Engineering Commons^™

Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to …

Analysis Of Multiple Degree-Of-Freedom Oscillatory Aquatic Propulsion, Seth Alan Brooks

Dissertations - ALL

Propulsive performance and flow field data were experimentally measured for a two degree-of-freedom fish platform. The fish platform was designed and constructed based on the yellowfin tuna (\textit{Thunnus albacares}) that is known to be both fast and efficient. This work extends the current understanding of oscillatory aquatic propulsion to a three-dimensional fish platform with full volume flow field data and propulsive performance. A parametric sweep of trailing-edge amplitude of the caudal fin ($A$), heave-to-pitch ratio ($h^*$), and phase offset between the two degrees-of-freedom ($\phi$) was used to explore a parameter space that encompasses and extends beyond the known biological domain. …

Direct Foam Writing In Microgravity, Guy Jacob Cordonier, Cicely Sharafati, Spencer Mays, Lukas Thackery, Ellena Gemmen, Samuel Cyphert, Megan Brown, John Quinn Napolillo, Savannah Toney, Hunter Moore, John M. Kuhlman `, Konstantinos A. Sierros

Faculty & Staff Scholarship

Herein we report 2D printing in microgravity of aqueous-based foams containing metal oxide nanoparticles. Such hierarchical foams have potential space applications, for example for in situ habitat repair work, or for UV shielding. Foam line patterns of a TiO2-containing foam have been printed onto glass substrates via Direct Foam Writing (DFW) under microgravity conditions through a parabolic aircraft flight. Initial characterization of the foam properties (printed foam line width, bubble size, etc.) are presented. It has been found that gravity plays a significant role in the process of direct foam writing. The foam spread less over the substrate when deposited …

State-Of-The-Art Of Thermal Control Solutions To Establish A Modular, Multi-Orbit Capable Spacecraft Thermal Management System Design Methodology, Robert C. Consolo Jr

Doctoral Dissertations and Master's Theses

Today, the exploration and exploitation of space continues to become a more common occurrence. All types of spacecraft (S/C) utilize various types of thermal management solutions to mitigate the effects of thermal loading from the unforgiving vacuum of space. Without an appropriately designed thermal system, components on-board the S/C can experience failure or malfunction due to fluctuations in temperatures either beyond the designed operational parameters or unstable oscillating temperatures. The purpose of this study is to perform a comprehensive review of technologies available today that are being used for thermal management onboard S/C in addition to investigating the means to …

Numerical Simulation Of A Cryogenic Spray, Neel Kishorkumar Shah

Doctoral Dissertations and Master's Theses

Cryogenic sprays have many applications in modern engineering. Cooling of electronic equipment subject to high heat flows, surgical ablation of gastrointestinal mucosae or orbital maneuvering are a few examples of their versatility. However, the atomization of a cryogenic liquid is a complex process. During such an event, aerodynamic effects associated with secondary atomization are further affected by thermodynamic flashing. A better understanding of the characteristics of cryogenic sprays is then necessary to allow for improved design and optimization in applications. The overarching objective of this study is to document such characteristics. The numerical simulation was performed over cryogenic nitrogen spray …

In-Situ Monitoring Of Additive Manufacturing Using Digital Image Correlation, Martina Jani

Doctoral Dissertations and Master's Theses

Advances in additive manufacturing over the past decade have led to applications in multiple fields. In particular, additive manufacturing answers the need for high flexibility in designing complex structures, however, the rapid thermal fluctuations during processing lead to numerous defects and processing-induced residual stresses. In this research, an in-situ approach using Digital Image Correlation (DIC) is developed to monitor the deformation during the processing, and thereby analyze the formation of defects and residual stresses. DIC is a visual technique that compares the changes in speckle pattern in consecutive images of a specimen to determine the displacements and strains. This research …

Astronaut Or Astronot?, David A. Gusis

Ideas: Exhibit Catalog for the Honors College Visiting Scholars Series

As space becomes more and more accessible to the general population, the terminology we used in the past to describe those who trained endlessly to become the pioneers of a new frontier is beginning to lose its meaning. Astronauts like Colonel Richard Covey have earned their title and to bestow it on others who haven't gone through the same training or have paid to visit space as a tourist is wrong. My hope is to provide the necessary background information about what it means to be an Astronaut and provoke thought about preserving the term and creating new terminology for …

The Biological Problems Of Space Travel, Madilyn R. Reid

Ideas: Exhibit Catalog for the Honors College Visiting Scholars Series

Colonel Richard Covey is a distinguished former astronaut who has logged over 646 hours of space travel. Over the years, National Aeronautics and Space Administration (NASA) and research scientists in the aerospace industry have become increasingly concerned about the biological complications of space travel. This article goes in-depth on what is already known about the biological problems of being in space and potential solutions to remedy the complications.

