Methods For Initial Relative Orbit Determination Using Angles-Only Observations,
2014
Old Dominion University
Methods For Initial Relative Orbit Determination Using Angles-Only Observations, Ethan M. Pratt
Mechanical & Aerospace Engineering Theses & Dissertations
An approximate second order nonlinear closed-form solution for three-dimensional relative motion assuming Keplerian dynamics and a circular reference track are applied to the relative initial orbit determination problem. A series of azimuth-elevation angular measurements locating a deputy satellite with respect to a chief satellite are coupled through the observation geometry with the nonlinear dynamics model for the relative motion in terms of linear, quadratic, and bilinear combinations of the deputy initial conditions and chief orbital elements. The resulting set of nonlinear measurement equations are analyzed, formulated, and solved using three separate non-iterative methods. By using a nonlinear dynamics model with …
Design Improvements For A Reusable Horizontal Takeoff And Landing Aircraft For Use On Mars,
2014
Old Dominion University
Design Improvements For A Reusable Horizontal Takeoff And Landing Aircraft For Use On Mars, Brian A. Skoog
Mechanical & Aerospace Engineering Theses & Dissertations
Unmanned aerial vehicle capabilities are required for expanded exploration of the Martian surface. These vehicles can not only gather data at an altitude otherwise unreachable by rovers and satellites, but also deliver small payloads and retrieve samples from distant off-site locations. Previous multi-purpose reusable Mars aircraft studies have been unable to achieve the flight ranges required for expanded exploration. This study has focused on increasing the range of prototype aircraft designs. Assuming that large precision cargo delivery capabilities have been developed and much of the infrastructure associated with a fixed Mars base is in place, the challenge of linking dispersed …
Improving And Expanding The Capabilities Of The Poly-Picosatellite Orbital Deployer,
2014
California Polytechnic State University, San Luis Obispo
Improving And Expanding The Capabilities Of The Poly-Picosatellite Orbital Deployer, David Pignatelli
Master's Theses
The Poly-Picosatellite Orbital Deployer (P-POD) has undergone a series of revisions over the years. The latest revision, described in this Master’s Thesis, incorporates new capabilities like EMI shielding, an inert gas purge system, and an electrical interface to the CubeSats after they are integrated into the P-POD. Additionally, some mass reduction modifications are made to the P-POD, while its overall strength is increased. The P-POD inert gas purge system successfully flew, on a previous revision P-POD. The P-POD components are analyzed to a set of dynamic loads for qualification, and successfully undergoes random vibration qualification testing. The P-POD encounters some …
Control Of A Spacecraft Using Mixed Momentum Exchange Devices,
2014
California Polytechnic State University, San Luis Obispo
Control Of A Spacecraft Using Mixed Momentum Exchange Devices, Blake J. Currie
Master's Theses
Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for …
Effects Of Low Velocity Impact On The Flexural Strength Of Composite Sandwich Structures,
2014
California Polytechnic State University, San Luis Obispo
Effects Of Low Velocity Impact On The Flexural Strength Of Composite Sandwich Structures, Jeffrey Scott Carter
Master's Theses
The use of composite sandwich structures is rapidly increasing in the aerospace industry because of their increased strength-to-weight and stiffness-to-weight characteristics. The effects of low velocity impacts on these structures, however, are the main weakness that hinders further use of them in the industry because the damages from these loadings can often be catastrophic. Impact behavior of composite materials in general is a crucial consideration for a designer but can be difficult to describe theoretically. Because of this, experimental analysis is typically used to attempt to describe the behavior of composite sandwiches under impact loads. Experimental testing can still be …
Laminar Deflagrated Flame Interaction With A Fluidic Jet Flow For Deflagration-To-Detonation Flame Acceleration,
2014
Old Dominion University
Laminar Deflagrated Flame Interaction With A Fluidic Jet Flow For Deflagration-To-Detonation Flame Acceleration, Joseph P. Mcgarry
Mechanical & Aerospace Engineering Theses & Dissertations
