent technological advancements, which have offered greater flexibility in rotor placement. Consequently, this has led to the emergence of innovative mission-specific designs that hold the potential to outperform traditional concepts. The central objective of this study is to evaluate the benefits of modern technologies for VTOL cargo aircraft and assess their performance relative to baseline VTOL aircraft. The results of this comparative …

Development Of A Constellation Simulator For A 5g/Iot Mission Planning System, Franco Criscola

Doctoral Dissertations and Master's Theses

The advancement of 5G and Internet-of-Things technologies has presented new challenges for telecommunications providers. One of the challenges is integrating these technologies with present networks. A solution has been found in low-Earth orbit satellite constellations. On one hand, this method increases coverage and reduces costs, but on the other it raises new problems like how to efficiently manage large constellations of spacecraft. This thesis introduces the Constellation Management System, developed in collaboration with i2Cat foundation. This novel tool is composed of two modules: the simulator and the scheduler. The former propagates satellite motion and computes visibility events to various targets …

Online Aircraft System Identification Using A Novel Parameter Informed Reinforcement Learning Method, Nathan Schaff

Doctoral Dissertations and Master's Theses

This thesis presents the development and analysis of a novel method for training reinforcement learning neural networks for online aircraft system identification of multiple similar linear systems, such as all fixed wing aircraft. This approach, termed Parameter Informed Reinforcement Learning (PIRL), dictates that reinforcement learning neural networks should be trained using input and output trajectory/history data as is convention; however, the PIRL method also includes any known and relevant aircraft parameters, such as airspeed, altitude, center of gravity location and/or others. Through this, the PIRL Agent is better suited to identify novel/test-set aircraft.

First, the PIRL method is applied to …

Rigid Body Constrained Motion Optimization And Control On Lie Groups And Their Tangent Bundles, Brennan S. Mccann

Doctoral Dissertations and Master's Theses

Rigid body motion requires formulations where rotational and translational motion are accounted for appropriately. Two Lie groups, the special orthogonal group SO(3) and the space of quaternions H, are commonly used to represent attitude. When considering rigid body pose, that is spacecraft position and attitude, the special Euclidean group SE(3) and the space of dual quaternions DH are frequently utilized. All these groups are Lie groups and Riemannian manifolds, and these identifications have profound implications for dynamics and controls. The trajectory optimization and optimal control problem on Riemannian manifolds presents significant opportunities for theoretical development. Riemannian optimization is an attractive …

Interfacial Thermomechanical Behavior Of Hybrid Carbon Fibers, Sriraj Srihari

Doctoral Dissertations and Master's Theses

The carbon fiber/epoxy interface is of great importance in composite design due to its load transfer mechanisms from the weak epoxy to the stronger fiber. Improving the strength of the interface reduces the risk of failure at the interface and improves the load transfer to the fiber. In this study, two types of nano-species ZnO nanowires and nickel-based metal organic frameworks were grown on carbon fibers to improve the interfaces. The interfacial mechanics of the enhanced fibers are evaluated using nanoindentation studies. Composite samples with Aeropoxy matrix and vertically aligned fibers are fabricated for this purpose. A Bruker TI-980 TriboIndenter …

The Influence Of Mixing Duct Length And Phase Of Flight On Wall Temperatures Of A Rocket Based Combined Cycle Engine In Ejector And Air-Augmented Modes, Jonathan Grow

Doctoral Dissertations and Master's Theses

Rocket Based Combined Cycle (RBCC) engines have been theorized as a possible means of powering launch vehicles and high-speed atmospheric vehicles. By incorporating aspects of both air-breathing and rocket propulsion, RBCC engines promise up to a 230 % increase in specific impulse over traditional chemical rocket propulsion by entraining a secondary flow of atmospheric air and mixing it with the exhaust of a rocket motor. Students within the Embry-Riddle Future Space Explorers and Developers Society (ERFSEDS) identified a
problem of excessive heating and structural failure of the mixing duct during launch and transonic flight of a student-built flight test vehicle. …

Neural Network Models For Generating Synthetic Flight Data, Nathaniel Sisson

Doctoral Dissertations and Master's Theses

Flight test data is a valuable resource used in many aerospace applications. However, procuring a sufficiently large database of flight test data poses several challenges. Nominal flight tests can be expensive and time-consuming and require much post-processing depending on the availability of sensors and the quality of the sensor output. Flight test performed outside of nominal flight conditions, or flight tests in which failures are introduced, add to the inherent risk and danger associated with flight tests. The most popular alternative to flight test, numerical simulations, may fail to fully capture all non-linear behavior. While flight tests will always be …

In-Situ Thermal And Deformation Characterization Of Additive Manufacturing Processes, Nicholas Phillips

Doctoral Dissertations and Master's Theses

Additive manufacturing (AM) is a rapidly growing industry with numerous applications in the aerospace industry such as aircraft parts and emergency tools on the International Space Station. Defects in additively manufactured structures, however, can waste a lot of time and money. Being able to monitor the manufacturing process for defects is one of the first steps which can be taken to mitigate these losses. This study focuses on the use of thermography in conjunction with deep learning to identify flaws during 3D printing of composite structures made using Onyx, a mixture of chopped carbon fiber and nylon, composite prints. In …

Modeling, Control, And Hardware Development Of A Thrust-Vector Coaxial Uav, Andrew North

Doctoral Dissertations and Master's Theses

This thesis introduces a unique thrust vector coaxial unmanned aerial vehicle (UAV) configuration and presents a comprehensive investigation encompassing dynamics modeling, hardware design, and controller development. Using the Newton-Euler method, a dynamic model for the UAV is derived to gain in-depth insights into its fundamental flight characteristics. A simple thrust model is formulated and modified by comparing it with data obtained from vehicle testing. The feasibility of manufacturing such a vehicle is assessed through the development of a hardware prototype. Finally, a linear state feedback controller is designed and evaluated using the non-linear dynamics model. The results demonstrate successful validation …