Aerospace Engineering Commons^™

L2 Certification Rocket Launch, Seungyou Cho

SACAD: Scholarly Activities

The LOC 835 high-power rocket with J275W-12 motor at Argonia, KS, for L2 certification, was auspiciously launched and returned. J means the motor can exert 640-1280 Ns of impulse, which makes a sizeable propelling sound. Even though four main hindrances occurred from the construction to the launch, the issues were revised correctly. The rail button and the tracker were severe issues, so I devised the method of drilling a hole for the rail button, but there was no way to replace a broken tracker. The wind speed on the launch day was so strong that the rocket flew 1-2 miles …

Emission Behavior At The Single Emitter Scale From A Porous Media Ionic Liquid Ion Source, Thomas Victor Kerber

Dissertations

Ionic liquid ion sources (ILIS) are being developed as one solution to fill a technology gap in low power, high efficiency, high specific impulse space propulsion systems. With a sufficiently intense electric field applied between an emitter electrode and an extractor electrode, charged particles are extracted from the fluid surface and accelerated out of the thruster. In this work, three experimental campaigns examine emission behavior of a single emitter ILIS made of porous material that allows passive propellant feed via capillary action of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF₄).

Repeated measurements of the emitter and extractor current as …

Towards Universal Non-Dimensional Characterization Of The Oscillatory Dynamics Of Wind Turbine Rotors Of Multiple Sizes, North Yates, Fernando L. Ponta, Alayna Farrell

Michigan Tech Publications

One concern in the field of Horizontal Axis Wind Turbines (HAWTs) is what control strategies are needed to handle gust pulses in the wind to prevent extreme oscillations of the blades to reduce fatigue stress, prevent blade rupture, and extend the turbine’s operational life. In order to design innovative control strategies to modify the blade’s oscillatory response, it is crucial to establish the fundamental vibrational behavior of the blades when excited by gust pulses of different frequencies and amplitudes present in the fluctuating wind inflow. In a series of previous works, the authors presented a novel Reduced-Order Characterization (ROC) technique …

Adaptive Control Of Thrusters To Account For Deficiencies In Actuator Effectiveness And Model Uncertainties, Matthew Stanko

Doctoral Dissertations and Master's Theses

Future space missions are expected to become ever more ambitious and challenging. A successful mission requires advanced and resilient control algorithms that enable missions, such as satellite refueling, on-orbit inspection, and end-of-life servicing. This thesis explores the development and application of robust and adaptive control laws for an over-actuated spacecraft system with 3 degrees of freedom (DoF) to mitigate the effects of actuator deficiencies and system uncertainties. Additionally, the nature of the system being over-actuated allows for particular actuator degradation and failure. For stability and command tracking, a novel controller is designed and augmented with sliding mode control, adaptive control, …

Engineering Anisotropic Porosity In Green Parts From Binder Jet 3d Printing, Reshma Chandrashekhar Kubsad

Doctoral Dissertations and Master's Theses

Binder Jet Additive Manufacturing (BJAM) is a promising metal additive manufacturing technique that enables the fabrication of complex geometries without the need for support structures. However, the inherent porosity in green parts, remains a challenge in achieving desired mechanical properties and performance. Instead of treating porosity as a limitation, this thesis explores engineering of anisotropic porosity engineering, where controlled variations in porosity in the green parts can be used to enhance functionality and efficiency in specific applications. The objective of this research is to investigate and analyze the key print parameters that influence green part density. By systematically varying layer …

Coupled Dynamics In The Cislunar Region And Spacecraft Attitude Prediction In A Higher-Fidelity Model​, Annika Anderson

Doctoral Dissertations and Master's Theses

The cislunar region of space is a complex, multi-body dynamical environment that cannot be modeled trivially. Traditional point-mass assumptions made to simplify the mission design process may be insufficient for accurately predicting spacecraft motion in environments where orbit-attitude coupling is non-negligible. One of the most famous of such models is the circular restricted three-body problem. This thesis advances the state of the art in astrodynamics by modeling all bodies in the problem as rigid bodies, allowing for spacecraft orientation to be propagated and considered. Two models are under consideration—the circular restricted full three-body problem (CRF3BP) and a full higher-fidelity ephemeris …

Stability Limits Of Uncertain Systems In The Presence Of Unmatched Coupled Dynamics And Actuator Dynamics With Adaptive Architectures, Bronson Saulo

Doctoral Dissertations and Master's Theses

Uncertain systems with coupled dynamics and actuator dynamics are prevalent in various applications spanning private, commercial, and government sectors. While stabilization and command tracking strategies exist, they often rely on idealized assumptions, such as negligible actuator bandwidth limitations and matched coupled dynamics. In order to mitigate actuator-induced limitations, we first employ standard model reference adaptive control (MRAC) architectures. We then proposed two architectures: modified hedging reference modeled based MRAC and modified expanded reference model based MRAC. In order to deal with coupled dynamics, we used an observer design to estimate the states of unmatched coupled dynamics. In addition, Lyapunov stability …

