Aerospace Engineering Commons^™

Experimental And Computational Analysis Of A 3d Printed Wing Structure, Aryslan Malik

Doctoral Dissertations and Master's Theses

Correct prediction of aeroelastic response is a crucial part in designing flutter or divergence free aircrafts within a designated flight envelope. The aeroelastic analysis includes specifically tailoring the design in order to prevent flutter (passive control) or eliminate it by applying input on control surfaces (active control). High-fidelity models such as coupled Computational Fluid Dynamics (CFD) - Computational Structural Dynamics (CSD) can obtain full structural and aerodynamic behavior of a deformable aircraft. However, these models are so large that pose a significant challenge from the control systems design perspective. Thus, the development of an aeroelastic modeling software that can be …

Adaptive Commanding Of Control Moment Gyroscopes With Backlash, Justin G. Bourke

Doctoral Dissertations and Master's Theses

The existence of backlash in mechanical systems provides significant challenges when attempting to control these systems to a high degree of precision. The imperfect meshing of gear or belt teeth deteriorates the performance of position controllers and tracking of small commands, producing unacceptable steady-state offsets, increased rise and settling times. Agile spacecraft often use control moment gyroscopes (CMGs) equipped with gear trains to efficiently provide torque for the fine attitude adjustments used in docking and precision stabilization maneuvers. A theoretical examination and a practical model is developed to study the effectiveness of both proportional-integral (PI) and model referencing adaptive controllers …

Preliminary Test Predictions For Scale Ram-Air Parachute Testing, Christian A. Guzman Zurita

Doctoral Dissertations and Master's Theses

The present thesis proposes a preliminary analysis to predict the aerodynamic performance for experimental tests of ram-air parachutes in a wind tunnel. A scaled experimental test setup is developed for determining the aerodynamic coefficients of lift (𝐶𝐿) and drag (𝐶𝐷) conducted in a wind tunnel. Additionally, a CFD approach where a steady-state parachute shape defined based on experiments, photographs, and literature, is presented. The accuracy of the simulation depends considerably on the ability to resolve the canopy geometry. Therefore, a CAD geometry generation is implemented for flexible control of the canopy structure by implementing design parameters, e.g., chord, span and …

Development Of Robust Control Laws For Disturbance Rejection In Rotorcraft Uavs, Johannes Verberne

Doctoral Dissertations and Master's Theses

Inherent stability inside the flight envelope must be guaranteed in order to safely introduce private and commercial UAV systems into the national airspace. The rejection of unknown external wind disturbances offers a challenging task due to the limited available information about the unpredictable and turbulent characteristics of the wind. This thesis focuses on the design, development and implementation of robust control algorithms for disturbance rejection in rotorcraft UAVs. The main focus is the rejection of external disturbances caused by wind influences. Four control algorithms are developed in an effort to mitigate wind effects: baseline nonlinear dynamic inversion (NLDI), a wind …

Low-Tip-Speed High-Torque Proprotor Noise Approximation For Design Cycle Analysis, Xavier G. Santacruz

Doctoral Dissertations and Master's Theses

Noise reduction in aviation would enable urban missions that cannot be own with current generation helicopters because of their noisiness. This goal can be achieved by using electric motors as they are quieter and can produce higher torque at lower RPMs. Therefore, a proprotor system can be designed to exploit this characteristic potentially abating noise levels. This research performed noise approximations included with rotor aerodynamics for a single, electric-driven, hovering proprotor by creating a code meant to be used in design cycle analysis. The approximation was based on geometry by using the blade element momentum theory, and calculating the pressure …

Covering Shock Wave Induced Interfacial Mixing: Numerical Study And A Control Primer, Erik S. Proaño

