Search Results (1 - 25 of 28 Results)

Sort By  
Sort Dir
 
Results per page  

BASCIANO JR., THOMAS E.THE UNIVERSITY OF CINCINNATI H.A.V.O.C. SOUNDING ROCKET PROJECT DESIGN STUDY AND FINAL RESULTS
MS, University of Cincinnati, 2001, Engineering : Aerospace Engineering
The thesis presented here is meant to give an overview of the objectives and technical aspects of designing, testing, and launching a sounding rocket. It is a compilation of the many lessons learned by the University of Cincinnati Student Sounding Rocket Team. The information contained in this thesis will help new student groups design launch vehicles and understand the philosophy behind NASA support, testing and launching of sounding rockets.

Committee:

Dr. David L. Richardson (Advisor)

Subjects:

Engineering, Aerospace

Keywords:

sounding rocket; rocket design; student aerospace projects; student rockets; college aerospace programs

Barritt, Brian JamesThe Modeling, Simulation, and Operational Control of Aerospace Communication Networks
Doctor of Philosophy, Case Western Reserve University, 2017, EECS - Computer Engineering
A paradigm shift is taking place in aerospace communications. Traditionally, aerospace systems have relied upon circuit switched communications; geostationary communications satellites act as bent-pipe transponders and are not burdened with packet processing and the complexity of mobility in the network topology. But factors such as growing mission complexity and NewSpace development practices are driving the rapid adoption of packet-based network protocols in aerospace networks. Meanwhile, several new aerospace networks are being designed to provide either low latency, high-resolution imaging or low-latency Internet access while operating in non-geostationary orbits -- or even lower, in the upper atmosphere. The need for high data-rate communications in these networks is simultaneously driving greater reliance on beamforming, directionality, and narrow beamwidths in RF communications and free-space optical communications. This dissertation explores the challenges and offers novel solutions in the modeling, simulation, and operational control of these new aerospace networks. In the concept, design, and development phases of such networks, the dissertation motivates the use of network simulators to model network protocols and network application traffic instead of relying solely on link budget calculations. It also contributes a new approach to network simulation that can integrate with spatial temporal information systems for high-fidelity modeling of time-dynamic geometry, antenna gain patterns, and wireless signal propagation in the physical layer. And towards the operational control of such networks, the dissertation introduces Temporospatial Software Defined Networking (TS-SDN), a new approach that leverages predictability in the propagated motion of platforms and high-fidelity wireless link modeling to build a holistic, predictive view of the accessible network topology and provides SDN applications with the ability to optimize the network topology and routing through the direct expression of network behavior and requirements. This is complemented by enhancements to the southbound interface to support synchronized future enactment of state changes in order to tolerate varying delay and disruption in the control plane. A high-level overview of an implementation of Temporospatial SDN at Alphabet is included. The dissertation also describes and demonstrates the benefits of the application of TS-SDN in Low Earth Orbiting (LEO) satellite constellations and High Altitude Platform Systems (HAPS).

Committee:

Frank Merat (Committee Chair); Rabinovich Michael (Committee Member); Daniel Saab (Committee Member); Mark Allman (Committee Member)

Subjects:

Aerospace Engineering; Computer Engineering; Computer Science

Keywords:

temporospatial; SDN; TS-SDN; aerospace; networks; satellites; LEO; NGSO; constellations; HAPS; high-altitude platforms; STK; wireless; mesh; networking; modeling; simulation; ns-3