Turbulence And Energetic Ion Production In The Partially Magnetized Hollow Cathode Plume, Margaret Mary Mooney

Dissertations

Hall effect thrusters (HETs) are the most widely used electric propulsion (EP) device for in-space satellite propulsion. EP devices provide high efficiencies for extended mission lifetimes and low thrust for precision maneuvers. The hollow cathode is a critical HET component and undergoes extensive lifetime testing in addition to the lifetime testing of the full HET. Significant density gradients, non-Maxwellian electron behavior, and magnetic fields sufficiently strong enough to magnetize electrons in hollow cathode plumes create favorable conditions for the formation of plasma instabilities, which have an impact on cathode lifetime. Cathode qualification testing is typically conducted independently and includes a …

Wind Tunnel Testing Of A Novel Quadrotor Design, Oliver Marius Tobisch

Mechanical & Aerospace Engineering Theses & Dissertations

This study presents the test development and aerodynamic evaluation of the Quadfoil UAV, a novel quadrotor configuration featuring a central lifting body in the form of an airfoil to enhance forward-flight efficiency. Flight tests conducted by Virginia Tech demonstrated a 25% increase in endurance and a 32% improvement in range compared to conventional quadcopters, validating the aerodynamic benefits of this design. To further investigate its performance, a dynamically adjustable angle of attack model support system was developed for wind tunnel testing, enabling precise replication of in-flight conditions. The support system, controlled via LabVIEW, adjusts angle of attack based on real-time …

Multiphase Iterative Algorithm For Mixed-Integer Optimal Control, Chaoying Pei, Sixiong You, Yu Di, Ran Dai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Mixed-integer optimal control problems (MIOCPs) frequently arise in the domain of optimal control problems (OCPs) when decisions including integer variables are involved. However, existing state-of-the-art approaches for solving MIOCPs are often plagued by drawbacks such as high computational costs, low precision, and compromised optimality. In this study, we propose a novel multiphase scheme coupled with an iterative second-order cone programming (SOCP) algorithm to efficiently and effectively address these challenges in MIOCPs. In the first phase, we relax the discrete decision constraints and account for the terminal state constraints and certain path constraints by introducing them as penalty terms in the …

Supercritical Water Oxidation For Removing Pfas Contaminants: A Numerical Study, Ashley Joy Poyner

Theses and Dissertations

Per – and polyfluoroalkyl substances (PFAS) are a group of stable pollutants known for their long lifetimes and resistance to treatment methods used traditionally to remove other contaminants. PFAS and their ability to accumulate in both aquatic and terrestrial environments present threats such as detrimental effects to people and ecosystems due to their ability to penetrate entire systems. Though many methods are being explored to treat PFAS contamination in different systems, Supercritical Water Oxidation (SCWO) is a promising method for both removing and decomposing PFAS, with the ability to completely oxidize these persistent contaminants. This study is a numerical investigation …

Exploring Strategies And Innovations In Airline Profitability Assessment: The Role Of Artificial Intelligence, Elif Degirmenci

Journal of Global Hospitality and Tourism

The airline industry's profitability assessment remains a complex yet critical aspect of strategic decision-making, spanning from hub profitability to individual flight performance. This paper explores the diverse methodologies and challenges involved in evaluating both line and network profitability, emphasizing the need for innovative approaches in reconciling variable costs associated with aircraft types and route assignments. Traditional methods are juxtaposed with innovative concepts like the Blended Aircraft Cost model, offering insights into enhancing market route profitability. Additionally, advanced methodologies such as horizontal and vertical methods are discussed, alongside the role of artificial intelligence in revolutionizing real-time profitability analysis. Through a comprehensive …

Dual Quaternions For Gravity Recovery Missions, Ryan Kinzie

Doctoral Dissertations and Master's Theses

A dual quaternion-based modeling, state estimation and control approach is introduced as a better alternative to the traditional methods which are currently utilized for gravity recovery missions. The proposed modeling and control approach was verified against and compared to the tangent bundle to Special Euclidean Group 3 through MATLAB simulations. The dual quaternion-based approach shows superior performance over traditional linearized and uncoupled methodologies, in both modeling accuracy of spacecraft translational position, and the ability to control the pose of a test mass relative to its host spacecraft. Utilizing data products from the Gravity Recovery and Climate Experiment Follow-On mission, a …

Exploring A Novel Adaptive Mesh Refinement Strategy For High-Speed Cfd, Arjun Jaishankar Vedam

Doctoral Dissertations and Master's Theses

Adaptive Mesh Refinement (AMR) techniques to efficiently and robustly achieve grid independent solutions on multi-element unstructured grids is a topic of practical interest within the CFD community.