A Brief History Of The Making Of An Astronaut, Sharon J. Kulali

Ideas: Exhibit Catalog for the Honors College Visiting Scholars Series

With more advancement in technology, recreational travel to space is increasingly becoming common. This raises the question of whether all individuals who travel to space are considered astronauts. In this paper, the astronaut requirements that the United States National Aeronautics and Space Administration (NASA) has had throughout the years are broken down. Furthermore, renowned former astronaut, Colonel Richard O. Covey, is used as an example to demonstrate these requirements.

Reduced-Order Dynamic Modeling And Robust Nonlinear Control Of Fluid Flow Velocity Fields, Anu Kossery Jayaprakash, William Mackunis, Vladimir Golubev, Oksana Stalnov

Publications

A robust nonlinear control method is developed for fluid flow velocity tracking, which formally addresses the inherent challenges in practical implementation of closed-loop active flow control systems. A key challenge being addressed here is flow control design to compensate for model parameter variations that can arise from actuator perturbations. The control design is based on a detailed reduced-order model of the actuated flow dynamics, which is rigorously derived to incorporate the inherent time-varying uncertainty in the both the model parameters and the actuator dynamics. To the best of the authors’ knowledge, this is the first robust nonlinear closed-loop active flow …

Development Of A Three Degree-Of-Freedom Control Simulation For A Group 3 Large Unmanned Aircraft System, Majka Anna Wilczynski

Theses and Dissertations

Aircraft modeling and simulation has become increasingly important in the aviation world. Simulations allow for safer and more economical training prior to flight testing. In this project, a three degree-of-freedom control simulation coded in a MATLAB environment is used to assess and simulate the dynamic stability of group three unmanned aircraft system. By calculating, evaluating, and simulating the static and dynamic stability derivatives of the aircraft, this project will allow for the estimation of the handling qualities of an unmanned aircraft system. This can help mitigate risks that come along with altering the mass and aerodynamic properties of an aircraft, …

Kinematics Of Inter-Ply Interfaces In Composite Manufacturing, Sandeep Chava

Doctoral Dissertations and Master's Theses

The ubiquitous usage of polymer matrix composites in many applications demands a comprehensive understanding of composite interfaces and processing induced residual stresses, which critically affect both the manufacturing processes and the deformation mechanisms. Processing induced residual stresses are often responsible for causing warping, delamination, and dimensional instability in composite structures. This research includes new in-situ experimental approaches, cure cycle design, interface modification, and thermomechanical modeling for developing a fundamental understanding of the cure kinetics during composite manufacturing. Strains, ply-movement, and formation of defects are observed in-situ using digital image correlation (DIC) during the autoclave cure cycle for the first time. …

Enhancing Situational Awareness For Rotorcraft Pilots Using Virtual And Augmented Reality, Ardit Pranvoku

Theses and Dissertations

Rotorcraft pilots often face the challenge of processing a multitude of data, integrating it with prior experience and making informed decisions in complex, rapidly changing multisensory environments. Virtual Reality (VR), and more recently Augmented Reality (AR) technologies have been applied for providing users with immersive, interactive and navigable experiences. The research work described in this thesis demonstrates that VR/AR are particularly effective in providing real-time information without detracting from the pilot's mission in both civilian and military engagements. The immersion of the pilot inside of the VR model provides enhanced realism. Interaction with the VR environment allows pilots to practice …

Utilizing Uas To Support Wildlife Hazard Management Efforts By Airport Operators, Flavio A. C. Mendonca, Ryan Wallace

Publications

The FAA requires airports operating under the Code of Federal Regulations Part 139 to conduct a wildlife hazard assessment (WHA) when some wildlife-strike events have occurred at or near the airport. The WHA should be conducted by a Qualified Airport Wildlife Biologist (QAWB) and must contain several elements, including the identification of the wildlife species observed and their numbers; local movements; daily and seasonal occurrences; and the identification and location of features on and near the airport that could attract wildlife. Habitats and land-use practices at and around the airport are key factors affecting wildlife species and the size of …

