Aerospace Engineering Commons^™

Numerical Study On Flow Separation And Performance Characteristics Of Slot Nozzle, Chase Charpentier

Doctoral Dissertations and Master's Theses

The altitude compensating nozzle (ACN) is a type of rocket nozzle or engine that tries to minimize the negative effects of overexpansion at low altitudes. There are many forms of ACN's but most of them are heavier than traditional bell nozzles, alter the geometry of the nozzle, which requires extensive research into optimizing the new geometry, or require complex systems that can lead to structural, heating, or material problems. Out of the ACN's, the slot nozzle is a passive ACN that builds upon the bell nozzle and requires no additional weight or complex systems.

This slot nozzle is comprised of …

Perturbation Solution Of Air-Water Mixture For Jet Noise Reduction, Juan Felipe Uribe Cifuentes

Doctoral Dissertations and Master's Theses

This work investigates passive jet-noise mitigation using externally positioned air–water curtains that attenuate radiated sound without altering the underlying jet dynamics. Two classes of multiphase media are examined: a gaseous carrier phase containing dispersed liquid droplets, and a liquid carrier phase containing entrained air bubbles. For both systems, suspended and dispersed regimes are represented through a generalized perturbation formulation derived from the volume-averaged multiphase equations, incorporating finite volume fractions, interphase momentum coupling, and slip between phases. Analytical and numerical solutions demonstrate that acoustic attenuation is primarily governed by dispersed-phase diameter, volume fraction, and excitation frequency, with additional sensitivity to phase-interaction …

Autonomous Landing Of An Unmanned Aerial Vehicle On An Unmanned Surface Vessel Using Model Predictive Control With An Adaptive-Covariance Extended Kalman Filter, Jorge Estupinan

Doctoral Dissertations and Master's Theses

This thesis presents the development of vision-based estimation and model predictive control (MPC) strategies to enable an Unmanned Aerial Vehicle (UAV) to land autonomously on an Unmanned Surface Vessel (USV) subjected to wave-induced motion. An innovative Adaptive-Covariance Extended Kalman Filter (AEKF) implementation was developed for the estimation of the 6 degree-of-freedom USV states using GPS and vision-based measurements of AprilTag markers on the USV landing platform. The AEKF employs an uncontrolled 6 degree-of-freedom nonlinear model augmented with second-order harmonic wave-induced motion dynamics. The AEKF implements two correction techniques: an adaptive covariance adjustment and an artificial covariance inflation regulated by a …

Exploration Of Physics-Informed Grid Generation Technique For Wall-Modeled Les Using Eagle3d, Dominic Schneider

Doctoral Dissertations and Master's Theses

Wall-Modeled Large Eddy Simulation (WMLES) is an area of interest due to its ability to lower computational costs of LES. 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. A novel technique for generating a lean, physics based WMLES grid is described.

The technique utilizes a RANS solution to extract turbulence information, user-specified values related to resolution of turbulent energy levels, acoustics waves, and shock waves, to generate a point cloud for producing a lean WMLES grid with in-house …

Unresolved Image Simulation For Space Situational Awareness Applications, Fox Coniglario

Doctoral Dissertations and Master's Theses

The knowledge of what lies in orbit around Earth is at best a guess. Decades of spaceflight, debris buildup, and vehicle collisions have contributed to a large number of objects that are simply not able to be catalogued. Ongoing efforts to catalog debris in orbit have reached limits by conventional measures and as such, research is active in the field of in-orbit space situational awareness. This thesis intends to help fill a hole in the development of such orbital platforms by assisting the development of image processing software pipelines though the simulation of unresolved space imagery. The simulation uses accurate …

Active Measurement Of A Micron-Order Gap Under High-Speed And High-Temperature Conditions, Andrew Becker

Doctoral Dissertations and Master's Theses

The hypersonic regime poses numerous challenges that researchers face in the development of hypersonic flight vehicles. Due to their excellent thermomechanical properties, ultra-high-temperature ceramics (UHTCs) have risen as a promising solution to act as a protective barrier between the harsh environment and surface materials of these flight bodies. The mechanical operation of a portable hypersonic simulation device was developed in-house and tested at Argonne National Laboratories (ANL) to gather in-situ material response of prospective UHTC samples when exposed to a hypersonic regime. An edge detection-based algorithm was developed and used in LabVIEW to monitor the health and operation of the …

