Aerospace Engineering Commons^™

A Relaxable Vortex Wake Model For Modern Supersonic Panel Methods, Joshua J. Hurwitz

All Graduate Theses and Dissertations, Fall 2023 to Present

This thesis presents an improved vortex wake model for unstructured, supersonic panel methods. Panel methods are numerical methods that utilize inviscid flow assumptions and other simplifications to allow efficient computation of pressure distributions, velocity fields, and aerodynamic forces. They are commonly used for preliminary design, automatic design codes, and automatic optimization routines. Most existing supersonic panel methods do not include automatic wake generation and relaxation. This prevents the accurate analysis of many geometries, including those with conventional horizontal stabilizers or canards. This thesis first outlines the derivation of a relaxable generalized supersonic vortex filament equation. Next, it explores other necessary …

Finite-Time Control Strategies For Rendezvous And Proximity Operations, John Tamotsu Akagi

All Graduate Theses and Dissertations, Fall 2023 to Present

One common metric to use when designing a controller is the time that the system will take to reach the desired state. Unfortunately, many approaches to developing controllers only guarantee that the system will approach, but not exactly reach, the desired state. This can become a limitation in time-sensitive situations where rapid and complete convergence is necessary. One group of control methods, known as finite-time control, does guarantee both faster convergence and that the desired state will be reached, but often fails to define exactly what time that will occur, how much control will be used to get there, and …

Equivalent-Area Studies For Sonic Boom Loudness Mitigation On A Commercial Supersonic Aircraft Configuration, Zachary N. Foster

All Graduate Reports and Creative Projects, Fall 2023 to Present

Since the early 1970s, the FAA has banned commercial supersonic flight over populated areas. This ban has limited aerospace manufacturers’ and commercial aircraft companies’ ability to design and operate subsonic aircraft in their fleets. Since then, research has been conducted to understand the sonic boom and learn how to minimize its loudness. The work presented in this project report aims to use a 1D low-fidelity analysis to study the effect of perturbations to the outer mold line (OML) of a representative model of the N+2 Quiet Commercial Supersonic Concept Aircraft. Using a 1D analysis that employs an equivalent area method, …

Controller Software: Evolution, Identification, And Implementation, Balaji Balasubramaniam

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

In the annals of automation history and advancement, one can find control technology is at the core. Modern-day controllers rely heavily on software capability to provide stability and improve the system's performance. In particular, drone flight controllers use autopilot control software to accomplish autonomous navigation from take-off to landing. However, we know very little about how the controller code modifications and its impact, particularly at the software level. No general framework has been developed to identify the control code changes and observe the real values of software control loops at the kernel layer.

In this thesis, we lay the foundation …

Computational Investigation Of Boundary-Layer Transition Mechanisms In A Blunt Cone, Arturo Rodriguez

Open Access Theses & Dissertations

In this study, we have performed two-dimensional steady-state hypersonic CFD and one-and-two-dimensional steady-state heat conduction numerical simulations. We are using them to guide and study hypersonic boundary-layer transition ground testing physical experiments to be performed at Holloman High-Speed Test Track. We use surface heat transfer and fluid flow spot signatures to identify fluid flow regimes using laminar and turbulent numerical simulation solvers to understand boundary-layer transition thermocouple temperatures and fluid flow-forming structures. We have also analyzed the fluid flow in the geometries to be inviscid. We passed the CFD solution into the boundary-layer Harris code developed by NASA to explore …

Multiphysics Modeling And Experimental Validation Of High-Strength Steel In Laser Powder Bed Fusion Process, M. Rangapuram, S. Babalola, J. W. Newkirk, L. N. Bartlett, F. W. Liou, K. Chandrashekhara, Stephen R. Cluff

Materials Science and Engineering Faculty Research & Creative Works

Laser powder bed fusion (LPBF) is a subset of the additive manufacturing process in which a laser beam selectively joins the metal powder into a desired part in a sequential layer process. Owing to its complex nature of rapid heating and cooling of the melt pool, there is a need to understand the melt pool behavior and its effects on the final manufactured part. a densely packed powder bed is highly desirable for fabricating a superior part using the LPBF process. in this work, discrete element model was used to generate powder beds with realistic powder properties and various factors …