The concept of the Pulse Detonation Engine (PDE) has been of interest for centuries. The issue was originally studied to understand flame propagation in mine shafts after explosions due to methane buildup. The flames would travel down the shafts, transitioning to turbulent flames due to the roughness of the shaft walls, and accelerate to detonation, delivering powerful, destructive forces. The potential for efficient energy production was noticed, and the theory behind flame propagation was later applied to developing propulsion systems. Recently, researchers have begun to understand the full potential of PDEs to efficiently produce an immense amount of thrust due …
Investigation Of Pulse Detonation Engine Flow Conditions For Turbomachinery Integration,
2014
Embry-Riddle Aeronautical University
Investigation Of Pulse Detonation Engine Flow Conditions For Turbomachinery Integration, Luis Estefano Ferrer-Vidal EspañA-Heredia
Doctoral Dissertations and Master's Theses
Pressure gain combustion has been known to be more thermodynamically efficient than its constant pressure counterpart, which employs deflagration. Integration of pressure gain combustors into gas turbine engines has been and still is one of the most important challenges facing the gas turbine industry. Pressure gain combustion devices are inherently unsteady. This unsteadiness affects turbomachinery components designed using steady operation assumptions, and results in mechanical inefficiencies which could outweigh the thermal efficiency benefits. Understanding of turbine components specifically made to operate in the exhaust conditions provided by a pressure gain combustor may yield new turbine design paradigms. As a first …
Reduction Of Secondary Flow Losses In A Turbine For Use In Man-Portable Power Generation,
2014
Embry-Riddle Aeronautical University - Daytona Beach
Reduction Of Secondary Flow Losses In A Turbine For Use In Man-Portable Power Generation, Andrew J. Yatsko
Doctoral Dissertations and Master's Theses
As the world has moved into a more energy-demanding environment, there has been the push for higher energy density in a smaller package. One of the potential solutions is through the application of a gas turbine engine; yet the challenge is extracting the energy efficiently through the small components. The focus of the research is on the turbine components and how the secondary flow losses from the generated airfoil shapes can be reduced to improve component performance. One of the secondary flow loss items to be addressed is the generation of the Horseshoe Vortex. The Horseshoe Vortex is an aerodynamic …
The Effects Of Rewards On The Ability Of An Autonomous Uav Controlled By A Reinforcement Learning Agent To Accomplish A Target Localization Task,
2014
Embry-Riddle Aeronautical University
The Effects Of Rewards On The Ability Of An Autonomous Uav Controlled By A Reinforcement Learning Agent To Accomplish A Target Localization Task, Hemali Dinesh Virani
Doctoral Dissertations and Master's Theses
The need for Unmanned Aerial System (UASs) is increasing in the fields of science, security, military and others. With an increasing number of challenges faced by mankind the need for system with advance autonomous and intelligent capabilities is growing rapidly. The required intelligent behavior can be achieved in an unmanned system with machine learning methods such as Reinforcement Learning (RL) theory. This theory presents algorithms which have the capability to learn how to adapt to its environment. Using RL methods, autonomous systems have the ability to use past experiences to improve future mission performance. In this research, the effects of …
Characterization And Low-Dimensional Modeling Of Urban Fluid Flow,
2014
Embry-Riddle Aeronautical University
Characterization And Low-Dimensional Modeling Of Urban Fluid Flow, Dietmar Rempfer, Candace Wark, Bruno Monnier, Sriharsha Kandala
Publications
This report describes work that was done under AFOSR Contract Number FA9550-11-1-0056, studying the structure of a model urban boundary layer flow. The model geometry consisted of a set of plexiglass blocks, and the flow around this geometry was studied both experimentally as well as computationally. For the experiment, a Stereoscopic Particle Image Velocimetry (SPIV) method was developed that allows for a three-dimensional description of this urban flow, and helps gain insight into the characteristic flow structures in the streets and canyons of our model urban geometry. On the computational side, a new spectral-element code was developed that was demonstrated …
