Aerospace Engineering Commons^™

Modeling, Fabrication, And Characterization Of Porous Inconel 718 Structures Using Selective Laser Melting Process, Srihari Srivathsan

Mechanical and Aerospace Engineering Theses - Archive

Bio-inspired cellular structures are of great interest these days for many applications, from engineering research to industries. Honeycomb, Body-Centered Cubic with/without Z-struts (BCC-Z/ BCC), Face Centered Cubic with/without Z-struts (FCC-Z/ FCC), and Triply Periodic Minimal Surface (TPMS) such as Gyroid, Diamond, and Schwartz lattices are the most common bio-inspired lattice structures. These structures can be tailored based on their structural organization resulting in superior materials with lightweight properties, adequate strength, and low stiffness. Thankfully, additive manufacturing (AM) has made the fabrication of these complex cellular materials realistic. However, the use of AM could lead to several defects, such as damaged …

Cfd Analysis On Liquid Cooled Cold Plate Using Copper Nanoparticles, Sarthak Agarwal

Mechanical and Aerospace Engineering Theses - Archive

In today’s world, most data centres have multiple racks with numerous servers in each of them. The high amount of heat dissipation has become the largest server-level cooling problem for the data centres. The higher dissipation required, the higher is the total energy required to run the data centre. Although still the most widely used cooling methodology, air cooling has reached its cooling capabilities especially for High-Performance Computing data centres. Liquid-cooled servers have several advantages over their air-cooled counterparts, primarily of which are high thermal mass, lower maintenance and eventually lower costs by maintenance by labour. Nano-fluids have been used …

Prediction And Validation Of Continuous Fiber Stiffened Plates Manufactured With Continuous Fiber Fabrication, Nabeel Ahmed Khan

Mechanical and Aerospace Engineering Theses - Archive

The purpose of this thesis was to develop an analytical method for predicting the structural properties of continuous fiber stiffened plates, which was then validated both experimentally and via finite element analysis. The MarkForged Mark Two 3D printer enables parts to be printed with continuous carbon fibers embedded within them. A manufacturing process was developed for printing stiffened grids with our without skins, with continuous fiber reinforcement on the top and bottom of the stiffening ribs, which allows bending stiffness can be maximized. An orthotropic grid was printed using Continues Filament Fabrication (CFF), an additive manufacturing process that embeds reinforcing …

Impact Of Viscoelastic Properties Of Low Loss Printed Circuit Boards (Pcbs) On Reliability Of Wcsp Packages Under Drop Test, Akshay Boovanahally Lakshminarayana

Mechanical and Aerospace Engineering Theses - Archive

Reliability of electronic packages is a major concern as different failure modes are induced due to factors such as temperature loads, mechanical stresses, humidity, corrosion and so on. Finite element analysis (FEA) is often performed to assess reliability under different loading conditions such as thermal cycling, drop testing, power cycling and vibrational loads. Having accurate material property data is one of the key requirements to perform successful FEA study, and a significant amount of time and money is spent to perform accurate material characterizations. Lump modeling approach, where components are represented by a block and assigned effective properties, is commonly …

Measurement Of Change In Cte Of Pcbs Due To Single Phase Immersion Cooling And Impact Of Changed Properties Of Pcbs On Solder Joint Reliability Of Bga Package, Sameer Hemant Dhandarphale

Mechanical and Aerospace Engineering Theses - Archive

Oil immersion cooling in high-density data centers is emerging as an alternative for traditional air cooling because of the less power consumption, capacity to handle high power density and less space requirement. To adopt this technique extensively, effect of immersion on reliability of server components in dielectric coolant needs to be evaluated. One of the major reliability concerns in BGA package is 2nd level solder joint failure. The primary reason of solder joint failure is CTE mismatch between the PCB and the package. Also, difference in stiffness of the PCB and the package affects the solder joint reliability. As properties …

Aerodynamic Interactions Of Synchronized Propellers, Nathan Welker, Samuel Johnson

