Organizational Unit:
Daniel Guggenheim School of Aerospace Engineering

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Publication Search Results

Now showing 1 - 10 of 17
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    Optimized communications protocol for low earth orbit cubesat
    (Georgia Institute of Technology, 2018-05) Desai, Baijun
    The purpose of this document is to describe and analyze the implementation of a communications protocol to transfer data between a CubeSat and ground station. The mission of the CubeSat is to track debris in low earth orbit (LEO). Data transfers to and from the satellite include images, telemetry, commands, and processed data. The communications channel operates on a half-duplex connection with a single linearly polarized half-wave UHF dipole attached to the CubeSat, and a circularly polarized Yagi-Uda antenna on the ground station. Data will pass through a Software Defined Radio (SDR) and on the ground station over packet radio. The challenges faced in designing the protocol include high packet loss, short and infrequent access times, high delay times, variable signal strength, and limited power. The designed protocol will be implemented and tested on the CubeSat. It is evaluated against other existing communications protocols for performance.
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    Design of a CubeSat Mission for Persistent Space Situational Awareness with Passive Optical Sensors
    (Georgia Institute of Technology, 2017-05) Alexander, Luke J.
    This paper will explore the design and implementation of a CubeSat with an electro- optical sensor for purposes of space situational awareness. The Introduction gives an overview of the current state-of-the-art for space-based space object detection. It is clear that the next step in space mission design for space situational awareness is the application of optical detection to the CubeSat form factor. The Methods and Materials section covers the abstract design parameters and theoretical concept of operations of a spacecraft that has the goal of detecting as many space objects as possible before exploring how hard- ware can be selected to best meet the goals of the science objective. The Results section discusses the requirements that were flowed down from this theoretical study to guide the development of a CubeSat to fulfill this mission profile. The Discussion then goes through the hardware selection process for every supporting flight system and treats trade studies for all major flight systems as guided by the system requirements, discussing tradeoffs and decisions that were made at all steps of the hardware selection and software design pro- cesses. An experimental concept of operations of the satellite is then proposed given the constraints that the selected hardware and operational parameters impose on the system. The Conclusion section gives an overview for the progress that has been made towards this design at the Georgia Institute of Technology with the Reconnaissance of Space Objects CubeSat and explains the next steps for this flight project with a development timeline to launch. Information on specific technical efforts can be found in the Appendix.
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    Mixing in compressible shear layers
    (Georgia Institute of Technology, 2016-07-18) Mohan, Ratheesvar
    Efficient fuel-air mixing is vital to supersonic combustion, which is the basis of supersonic combustion RAMjets, or SCRAMjets, the preferred method of combustion for hypersonic flight. This study investigates mixing in compressible shear layers and its dependence on convective Mach number. The primary stream is air at Mach 2.5 and the secondary stream is seeded with acetone. PLIF and Schlieren imaging techniques are used to quantify mixing. Reduction of data is still in progress; this thesis reviews literature on the topic, outlines the experimental method employed, presents preliminary Schlieren results and presents the raw data obtained. Additionally, mass flow rates of both streams are calculated. It was determined that the experiments are highly repeatable, evidenced by the low standard deviations of the mass flow rates during runs.
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    Qualitative Comparison of Commercial and Open Source Particle Image Velocimetry Softwares
    (Georgia Institute of Technology, 2016-07-18) Johnson, Henderson Johnson
    Complex chemical and fluid dynamic mechanisms present in combustion systems necessitate the validation of computational fluid dynamics (CFD) models using flow visualization and velocity field measurement techniques. Two cutting edge measurement techniques for reacting flows are planar-laser induced fluorescence (PLIF), which images combustion radicals within the flame, and stereoscopic particle image velocimetry (sPIV), which is a non-intrusive laser-based velocity measurement. These measurements and others are often synchronized and coupled together to gain a complete picture of flow field variation (i.e. pressure, temperature, velocity, etc.). The PIV measurement in particular poses a variety of challenges especially during the data processing phase which can be achieved using either commercial or open-source software packages. This papers explores the qualitative difference between each software with the intent of providing a recommendation on which form of software should be used. By understanding the types of software that should be used, one can develop lab infrastructure that maximizes the effectiveness of using said software.
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    The Effect of Sweep and Taper on Static Performance for Small Propellers
    (Georgia Institute of Technology, 2016-07-18) Kadri, Tobi
    These past few years have been the years of the UAV. UAVs, also called drones, now have the friendly tasks of filming sports or movie scenes, civilian surveillance, and simple general aviation. Some companies see a future where UAVs are delivering pizza or packages. All of this shows a demand for civilian UAVs, typically in the form of quadcopters, but can also be small R/C planes. These aircraft are usually powered by small propellers and the design for propellers has not changed much despite the recent wave of UAV popularity. Two universities have made serious progress in the tabulation of small and micro propeller performance, but the realm of small and micro propeller geometry has not been pursued. Most propellers today are only classified by diameter and pitch, a measure of how far a propeller would “screw” into a solid object but other geometries of the propeller may lead to enhanced performance as well. In this study, seventeen 9 in. propellers were fabricated and tested. Thrust and torque coefficients were plotted against RPM since the tests were conducted statically. Forward sweep has adverse effects on both thrust and torque with only a hint that a higher sweep magnitude might yield significant performance improvements. Aft sweep yields substantial increases in thrust and torque, at the expense of higher power, and should qualify as a viable parameter for propeller manufactures to include in designs. A taper ratio greater than 1 has negligible increases in both thrust and torque while a taper ratio less than 1 has adverse effects on both. Varying taper ratio, at least solely from root to tip, is therefore not an effective strategy for thrust or torque augmentation, however small taper does reduce the induced power for a given thrust.