Buettner, Robert W.Dynamic Modeling and Simulation of a Variable Cycle Turbofan Engine with Controls
Master of Science in Mechanical Engineering (MSME), Wright State University, 2017, Mechanical Engineering
Next generation aircraft (especially combat aircraft) will include more technology and capability than ever before. This increase in technology comes at the price of higher electrical power requirements and increased waste heat that must be removed from components to avoid overheating induced shutdowns. To help combat the resulting power and thermal management problem, a vehicle level power and thermal management design and optimization toolset was developed in MATLAB®/Simulink®. A dynamic model of a three-stream variable cycle engine was desired to add to the capabilities of the power and thermal management toolset. As an intermediate step to this goal, the dynamic mixed-flow turbofan engine model previously developed for the toolset was modified with an afterburner, a variable geometry nozzle, and a new controller to automatically control the new components. The new afterburning turbofan engine model was tested for a notional mission profile both with and without power take-off. This testing showed that the afterburning turbofan engine model and controller were successful enough to justify moving on to the development of the three-stream variable cycle engine model. The variable cycle engine model was developed using the components of the afterburning turbofan model. The compressor and turbine components were modified to use maps that incorporate the effects of variable inlet guide vane angles. The new engine model and components were sized by attempting to match data from a Numerical Propulsion System Simulation model with similar architecture. A previously developed heat exchanger model was added to the third stream duct of the new engine model. Finally, a new simplified controller was developed for the variable cycle engine model based on the controller developed for the afterburning turbofan model. The new variable cycle engine model was tested for a notional mission profile for five cases. The first case operated the engine model without power take-off and with the third stream heat exchanger removed. The second case added shaft power take-off. The third and fourth cases did away with the power take-off and added the heat exchanger to the engine model with two different hot-side mass flow rate conditions. The fifth case tested the engine with both power take-off and the third stream heat exchanger. The results were promising, showing that the variable cycle engine model had variable cycle tendencies even with a minimum of controlled variable geometry features. The controller was found to be effective, though in need of upgrades to take advantage of the benefits offered by a variable cycle engine. Additionally, it was found that both power take-off and heat rejection to the third stream impact the entire engine cycle.

Committee:

Rory Roberts, Ph.D. (Advisor); Mitch Wolff, Ph.D. (Committee Member); Rolf Sondergaard, Ph.D. (Committee Member); Robert Fyffe, Ph.D. (Other)

Subjects:

Aerospace Engineering; Mechanical Engineering

Keywords:

mechanical engineering; aerospace engineering

Sharma, Arvindh RLiquid Jet in Oscillating Crossflow: Characterization of Near-Field and Far-Field Spray Behavior
MS, University of Cincinnati, 2015, Engineering and Applied Science: Aerospace Engineering
An experimental investigation of response characteristics of a liquid jet in oscillating crossflow is undertaken to understand the behavior of a liquid fuel spray in the presence of combustion instabilities. The effect of crossflow oscillations on the liquid jet is studied in the near-field (within x/d˜8) and the far-field (x/d˜50) spray region. Experiments are conducted in bag breakup, multimode and shear breakup regimes by varying crossflow Weber number from 18 to 250, while momentum flux ratio is varied between 10 and 30. The crossflow is modulated in the frequency range of 90 Hz to 450 Hz, with modulation level varying between 5% and 20%, using a mechanical modulating device. High speed shadowgraph is employed to study the near-field and far-field spray movement while intensified high-speed camera images of laser Mie-scattering intensity are utilized in studying the spray cross-section in the far-field. A technique to extract time-varying momentum flux ratio from the windward trajectory of liquid jet in the near-field is developed. The response of near-field spray is quantified in terms of a ratio of the observed momentum flux ratio extracted from a correlation of upper penetration to the expected momentum flux ratio corresponding to the instantaneous crossflow velocity. The liquid jet penetration is found to respond to oscillations in the crossflow at all oscillation frequencies in the near-field. The strength of the response is found to be mainly dependent on the crossflow oscillation frequency, with the strength of response decreasing with increase in frequency. The momentum flux ratio and the modulation level are found to have relatively negligible effects on the level of normalized spray response. The spray response in the far-field is studied by observing the high-speed shadowgraphs and Mie-scattering intensity images at an axial distance of x/d=50. The spray field in the axial location is divided into ten bins and the intensity change in each bin is analyzed to quantify spray response. The spray is found to respond to crossflow oscillations by exhibiting a “flapping” behavior in the far-field. The binning method and Mie-scattering intensity image analysis suggest that the spray oscillation decreases with increasing crossflow frequency. The spray width and height fluctuate in the spray cross-section in the presence of crossflow oscillation. The amplitude of spray height fluctuation is higher in low frequency crossflow, and decreases with an increase in frequency. The total Mie-scattering intensity in the cross-section also exhibits a periodic response to crossflow oscillation, suggesting that the droplet characteristics are affected by crossflow fluctuation. The liquid spray near-field and far-field study indicates that the crossflow oscillation frequency plays a large role in determining spray response.