Passive Phase Separation Of Microgravity Bubbly Flows Using Conduit Geometry,
2014
IRPI
Passive Phase Separation Of Microgravity Bubbly Flows Using Conduit Geometry, Ryan M. Jenson, Andrew Paul Wollman, Mark M. Weislogel, Lauren Sharp, Robert Green, Peter J. Canfield, Jörg Klatte, Michael E. Dreyer
Mechanical and Materials Engineering Faculty Publications and Presentations
The ability to separate liquid and gas phases in the absence of a gravitational acceleration has proven a challenge to engineers since the inception of space exploration. Due to our singular experience with terrestrial systems, artificial body forces are often imparted in multiphase fluid systems aboard spacecraft to reproduce the buoyancy effect. This approach tends to be inefficient, adding complexity, resources, and failure modes. Ever present in multiphase phenomena, the forces of surface tension can be exploited to aid passive phase separations where performance characteristics are determined solely by geometric design and system wettability. Said systems may be readily designed …
Investigation Of Conjugate Heat Transfer In Fluid-Structure Interaction Modeling Using Openfoam,
2014
California Polytechnic State University, San Luis Obispo
Investigation Of Conjugate Heat Transfer In Fluid-Structure Interaction Modeling Using Openfoam, Andrew Brown
Aerospace Engineering
No abstract provided.
Design Of A Frequency-Selective Surface Strain Sensor,
2014
Missouri University of Science and Technology
Design Of A Frequency-Selective Surface Strain Sensor, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Frequency Selective Surfaces (FSS) have long been used in the RF/microwave community to control radar cross-section. The scattering parameters of the FSS form a signature which is a function of the frequency, element size and spacing, as well as the local electromagnetic environment. This paper considers a FSS as a strain sensor on the surface of a structural element. By interrogating the FSS with a series of polarized far-field measurements in a bistatic configuration the biaxial plane strain, including shear, can be resolved.
Optimal Control Of Fully Routed Air Traffic In The Presence Of Uncertainty And Kinodynamic Constraints,
2014
Air Force Institute of Technology
Optimal Control Of Fully Routed Air Traffic In The Presence Of Uncertainty And Kinodynamic Constraints, Christopher D. Arendt
Theses and Dissertations
A method is presented to extend current graph-based Air Traffic Management optimization frameworks. In general, Air Traffic Management is the process of guiding a finite set of aircraft, each along its pre-determined path within some local airspace, subject to various physical, policy, procedural and operational restrictions. This research addresses several limitations of current graph-based Air Traffic Management optimization methods by incorporating techniques to account for stochastic effects, physical inertia and variable arrival sequencing. In addition, this research provides insight into the performance of multiple methods for approximating non-differentiable air traffic constraints, and incorporates these methods into a generalized weighted-sum representation …
Experimental Uncertainty Associated With Traveling Wave Excitation,
2014
Air Force Institute of Technology
Experimental Uncertainty Associated With Traveling Wave Excitation, Geofrey S. Cox
Theses and Dissertations
This dissertation research produces the experimental techniques required to evaluate mistuning in any rotor. Within operation, a rotor is subjected to a unique pattern of frequencies acting to excite the rotor. Utilizing traveling wave excitation, a rotor's critical frequencies and the respective excitation pattern are reproduced. Individual rotor blade frequency response functions are evaluated and statistically analyzed. The experimental results serve to not only verify the degree to which a rotor is mistuned, but also to provide an indication of the forced response amplification the mistuning induces. Within the experiment, definitive specifications were developed to ensure peak rotor responses. Numerical …
Convective Heat Transfer With And Without Film Cooling In High Temperature, Fuel Rich And Lean Environments,
2014
Air Force Institute of Technology
Convective Heat Transfer With And Without Film Cooling In High Temperature, Fuel Rich And Lean Environments, Nathan J. Greiner
Theses and Dissertations