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    Design of a thermoelectric edu-kitchen system
    (Georgia Institute of Technology, 2013-05-08) Srivastava, Akshaya
    The driving force behind this project is to aid the people who live in ru- ral areas of the world and have difficulties in accessing basic electricity and kitchen efficiencies. The most basic kitchen is a pot over a fire. However, this setup will pollute the environment drastically. This project proposes to reduce the pollution by powering a fan to help regulate air intake and make the flames burn more efficiently. The question posed then is how to power the fan. The solution provided by this project is to use a thermoelectric panel, similar to those used in space missions, but of a lower cost and power. This thermoelectric component will utilize the Seebeck effect to charge a battery that will then serve to run the fan. The battery can also power an LED light to provide light while cooking. Additionally, the battery could also be connected to an ultraviolet LED, an integral part to a recently developed water purification system.
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    Design Tool for Simulation of Nanocomposite Material Properties
    (Georgia Institute of Technology, 2013-05-08) Worthy, Johnny Lee, III
    The development of nanocomposites is one of the rapidly evolving areas of composite materials research due to the unique properties exhibited by nanoscale reinforcements. Carbon nanotubes (CNTs), for example, have superior mechanical properties with a Young’s Modulus on the order of 1 TPa. However, there exists a considerable gap between the individual properties of CNTs and their stress transfer efficiency in composites. Computational modeling techniques for the determination of mechanical properties of nanocomposites have proven to be very effective through parametric studies to facilitate the design and development of nanocomposites. An integrated design and anslysis tool for composite materials with nanofiller are presented in this paper. This tool combines statistical image analysis with 3D modeling to automate the creation of a Representative Volume Element (RVE) model capable of simulating the material properties of nanocomposites in order to better understand how nanoscale reinforcements enhance materials.
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    Effect of flame temperature ratio on bluff body wakes
    (Georgia Institute of Technology, 2012-05-07) Lundrigan, Julia
    Safe operation of aircraft and aeroderivative industrial gas turbine engines relies heavily on the stability of the combustion process. Combustion instabilities are of interest because they may lead to harmful pressure oscillations and increases in temperatures within the engine that could be destructive to engine components. Fluid dynamics in the combustor directly affects combustion instabilities and is the subject of this research. The two types of hydrodynamic instabilities linked with combustion instabilities explored in this research are the Kelvin-Helmholtz and the Benard/von Karman instabilities. Previous research has shown that a high flame temperature ratio (the ratio between the temperature of the products and the temperature of the unburned reactants) suppresses the Von Karman street, allowing for the wake to be characterized by the higher frequency Kelvin-Helmholtz instability from which vortices are shed by the shear layers. However, at a low temperature ratio, the flame loses its ability to suppress the Von Karman instability. The result of the changing of wake structures is fluctuations in heat release and pressure, which can result in damaged hardware and loud audible tones. Research previously conducted in Georgia Tech's Ben T. Zinn Combustion Laboratory using chemiluminescence has given an approximation of the flow field disturbances caused by the Von Karman response by measuring flame response. The proposed research will utilize knowledge gained from previous flow field disturbance approximations and improve the approximations by using data acquisition hardware that will allow for the exact flow field to be measured. The purpose of this research is to demonstrate that hydrodynamic stability calculations can be used to predict the onset of the Benard/von Karman instability in bluff body flames.
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    Multi-point Optimization of Airfoils
    (Georgia Institute of Technology, 2011-05-09) Chiguluri, Bhanu S.
    Many previous studies focused on developing optimum airfoils for steady flight conditions. However, with minimal extensions airfoils could be designed to perform better at the take-off conditions which would result in the efficient take-offs at shorter runways. An inverse design technique called the Modified Garabedian McFadden (MGM) technique was applied to NACA 0012 airfoil which resulted in an airfoil with drag bucket at the normal flight operation conditions. A newly developed optimization technique was applied to the three-element take-off configuration and a configuration that produced higher lift was obtained. Future work could be conducted on extending these design techniques for various airfoil configurations.
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    Development and application of a rapid military model development framework
    (Georgia Institute of Technology, 2010-12-20) Andriano, Nelson Gregory
    Military operations are complex systems composed of the interactions of many smaller discrete systems, or assets: aircraft, watercraft, troops, etc. Historically, the requirements for new assets have been created based on standalone optimization. It is not just necessary to optimize requirements for a single scenario, such as a wartime operation, but instead to optimize the requirements that will benefit the entire military operation as a whole in a number of different scenarios, such as wartime and peace time. To better define future military assets it is necessary sample a large number of scenarios. To capture all of the interactions and develop a complete understanding of the overall system, it is necessary to model both combat and logistics, which have traditionally been modeled and analyzed separately. To characterize military operations and the assets that contribute to them, it is necessary to move beyond the traditional models that use aggregated approximations for combat and stand alone nodal analysis for logistics. A unique need for a framework which captures the complex interaction between combat and logistics while allowing a large number of automated cases and scenarios to run with no human in the loop. The framework this paper discusses was created to facilitate the making of models to analyze and characterize military operations and the effects that future assets will have on entire operations. The framework is agent-based, allowing bottom up definition and the gathering of emergent behavior, and uses a modified Hughes salvo method for combat, the Foundation for Intelligent Physical Agents messaging structure, and the beliefs, desires, and intentions (BDI) agent model. The modeling of communication and BDI creates myopic agents that are constrained by the information they can obtain, process, and react to. In this paper, the framework is first depicted and then validated by the creation of a model with the purposes of defining the requirements for a future asset, the Transformable Craft. The creation and testing of the model prove that the requirements for the framework have been met with success. The potential applications of the framework ranges from data-farming military operations models for future asset requirement, characterizing military operations systems, and providing a stepping stone for future agent-based military operations modeling and simulation work.