Committee:

Jongguen Lee, Ph.D. (Committee Chair); Milind Jog, Ph.D. (Committee Member); Mark Turner, Sc.D. (Committee Member)

Subjects:

Aerospace Materials

Keywords:

Jet in crossflow;Inlet air modulation;Oscillating crossflow;Liquid spray penetration;Near-field spray;Far-field spray;Aerospace Propulsion;Experimental Fluid Dynamics

Mustafa, MansoorInvestigation into Offset Streams for Jet Noise Reduction
Master of Science, The Ohio State University, 2015, Aero/Astro Engineering
This effort investigates the near field behavior of two ideally-expanded subsonic dual-stream jets. One case implements a traditional symmetric, concentric dual-stream nozzle configuration while the other imposes an asymmetric, eccentric layout to model the behavior of an offset stream. The essence of an offset stream is to force an uneven azimuthal distribution of the secondary coflow and create an outside stream that varies in thickness. Past studies have shown a benefit in acoustic propagation in the direction of the thickest coflow and the present work further analyzes this phenomenon. A LES (Large Eddy Simulation) approach is implemented to run the simulations for both cases and a number of qualitative and quantitative analyses tools are used for post-processing. A reduction in the noise levels for the lower, thicker side of the eccentric nozzle is observed in comparison to the baseline concentric case. Examination of the mean flow behavior shows a shorter, thinner primary potential core for the offset case and a faster axial velocity decay rate. The asymmetric distribution of the coflow causes varying velocity profiles in the radial direction for the top and bottom regions and consequently produces unique flow features on either side. Lower levels of shear stress and slower decay rates lead to less turbulence production on the lower side of the eccentric nozzle. An investigation into the flow structures reveals lower vorticity and weaker convective structures on the bottom which influences propagation in that direction. Two-point correlation analysis reveals the presence of smaller turbulence scales in the lower, thicker portion of the eccentric case. This is further confirmed by an Empirical Mode Decomposition (EMD) study that shows lower frequency ranges dominate the concentric near field in comparison to the eccentric. The combination of these unique features demonstrate the principles behind the acoustic benefit of implementing offset stream flows in dual-stream nozzle configurations.

Committee:

Datta Gaitonde (Advisor); Mei Zhuang (Committee Member)

Subjects:

Aerospace Engineering

Keywords:

offset; noise reduction; jets; aerospace; aerodynamics; LES; computational simulation; jet noise; eccentric; concentric; dual-stream; nozzle

El Rimawi, NidalDevelopment of an Audio Visual Tool for Medical Training at Kennedy Space Center
Master of Science (MS), Wright State University, 2006, Aerospace Medicine
El Rimawi, Nidal. M.D. M.S., Department of Aerospace Medicine, Wright State University, 2006. Development of an Audio-Visual Tool for Medical Training at Kennedy Space Center As part of an effort to improve efficiency of space-flight medical support at Kennedy Space Center, a training video was created to replace a series of lectures given before a launch or landing of the Space Shuttle. The video was designed to familiarize volunteer physicians from around the country with the specific emergency response protocols for a Space Shuttle launch or landing emergency at Kennedy Space Center. The methods used were consistent with standard film making techniques as outlined in several film making texts. The Production was divided into three phases; A pre-production phase wherein the research, screenwriting and production planning took place, a Production phase consisting of the actual filming of the various scenes in the script and finally, a post-production phase during which the video was edited, music was added and the finished video screened and copied. The result was that the video was completed in seven months with the participation of over a hundred people. The final video won several awards for educational and government film and met all expectations of the author and the medical department. It was ultimately given to the Aerospace Medicine Residency program at Wright State University and to the medical staff at Kennedy Space Center.

Committee:

Robin Dodge (Advisor)

Keywords:

Aerospace Medicine; Space Medicine; Medical Education; Audio-Visual Tool; Kennedy Space Center; Space Medical Support; Emergency Medicine; Spaceflight Support; Spaceflight Emergencies; Film Production

Jones, George PaulSelecting company research and development projects in the aerospace industry /
Doctor of Philosophy, The Ohio State University, 1965, Graduate School

Committee:

Not Provided (Other)

Subjects:

Economics

Keywords:

Aerospace industries;Aeronautics

Stanfield, Scott AlanA SPECTROSCOPIC INVESTIGATION OF A SURFACE-DISCHARGE-MODE, DIELECTRIC BARRIER DISCHARGE
Doctor of Philosophy (PhD), Wright State University, 2009, Engineering PhD