Characterization Of Cooled Turbine Efficiency For Off-Design Performance Models, Alberto Garcia

Doctoral Dissertations and Master's Theses

Gas turbine performance modeling is essential for predicting engine behavior across design and off-design conditions. Yet the treatment of cooling or service flows remains inconsistent, as these streams interact with the main flow in complex ways and their contribution to turbine work depends on how they are represented in performance models. The challenge is especially present in “black-box” approaches, where only inlet and outlet conditions are known and engineers must decide whether to introduce cooling flows upstream (if performing useful work) or downstream (if not). This thesis examines how different definitions of isentropic power and cooling-flow treatment affect the apparent …

High-Fidelity Modeling Of Evtol Rotor Unsteady Aerodynamic And Aeroacoustic Response To Time-Harmonic Gust, Vadim Voropayev

Doctoral Dissertations and Master's Theses

The rapid emergence of Urban Air Mobility (UAM) demands accurate prediction and mitigation of noise generated by electric vertical take-off and landing (eVTOL) aircraft operating in complex urban environments. Among the various noise sources, the aerodynamic and acoustic response of rotors to unsteady inflow represents a major uncertainty in community-noise assessment and certification. This thesis investigates the aerodynamic and aeroacoustic behavior of a representative eVTOL rotor subjected to time-harmonic inflow disturbances, providing a detailed numerical framework to quantify how periodic gusts influence rotor performance, unsteady loading, and sound radiation.

The study employs a three-stage computational methodology using the open-source solver …

Additively Manufactured Bioinspired Microstructures For Active Surface Modification, Zefu Ren

Doctoral Dissertations and Master's Theses

Advancements in additive manufacturing have facilitated the development of bioinspired microstructures, which hold promise for applications, such as liquid transport, self-cleaning, and anti-icing. However, the controllability of these microstructures remains an area requiring further exploration. This research explores the design, fabrication, and active control of 3D-printed bioinspired microstructures for dynamic wettability modulation. First, the anisotropic scales of butterfly wings were replicated through optimized two-photon polymerization printing strategies, achieving directional droplet motion controlled by structural geometry and arrangement. The reversed wetting trend compared with natural wings revealed key insights into the structure–performance relationship. Next, microstructures were integrated with dielectric elastomer actuators …

Adaptive Control For Spacecraft With Flexible Appendages With Unknown Parameters, Nicolo Woodward

Doctoral Dissertations and Master's Theses

Flexible spacecraft pose several challenges in control design due to the uncertain dynamical model and the underactuated nature of these systems. Adaptive and robust controllers are the common choice for these systems to either meet operational requirements like attitude pointing or to suppress vibrations. However, these controllers add complexity in the design of onboard Attitude Determination and Control Systems (ADCS) and the Reaction Control Systems (RCS) for spacecraft maneuvering. The objective of this research is to control a system that undergoes unpredictable and unknown disturbances through onboard derivation of an equivalent reduced order model designed around mounted sensors. The proposed …

Orbital Maneuvers And Interplanetary Trajectory Design Via Reinforcement Learning, Roberto Cuéllar Rangel

Doctoral Dissertations and Master's Theses

This dissertation investigates the application of reinforcement learning (RL) to the design and optimization of low-thrust spacecraft trajectories, with an emphasis on autonomy, adaptability, and robustness in the presence of system uncertainties and unmodeled perturbations. Classical approaches to low-thrust trajectory design are predominantly grounded in optimal control theory, which relies on the availability of precise dynamical models and often requires problem-specific reformulation and solver tuning. While optimal control methods offer high accuracy under deterministic conditions, their sensitivity to stochastic disturbances and computational limitations in highly nonlinear or uncertain environments pose significant challenges for future autonomous space missions.

To address these …

Design Of A Fan-Based Test Stand For Evaluating Multicopter Handling In Turbulent Flow, Salim Roig

Doctoral Dissertations and Master's Theses

With the innovation of eVTOL rotorcraft the need to analyze how turbulence-induced disturbances from orthogonal flow affect various rotorcraft configurations outside of simulations have grown significantly. To investigate the behavior of this type of flow and how it interacts with various rotorcraft configurations, a turbulent inducing test stand was designed and constructed. The test stand will have two walls of computer fans arranged in an L-shape frame, creating wind gusts that simulate the non-linear turbulent wind experienced by eVTOL. This also aids the Eagle Flight Research Center (EFRC) in their efforts to better understand how disturbances affect the handling qualities …