Biaxial Strain Tuned Upconversion Photoluminescence Of Monolayer Ws2, Shrawan Roy, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Monolayer tungsten disulfide (1L-WS₂) is a direct bandgap atomic-layered semiconductor material with strain tunable optical and optoelectronic properties among the monolayer transition metal dichalcogenides (1L-TMDs). Here, we demonstrate biaxial strain tuned up conversion photoluminescence (UPL) from exfoliated 1L-WS₂ flakes transferred on a flexible polycarbonate cruciform substrate. When the biaxial strain applied to 1L-WS₂ increases from 0 to 0.51%, it is observed that the UPL peak position is redshifted by up to 60 nm% strain, while the UPL intensity exhibits exponential growth with the up-conversion energy difference varying from − 303 to − 120 meV. The measured …

2024 Summer-Fall Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for summer and fall 2024. Includes photographs, upcoming events, recent publications, and student profiles.

Performance Of Multi-Composite Materials With Corrugated And Cell Geometries Under Low-Velocity Impact, Lukas S. Kolbl

Master's Theses

Composite structures have demonstrated great potential to improve mechanical performance in various applications, including ballistics protection. This study demonstrates that the integration of geometrically optimized composites into core-face sheet assemblies provide great impact resistance. The research investigated the performance of two composite manufacturing methods under low-velocity impact through residual strength and damage comparisons. Corrugated core composites were produced with traditional manufacturing methods, namely compression molding, using twelve stacking sequences. These stacking sequences were chosen to represent four laminate groups, where a unique fiber orientation scheme was employed across three laminate thicknesses (6, 8, and 12 layers). In contrast, honeycomb and …

Computational Representation, Analysis And Verification Of Requirements In Engineering Design And Systems Engineering, Chandan Kumar Sahu

All Dissertations

Systems are developed to satisfy a set of requirements derived from stakeholders’ needs, defining the problem space for which the system is created as a feasible solution. The system design process begins with eliciting these requirements and concludes with validating whether the created system meets them. Requirements engineering (RE) encompasses elicitation, representation, analysis, documentation, verification, and validation. However, challenges in RE, such as imprecision in natural language (NL), proprietary restrictions, and a lack of standardized quality metrics, hinder the creation of well-formed and comprehensive requirements. These challenges complicate formalization and analysis of requirements.

This dissertation addresses these challenges by proposing …

Learning-Based Feature Identification For Rendezvous And Capture Of Non-Cooperative Space Objects, Trupti Mahendrakar

Theses and Dissertations

In recent years, On-Orbit Servicing (OOS) and Active Debris Removal (ADR) have attracted increasing interest due to growing concerns about space debris. This debris poses a significant risk to spacecraft, as collisions can catastrophically end missions and potentially trigger a cascading chain reaction of more debris. Space debris ranges from tiny paint chips to large non-functional spacecraft and even launch vehicle components. One way to mitigate the formation of additional space debris is to reduce the total number of large non-cooperative resident space objects present in operational orbits. This can be achieved through two approaches: de-orbiting these objects as part …

Loss Of Control In General Aviation: An Investigation Into The Mooney M20 And The Full Trimming Tail Design, Trenton Neil Wright

Theses and Dissertations

Loss of Control (LOC) in General Aviation (GA) remains one of the leading causes of aviation accidents, with 94% of all accidents in 2022 occurring in this sector, and 42% attributed directly to LOC [2][3]. This thesis focuses on the Full Trimming Tail (FTT) in Mooney aircraft, hypothesizing that the FTT design significantly increases the likelihood of LOC, particularly during go-arounds and touch-and-go landings. Prior studies have shown that certain trim systems can amplify pitch-up moments following rapid configuration changes, leading to stalls or LOC if not adequately managed by the pilot [23][24][25].