Utah Space Grant Consortium

Emerging advances in electric-propulsion technology are enabling aircraft to use distributed electric propulsion (DEP) to increase efficiency and maneuverability. Distributed electric propulsion can also provide unique take-off and landing abilities which are not commonly found on traditional aircraft. The implementation of DEP effectively decreases the spacing between propellers, introducing complex aerodynamic interactions that are not well understood. This study aims to obtain experimental measurements of the flow fields of synchronized propellers at close-proximity in a side-by-side configuration using particle image velocimetry (PIV) in a wind tunnel. The results of this work will be focused on identifying the impact closely-spaced propellers …

Monte-Carlo Methods And The Step-Back Kalman Filter For Orbital State Estimation, Louis Tonc

Utah Space Grant Consortium

This research assesses the performance of filtering schemes for tracking uncooperative satellites through space-based optical measurements, and identifies a simple and numerically stable methodology that ameliorates the poor performance of standard filtering schemes at a substantially reduced cost in comparison to nonlinear particle filter-based remedies. Traditional filtering schemes, such as the extended Kalman filter (EKF) and unscented Kalman filter (UKF), both diverge when tracking a resident space object (RSO) in geosynchronous orbit (GEO) when there is a long time duration between measurements. This divergence is identified as a consequence of nonlinearity in the dynamics and nonlinearity in the optical measurements, …

On The Advantages Of The Disabled In Space., Samantha R. Timmers

College of Arts & Sciences Senior Theses

Since the start of the astronaut program in the 1960s, candidates have had to prove to be in prime physical shape before being granted clearance to fly, whereas those with physical disabilities such as blindness or deafness are automatically disqualified. The stigma that disabled persons are less qualified to succeed in a physically alien environment has persisted, though little research exists in revisiting the difficulties posed by allowing this group into the space program. This paper aims to reconsider the advantages and disadvantages of a disability-friendly space program, to include cost considerations, potential challenges, and the unique benefits posed by …

Design Optimization Of An Elastically Supported Multi-Beam Rotordynamic System To Minimize Flexural Response With Considerations For Robustness, Bret R. Hauser

Mechanical and Aerospace Engineering Dissertations - Archive

Modern rotating machines are often required to operate with a small physical footprint and/or overall weight; necessitating that they utilize wide-ranging shaft speed to accomplish needed power levels. It is not uncommon that these designs also be required to support operation through a speed range encompassing multiple Critical Speeds while also limiting flexural vibrations to acceptable levels. Design optimization of this class of problem can be particularly difficult in that responses can be highly multi-modal and, when coupled with Finite Element (FE) solvers meet the conditions of a High Dimensional, Computationally Expensive Black Box (HEB) system. Because of this, some …

Shape Optimization Of Microfiber Composite Energy Harvesters, Suyash Lahoti

Doctoral Dissertations and Master's Theses

A model of energy harvesting beam with a piezoelectric material, microfiber composite (MFC), in a unimorph configuration was setup in Matlab using the governing equations of motions of a coupled electromechanical system. The equations of motion were derived using Hamilton’s variational principles and constitutive relations of a piezoelectric material. The mathematical model developed in Matlab was validated with an experiment and frequency response functions. The validated model was used to perform shape optimization so as to obtain the shape of the beam and the patch that harvests the largest voltage. The shape variables were length of the beam (LB), length …

Machine Learning Modeling Of Horizontal Photovoltaics Using Weather And Location Data, Christil Pasion, Torrey Wagner, Clay Koschnick, Steven Schuldt, Jada Williams, Kevin Hallinan

Mechanical and Aerospace Engineering Faculty Publications

Solar energy is a key renewable energy source; however, its intermittent nature and potential for use in distributed systems make power prediction an important aspect of grid integration. This research analyzed a variety of machine learning techniques to predict power output for horizontal solar panels using 14 months of data collected from 12 northern-hemisphere locations. We performed our data collection and analysis in the absence of irradiation data-an approach not commonly found in prior literature. Using latitude, month, hour, ambient temperature, pressure, humidity, wind speed, and cloud ceiling as independent variables, a distributed random forest regression algorithm modeled the combined …