Doctoral Dissertations and Master's Theses

This document is aiming toward deepening the understanding of the phenomena of mixing and the effect of the initial conditions in the cylindrical & spherical Richtmyer-Meshkov and Rayleigh-Taylor Instabilities. This work is focused on identifying the most energetic structures of the ow in order to define a reduced order model intended for modeling the evolution of the mixing layer after reshocking the density interface. Initially, Simulations are implemented for the two dimensional case of a cylindrical shock wave convergently approaching an initially wave-like perturbed density discontinuity formed by a target of Sulfur Hexauoride immersed into unshocked air with Atwood number …

Cfd Study Of Taylor-Like Vortices In Swirling Flows, Sattar Panahandehgar

Doctoral Dissertations and Master's Theses

Swirling flows are complex fluid motions that appear in various natural phenomena and man-made devices. Numerous engineering applications such as turbomachinery, jet engine combustion chambers, mixing tanks and industrial burners involve swirling flows. This wide range of applications is due to unique characteristics offered by swirling flows such as increase in mixing rate, heat transfer rate and wall shear stress. In this study the axisymmetric swirling flow behavior in the context of a hybrid rocket engine have been analyzed. While modeling the flow inside a cylindrical chamber using CFD, a similarity with the Taylor vortices instability has been observed. Similar …

Optimal Battery Weight Fraction For Serial Hybrid Propulsion System In Aircraft Design, Tsz Him Yeung

Doctoral Dissertations and Master's Theses

This thesis focuses on electric propulsion technology associated with serial hybrid power plants most commonly associated with urban air mobility vehicles. While closed form analytical solutions for parallel hybrid aviation cases have been determined, optimized serial hybrid power plants have not seen the same degree of fidelity. Presented here are the analytical relationships between several preliminary aircraft design objectives and the battery weight fraction. These design objectives include aircraft weight, range, operation cost, and carbon emissions. The relationships are based on a serial hybrid electric propulsion architecture from an energy standpoint, and can be applied to hybrid aircraft of different …

A Hybrid Vortex Solution For Radial Equilibrium In Axial Compressors, Wenyu Li

Doctoral Dissertations and Master's Theses

A hybrid vortex solution using the radial equilibrium equation for three dimensional design in axial compressors is generated. One of the most common used vortex solutions is Free Vortex. However, it ignores the fact that axial velocity varies with radius. The Hybrid Vortex includes axial velocity distribution with radius, which gives a more effective design. A single stage is first designed using the Free Vortex design method. A low hub-to-tip ratio is set to ensure subsonic flow. The axial velocity profile is exported from the CFX solver of the inlet diffuser. Using the Hybrid Vortex solution to the radial equilibrium …

Hypervelocity Impact Analysis Of Hybrid Nanocomposite Sensors For Inflatable Space Structures, Yachna Gola

Doctoral Dissertations and Master's Theses

Future space exploration requires easy-to-transport, and easy-to-build and deploy space habitats. NASA and Bigelow Aerospace have collaborated so that human habitation can be made safe and easy with inflatable space habitats (Litteken, 2017). One of the biggest threats faced by these structures in outer space is impact damage by micrometeoroid orbital debris (MMOD) traveling at velocities as high as 15 km/s (Lemmens, Krag, Rosebrock, & Carnelli, 2013). This work presents fabrication and testing of hybrid nanocomposites with carbon nanotubes (CNT) and coarse graphene nanoplatelets (GNP) as fillers and flexible epoxy matrix, that are proposed to be used for sensing the …

The Changing Face Of Airmanship And Safety Culture Operating Unmanned Aircraft Systems, Tracy Lamb

Student Works

The notion of using drones for commercial purposes has evolved in the past 5 years from the initial “boom” of excitement around this, somewhat of a novelty and curiosity, to more calculated and sophisticated use of unmanned aircraft systems (UAS), or drones. In the hands of true professionals, drones can offer highly efficient and profitable solutions for industrial, and commercial inspections and other data capturing tasks. The appetite for safe and efficient collection of data is a changing face of safety cultures and how teams and individuals apply airmanship principles, and how inspection crew and UAS crew interact. UAS are …