Impact Of Uncertainties On Structures Damage Tolerance Parameters, Breno De Bruns

Doctoral Dissertations and Master's Theses

This research aims to enhance the understanding and management of aerospace structural integrity. Traditional fracture control methods, such as damage tolerance analysis (DTA), assume deterministic factors, considering uncertainties inherent in material properties, inspections, and operational conditions only at the final stage by applying safety factors. This research seeks to incorporate these uncertainties throughout the analysis by integrating Monte Carlo simulation with Linear Elastic Fracture Mechanics (LEFM). The objective is to investigate how varying parameters affect crack growth prediction and the effectiveness of inspection strategies. The methodology involves systematically analyzing inspection intervals, considering factors like material properties, probability of detection (POD), …

Robust Adaptive Rigid Body State And Mass Property Estimation Via Unscented Kalman Filter On Tse(3) With Process Noise Estimation, Herman Gunter

Doctoral Dissertations and Master's Theses

Mass property estimation, including mass, center of mass, and moment of inertia, is a crucial yet challenging problem in spacecraft autonomy and astrodynamics. Knowledge of mass properties of a spacecraft is essential for future astronautical missions, as changes in the mass properties of a spacecraft due to a shift in cargo distribution often require a careful and costly recalculation to ensure applied control inputs produce the desired results. As spacecraft missions grow in both duration and number, meeting the need for precise and accurate measurements becomes increasingly complex. Stochastic effects, such as angle and velocity random walks, along with persistent …

Design For Additive Manufacturing: Simultaneous Optimization Of Structural Integrity And Minimal Support Structures, Naresh Ahuja

Doctoral Dissertations and Master's Theses

This dissertation addresses two core challenges limiting the widespread application of Topology Optimization (TO): the difficulty in fabricating its complex designs, especially for Additive Manufacturing (AM), and its significant computational costs. It develops a unified design framework that directly embeds AM constraints such as overhang angles and build direction into robust TO formulations. To enhance manufacturability, two distinct methodologies are proposed. Firstly, a Solid Isotropic Material with Penalization (SIMP) framework introduces a three-stage robust optimization algorithm. Secondly, the Geometric Projection Topology Optimization (GPTO) method inherently integrates overhang constraints by controlling individual geometric components and their inclined angles relative to a …

Analyzing The Interfacial Properties Of Natural Fiber Composites, Rahul Kumar Arram

Doctoral Dissertations and Master's Theses

In response to growing environmental concerns and the urgent demand for sustainable development, the composite materials industry is increasingly challenged to balance high performance with environmental responsibility. Conventional composites, typically composed of synthetic fibers and petroleum-based resins, offer outstanding mechanical properties but are associated with significant ecological drawbacks due to their non-biodegradable nature and energy-intensive production. This has led to increased interest in the development of sustainable composites that minimize environmental impact without compromising functionality. This study presents the development of eco-friendly composites reinforced with natural bast fibers—specifically ramie and jute—through a comprehensive program of materials processing and characterization. To …

Experimental Analysis Of Satellite Operator Training Using Game-Based Virtual Reality Simulation, Lana Laskey

Doctoral Dissertations and Master's Theses

Satellite data plays a vital role in modern global infrastructure by enabling communications, navigation, and weather forecasting. As demand for satellite technology grows, so does the need for highly trained satellite ground operators. Traditional training regimens for satellite operators employ simulation using two-dimensional computer console displays paired with the varied ability of trainees to generate abstract mental imagery of the scenario. However, this development of mental imagery imposes a considerable learning curve and cognitive workload on the trainee, which may negatively impact the user experience and knowledge gained during the training scenario.

This experimental study investigated the effects of game-based …

Mno2 Nanoscale Interface Modification, Alexander C. Skoppe

Doctoral Dissertations and Master's Theses

Interface modification of carbon fibers has been shown to improve the mechanical performance of composites. In addition, interface modification of carbon fiber composites can impart multifunctionality into the resulting composite. This work will explore ZnO and MnO2 as interface modifications for use on carbon fibers. When exposed to high temperatures, carbon fibers undergo fiber degradation, leading to the need for low-temperature hydrothermal processes. This work will develop and characterize a nanoscale ZnO and MnO2 interface modification for use on carbon fibers. These nanomodifications will be developed with low-temperature processes, minimizing the fiber degradation that the fibers undergo. Fourier transform infrared …