Helios And Tenasi Results For The Workshop For Integrated Propeller Prediction, Aaron Crawford

Honors Theses

Beginning in 2018, the AIAA began the workshop for integrated propeller prediction. This effort was intended to bolster the CFD prediction capabilities of the aerospace community due to a resurgent interest in propeller driven vehicles for electric applications. The test bed for this workshop is the NASA X-57, a model of which was experimentally tested in the Lockheed Martin Low Speed Wind Tunnel in January 2019. Using the 3D scanned geometry provided by the workshop a mesh was created and all priority one simulations were performed using two flow solvers. The flow solvers used were Helios, developed by the ADD …

Augmented Reality In A Dynamic Drone Based Environment, Christopher Davis

Honors Theses

Augmented Reality (AR) and Unmanned Ariel Vehicles (UAVs) are fast advancing technologies, and this research seeks to combine them to offer an effective, user friendly approach for monitoring infrastructure. Drones provide a means to easily access otherwise difficult to reach locations and visualize useful information with Augmented Reality. A UAV employs a wide-angle view and, when paired with AR, this will enable the user to better complete their task by effortlessly providing the critical information they need in the most intuitive way possible. This research is particularly applicable for civil applications such as construction and monitoring of difficult to access …

Studies Of Oval Tube And Fin Heat Exchangers, Phillip Nielsen

Undergraduate Student Works

Heating Ventilation and air-conditioning (HVAC) is a system which changes the temperature of the surroundings for the purposes of cooling or heating. This system requires energy to maintain a temperature difference from the outside temperature. Optimizing the flow over the evaporator coils is one way to increase the cooling efficiency. This will reduce the power required to have a sustainable system. Optimizing the flow to increase the energy transfer between the fins and the incoming air could result in a greater Coefficient of Performance (COP). This will be achieved by changing the geometry of the tubes for greater interaction with …

2020 Spring Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for spring 2020. Includes photographs, upcoming events, recent publications, and student profiles.

Cfd Modeling Of Vertical Axis Wind Turbine Arrays Using Actuator Cylinder Theory, Cory Schovanec

McKelvey School of Engineering Graduate Student Theses & Dissertations

The goal of this thesis is to analyze the flow field and power generation from a vertical axis wind turbine (VAWT) by extending the Actuator Cylinder Model to include the viscous effects. Turbulent flow effects in the Actuator Cylinder Model are modeled by solving the Reynolds-Averaged Navier-Stokes (RANS) equations with the Spalart-Allmaras (SA) turbulence model in ANSYS FLUENT. A study is performed to establish mesh independence of the solutions. Numerical solutions on a fine mesh are compared to existing theoretical results based on inviscid theory for a series of flow conditions and turbine sizes. Similar trends in the present turbulent …

Impact Of Parasitic Drag On A Family Of Optimal Lift Distributions, Austin J. Stewart

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Minimizing drag is a variational problem, and several minimum induced drag solutions have been found using different design constraints. The elliptic lift distribution is commonly used to minimize induced drag, but is only the optimal solution under one set of design constraints. Non-elliptic lift distributions are able to reduce induced drag, when compared to the elliptic lift distribution, by increasing the wingspan while maintaining a consistent wing–structure weight. However, these non-elliptic lift distributions are only optimal if the effects of viscous drag are neglected. In this study, numerical tools are used to estimate the total drag on rectangular wings that …

Practical Optical Survey Strategies For Near Geostationary Orbital Debris, Akhter Mahmud Nafi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Uncontrolled space objects, more commonly known as space debris, consist of dead satellites, satellite deployment packages, and lost elements of these systems such as insulation blankets. These uncontrolled objects represent hazards to our nation’s most valuable space assets which include communication satellites, weather satellites, Earth monitoring systems, and military assets. To help mitigate this problem, this research proposes using the known astrodynamics of the near geosynchronous orbit (GEO) along with the known concentration of the uncontrolled GEO objects and observation constraints to design ground-based optical surveys that will detect uncatalogued debris. Furthermore, a scoring metric is developed to evaluate the …

