Aerospace Engineering Commons^™

Interaction Of A Shock Tube Exhaust Flow With A Non-Pre-Mixed Flame, Graham Doig, Zebulan Johnson, Rachel Mann

Aerospace Engineering

No abstract provided.

Experimental Investigation Of Blowing Effects On Turbulent Flow Over A Rough Surface, Mark A. Miller, Alexandre Martin, Sean C. C. Bailey

Mechanical Engineering Faculty Publications

A high Reynolds number turbulent channel flow facility was used to study the combined effects of roughness and flow injection on the mean flow and turbulence characteristics. It was found that the additional momentum injection through the surface enhanced the roughness effects and for the mean flow the effect of blowing was indistinguishable from that of increased roughness. However, for the turbulence statistics, this analogy broke down in that the addition of blowing resulted in behavior which did not follow that predicted by Townsend’s hypothesis. This was observed as a reduction of outer-scaled Reynolds stress well into the outer layer. …

Design, Fabrication And Test Of An Operationally Responsive Aircraft With Niirs Evaluated Imager, Colin Burt

Master's Theses

Unmanned Aerial Systems (UAS) are a growing asset. Currently UAS are on the cutting edge with resources being spent developing the capabilities mostly for military use. This project is intended to create a system for non-defense customers. Specifically, the Operationally Responsive Aircraft (ORA) will appeal to academic institutions, individual consumers, future customers new to the UAS industry, as well as anybody trying to get airtime for custom sensors.

The system developed in this project utilizes dual aluminum external payload bays attached to a ParkZone Radian aircraft. Each external payload bay can contain approximately 500 $\text{cm}^3$, with a height and width …

Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd

Mechanical and Aerospace Engineering Faculty Publications

This study investigates whether use of muscle excitation controls constructed from subjectspecific muscle synergy information can improve optimization prediction of knee contact forces and muscle excitations during walking. Muscle synergies quantify how a large number of experimental muscle electromyographic (EMG) signals can be reconstructed by linearly mixing a much smaller number of neural commands generated by the nervous system. Our hypothesis was that controlling all muscle excitations with a small set of experimentally calculated neural commands would improve prediction of knee contact forces and leg muscle excitations compared to using independently controlled muscle excitations.

A Comparative Study Of The Gas Turbine Simulation Program (Gsp) 11 And Gasturb 11 On Their Respective Simulations For A Single-Spool Turbojet, Rayne Sung

Masters Theses

GasTurb 11 and the Gas Turbine Simulation Program (GSP) 11 are two commercially available gas turbine simulation programs used by industrial professionals and academic researchers throughout the world. The two programs use a pseudo-perfect gas assumption in their calculations, where the specific heat is taken as a function of temperature and gas composition but not pressure. This assumption allows the two programs to make more realistic calculations of gas turbine engine performance. This is in contrast to the ideal and perfect gas assumptions used in classroom calculations. In addition, GasTurb 11 and GSP 11 both utilize component maps, comprised from …

Analysis And Optimization Of Unsteady Flow Past A Circular Cylinder Using A Harmonic Balance Method, Emily Buckman Clark

Masters Theses

Two-dimensional laminar flow over a circular cylinder was investigated in this work. Three cases were considered in which the cylinder was either stationary, in constant rotation, or in periodic rotation. The purpose of this work was to investigate the effects of a rotating cylinder for lift enhancement, drag reduction, and the suppression of vortex shedding. The governing coupled nonlinear Navier-Stokes equations were solved using a finite difference discretization and Newton’s method. In this way, three flow solvers were developed for this research: a steady solver, an unsteady time-accurate solver, and an unsteady harmonic balance solver. The force coefficients were of …

T/O Overruns And Veer-Offs On Slippery Runways With Crosswinds, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Fluid-Structure Interaction And Multidisciplinary Design Analysis Optimization Of Composite Wind Turbine Blade, Naishadh G. Vasjaliya

