Engineering Commons^™

Path Following By A Quadrotor Using Virtual Target Pursuit Guidance, Abhishek Manjunath

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Missile guidance laws have been solely developed to follow and intercept a target thereby destroying or damaging it. In this research, the primary objective is to modify and adopt a missile guidance law to be used on a quadrotor to follow a virtual target. The target is termed 'virtual' as it only exists mathematically in the form of equations. The goal is to have the quadrotor successfully following the predefined path (described by the target) while maintaining a fixed distance from the virtual target. To ensure viability and assess performance, a detailed comparison with another path following law is made.

Throttleable Gox/Abs Launch Assist Hybrid Rocket Motor For Small Scale Air Launch Platform, Zachary S. Spurrier

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The ability for an aircraft-based launch platform to place an orbital payload onto a nominal launch trajectory at a higher energy state -- altitude, velocity, flight path angle, and azimuth --using highly-efficient air breathing propulsion instead of a much lower-efficiency rocket system, offers the potential for a significantly smaller launch vehicle. An airborne platform also provides the ability to launch from multiple locations and allows for significantly increased "system responsiveness." The NASA Armstrong Flight Research Center’s Towed Glider Air-Launch System (TGALS) is a small-scale flight research project investigating the feasibility for a remotely-piloted, towed, glider system to act as a …

Investigating The Effect Of Capping Layers On Final Thin Film Morphology After A Dewetting Process, Benjamin C. White

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nanoparticles on a substrate have numerous applications in nanotechnology, from enhancements to solar cell efficiency to improvements in carbon nanotube growth. Producing nanoparticles in a cheap fashion with some control over size and spacing is difficult to do, but desired. This work presents a novel method for altering the size and spacing of nickel and gold nanoparticles. Dewetting is a methodology to reduce thin films to an ensemble of discrete droplets. The introduction of alumina capping layers to thin nickel films during a pulsed laser-induced dewetting process has yielded reductions in the mean and standard deviation of radii and pitch …

Quadrotor Uav Path Following Using Trajectory Shaping, Parwinder Singh Mehrok

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The propose of this research is to develop a path following control law known as Trajectory Shaping. The approach is to develop a three- dimensional (3D) version of it from an existing two-dimensional (2D) model. Apart from research on this 3D control law, a multirotor unmanned aerial vehicle (UAV) platform, having four rotors and known as quadrotor is designed from the ground up for validating the concept of path following. Several pre-defined paths like the circle and figure-eight trajectories are used to apply the newly developed version of this control law. The existing 2D concept of Trajectory Shaping guidance …

Impact Of Mass And Bond Energy Difference And Interface Defects On Thermal Boundary Conductance, Changjin Choi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many portions of energy generated in the U.S. are not used and take the form of wasted heat due to a poor heat transfer efficiency. This fact leads research communities to focus on thermoelectrics as a means for using waste heat through direct thermal to electrical energy conversion. One way to enhance thermoelectric efficiency is to reduce thermal conductivity through nanostructuring. In nanostructures, understanding energy transport across the interface of two materials is important because interfaces dominate the resistance to overall thermal transport of the system and can be described by thermal boundary conductance (TBC). Also of note, an understanding …

Effects Of Radiation Heating On Additively Printed Hybrid Fuel Grain Oxidizer-To-Fuel Ratio Shift, Stephen L. Merkley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis examined the hypothesis that radiative heat transfer in small-scale printed-fuel hybrid rocket motors is responsible for the observed decreasing oxidizer-to-fuel (O/F) ratio shift. The magnitude of the radiation term was negligible for the motor sizes and types of propellants that have been previously tested, but was reintroduced in this study. To prove this hypothesis, a detailed enthalpy balance model was developed and tested using experimental fuel regression rate data obtained from a variety of motor scales using additively-manufactured acrylonitrile butadiene styrene (ABS) fuel grains.

Benchmark Experiments For Natural Convection In Nuclear Fuel Rod Bundles, Kyle L. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Buoyancy is the mechanism through which heated air causes fluid motion due to a difference in temperature between a body and the surrounding fluid. This fluid motion can be very erratic and unstable, which creates a difficult problem when attempting to simulate this fluid motion. Using high performance computational power the capability of simulating these complex interactions is available but requires assessment to determine the accuracy of these difficult flow scenarios. This study provides experimental data that can be used to assess the simulation’s accuracy and to ensure the computational models are achieving the correct solution. The Rotatable Buoyancy Tunnel …

Microalgae Sorption Of Ten Individual Heavy Metals And Their Effects On Growth And Lipid Accumulation, Eric M. Torres

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this study is to determine the potential microalgae have for being a heavy metal remediation tool. Heavy metals are naturally occurring elements that can be found inside the earth or on its surface. Typically, heavy metals are found naturally at low concentrations. However, through human activities, heavy metals are continually making their way to the surface and being concentrated. This happens largely through mining and manufacturing operations. For example, NiCd batteries produce waste containing nickel and cadmium, and paper manufacturing produces waste containing high levels of lead. As underdeveloped nations continue to industrialize and the world population …

Development Of A Three-Dimensional High-Order Strand-Grids Approach, Oisin Tong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The strand-Cartesian grid approach is a unique method of generating and computing fluid dynamic simulations. The strand-Cartesian approach provides highly desirable qualities of fully-automatic grid generation and high accuracy. This work focuses on development of a high-accuracy methodology (high-order scheme) on strand grids for two and three dimensions.

In this work, the high-order scheme is extended to high-Reynolds number computations in both two and three dimensions with the Spalart-Allmaras turbulence model and the Menter SST turbulence model. In addition, a simple limiter is explored to allow the high-order scheme to accurately predict discontinuous flows.

Extensive verification and validation is conducted …

Effects On A Wedge Flowmeter Installed Downstream Of A Double Elbow Out Of Plane, Devan S. Radle

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Precise flow measurement is a critical part of many industries including industrial, hydropower, petroleum, nuclear, and water/wastewater. Lengthy upstream piping is required for many flowmeters to obtain accurate results. Due to piping constraints, sub- optimal flow meter installations can occur. One of these conditions is the installment of a flow meter in close proximity downstream of a double elbow out of plane (DEOP). A DEOP can cause swirl to form in the flow and can cause inaccurate metering results due to the non-uniform flow and pressure conditions. This study investigated the effect of installing a differential pressure producing wedge flow …