The use of aerodynamic actuators, such as leading edge slats, trailing edge flaps, roughing strips and ailerons interact with the air during flight, providing maneuverability for air vehicles. These mechanical devices have many inherent, detrimental attributes, such as space requirements on the wing, added wing weight, second response times, increased drag, and increased airframe vibration, resulting in the production of noise. The potential to eliminate or improve upon these detrimental attributes may be realizable by replacing the current mechanical actuators with plasma actuators. Specifically, the surface-discharge-mode, dielectric barrier discharge (SDBD), plasma actuator has a response time on the order of microseconds to milliseconds, does not increase vibration by mounting flush to the wing surface, does not increase drag, and adds negligible weight to the wing. Unfortunately, these devices are not yet powerful enough to perform many of the tasks required for aerodynamic applications; however, they have demonstrated the potential to do so, providing motivation for the current study. Currently, the approach of the research community has focused on coordinating studies designed to determine the physics of the device and parametric studies to determine optimal configurations required for immediate application.

In this work, an experimentally based study utilizing optical emission spectroscopy, current-voltage measurements, and a force balance have been successfully applied, contributing new, specific detail to the morphology and characterization of the SDBD. The results of this study were tailored to aid the development of the appropriate, essential physics required for computational modeling of the SDBD. Initially, force measurements of the induced thrust were obtained to demonstrate how week the induced thrust is, justifying the need for a fundamental study. These results are also important in understanding an apparent discrepancy in the reported dependence of the induced thrust upon applied voltage amplitude.

Electrical properties of the device such as breakdown voltage, surface charge voltage, effective capacitance with and without a discharge, electrical current, dissipated power, and the details of breakdown are measured as a function of applied voltage. The measured surface potential is of particular interest because it provides information about one of the boundary conditions needed to solve Maxwell equation’s of electromagnetics. Measurements showed that the surface charge potential along the dielectric surface is around 4000 and 4200 volts for the positive and negative voltage half-cycle, respectively, at an applied potential of 6000 volts.

Properties determined from emission, including the relative concentrations of N2(C3Πu) and N2+(B2Πg), and rotational and vibrational temperatures, as a function of position, voltage amplitude and phase of the driving voltage, have been measured. The spatially resolved relative concentrations of N2(C3Πu) and N2+(B2Πg) are useful in demonstrating the difference in structure between the discharge occurring during the positive voltage half-cycle versus the discharge occurring during the negative voltage half-cycle. The rotational temperature obtained from the 1st negative band system of N2+ was shown to be significantly greater than the rotational temperature obtained from the 2nd positive band system of N2 and was shown to be a direct consequence of the local electric field. This is shown to be important when calculating the rate constants for reactions involving ions and neutrals. For example, neglecting this deviation in temperature results in an order-of-magnitude difference in rate constants. Therefore in modeling the plasma, measurements show it is important to calculate the ion temperature via the Wannier relationship and then calculate the rate constants.

The details of these experiments including set-up, results, significance and discussion, along with an exhaustive summary of the current understanding of the surface-discharge-mode, dielectric barrier discharge, constitutes the bulk of this dissertation.

Committee:

James Menart, PhD (Advisor); William Bailey, PhD (Committee Member); Jerry Clark, PhD (Committee Member); Roger Kimmel, PhD (Committee Member); Joseph Shang, PhD (Committee Member); Henry Young, PhD (Committee Member)

Subjects:

Electrical Engineering; Fluid Dynamics; Mechanical Engineering; Physics

Keywords:

DBD; optical emission spectroscopy; rotational temperature; vibrational temperature; dielectric barrier discharge; aerospace

Nguyen, QuynhGiao N.High Temperature Volatility and Oxidation Measurements of Titanium and Silicon Containing Ceramic Materials
Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2008, College of Science
Titanium (Ti) and silicon (Si) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. A continuous exterior oxide layer is desirable to reduce the oxidation rate of these two materials. At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluated several hot-pressed Ti and Si-containing compositions at high temperatures as a function of oxidation resistance. This study also evaluated cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400°C - 1200°C in water containing environments to determine the volatile hydoxyl species using the transpiration method. The water content ranged from 0-76 mole % and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Results indicate that oxygen is not a key contributor at these temperatures and a volatile Ti-O-H species has been identified.