The current effort focuses on the efficiency of a novel Adaptive Mesh Refinement (AMR) strategy that is developed and evaluated for transonic high-speed flows using Ansys Fluent. The algorithm for marking cells for adaptation is designed to systematically reduce local truncation errors based on the curvature of the primitive vector field. The algorithm for marking cells for adaptation is described in sufficient detail to be portable to other flow solvers that offer AMR. …

The Interaction Of A Transient Forward Axial Disturbance Flow With A Rotor, Zhuorui Li

Doctoral Dissertations and Master's Theses

This research presents an in-depth investigation of the aeroacoustic characteristics of a scaled-down Joby Aviation rotor, focusing on its performance under realistic conditions for urban air mobility (UAM). Utilizing a high-fidelity numerical simulation approach that combines Large-Eddy Simulation (LES) and Unsteady Reynolds-Averaged Navier-Stokes (URANS) models, the study effectively captures the complex aerodynamic and acoustic interactions inherent in rotor operations. Validation of the numerical framework was achieved through comprehensive comparisons with available experimental data, demonstrating a high level of accuracy in predicting both aerodynamic performance metrics, including thrust and torque, as well as acoustic emissions. The simulation revealed significant impacts resulting …

Aeroacoustics Applications To Jets And Rotors, Michael Marques G.

Doctoral Dissertations and Master's Theses

Aeroacoustics plays a critical role in the advancement of propulsion technologies for both conventional and emerging aerial systems. This dissertation investigates two key topics: noise suppression in supersonic rectangular jets and rotor noise characterization in hover and ground effect. Using high-fidelity numerical simulations and theoretical analyses, this research aims to develop effective noise mitigation strategies and improve predictive methodologies.

The first part of this study focuses on the reduction of noise in supersonic rectangular jets through active control techniques. A novel approach utilizing unsteady microjet actuation at the nozzle lip is explored to disrupt the formation of large-scale turbulent structures …

Experimental Investigation Of Heat Transfer To Tightly Packed Cylinder Arrays, Cameron M. Sexsmith

Doctoral Dissertations and Master's Theses

With the increased emphasis on the development of hybrid electric aircraft and other electric driven vehicles, the thermal demand on batteries is increasing. Unique to the aviation sector is the combined need of high battery thermal loads and a light-weight thermal management system. A proposed configuration is an array of batteries directly cooled with a dielectric coolant. The knowledge of heat transfer characteristics of battery cooling is becoming an ever pressing issue due to the need to optimize volume and mass in a safe manner. Tighter spacings between batteries provide higher pack densities, however, at the cost of increased cooling …

Modeling The Dynamics Of Flexible Aerospace Vehicles Using The Theory Of Functional Connections, Carlo Lombardi

Doctoral Dissertations and Master's Theses

Modeling and control of flexible vehicles is a topic of high interest in the aerospace field and a key challenge lies in finding accurate mathematical representations of the flexible dynamics of continuous elastic structures that allow simple integration into estimation and control algorithms. The answer was found in approximating the dynamics of these systems with sets of coupled Ordinary Differential Equations (ODE) for which a well-established estimation and control theory is available. Each of the techniques employed to achieve this goal is characterized by its own strengths and limitations. Hence, the main objective of this research is to develop the …

Machine Learning Methods For Hypervelocity Fragment Flyout Characterization, Katharine Larsen

Doctoral Dissertations and Master's Theses

Resulting from breakup events, such as collisions and explosions, hypervelocity fragments create potential hazards for both terrestrial and on-orbit environments, such as terrestrial weapons explosions and satellite breakup events, respectively. To avoid unnecessary damage, an accurate understanding or characterization of hypervelocity fragmentation events is vital. Currently, publicly available two-line elements collected from on-orbit breakup events are limited, excluding pre-detonation parent body conditions, such as orientation, and information of smaller fragments. The uncertainty of these datasets varies between each collected set. Therefore, the overall goal of this work is to employ machine learning to estimate distribution characteristics of a space debris …

Wind Tunnel Automation For Propeller Testing, David Ricardo Lara

Mechanical & Aerospace Engineering Theses & Dissertations

An automated propeller test capability for the ODU Low-Speed Wind Tunnel Facility is demonstrated; implementing automation improved both ease of testing and quality of results. An experiment was performed with and without automation to compare results. Prior to this effort, propeller RPM and airstream velocity were manually controlled, leading to time consuming experiments. The setpoint for RPM had to be adjusted at each run to compensate for changes in airstream velocity.

LabVIEW, a graphical programming software, was used to develop the controllers and automation algorithm. A Proportional Integral Derivative (PID) control approach was developed to simultaneously control airstream velocity and …