Potential Of Hydrodynamic Metamaterial Cloak For Drag Reduction, Rong Zou

McKelvey School of Engineering Graduate Student Theses & Dissertations

Metamaterials are rationally designed artificial materials composed of tailored functional building blocks densely packed into an effective material. While metamaterials historically are primarily thought to be associated with negative index of refraction and invisibility cloaking in electromagnetism or optics, it turns out that the simple metamaterial concept also applies to many other areas of physics namely the thermodynamics, classical mechanics including elastostatics, acoustics, fluid dynamics and elastodynamics, and in principle also to the quantum mechanics. The goal of this thesis is to introduce and evaluate the potential of a hydrodynamic metamaterial cloak for drag reduction of objects in viscous flow. …

Numerical And Experimental Analysis Of Air-Cooled Condensers, Kaipo Kekaula

UNLV Theses, Dissertations, Professional Papers, and Capstones

The scope of this project is to numerically and experimentally dry cooling process in air-cooled condensers (ACCs) designed for concentrated solar power (CSP) applications. This effort is driven by the growing economic and political pressure to reduce water consumption during power generation due to limited water resources in the arid geographic climate of the southwestern United States. A computational approach is used in conjunction with experimental validation to gain a more complete understanding of these systems.

Traditionally research into ACCs have been largely limited to air-side heat transfer modelling as it accounts for a large portion of the total thermal …

Discrete Vortex Modeling Of Aerodynamic Flutter Of A Flat Plate With Damped Oscillations, Emma Chao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerodynamic flutter is the unstable oscillation of a body caused by the interaction of aerodynamic forces, structural elasticity, and inertial effects induced by vortex shedding. Current models of this phenomenon require finite element analysis and extensive computational power and processing time. The purpose of this study was to develop and validate a program that is faster and more efficient than existing approaches by using the discrete vortex method (DVM). By reducing the complexities of flutter to the shedding of vortices in an inviscid model of a two-dimensional flat plate with a torsional spring constant at its center, this phenomenon can …

Use Of Garmin Autopilot Envelope Protection System For Simplified Vehicle Operations In General Aviation, Stephen Sullivan

Theses and Dissertations

The general aviation industry suffers from high rates of fatalities and accidents occurring due to loss of control while in flight. This thesis research aims to implement a simple yet effective simplified vehicle operations (SVO) scheme that uses a Garmin autopilot system to create a pilot-on-the-loop controller to help prevent loss of control incidents from occurring. With this scheme, the pilot is controlling turns and climb rates instead of elevator and aileron deflections and is protected from the risk of under-speed and stall through the Garmin autopilots built-in limits. To interface with the autopilot system, a Raspberry Pi and Pythonbased …

Towards Gross-Pitaevskiian Description Of Solar System & Galaxies, Florentin Smarandache, Victor Christianto, Yunita Umniyati

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper, we argue that Gross-Pitaevskii model can be a more complete description of both solar system and spiral galaxies, especially taking into account the nature of chirality and vortices in galaxies. We also hope to bring out some correspondence among existing models, e.g., the topological vortex approach, Burgers equation in the light of KAM theory, and the Cantorian Navier-Stokes approach. We hope further investigation can be done around this line of approach.