Committee:

Lily M. Ng, PhD (Committee Chair); James L. Smialek, PhD (Advisor); Kang N. Lee, PhD (Committee Member); John F. Turner II, PhD (Committee Member); Mary V. Zeller, PhD (Committee Member)

Subjects:

Aerospace Materials; Chemistry; Materials Science

Keywords:

aerospace; ceramic; combustion environment; high temperature; hydroxyl species; oxidation; materials; Si; silicon; titanium dioxide; TiO2; Ti-O-H; transpiration method; transpiration technique; volatility; water vapor

Singhal, Achal SudhirUnsteady Flow Separation Control over a NACA 0015 using NS-DBD Plasma Actuators
Master of Science, The Ohio State University, 2017, Mechanical Engineering
Flow field surrounding a moving body is often unsteady. This motion can be linear or rotary, but the latter will be the primary focus of this thesis. Unsteady flows are found in numerous applications, including sharp maneuvers of fixed wing aircraft, biomimetics, wind turbines, and most notably, rotorcraft. Unsteady flows cause unsteady loads on the immersed bodies. This can lead to aerodynamic flutter and mechanical failure in the body. Flow control is hypothesized to reduce the load hysteresis, and is achieved in the present work via nanosecond pulse driven dielectric barrier discharge (NS-DBD) plasma actuators. These actuators have been effective in the delay or mitigation of static stall. The flow parameters were varied by Reynolds number (Re=167,000-500,000), reduced frequency (k=0.025-0.075), and excitation Strouhal number (Ste=0-10). It was observed that the trends of Ste were similar for all combinations of Re and k, and three major conclusions were drawn. It was first observed that low Strouhal number excitation (Ste<0.5) results in oscillatory aerodynamic loading in the stalled stage of dynamic stall. At high Strouhal number excitation (Ste>2), this behavior is not observed, as in the static stall cases. Second, all excitation resulted in earlier flow reattachment. Lastly, it was shown that excitation resulted in reduced aerodynamic hysteresis and dynamic stall vortex strength. The decrease in the strength of the dynamic stall vortex is achieved by the formation of excited structures that bleed the leading edge vorticity prior to the ejection of the dynamic stall vortex. At sufficiently high excitation Strouhal numbers (Ste˜10), the dynamic stall vortex was suppressed.

Committee:

Mo Samimy (Advisor); Datta Gaitonde (Committee Member); James Gregory (Committee Member)

Subjects:

Aerospace Engineering

Keywords:

Flow Control; Aerospace; Dynamic Stall; Plasma Actuators

Raja, Muneeb MasoodExtended Kalman Filter and LQR controller design for quadrotor UAVs
Master of Science in Electrical Engineering (MSEE), Wright State University, 2017, Electrical Engineering
A quadrotor is a unique class of UAVs with vertical take off and landing (VTOL) capability and has attracted significant attention due to its importance in various applications. This thesis presents the design and experimental implementation of Extended Kalman Filters (EKFs) to estimate the states of a quadrotor and a Linear Quadratic Regulator (LQR) controller with integral action to meet the desired control objectives. In case of the Extended Kalman Filters, two different situations are considered: (1) all the states including the Inertial Measurement Unit (IMU) biases are estimated; (2) only the attitude, altitude, and vertical velocity are estimated. The second case is added as a safety feature to provide enough feedback signals to stabilize and land the quadrotor in the event of a position measurement loss, e.g. from a GPS due to jamming. A double loop control structure is implemented using an LQR controller with integral action, the inner loop contains the attitude and the altitude control, and the outer loop consists of x and y translational positions control. Finally, some preliminary results on the integration of C codes with Simulink using C MEX S-functions is described. A C library of a laser rangefinder sensor is transferred to a C MEX S-function to generate a 2D map of the environment using the laser sensor distance measurements to identify obstacles present within the range of the sensor. The concept of multi-threading and the integration of pthread library with Simulink using C MEX S-function are also described.

