Experimental Measurements Of Hypseronic Instabilities Over Ogive-Cylinders At Mach 6,
2020
Air Force Institute of Technology
Experimental Measurements Of Hypseronic Instabilities Over Ogive-Cylinders At Mach 6, Jonathan Luke Hill
Theses and Dissertations
Hypersonic boundary layer transition experiments were performed in the Air Force Research Lab (AFRL) Mach 6 Ludwieg tube over a meter long ogive-cylinder model with interchangeable nose tip angles and bluntnesses. Measurements of instabilities were captured via focused laser differential interferometry (FLDI), surface mounted pressure sensors, and high speed Schlieren imagery at nominal unit Reynolds numbers ranging from 4.0*106/m to 1.4*107/m. This study attempts to isolate the effects of increasing tip angle and spherical bluntness on instabilities measured downstream over the cylindrical body of the model.
Laser Shock Peening Pressure Impulse Determination Via Empirical Data-Matching With Optimization Software,
2020
Air Force Institute of Technology
Laser Shock Peening Pressure Impulse Determination Via Empirical Data-Matching With Optimization Software, Colin C. Engebretsen
Theses and Dissertations
Laser shock peening (LSP) is a form of work hardening by means of laser induced pressure impulse. LSP imparts compressive residual stresses which can improve fatigue life of metallic alloys for structural use. The finite element modeling (FEM) of LSP is typically done by applying an assumed pressure impulse, as useful experimental measurement of this pressure impulse has not been adequately accomplished. This shortfall in the field is a current limitation to the accuracy of FE modeling, and was addressed in the current work. A novel method was tested to determine the pressure impulse shape in time and space by …
The Effect Of Passive And Active Boundary-Layer Fences On Delta Wing Performance At Low Reynolds Number,
2020
Air Force Institute of Technology
The Effect Of Passive And Active Boundary-Layer Fences On Delta Wing Performance At Low Reynolds Number, Anna C. Demoret
Theses and Dissertations
The effect of passive and active boundary-layer fences (BLFs) on performance is evaluated on a NACA 0012 delta wing (croot = 14in, ctip = 2.8in, Λ = 45°, b = 23.5in) at a Reynolds number (Re) of 5.0 x 105 based on the root chord. The performance improvements of a passive BLF are replicated and improved upon using an active flow control (AFC) fluidic fence created by a wall-normal steady-blowing jet from a slot. The application of a passive BLF at a spanwise location of 70% z/b resulted in an 8.7% increase in CLmax compared to …
Solution Anneal Heat Treatments To Enhance Mechanical Performance Of Additively Manufactured Inconel 718,
2020
Air Force Institute of Technology
Solution Anneal Heat Treatments To Enhance Mechanical Performance Of Additively Manufactured Inconel 718, David J. Newell
Theses and Dissertations
The nickel-based superalloy Inconel 718 (IN718) is an excellent candidate among aerospace alloys for laser powder-bed fusion (LPBF) manufacturing. As-built LPBF IN718 has a vertically aligned columnar (001) microstructure which translates into orthotropic mechanical behavior. The post-process heat treatments for IN718 were developed 60 years ago for wrought and cast processes and do not mitigate the columnar microstructure of the LPBF process. Recrystallization is required to remove the columnar microstructure, which would allow for parts to be fabricated on different machines or in different orientations but still achieve the same properties. This research investigated the microstructure of LPBF IN718 as …
Development Of A Small Scale Rotating Detonation Engine,
2020
Air Force Institute of Technology
Development Of A Small Scale Rotating Detonation Engine, Joseph R. Dechert
Theses and Dissertations
The Rotating Detonation Engine (RDE) has been researched extensively in recent years, but the minimum size limits of an RDE have not been well investigated. The goal of this research was to build an RDE small enough to produce a detonation frequency above 20 kHz with a single detonation wave while also reducing the engine's mass ow rate. An engine with these design characteristics would reduce hazards associated with previous RDE testing. This research objective resulted in the design of an RDE with an outer diameter sized at 28 mm using ethylene and nitrous oxide as a fuel and oxidizer. …
Detonation Confinement In A Radial Rotating Detonation Engine,
2020
Air Force Institute of Technology
Detonation Confinement In A Radial Rotating Detonation Engine, Kavi Muraleetharan