Flight Path Control During Hypersonic Atmospheric Entry Using Active Magnetic Arrays, Matthew Tyler Austin

Theses and Dissertations

The purpose of this thesis is to study the reaction to the Lorentz force induced during the hypersonic regime of flight by an active magnetic field. The effect that a magnetic array has on the flight characteristics of a blunt body during Earth atmospheric entry is characterized and isolated for independent analysis. This is done to show that mission-specific benefits to utilizing this method of entry control exist and therefore warrant further study. To conduct this analysis, a 1000 kg blunt body test case was used. This craft contains three separate magnets located behind the nose with two of them …

Flight Testing Of The Piper J4a Cub Coupe, Kenneth Burton Connick

Theses and Dissertations

Flight testing is an important part of in the airplane design process. This testing is performed to ensure that the airplane complies with the established requirements and regulations for flight safety, as well as to ensure it meets its mission objectives. The Federal Aviation Administration (FAA) currently governs these requirements and regulations for civilian aircraft and provides airworthiness certifications. The FAA regulations were introduced in 1965. Prior to that, civilian aircraft were certified through the Civil Aeronautics Administration using Civil Air Regulations (CARs).

Active Drag Reduction Of Ground Vehicles Using Air-Jet Wheel Deflectors, Kaloki Nabutola

Doctoral Dissertations and Master's Theses

Seven turbulence models were used to simulate the flow within the wheelhouse of a simplified vehicle body. The performance of each model was evaluated by comparing the aerodynamic coefficients obtained using computational fluid dynamics (CFD) to data collected from wind tunnel experiments. The performance of large eddy simulation (LES) and detached eddy simulation (DES) was largely dependent on the time step and grid size to accurately resolve turbulent eddies. The standard k-e, realizable k-e, k-w, DES, and LES all trended towards a drag coefficient which was 20% lower than the experimental value. In all numerical cases, the lift coefficient was …

Analysis Of Local Convection Heat Transfer Rates Of Supercritical Carbon Dioxide In Tubes, Yang Chao

Doctoral Dissertations and Master's Theses

Numerical investigation on thermodynamic characteristics of pure supercritical carbon dioxide (𝑆𝐶𝑂2) and mixtures of Helium and 𝑆𝐶𝑂2 in horizontal straight tubes with diameter of 6mm under cooling and heating conditions is carried out by using SST 𝑘 − 𝜔 turbulence model. The computations are conducted at operating pressure of 8MPa with various operating conditions. Simulations are conducted by using the latest poly-hexcore mesh method in ANSYS FLUENT 19.2 and tetrahedral mesh method in CFX 19.2, results and solving time are compared. The effect of heat flux, mass flux, inlet temperature and buoyancy on heat transfer performance are studied, pressure drop …

Dmd And Pod Modal Analysis For Store Separation, Nicholas Peters

Doctoral Dissertations and Master's Theses

Store separation from aircraft and spacecraft has historically been a critical and in some cases fatal issue for the aerospace industry. Given the severity of the issue much effort has been spent on the development of processes to identify failure flight conditions for store separation. The processes currently used for identifying potential failure conditions however are both resource intensive and iterative processes. A potential remedy to reducing resource use and improve turn around time in this process is the implementation of a mode based reduced order model (ROM) for modeling store separation. The objective of this study was to first …

Unsteady Internal Ballistics Of A Hybrid Rocket, Naveen Sri Uddanti

Doctoral Dissertations and Master's Theses

With the recent progress made in the field of space tourism, hybrid rocket engines have gained a renewed interest due to their simplicity, low cost, operational flexibility, and safety. The flow in the ports of a hybrid rocket motor involves several coupled unsteady phenomena like moving walls, combustion in a boundary layer flow and mass addition along the port, through the regression of the solid fuel wall. The flow in the combustion chamber of a hybrid rocket is inherently unsteady because the geometry of the port varies as a function of space and time. In the current research, we develop …

Viscoplastic Study Of 3d Printed Carbon Fiber Composites, Alexander M. Seifans

Doctoral Dissertations and Master's Theses

The research presented here involves an attempt to model the viscoplastic response of 3D printed carbon fiber composites made using the Mark Two 3D printer by Markforged. The ability to manufacture composites through the use of 3D printers is relatively new and contains gaps in the various mechanical properties of the material, of interest is the viscoplastic response.

Due to the fabrication method, the properties of the composites cannot be assumed to be similar to that of conventionally made composites as the fused deposition in printing alters the material properties. In order to understand the effects of the printed fiber …