Committee:

Xiaodong Zhang, Ph.D. (Advisor); Kuldip Rattan, Ph.D. (Committee Member); Jonathan Muse, Ph.D. (Committee Member)

Subjects:

Aerospace Engineering; Electrical Engineering

Keywords:

electrical engineering; aerospace engineering

Sinnamon, Ryan R.Analysis of a Fuel Cell Combustor in a Solid Oxide Fuel Cell Hybrid Gas Turbine Power System for Aerospace Application
Master of Science in Engineering (MSEgr), Wright State University, 2014, Mechanical Engineering
Over the last few years, fuel cell technology has significantly advanced and has become a mode of clean power generation for many engineering applications. Currently the dominant application for fuel cell technology is with stationary power generation. Very little has been published for applications on mobile platforms, such as unmanned aerial vehicles. With unmanned aerial vehicles being used more frequently for national defense and reconnaissance, there is a need for a more efficiency, longer endurance power system that can support the increased electrical loads onboard. It has already been proven by others that fuel cell gas turbine hybrid systems can achieve higher system efficiencies at maximum power. The integration of a solid oxide fuel cell combustor with a gas turbine engine has the potential to significantly increase system efficiency at off-design conditions and have a higher energy density compared to traditional heat based systems. This results in abilities to support larger onboard electrical loads and longer mission durations. The majority of unmanned air vehicle mission time is spent during loiter, at part load operation. Increasing part load efficiency significantly increases mission duration and decreases operational costs. These hybrid systems can potentially have lower power degradation at higher altitudes compared to traditional heat based propulsion systems. The purpose of this research was to analyze the performance of a solid oxide fuel cell combustor hybrid gas turbine power system at design and off-design operating conditions at various altitudes. A system level MATLAB/Simulink model has been created to analyze the performance of such a system. The hybrid propulsion system was modeled as an anode-supported solid oxide fuel cell integrated with a commercially-available gas turbine engine used for remote control aircraft. The design point operation of the system was for maximum power at sea-level. A steady-state part load performance analysis was conducted for various loads ranging from 10 = L = 100 percent design load at varying altitudes ranging from 0 = Y = 20,000 feet. This analysis was conducted for four different fuel types: humidified hydrogen, propane, methane, and JP-8 jet fuel. The analysis showed that maximum system efficiency was achieved at loads of 40 = L = 60 percent design load at each altitude and fuel type. The system utilizing methane fuel, internally-steam reformed within the fuel cell, proved to have the highest system efficiency of 46.8 percent (LHV) at a part load of L = 60 percent and an altitude of Y = 20,000 feet.

Committee:

Rory Roberts, Ph.D. (Advisor); Scott Thomas, Ph.D. (Committee Member); Hong Huang, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

SOFC; Fuel Cell; Aerospace; UAV; Hybrid Power System; Unmanned Aircraft;

Gordon, Neal AMaterial Health Monitoring of SIC/SIC Laminated Ceramic Matrix Composites With Acoustic Emission And Electrical Resistance
Master of Science in Engineering, University of Akron, 2014, Mechanical Engineering
Ceramic matrix composites (CMC) composed of Hi-Nicalon Type S™ fibers, a boron-nitride (BN) interphase, and pre-impregnated (pre-preg) melt-infiltrated silicon / silicon-carbide (SiC) matrix have been studied at room-temperature consisting of unidirectional and cross-ply laminates. Quasi-static, hysteretic and uniaxial tensile tests were done in conjunction with a variety of temporary, laboratory-based material health-monitoring techniques such as electrical resistance (ER) and acoustic emission (AE). The mechanical stress-strain relationship paired with electrical and acoustic measurements were analyzed to expand upon current composite knowledge to develop a more fundamental understanding of the failure of brittle matrix laminates, their constituents, and interactions. In addition, a simple but effective method was developed to allow visual confirmation of post-test crack spacing via microscopy. To enhance fidelity of acquired data, some specimens were heat-treated (i.e. annealing) in order to alter the residual stress state. Differences in location, acoustic frequency, and magnitude of matrix cracking for different lay-ups have been quantified for unidirectional and [0/90] type architectures. Empirical results shows complex hysteretic mechanical and electrical behavior due to fiber debonding and frictional sliding of which no general model exists to capture the essence of this CMC system. The results of this work may be used in material research and development, stress analysis and design verification, manufacturing quality control, and in-situ system and component monitoring.