Modern turbine engines require high turbine inlet temperatures and pressures to maximize thermal efficiency. Increasing the turbine inlet temperature drives higher heat loads on the turbine surfaces. In addition, increasing pressure ratio increases the turbine coolant temperature such that the ability to remove heat decreases. As a result, highly effective external film cooling is required to reduce the heat transfer to turbine surfaces. Testing of film cooling on engine hardware at engine temperatures and pressures can be exceedingly difficult and expensive. Thus, modern studies of film cooling are often performed at near ambient conditions. However, these studies are missing an …
A Comparison Of Afghanistan, Yuma, Az, And Manufactured Sands Melted On Eb-Pvd Thermal Barrier Coatings,
2014
Air Force Institute of Technology
A Comparison Of Afghanistan, Yuma, Az, And Manufactured Sands Melted On Eb-Pvd Thermal Barrier Coatings, Nathaniel P. Opie
Theses and Dissertations
Sand ingestion into military aircraft turbine engines from desert environments have tested the performance and life of the engine. In particular, turbine section blades and nozzles are coated with a molten glass when the sand is heated to melting temperatures. This molten glass attacks protective coatings on the surface of these parts. Further research is needed to understand the sands behavior on thermal barrier coatings (TBC) when heated to melting temperatures. Also, further research is needed with manufactured sand used in current engine testing to understand the sand ingestion discrepancies between test engines and operational engines. In this study natural …
Feasibility Considerations For A Long-Range Passive Vibrometer,
2014
Utah State University
Feasibility Considerations For A Long-Range Passive Vibrometer, Alan Marchant, Chad Fish, Jie Yao, Phillip Cunio, Wellesley Pereira
Space Dynamics Laboratory Publications
Hypertemporal imaging enables the long-range characterization of vibration modes and amplitudes of a passively illuminated structure. The vibration signature arises from modulation of the bidirectional reflection distribution function (BRDF) as the surface normal oscillates with respect to a fixed, directional source. This paper considers the instrument design characteristics and environmental factors that limit passive vibrometer performance including BRDF angle sensitivity, receiver spatial resolution, interference from atmospheric scintillation, and intrinsic detector performance. It also identifies a sensor architecture that is capable of characterizing surface vibration at amplitudes below 1 mrad rms and discuss detector technology that can further improve long-range vibrometer …
An Experimental Study Of The Implementation Of A Fluid Diode Inside A Sano Shunt,
2014
University of Nebraska-Lincoln
An Experimental Study Of The Implementation Of A Fluid Diode Inside A Sano Shunt, Patrick Austin Lane
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
Fluid diodes are fluidic devices that enhance fluid flow in a particular direction while inhibiting it in the opposite direction without the use of moving parts. This is accomplished through the use of nozzle shaped geometry on one side of the diode, and cusp shaped geometry on the opposing side. Fluid meets very little resistance as is travels though the nozzle side of the diode. The cusps on the other side of the diode reduce the effective flow area, thereby inhibiting flow. The objective of this study is to determine the effectiveness of a fluid diode installed in a reconstructed …
On Uav Robust Nonlinear Control In Presence Of Parametric Uncertainties,
2014
Embry-Riddle Aeronautical University
On Uav Robust Nonlinear Control In Presence Of Parametric Uncertainties, Vladimir V. Golubev, William Mackunis
Publications
We examine a new robust nonlinear flight control technology that employs an array of synthetic-jet micro-actuators embedded in UAV wing design in order to completely eliminate moving parts (such as ailerons) thus greatly enhancing maneuverability required for small fixed-wing air vehicles operating, e.g., in tight urban environments. Estimated fast response times are critical in mitigating gust effects while greatly improving flight stability and control. The new controller design is particularly advantageous for high levels of uncertainty and nonlinearity present both in the unsteady flowpath environment and in the embedded actuator’s response. The current work focuses on a benchmark case of …