This research utilized a combination of logistic …

Improving Robustness Of Learning-Based Approaches In Autonomous Systems And Engineering Education, Godwyll Aikins

Theses and Dissertations

This dissertation advances the development of robust learning-based approaches across two complementary domains: engineering education and autonomous systems. Through four studies, this research addresses critical challenges in preparing data-proficient engineers and developing reliable autonomous systems that can operate under uncertainty and incomplete information. The engineering education study examines how mechanical and aerospace engineering undergraduates conceptualize and develop data proficiency skills essential for modern engineering practice. Through interviews with 27 students, the research employs the How People Learn framework to analyze student perspectives on information literacy, data interpretation, and computational thinking. The findings inform pedagogical strategies for developing data proficiency in …

Impact Of Weather Systems On Uav Parameters Using Computational Fluid Dynamics, Saif Aljuhaishi, Yaseen K. Al-Timimi, Basim I. Wahab

Karbala International Journal of Modern Science

Since drones cannot fly in any kind of weather, they are not safe for time-sensitive activities. The study examines how the passage of weather systems in Iraq leads to the ban on drone flights, and how these weather conditions impact the aerodynamic forces of the drone. Hourly climate data for the study area were obtained from ECMWF ERA5 and CAMS in NetCDF format for four climate stations (Erbil, Baghdad, Rutbah, and Basrah). A ScanEagle drone was chosen for this study. The Python programming language was used to perform mathematical operations to calculate the ban on drone flights. ArcGIS 10.8 was …

Notes For Contributors To Space & Defense

Space and Defense

No abstract provided.

Front Matter, Damon Coletta

Space and Defense

No abstract provided.

Design Of A Safe And Sustainable Airplane For Future, Henil Patel, Carlie Vogt, Matthew Talty, Jemimah Davies, Kyle Smothers, Mellisa Pritchet

Sustainability Conference

As a part of Airplane Preliminary Design course, this Design Note estimates the capabilities, performance, and stability behaviors of our conceptual airplane design, Boeing 7S7 – Sanctum prior to proceeding to the preliminary stage. This aircraft seeks to create a solution to achieving Net Zero Emissions by 2050 and increasing the safety measures. The design of this aircraft uses various analytical methods such as the DAPCA IV model, other methods were derived from design books. This design involved the use of software such as CATIA, VSP, SURFACES, Microsoft Excel, and Python. Results demonstrates that this aircraft is able to fly …

The Future Of Flying: An Exploration Of New Aircraft Design And Energy Required To Support Advanced Air Mobility – Part 3, Sarah Nilsson

Publications

Lecture exploring new aircraft design and energy required to support advanced air mobility.

Unleaded Fuel For General Aviation, Carolina Anderson, Laura Garcia

Sustainability Conference

The Clean Air Act, passed in the late 1970s, mandating the removal of lead from most fuels due its detrimental effects on public health, yet piston-driven aircraft continue to rely on leaded aviation gas (AvGas 100LL). This fuel remains the last lead-containing fuel regulated by the Department of Transportation (DOT). Lead, added as tetraethyl lead (TEL), enhances octane levels and prevents engine detonation, vital for high-compression aircraft engines. In response to the health effects, regulating bodies like the Environmental Protection Agency (EPA) have tightened lead standards and are assessing the risk posed by AvGas. Research links even low-level lead exposure …

Disciplinary Policy Research On Science Development Strategies For Crewed Lunar Exploration, Wei Yang, Yuyang He, Jinting Kang, Ruiyi Chen, Huihong Cheng, Li Sun, Pan Deng, Yong Wei, Yangting Lin, Xianhua Li

Bulletin of Chinese Academy of Sciences (Chinese Version)

In order to better serve China’s crewed lunar exploration, this study researched and analyzed the current status of lunar exploration and planetary science research in China and the United States. Additionally, we conducted interviews and a questionnaire survey with experts in planetary science and deep-space exploration, and formed the following four policy recommendations: 1) Strengthening the layout and management of the disciplines of lunar and planetary sciences, and setting up a long-term and stable funding mechanism; 2) Improving the system of talent cultivation, and encouraging young talents to participate in deep-space exploration missions; 3) Strengthening the protection of original ideas, …