Committee:

Gregory Morscher, Dr. (Advisor); Wieslaw Binienda, Dr. (Committee Member); Tirumalai Srivatsan, Dr. (Committee Member)

Subjects:

Aerospace Materials; Mechanical Engineering

Keywords:

Ceramic Matrix Composite,CMC;Aerospace;Non-Destructive Evaluation,NDE;Structural Health Monitoring,SHM;Composites;Acoustic Emission;Electrical Resistance

Ambro, SharonTwo Technical Communication Projects Performed During an Internship with Analex Corporation
Master of Technical and Scientific Communication, Miami University, 2002, Technical and Scientific Communication
This report describes and analyzes my work as a technical writer for Analex Corporation during my 16-week Master of Technical and Scientific Communication internship period. Analexs Cleveland branch works in the aerospace industry and primarily contracts for NASAs Glenn Research Center. This report details my work on two projects during this time: Combustion Module-2 (CM-2) and Fluids and Combustion Facility (FCF). For the CM-2 project, I wrote procedures for astronauts to run combustion science experiments on board the space shuttle. For the FCF project, I edited requirements documents for experiment hardware that will be on board the International Space Station. This report discusses background information for each project and analyzes my writing and editing processes in terms of the Anderson Problem-Solving Model for technical communication. The final chapter describes my learning experiences and how these experiences contributed to my development as a technical communicator.

Committee:

Paul Anderson (Advisor)

Keywords:

Technical Communication; Technical Writing; Scientific Communication; Science Writing; Aerospace Industry; Problem-Solving Model

Rinehart, Aidan WalkerA Characterization of Seal Whisker Morphology and the Effects of Angle of Incidence on Wake Structure
Master of Science in Mechanical Engineering, Cleveland State University, 2016, Washkewicz College of Engineering
Seal whiskers have been found to produce unique wake flow structures that minimize self-induced vibration and reduce drag. The cause of these wake features are due to the peculiar three-dimensional morphology of the whisker surface. The whisker morphology can be described as an elliptical cross section with variation of diameter in the major and minor axis along the length and, angle of incidence, rotation of the elliptical plane with respect to the whisker axis, α at the peak and β at the trough. This research provided a more complete morphology characterization accomplished through CT scanning and analysis of 27 harbor and elephant seal whisker samples. The results of this study confirmed previously reported values and added a characterization of the angle of incidence finding that the majority of angles observed fall within ±5° and exhibit a random variation in magnitude and direction along the whisker length. While the wake effects of several parameters of the whisker morphology have been studied, the effect of the angle of incidence has not been well understood. This research examined the influence of the angle of incidence on the wake flow structure through series of water channel studies. Four models of whisker-like geometries based on the morphology study were tested which isolate the angle of incidence as the only variation between models. The model variations in angle of incidence selected provided a baseline case (α = β = 0°), captured the range of angles observed in nature (α = β = -5°, and α = β = -15°), and investigated the influence of direction of angle of incidence (α = -5°, β = -5°). The wake structure for each seal whisker model was measured through particle image velocimetry (PIV). Angle of incidence was found to influence the wake structure through reorganization of velocity field patterns, reduction of recovery length and modification of magnitude of Tu. The results of this research helped provide a more complete understanding of the seal whisker morphology relationship to wake structure and can provide insight into design practices for application of whisker-like geometry to various engineering problems.

Committee:

Wei Zhang, PhD (Advisor); Ibrahim Mounir, PhD (Committee Member); Shyam Vikram, PhD (Committee Member)

Subjects:

Aerospace Engineering; Aquatic Sciences; Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

seal; whisker; PIV; biomimicry; fluid dynamics; particle image velocimetry; bio-engineering; engineering; mechanical engineering; aerospace engineering; experimental fluid dynamics;

Olsen, Kirk WilliamFatigue Crack Growth Analyses and Experimental Verification of Aerospace Threaded Fasteners
Doctor of Philosophy, Case Western Reserve University, 2004, Mechanical Engineering
Because fatigue crack growth in a threaded fastener can cause the loss of an aircraft, damage tolerant analyses are required. Therefore, aerospace designers must be able to perform accurate crack growth analyses on fasteners. However, threaded fasteners are difficult to analyze and fastener fatigue crack growth data is scant, especially for non-dimensionalized crack depths of (a/d) < 0.1. The objective of this research is to determine the stress intensity multiplication factor (Y), as a function of a/d, in the threads of a nut loaded, aerospace, roll-threaded bolt under tensile fatigue conditions as a/d approaches zero. Y(a/d) can then be used to improve the accuracy of fatigue crack growth life estimations. The research objectives were achieved through bolt material characterization, cyclic testing, and numeric modeling. X-ray diffraction was used to determine the residual stress within the thread root of the test bolts. Unflawed and flawed aerospace bolts were fatigue tested at a maximum stress (S) ranging from the ultimate tensile strength (UTS) to the surface endurance limit of the test bolt and loading ratios of 0.1 < R < 0.9. The following data was collected: cycles to failure (Nf), fracture surface striation spacing, and crack front shape. The numeric studies accounted for residual stress. The fracture analysis code, FRANC3D, was used because it could predict crack front shape and stress intensity factor (K). The thread root, residual compressive stress reached 65% of the material UTS. The S- Nf plots showed test bolt fatigue strength decreased as R decreased and 10% reduction in allowable fatigue stress due to flaws. The shape of the crack front in the unflawed and flawed stainless steel, test bolts were different and both changed as the crack grew. The developed numeric models also predicted a changing crack front and the stress intensity factor. By curve fitting the numeric and experimental data, a new Y(a/d) solution was determined. The use of this Y(a/d) solution produces conservative crack growth life estimates. Based on test bolt fatigue data, greater accuracy may be possible with this Y(a/d) solution.