Navigating Perceptions: How Organizational Type And Message Source Affect Willingness To Fly In Automated Air Taxis, Cody James Sweatt

Doctoral Dissertations and Master's Theses

A new era of transportation and business is beginning to emerge. Advanced air mobility (AAM), which uses highly automated aircraft that transport passengers and cargo in the underutilized, low-altitude airspace above and around urban areas, is rapidly becoming a reality (FAA, 2023). These new companies will utilize air taxis, which are automated, electric, vertical takeoff and landing (eVTOL) aircraft and will potentially foster a revolutionary new commerce infrastructure. Unfortunately, it is not currently understood how the credibility of a message source or specific type of organization that owns and operates an automated air taxi company influences a customer’s willingness to …

Self-Regulated Thermal Management With Shape-Memory Alloy Torsional Tubes, Paula Sanjuan Espejo

Doctoral Dissertations and Master's Theses

The need for dynamic thermal management that adapts to varying system needs and requirements is a growing topic of interest in different engineering disciplines, most prominently aerospace and electronics. This demand for improved thermal management systems comes from the general increase of system efficiencies leading to an increase in component energy density. Shape-memory alloy actuators, which respond with a mechanical shape recovery to variations in temperature, can be used as self-regulated thermal management actuators that are able to respond to environmental thermal changes autonomously. In this dissertation, modeling and experimental analysis of a two-way shape-memory effect trained SMA torsional tube …

Embeddable Multi-Material Wireless Micro-Sensors Utilizing Additive Manufacturing And Enhanced Microstructure, Nicholas Reed

Doctoral Dissertations and Master's Theses

The development of embeddable, multi-material wireless microsensors offers transformative potential for structural health monitoring (SHM) in aerospace applications. This work integrates additive manufacturing (AM) techniques with advanced microstructural design to produce flexible, high-resolution sensors that can be directly embedded into polymer substrates. By utilizing the vat photopolymerization process, customized embedded sensors are seamlessly integrated into polymer AM structures. These sensors are then continuously refined, targeting increases in performance, both internal and external. Microstructural enhancements are explored to modify the rheological properties of the fabricated embedded sensing channels and enhance the adhesive bonding between the embedded sensor and the AM structure. …

Solar Sailing Adaptive Control Around The Earth-Moon Lagrange Point L4 For Stellar Observations, Luis Mendoza Zambrano

Doctoral Dissertations and Master's Theses

To expand our knowledge about the influence of the Sun in the cislunar region, as well as our understanding of shocks due to Coronal Mass Ejections and large coronal magnetic reconnection, a solar sailing approach is proposed to separately capture lunar occultations and observe the solar corona from L₄ of the Earth-Moon system. Single and multiple shooting techniques are described along with a pseudo arc-length continuation method for preliminary orbit design. Periodic orbits in the vicinity of L₄ are obtained in the context of the Earth-Moon circular restricted three-body problem (CR3BP) and the Sun-Earth-Moon bi-circular restricted four-body problem …

Satellite Reorientation Using Reinforcement Learning Under Unknown Attitude Failure, Matthew Willoughby

Doctoral Dissertations and Master's Theses

This study presents a reinforcement learning (RL) approach for reestablishing communication with deep-space satellites under unknown attitude determination and control system (ADCS) failures. When traditional fault-tolerant control methods cannot restore signal, the proposed RL controller acts as a last-resort measure by autonomously reorienting the satellite’s antenna toward Earth while charging the battery via solar panels. A generic reward function, designed for the RL-based method, enables the controller to adapt to diverse failure scenarios, including severe actuator noise, misalignment, and complete actuator failure. Simulations are conducted in the Basilisk environment and trained with the tonic framework and demonstrate ranging capabilities of …

Utilizing Augmented Reality For Immersive Space Mission Design, Joseph Anderson

Doctoral Dissertations and Master's Theses

Designing spacecraft mission trajectories is a complex, tedious, and stringent process that requires a strong background in astrodynamics and programming due to the complex dynamical environment of space. The current 2D visualization methods for displaying these geometrically abstract trajectories make it difficult to understand the true nature of more complex orbits. Advancements in immersive headsets and their intuitive interaction capabilities make them ideal for solving and understanding 3D problems that require complex spatial representations, revealing an innovative and unique opportunity for the astrodynamics and space mission planning field. This effort covers the development of an immersive space mission design tool …

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 …

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 …

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 …

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 …