Doctoral Dissertations and Master's Theses

A multidisciplinary design analysis optimization (MDAO) process is defined for a composite wind turbine blade to optimize its aerodynamic and structural performance by developing a fluid-structural interaction (FSI) system. The objectives are to maximize aerodynamic efficiency and structural robustness while reducing blade mass and total cost. In the previous research, a MDO process of a composite wind turbine blade has been pioneered as an effective process to develop structurally optimized blade design. Present MDAO process is defined in conjunction with structural and aerodynamic performance of the blade which is divided into three steps and the design variables considered are related …

A Study Of The Collisional Evolution Of Orbital Debris In Geopotential Wells And Geo Disposal Orbits, Christina R. Diaz

Master's Theses

This thesis will present the effects of the orbital debris evolution in two key areas: the geosynchronous disposal orbit regime known as “graveyard” and the two geopotential wells found in 105◦ W and 75◦ E longitude bins. After developing a GEO specific orbit propagator for NASA Johnson Space Center’s Orbital Debris Of- fice, collisions were simulated throughout these regimes using a low velocity breakup model. This model considered the effects of perturbations particularly non-spherical Earth effects (specifically sectorial and zonal harmonics), lunar effects, third body effects and solar radiation pressure effects. The results show that CDPROP does well in simulating …

Geosynchronous Earth Orbit/Low Earth Orbit Space Object Inspection And Debris Disposal: A Preliminary Analysis Using A Carrier Satellite With Deployable Small Satellites, Derick A. Crockett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

From communication to weather prediction, to national security, geosynchronous satellites play an important role in our society. Geosynchronous satellites are about 35,786 km (22,236 miles) from the surface of the earth. Getting a satellite to this altitude is very expensive, making geosynchronous satellites highly valued assets. Ground-based observation of these satellites is very limited and provides little insight when failures or anomalies occur. To provide detailed images and information of these critical satellites, highly functioning smaller satellites can be employed. This study explores the potential benefits of using these smaller satellites to perform on-orbit proximity inspections of geosynchronous satellites. The …

Linear Covariance Analysis For Gimbaled Pointing Systems, Randall S. Christensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Linear covariance analysis has been utilized in a wide variety of applications. Historically, the theory has made significant contributions to navigation system design and analysis. More recently, the theory has been extended to capture the combined effect of navigation errors and closed-loop control on the performance of the system. These advancements have made possible rapid analysis and comprehensive trade studies of complicated systems ranging from autonomous rendezvous to vehicle ascent trajectory analysis. Comprehensive trade studies are also needed in the area of gimbaled pointing systems where the information needs are different from previous applications. It is therefore the objective of …

Thermal Analysis Of A Monopropellant Micropropulsion System For A Cubesat, Erin C. Stearns

Master's Theses

Propulsive capabilities on a CubeSat are the next step in advancement in the Aerospace Industry. This is no longer a quest that is being sought by just university programs, but a challenge that is being taken on by all of the industry due to the low-cost missions that can be accomplished. At this time, all of the proposed micro-thruster systems still require some form of development or testing before being flight-ready. Stellar Exploration, Inc. is developing a monopropellant micropropulsion system designed specifically for CubeSat application.

The addition of a thruster to a CubeSat would expand the possibilities of what CubeSat …

The Feasibility And Application Of Observing Small Leo Satellites With Amateur Telescopes, Brock Schmalzel

Master's Theses

This thesis demonstrates that any individual can provide relevant observational data to further research efforts within the Aerospace community, through the use of amateur telescopes. A Meade LX200 12 in. telescope and Lumenera Skynyx 2.0 camera were utilized to observe small LEO satellites, using a well-documented point-and-wait staring method. Over a period of three months, a total of 186 observation attempts were made resulting in 97 successful captures. From the gathered data, three possible aerospace applications were analyzed: validation of a satellite brightness prediction model, angles-only orbit determination including extended Kalman filtering, and temporal error growth in TLE-based orbit propagation. …

An Interoperable Executive Library For Loosely Coupled Physics Systems, Andrew Austin Kail