Task 1: Silver-Based Microbial Check Valve For Spacecraft Potable Water Systems, Eric Beitle

Chemical Engineering Undergraduate Honors Theses

As human space exploration increases, the development of a more efficient potable water treatment system suited for spacecraft becomes crucial. This Waste-management Education Research Consortium (WERC) challenge was designed to explore the viability of microbial control through the utilization of silver ions as a biocide for possible integration into the Tranquility Node 3 water purification system aboard the International Space Station (ISS). Current systems using iodine risk causing hyperthyroidism from overexposure; however, silver can be safely ingested without this side effect. After researching silver delivery methods including electrochemical ion production, controlled release, or a combination of the two, our team …

Reconstruction Of Attenuated Hybrid Rocket Motor Chamber Pressure Signals Using Maximum Likelihood Estimation And Optimal Deconvolution, Evan M. Zelesnik

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Chamber pressure, as it develops during rocket combustion, strongly correlates with many of the internal motor ballistics, including combustion stability, fuel regression rate, and mass flow. Chamber pressure is also an essential measurement for calculating achieved thrust coefficient and characteristic velocity. Due to the combustion environment hostility, sensing chamber pressure with high-fidelity presents a difficult measurement problem, especially for solid and hybrid rocket systems where combustion by-products contain high amounts of carbon and other sooty materials. These contaminants tend to deposit within the pneumatic tubing used to transmit pressure oscillations from the thrust chamber to the sensing transducer. Partially clogged …

Investigation Of Thermoplastic Polymers And Their Blends For Use In Hybrid Rocket Combustion, Spencer D. Mathias

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis set out to find a blend of thermoplastics that had better combustion properties than the current ABS (acrylonitrile butadiene styrene) plastic or “Lego ^TM plastic” used by Utah State University. The current work is in an effort to eliminate toxic propellants from small space applications. High and low density polyethylene plastics were used because they are common plastic waste items. In this way rocket fuel can be made from these items to reduce the waste found in landfills. Three plastics were considered for replacement and as mixture components with the ABS plastic, namely low and high density polyethylene, …

A First-Principle Power And Energy Model For Evtol Vehicles, Max Skuhersky

Theses and Dissertations

A number of well-established aircraft manufacturers, such as Airbus, Boeing, or Bell, along with new startups have begun developing flying prototypes of electric Vertical Takeoff and Landing vehicles (eVTOL). To certify this emerging type of air mobility vehicles for commercial use, the Federal Aviation Administration (FAA) is considering adjusting currently used certification procedures for small aircraft to include eVTOL vehicles. One of the hurdles to this approach is that eVTOL vehicles are neither able to glide like a small, fixed-wing aircraft, nor to autorotate, like a helicopter, if the batteries are depleted. Therefore, active energy management and energy awareness by …

Space Image Processing And Orbit Estimation Using Small Aperture Optical Systems, David Zuehlke

Doctoral Dissertations and Master's Theses

Angles-only initial orbit determination (AIOD) methods have been used to find the orbit of satellites since the beginning of the Space Race. Given the ever increasing number of objects in orbit today, the need for accurate space situational awareness (SSA) data has never been greater. Small aperture (< 0:5m) optical systems, increasingly popular in both amateur and professional circles, provide an inexpensive source of such data. However, utilizing these types of systems requires understanding their limits. This research uses a combination of image processing techniques and orbit estimation algorithms to evaluate the limits and improve the resulting orbit solution obtained using small aperture systems. Characterization of noise from physical, electronic, and digital sources leads to a better understanding of reducing noise in the images used to provide the best solution possible. Given multiple measurements, choosing the best images for use is a non-trivial process and often results in trying all combinations. In an effort to help autonomize the process, a novel “observability metric” using only information from the captured images was shown empirically as a method of choosing the best observations. A method of identifying resident space objects (RSOs) in a single image using a gradient based search algorithm was developed and tested on actual space imagery captured with a small aperture optical system. The algorithm was shown to correctly identify candidate RSOs in a variety of observational scenarios.