Theses and Dissertations
Radial Rotating Detonation Engines (RRDE) have provided an opportunity for use of a pressure-gain combustor in a more compact form compared to an axial RDE. A successfully tested RRDE has operated over a wide range of test conditions and produced detonation modes with one, two, and three waves. The presence of multiple waves located the detonation waves to the outer radius, while one wave modes operated closer to the inner radius. Locating the detonation wave closer to the inner diameter resulted in less time for combustion prior to the radial turbine. Subsequently, this tended to decrease efficiency. To attempt to …
Space-Based Localization Of Radio Frequency Transmitters Utilizing Macaulay Resultant And Heuristic Optimization Methods,
2020
Air Force Institute of Technology
Space-Based Localization Of Radio Frequency Transmitters Utilizing Macaulay Resultant And Heuristic Optimization Methods, Jessica M. Wightman
Theses and Dissertations
This research focuses on radio frequency geolocation of space objects utilizing space-based platforms. Geolocation has long been the solution for locating objects. In particular, this study examines the scenario of two cooperative receivers geolocating a transmitter in close proximity. An algorithm is developed to calculate the initial estimated transmitter location and projected orbital trajectory. The algorithm uses the Macaulay method of solving a system of polynomials as well as heuristic optimization techniques to locate a transmitter with respect to receivers at different time intervals. For the scenarios investigated, both Macaulay and heuristic optimization methods achieve initial relative orbit determination.
Spacecraft Position Estimation And Attitude Determination Using Terrestrial Illumination Matching,
2020
Air Force Institute of Technology
Spacecraft Position Estimation And Attitude Determination Using Terrestrial Illumination Matching, Liberty M. Shockley
Theses and Dissertations
An algorithm to conduct spacecraft position estimation and attitude determination via terrestrial illumination matching (TIM) is presented consisting of a novel method that uses terrestrial lights as a surrogate for star fields. Although star sensors represent a highly accurate means of attitude determination with considerable spaceflight heritage, with Global Positioning System (GPS) providing position, TIM provides a potentially viable alternative in the event of star sensor or GPS malfunction or performance degradation. The research defines a catalog of terrestrial light constellations, which are then implemented within the TIM algorithm for position acquisition of a generic spacecraft bus. With the algorithm …
Distributed Adaptive State Estimation And Tracking By Using Active-Passive Sensor Networks,
2020
Missouri University of Science and Technology
Distributed Adaptive State Estimation And Tracking By Using Active-Passive Sensor Networks, Akhilesh Raj, Sarangapani Jagannathan, Tansel Yucelen
Electrical and Computer Engineering Faculty Research & Creative Works
Heterogeneous sensor networks (HSN) find a wide range of applications in the field of military and civilian environments, where sensor nodes are utilized to estimate the position of a target with both dynamics and control input being unknown for the purposes of tracking. In the HSN, nodes are considered active depending upon their ability to sense the target output while the others are taken passive. Accurate estimation requires local information exchange among the spatially located sensor nodes, so that the active nodes as well as the passive nodes converge simultaneously to the same value. The local information exchange among the …
Verifying And Improving A Flight Reference System's Performance,
2020
Air Force Institute of Technology
Verifying And Improving A Flight Reference System's Performance, Loren E. Myers
Theses and Dissertations
The 746th Test Squadron (746 TS) at Holloman AFB, NM operates the Ultra High Accuracy Reference System (UHARS) as part of its mission positioning and navigation test. This research presents a method for verifying the performance of a flight reference system using a Delta-Position velocity derived from radio navigation positioning measurements. The algorithm presented may utilize Global Positioning System (GPS) or the Locata ground based positioning system. In the latter case, Locata provides a velocity truth independent from GPS. The accuracy of Locata and GPS are assessed and UHARS velocity measurements are characterized both in nominal and GPS denied applications.
