Aerospace Engineering Commons^™

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 …

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

Aerospace Engineering

No abstract provided.

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

Aviation Department Publications

No abstract provided.

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 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 …

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. …

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 …

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 …

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 …

Design Practice, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Design Practice" on July 30, 2013.

Power Storage & Control, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Power Storage & Control" on July 30, 2013.

Overview Of Eps, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on an "Overview of EPS" on July 30, 2013.

Power Sources, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Power Sources" on July 30, 2013.

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.

Simulations Of Ion Thruster Plume Contamination With A Whole Grid Sputtered Mo Source Model, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A particle simulation based source model is developed to calculate the density distribution of the sputtered Mo atoms for a whole ion optics grid. The source model is used in PIC simulation of ion thruster plume contamination for 3-grid and 2-grid ion thrusters. The results show that the commonly used point-source approximation for sputtered Mo atoms is oversimplified and would lead to over-prediction of contamination deposition.

Improving Affordability: Separating Research From Development And From Design In Complex Programs, Bohdan W. Oppenheim

Systems Engineering Faculty Works

This paper presents arguments for why defense programs creating physical systems should clearly separate three developmental phases from each other: research, development and design. Research is to be performed first by small teams of scientists addressing the "unknown unknowns" and maturing fundamental science from TRL of 1 to about 3. Next, development of physical modules is to be performed by small and highly specialized engineers. Finally, the system-level design should focus on efficient trading off the module locations, sizes and shapes versus system performance, mass, power requirements, etc. The design with all modules mature and available is equivalent to a …

Design Advantages Of Skin Friction Drag Reduction Using Riblets, John Michael Gregory

Mechanical & Aerospace Engineering Theses & Dissertations

The research reported here has examined the potential improvements in overall aircraft performance that can result from integrating skin friction reduction technology, such as riblets, early in the aircraft design cycle. This study has shown that riblets can improve the payload capacity, increase the range, and improve performance of transport aircraft. If recent advances in fabrication techniques make it possible to create aluminum wing surfaces with integral riblet geometries, the applications could be widespread and the gains significant.