2019 Spring Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for spring 2019. Includes photographs, upcoming events, recent publications, and student profiles.

Fast Yield Estimation Of Multi-Band Patch Antennas By Pc-Kriging, Xiaosong Du, Leifur Leifsson, Slawomir Koziel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The PC-Kriging metamodeling method is proposed for yield estimation of multi-band patch antennas. PC-Kriging is a combination of polynomial chaos expansion (PCE) and Kriging metamodeling, where PCE is used as a trend function for the Kriging interpolation metamodel. The method is demonstrated on the Ishigami analytical function and a dual-band patch antenna. The PC-Kriging is shown to reach the prescribed accuracy limit with significantly fewer training points than both PCE and Kriging. This translates into considerable computational savings of yield estimation over alternative metamodel-based procedures and direct EM-driven Monte Carlo simulation. The saving are obtained without compromising evaluation reliability.

Point Cloud Based Relative Navigation For Small Satellite Rendezvous, Branden William Blackwell

Theses and Dissertations

The thesis describes the development and testing of a point cloud based relative navigation sensor. The objective of this research is to provide a low cost, lightweight, low power, and low volume alternative to established rendezvous sensors , in order to enable small satellites to conduct missions such as in-space inspection, on-orbit servicing, and space debris removal. The sensor system must be able to provide relative position and orientation data to a control system independent of the cooperation of the target spacecraft or object. This is done using commercially available hardware (Microsoft Kinect v2) and an open source C++ library …

Numerical Study Of Spacer Grid Geometry In A 5 X 5 Nuclear Fuel Rod Bundle, Wan Chuan Fan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reactor fuel rod bundles serve as the primary heat source in light water reactors (LWRs), commonly found in the aforementioned PWR plants. The fuel rod bundles’ structure consists of a collection of fuel rods put into a parallel grid configuration. The bundles also include fuel rod spacers, which hold the fuel rods in place, in accordance with the grid. Repeating structures of the fuel bundles create the meta-structure in the reactor. In other words, the grid configuration repeats until it fills the entire space of the reactor. This results in reactor fuel rods suspended in the working fluid domain, oriented …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

Numerical Analysis And Fluid Flow Modeling Of Incompressible Navier-Stokes Equations, Tahj Hill

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Navier-Stokes equations (NSE) are an essential set of partial differential equations for governing the motion of fluids. In this paper, we will study the NSE for an incompressible flow, one which density ρ = ρ0 is constant.

First, we will present the derivation of the NSE and discuss solutions and boundary conditions for the equations. We will then discuss the Reynolds number, a dimensionless number that is important in the observations of fluid flow patterns. We will study the NSE at various Reynolds numbers, and use the Reynolds number to write the NSE in a nondimensional form.

We will …

Study Of A Crew Transfer Vehicle Using Aerocapture For Cycler Based Exploration Of Mars, Larissa Balestrero Machado

Theses and Dissertations

This thesis presents the results of a conceptual design and aerocapture analysis for a Crew Transfer Vehicle (CTV) designed to carry humans between Earth or Mars and a spacecraft on an Earth-Mars cycler trajectory. The thesis outlines a parametric design model for the Crew Transfer Vehicle and presents concepts for the integration of aerocapture maneuvers within a sustainable cycler architecture. The parametric design study is focused on reducing propellant demand and thus the overall mass of the system and cost of the mission. This is accomplished by using a combination of propulsive and aerodynamic braking for insertion into a low …