Lupa: An Excursion Vehicle For The Moons Of Mars, Shannon Kavanagh, Bo Lewis, Alex Odinamba, Joshua Mulhern

Senior Design Project For Engineers

Our team has designed a spacecraft and mission for exploring the moons of Mars. The Lithological and Ultraviolet Photometry Assessment (LUPA) excursion vehicle is capable of crew habitation, autonomous rendezvous, and in-vacuum sample collection all in support of a parallel Mars surface mission to be carried out in the year 2040. Our project's key focus areas revolve around orbital mechanics, space vehicle propulsion analysis, scientific exploration, and the management of various interconnected spacecraft subsystems.

Project Scrappie (Clear Constellation), Jacob Bertram, Jacob Britt, Bill Ngo, Mike Diesing

Senior Design Project For Engineers

Clear Constellation™ is a nationwide competition hosted by Rubicon® to combat the growing problem of space debris in Low Earth Orbit. Project Scrappie is our team’s solution to this problem. Scrappie is an autonomous apparatus will make use of Whipple shield technology to collide with debris at high velocities and effectively destroy the debris throughout selected orbital paths.

Stress Intensity Factor - Simple Solution For A Complex Problem, Hamid A. Ghassri, Alberto Mello

Beyond: Undergraduate Research Journal

This research explores the modeling of a cracked structure using a linear elastic finite element method (FEM) analysis with the objective of determining the stress intensity factor (SIF) for complex geometries. The analysis uses a mapping of the stress concentration area ahead of the crack tip to asymptotically determine the SIF. For model calibration, Irwin’s approximation method was used in two known crack case solutions subjected to a uniform tensile loading (Mode I – Opening) with fixed geometric dimensions. With focus on aircraft airworthiness application, two more complex geometries with irregular stress distributions were analyzed and the results were extracted …

Systems And Methods For Suppressing Noise From An Aircraft Engine, Reda R. Mankbadi

Publications

Systems and methods for noise suppression for aircraft are disclosed. The aircraft may include a fuselage. The aircraft may include a plurality of wings connected to or formed with the fuselage. The aircraft may include at least one engine configured to generate a propulsion force to propel the aircraft. The at least one engine may include a nozzle assembly having a nozzle body with an outlet that releases an exhaust air or a jet flow. The aircraft may include a noise suppression assembly. The noise suppression assembly may be configured to interact with the exhaust air or jet flow to …

Entropy-Based Analysis For Application To Highly Compressible Flows, Ethan A. Vogel

Doctoral Dissertations

Matrix normalizations are a critical component of mathematically rigorous aerodynamics analysis, especially where kinematic and thermodynamic behaviors are of interest. Here, a matrix normalization based around the entropy of a perturbation is derived according to the principles of mathematical entropy analysis and using a general definition of entropy amendable to physical phenomena such as thermal nonequilibrium and caloric and thermal imperfection. This normalization is shown to be closely related to the contemporary Chu energy normalization, expanding the range of validity of that normalization and clarifying the details of its interpretation. This relationship provides a basis for deriving other normalizations. Entropy …

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 …

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 …

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

Electronic Theses and Dissertations, 2020-

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 …

Thermodynamic Analysis Of An Autogenous Pressurization System, Samuel H. Smith

Masters Theses

Pressurized gas feed systems have been vital to spacecraft where a pump-fed design would prove too large, heavy, or complicated to be effective. This project investigates autogenous pressurization – a pressurized feed system where the intentional vaporization of liquid propellant to fill the ever-increasing ullage space with its own warm, low-density gas. Motivation for this research originates from the University of Tennessee Space Institute’s (UTSI) contract with Gloyer-Taylor Laboratories (GTL) to assist the development of an innovative pressurization system.