Masters Theses

The complexity of simulating any system-wide process involving biomedical processes or thermal-fluid systems goes beyond the reach of a single computer code. In this document I present an Interoperable Executive Library (IEL) that has been designed to run, in parallel, a collection of multi-component physics simulations. The IEL is a light-weight integrator responsible for managing the distribution of data and memory, coordinating communication among parallel processes, and direct execution of a set of loosely coupled numerical and physics tasks HPC resources

Presented are two case studies utilizing the IEL. The first case simulates conjugate heat transfer coupled with a potential …

Non-Destructive Testing (Ndt) By Laser Shearography And Fringe Projection, Xiaoran Chen, Morteza Khaleghi, Ivo Dobrev, Cosme Furlong

Morteza Khaleghi

Non-destructive testing (NDT) is critical to many precision industries because it can provide important information about the structural health of critical components and systems. In addition, NDT can also identify situations that could potentially lead to critical failures. Specifically, NDT by optical methods have become popular because of their non-contact and non-invasive nature. Shearography is a high-resolution optical NDT method for identification and characterization of structural defects in components and has gained wide acceptance over the last decade; however, as a drawback, shearography cannot locate the position of defects in 3D. To overcome this limitation, we are combining shearography with …

Computing Radiation Exchange, Jonathan L. Nutzati Fontaine

Doctoral Dissertations and Master's Theses

A computational tool to simulate thermal radiation between surfaces is developed. The output is verified against cases for which the analytical solutions are available. The tool can be used as a stand-alone program, or as an interactive module for CFD. In such an application the module would augment other heat transfer boundary conditions. The tool is demonstrated by post-processing surface temperature field data from a supersonic CFD calculation. The result is a net thermal radiation surface data field - the black body radiative effluxes as functions of temperature, less the integrated influxes multiplied by their geometric view factors from other …

More Effective Human Spaceflight Programs And Their International Security Implications, Bert Chapman, Sarag J. Saikia

Libraries Faculty and Staff Scholarship and Research

NASA can more effectively perform its missions by transferring its aeronautic responsibilities to the Federal Aviation Administration and be renamed the National Space Agency. The U.S. must also recognize that space is an emerging arena of international competition and conflict and militarily protect its space assets from China which seeks to use space to restrict the U.S.' ability to defend its strategic interests in regions such as the Western Pacific.

The Formulation And Computation Of The Nonlocal J-Integral In Bond-Based Peridynamics, Wenke Hu, Youn Doh Ha, Florin Bobaru, Stewart A. Silling

Florin Bobaru Ph.D.

This work presents a rigorous derivation for the formulation of the J-integral in bond-based peridynamics using the crack infinitesimal virtual extension approach. We give a detailed description of an algorithm for computing this nonlocal version of the J-integral.We present convergence studies (m-convergence and δ-convergence) for two different geometries: a single edge-notch configuration and a double edge-notch sample.We compare the results with results based on the classical J-integral and obtained from FEM calculations that employ special elements near the crack tip.We identify the size of the nonlocal region for which the peridynamic J-integral value is near the classical FEM solutions.We discuss …

The Meaning, Selection, And Use Of The Peridynamic Horizon And Its Relation To Crack Branching In Brittle Materials, Florin Bobaru, Wenke Hu

Florin Bobaru Ph.D.

This note discusses the peridynamic horizon (the nonlocal region around a material point), its role, and practical use in modeling. The objective is to eliminate some misunderstandings and misconceptions regarding the peridynamic horizon. An example of crack branching in a nominally brittle material (homalite) is addressed and we show that crack branching takes place without wave interaction. We explain under what conditions the crack propagation speed depends on the horizon size and the role of incident stress waves on this speed.

Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru

Florin Bobaru Ph.D.

We propose a computational method for a homogenized peridynamics description of fiber-reinforced composites and we use it to simulate dynamic brittle fracture and damage in these materials. With this model we analyze the dynamic effects induced by different types of dynamic loading on the fracture and damage behavior of unidirectional fiber-reinforced composites. In contrast to the results expected from quasi-static loading, the simulations show that dynamic conditions can lead to co-existence of and transitions between fracture modes; matrix shattering can happen before a splitting crack propagates. We observe matrix–fiber splitting fracture, matrix cracking, and crack migration in the matrix, including …