Linear Regression Models Applied To Imperfect Information Spacecraft Pursuit-Evasion Differential Games,
2020
Air Force Institute of Technology
Linear Regression Models Applied To Imperfect Information Spacecraft Pursuit-Evasion Differential Games, Dax Linville
Theses and Dissertations
Within satellite rendezvous and proximity operations lies pursuit-evasion differential games between two spacecraft. The extent of possible outcomes can be mathematically bounded by differential games where each player employs optimal strategies. A linear regression model is developed from a large data set of optimal control solutions. The model is shown to map pursuer relative starting positions to final capture positions and estimate capture time. The model is 3.8 times faster than the indirect heuristic method for arbitrary pursuer starting positions on an initial relative orbit about the evader. The linear regression model is shown to be well suited for on-board …
Structural Dynamic And Inherent Damping Characterization Of Additively Manufactured Airfoil Components,
2020
Air Force Institute of Technology
Structural Dynamic And Inherent Damping Characterization Of Additively Manufactured Airfoil Components, Andrew W. Goldin
Theses and Dissertations
The push for low cost and higher performance/efficient turbine engines have introduced a new demand for novel technologies to improve robustness to vibrations resulting in High Cycle Fatigue (HCF). There have been many proposed solutions to this, some passive and some active. With the advent of Additive Manufacturing (AM), new damping techniques can now be incorporated directly into the design and manufacture process to suppress the vibrations that create HCF. In this study, this novel unfused pocket damping technology is applied to a blade structure and the resulting damping effectiveness is quantified. The application of this technology to complex geometries …
Comparison Of Signaling Profiles In The Low Dose Range Following Low And High Let Radiation,
2020
Lawrence Berkeley National Laboratory
Comparison Of Signaling Profiles In The Low Dose Range Following Low And High Let Radiation, Deepa M. Sridharan, Lung-Chang Chien, Francis A. Cucinotta, Janice M. Pluth
Environmental & Global Health Faculty Research
During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82–6, was exposed to a range of lower doses (0.05–0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si …
Angular Correlation Using Rogers-Szego-Chaos,
2020
Missouri University of Science and Technology
Angular Correlation Using Rogers-Szego-Chaos, Christine Schmid, Kyle J. Demars
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Polynomial chaos expresses a probability density function (pdf) as a linear combination of basis polynomials. If the density and basis polynomials are over the same field, any set of basis polynomials can describe the pdf; however, the most logical choice of polynomials is the family that is orthogonal with respect to the pdf. This problem is well-studied over the field of real numbers and has been shown to be valid for the complex unit circle in one dimension. The current framework for circular polynomial chaos is extended to multiple angular dimensions with the inclusion of correlation terms. Uncertainty propagation of …
Dislocation-Oxide Interaction In Y2o3 Embedded Fe: A Molecular Dynamics Simulation Study,
2020
Missouri University of Science and Technology
Dislocation-Oxide Interaction In Y2o3 Embedded Fe: A Molecular Dynamics Simulation Study, M. Mustafa Azeem, Qingyu Wang, Zhongyu Li, Yue Zhang
Civil, Architectural and Environmental Engineering Faculty Research & Creative Works
Oxide dispersed strengthened (ODS) steel is an important candidate for Gen-IV reactors. Oxide embedded in Fe can help to trap irradiation defects and enhances the strength of steel. It was observed in this study that the size of oxide has a profound impact on the depinning mechanism. For smaller sizes, the oxide acts as a void; thus, letting the dislocation bypass without any shear. On the other hand, oxides larger than 2 nm generate new dislocation segments around themselves. The depinning is similar to that of Orowan mechanism and the strengthening effect is likely to be greater for larger oxides. …
Ground And In-Flight Calibration Of The Osiris-Rex Camera Suite,
2020
University of Arizona
Ground And In-Flight Calibration Of The Osiris-Rex Camera Suite, D. R. Golish, C. Drouet D'Aubigny, B. Rizk, D. N. Dellagiustina, P. H. Smith, K. Becker, N. Shultz, T. Stone, M. K. Barker, E. Mazarico, E. Tatsumi, R. W. Gaskell, L. Harrison, C. Merrill, C. Fellows, B. Williams, S. O'Dougherty, Michael Whitely, Jed Hancock, B. E. Clark, C. W. Hergenrother, D. S. Lauretta