While other pressurization systems have been studied and used extensively, modeling of an autogenous system is less established. Despite the relative …

Crashworthiness Of Metallic Tubes Under Off-Axial Loading, Victor Manuel Bautista Katsalukha

Theses and Dissertations

Energy absorbing structures (EAS) are structures used to make the frame of a vehicle absorb energy during an impact scenario and keep the deceleration forces within survivable limits for the occupant(s). These structures are found in all sorts of vehicles, such as cars, helicopters, airplanes, etc., and come in many types of shapes (circular, square, triangular tubes and flat or curved plates) and materials (metals and composites). In this thesis, 304 Stainless Steel tubes with circular and square cross-sections are investigated when subject to off-axis loading at angles at 0, 5, 15 and 25°. The square tubes had two different …

Helicopter Flight Energy Modeling And Scaling For Urban Air Mobility Applications, Nolan Gene Hopkins

Theses and Dissertations

The costs associated with conducting full-scale helicopter flight tests in terms of both time and money beg to question the validity of using small-scale model helicopters in order to predict full-scale performance. To do this, the energy change for a small time interval is determined throughout a full-scale helicopter’s flight of a given profile, and the overall energy use compared to model results. The profile is then scaled based on a variety of factors, and the accuracy of energy scaling compared for each. Scaling dimensions based off helicopter weight and energy reserve modeling show promising results, but comparison of relative …

Flight Test Evaluation Of Elevator Stick Force Gradients On General Aviation Aircraft, Isaac Lee Faust

Theses and Dissertations

The objective of this research is to establish a suitable method of changing elevator stick force gradients on a Piper Warrior II. After finding a range of stick force gradients, the gradients will later be evaluated to get handling qualities ratings. A stick force gradient is the change in stick force as the airspeed deviates from trim condition. An aircraft’s yoke force gives pilots haptic feedback which improves their situational awareness without the need to assess instrument readings. A high stick force gradient will give the pilots a lot of feedback but will require more physical exertion to fly the …

Exploration Of Simplified Vehicle Operations For Electric Vertical Takeoff And Landing Through A Garmin Autopilot On A Piper Warrior, William Stefan Dietrich

Theses and Dissertations

Urban Air Mobility is an emerging concept that would allow urban transportation of both people and cargo through the air in large metropolitan cities. Because of new propulsion methods like distributed electrical propulsion, the Urban Air Mobility is concentrating on Electric Vertical Takeoff and Landing aircraft to implement its concept. Controlling and maneuvering these aircraft are very different than piloting traditional general aviation even through Electric Vertical Take and Landing aircraft aim to be in the same size category. Because of the more complex controls needed for Electric Takeoff and Landing aircraft, Simplified Vehicle Operation schemes are being developed in …

Autonomous Feature Detection For Capture Path Planning For Rendezvous And Docking With Non-Cooperative Spacecraft, Trupti Mahendrakar

Theses and Dissertations

With the increasing risk of collisions with space debris and the growing interest in on-orbit servicing, the ability to autonomously capture non-cooperative, tumbling target objects remains an unresolved challenge. This thesis provides an autonomous and artificial intelligence solution to either inspect, avoid, or perform on-orbit spacecraft servicing of an uncooperative resident space object (RSO). The solution is built on the fundamentals of Convolutional Neural Networks (CNN), which is used to classify the four most targeted features of a spacecraft essential for docking and collision avoidance during rendezvous, such as solar panels, antennas, spacecraft bodies, and thrusters. The solution was then …

Numerical Validation Of A Cryogenic Thermo-Fluid Mixing Model, Sean William Bowman

Theses and Dissertations

Thermal management of a hot convective gaseous flow can be achieved by the injection of a cold liquid stream. This cooling effect is constrained by the amount of liquid injected, the rate of evaporation of the liquid, and the length of the domain. In this study, such a domain is referred to as a “mixer”. The mixer used to facilitate this process is designed with a venturi geometry, such that the throat of the pipe creates a drop in the static pressure of the gaseous crossflow. Liquid coolant can thereby be passively entrained from a central pipe (plenum) by the …

Experimental Study Of Progressive Crushing Behaviour In Pultruded E-Glass Tubes Using Crown Triggers And A New Perforated Trigger, Chirag Mohan Dodani

Theses and Dissertations

An experimental study is conducted on the progressive crushing behavior and the energy absorption during crushing of pultruded fiberglass tubes, initiated by two types of crush triggers, a previously tested crown trigger, and a new perforated trigger. These crush triggers are introduced at the loading end of a pultruded E-Glass/vinyl-ester, circular tube coupon. Coupons with various trigger diameters and number of holes are crushed under quasi-static compression, to evaluate the trigger effectiveness, crushing response, and energy absorption during sustained crushing. It is observed that all trigger types induced progressive crushing in the splaying mode, characterized by the formation of a …