Development And Testing Of Additively Manufactured Aerospike Nozzles For Small Satellite Propulsion, Isaac W. Armstrong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Automatic altitude compensation has been a holy grail of rocket propulsion for decades. Current state-of-the-art bell nozzles see large performance decreases at low altitudes, limiting rocket designs, shrinking payloads, and overall increasing costs. Aerospike nozzles are an old idea from the 1960’s that provide superior altitude-compensating performance and enhanced performance in vacuum, but have survivability issues that have stopped their application in satellite propulsion systems. A growing need for CubeSat propulsion systems provides the impetus to study aerospike nozzles in this application. This study built two aerospike nozzles using modern 3D metal printing techniques to test aerospikes at a size …

Extreme Altitude Search And Rescue Helicopter, Matthew J. De Sieno, Anthony Chavarria, David Stuver, Zach Boss

Senior Design Project For Engineers

The goal of this design was to develop an extreme altitude rescue helicopter capable of retrieving hikers stranded on top of Mount Everest. Using the Eurocopter AS350 as a baseline, a conceptual model was produced that is fully capable of hovering and delivering forward flight at the desired altitude of 8,848 meters. Combined blade element momentum theory, proper airfoil selection, and forward flight calculations were utilized in order to optimize the rotor for the given flight conditions on top of Mount Everest. Conceptual fluid dynamics and CAD modeling aided in the process of visually designing the fuselage and rotor. Not …

Deployable Solar Array Structure: G1:3, Daniel Bain, Craig Patton, Andrew Tendean

Senior Design Project For Engineers

This design project is in response to an AIAA RFP (Request-For-Proposal) to build a compact, durable, non-hinged solar array to be deployed from a spacecraft on its way from the Earth to Mars. The solar array structures are used to provide the continual supply of power to operate onboard equipment. A large array will be required but must fit within the fairing of the launch vehicle. Origami principles will be utilized to fit the given constrained stored volume of 10 cm³ while satisfying the power requirements and avoiding structural complications due to tight folds.

Unmanned Aerial Power Line Surveillance Drone, Brock Arp, Wade Vine, Cameron Whigham, Lorenzo Stewart

Senior Design Project For Engineers

The purpose of our project is to provide power line workers and linemen with a safe way to inspect the power lines. Our Aircraft is an UAV that is capable of surveying 200 linear miles in a normal working shift. The aircraft will be launched/landed and operated from an F-150 pickup truck with a facilitated launch mechanism attached. The aircraft must maintain an altitude of 150-400 ft. It will be recovered via net that will extend from the truck as the plane comes in for a landing, This will eliminate the need for landing gear. The goal for this project …

Conceptual Design Of A Combat Search And Rescue Surveillance Unmanned Aerial Aircraft, Juan M. Chirinos-Paiz, Keegan J. Musser, Robert M. Zenko, Joshua Hunter

Senior Design Project For Engineers

Unmanned aerial vehicles (UAV) are becoming more efficient and widely used. The military uses UAV’s because it greatly reduces civilian and combatant deaths and injuries. UAV’s also are used in search and rescue mission to find distress civilians. The team wanted to create an UAV for search and rescue missions and military applications. The aircraft needed to be compact, perform better than other UAV’s, and be low cost. The team did reach a successful aircraft that meet the design requirements. The aircraft was successfully sized around the electronics and allows utilization of additive manufacturing techniques. Project management techniques showed that …

Adaptive And Supertwisting Adaptive Spacecraft Orbit Control Around Asteroids, Keum W. Lee, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

This paper addresses the development of control systems for the orbit control of spacecraft around irregularly shaped rotating asteroids with uncertain parameters. The objective is to steer the spacecraft along prescribed orbits. First, a nonlinear adaptive law for orbit control was designed. This was followed by the design of a supertwisting adaptive (STWA) control system. In the closed-loop system, which includes the adaptive law or the STWA law, all the signals remain bounded, and the trajectory tracking error asymptotically converges to zero for any initial condition. Finally, under the assumption of boundedness of the derivative of the uncertain functions of …

Thermal Management Design Tool System For Cubesat Applications, Siakrishna Reddy Kanumuru

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Saikrishna Reddy Kanumuru on April 26, 2019.