Space Dynamics Laboratory Publications
The OSIRIS-REx Camera Suite (OCAMS) onboard the OSIRIS-REx spacecraft is used to study the shape and surface of the mission’s target, asteroid (101955) Bennu, in support of the selection of a sampling site. We present calibration methods and results for the three OCAMS cameras—MapCam, PolyCam, and SamCam—using data from pre-flight and in-flight calibration campaigns. Pre-flight calibrations established a baseline for a variety of camera properties, including bias and dark behavior, flat fields, stray light, and radiometric calibration. In-flight activities updated these calibrations where possible, allowing us to confidently measure Bennu’s surface. Accurate calibration is critical not only for establishing a …
Differential Vector Phase Locked Loop Gps Reception Method,
2020
Air Force Institute of Technology
Differential Vector Phase Locked Loop Gps Reception Method, James Brewer, John F. Raquet
AFIT Patents
A method for enhancing GPS location accuracy includes providing a base station receiver having a known surveyed location, and a roving receiver at a location distinct from the base station receiver. The method further includes receiving single-frequency code and carrier-phase measurements from the base station, and translating the single-frequency code and carrier-phase measurements to a Kalman filter-predicted location of the roving receiver. The translated single frequency code and carrier phase measurements are used to generate a local replica of the Kalman filter-predicted location signals for each channel of the roving receiver. The method further includes correlating the local replicas with …
Congressional Committee Resources On Space Policy During The 115th Congress (2017-2018): Providing Context And Insight Into U.S. Government Space Policy,
2020
Purdue University
Congressional Committee Resources On Space Policy During The 115th Congress (2017-2018): Providing Context And Insight Into U.S. Government Space Policy, Bert Chapman
Libraries Faculty and Staff Scholarship and Research
Article 1 of the US Constitution assigns the US Congress numerous responsibilities. These include creating new laws, revising existing laws, funding government programs, and conducting oversight of these programs' performance. Oversight of US Government agency space policy programs is executed by various congressional space policy committees, including the House and Senate Science Committees, Armed Services, and Appropriations Committees. These committees conduct many public hearings on space policy which invite witnesses to testify on US space policy programs and feature debate on the strengths and weaknesses of these programs. Documentation produced by these committees is widely available to the public, except …
Characterization Of Inertial Particles In The Turbulent Wake Of A Porous Disk,
2020
Portland State University
Characterization Of Inertial Particles In The Turbulent Wake Of A Porous Disk, Kristin Nichole Travis
Dissertations and Theses
This study presents the findings of a wind tunnel experiment investigating the behaviour of micrometric inertial particles in the turbulent wake of a stationary porous disk. Various concentrations [Φv ∈ (2.95 x 10-6 - 1.22 x 10-5)] of polydisperse water droplets (diameter 13-41 µm) are compared to sub-inertial tracer particles. Hot-wire anemometry, phase Doppler interferometry and particle image velocimetry were implemented in the near and far wake regions to study the complex dynamics of the particles. Turbulence statistics and particle size distributions are presented and used to explore the particle wake interaction.
Near-Field Pressure Signature Splicing For Low-Fidelity Design Space Exploration Of Supersonic Aircraft,
2020
Utah State University
Near-Field Pressure Signature Splicing For Low-Fidelity Design Space Exploration Of Supersonic Aircraft, Christian R. Bolander, Douglas F. Hunsaker
Mechanical and Aerospace Engineering Student Publications and Presentations
As interest in supersonic overland flight intensifies, new ways to meet government restrictions on sonic boom loudness must be implemented. Low-fidelity aerodynamic tools, such as PANAIR, can estimate the near-field pressure signature that ultimately determines the loudness of the sonic boom at the ground. These tools can greatly benefit the exploration of large design spaces due to their computational efficiency. One of the limitations of low-fidelity tools is the accuracy of the solution produced, which is dependent on the fundamental physical assumptions made in the development of the governing equations. If flow patterns are produced that severely violate these fundamental …