Committee:

Clare Rimnac (Advisor)

Keywords:

Fatigue Crack Growth; Aerospace Threaded Fasteners; FRANC3D; Bolts

Guarendi, Andrew NNumerical Investigations of Magnetohydrodynamic Hypersonic Flows
Master of Science, University of Akron, 2013, Mechanical Engineering
Numerical simulations of magnetohydrodynamic (MHD) hypersonic flow are presented for both laminar and turbulent flow over a cylinder and flow entering a scramjet inlet. ANSYS CFX is used to carry out calculations for steady flow at hypersonic speeds (Mach number > 5). The low magnetic Reynolds number (<<1) calculated based on the velocity and length scales in this problem justifies the quasistatic approximation, which assumes negligible effect of velocity on magnetic fields. Therefore the governing equations employed in the simulations are the compressible Navier-Stokes and the energy equations with MHD-related source terms such as Lorentz force and Joule dissipation. Turbulence effects are accounted for when applicable and multiple turbulence models are compared. The results demonstrate the ability of the magnetic field to affect the flowfield, and variables such as location and magnitude of the applied magnetic field are examined. An examination of future work is provided through the implementation of a semi-discrete central scheme in-house code toward the solution of the Orszag-Tang vortex system.

Committee:

Abhilash Chandy, Dr. (Advisor); Scott Sawyer, Dr. (Committee Member); Alex Povitsky, Dr. (Committee Member)

Subjects:

Aerospace Engineering; Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

Hypersonic; Hypersonic Flow; Flow over a cylinder; Magnetohydrodynamic; MHD; Lorentz; Hypersonic MHD; Numerical Methods; CFD; Computational fluid dynamics; fluid dynamics; Aerospace;

Miller, Ian TimothyProbabilistic finite element modeling of aerospace engine components incorporating time-dependent inelastic properties for ceramic matrix composite (CMC) materials
Master of Science, University of Akron, 2006, Applied Mathematics
The research included in this abstract pertains to probabilistic finite-element creep analysis of a composite combustor liner. A composite combustor liner is an aerospace engine component that is subjected to very high temperatures, ranging between 1500 - 2100 degrees Fahrenheit. A creep analysis of this component is essential for rational design as creep (a slow time-dependent information under constant load) is prevalent at high temperatures. In a probabilistic analysis, many, if not all, of the state variables are represented by random variables with appropriate probability distributions incorporating relevant parameters. This formalism is much more realistic, as it more accurately describes the variability in properties and loadings that are inherent in the composition of aerospace materials and loadings encountered by aerospace components.

Committee:

Ali Hajjafar (Advisor)

Keywords:

Creep Analysis; Reliability Analysis; Aerospace Engine Components; Ceramic Matrix Composite Materials; Finite Element Analysis

Hall, Kara LynnDynamic Control for a Pneumatic Muscle Actuator to Achieve Isokinetic Muscle Strengthening
Doctor of Philosophy (PhD), Wright State University, 2011, Engineering PhD

A pneumatic muscle actuator (PMA) is a device that mimics behavior of skeletal muscle by contracting and generating force in a nonlinear manner when activated. PMAs have a high power to weight ratio and possess unique characteristics which make them ideal for human interaction. Due to their nonlinear dynamics, PMAs are difficult to control, presenting challenges in system implementation. Despite these challenges, PMAs have great potential as a source of resistance for strength training and rehabilitation. The main goal of this work was to control a PMA for use in isokinetic exercise, potentially benefiting anyone in need of optimal strength training through a joint's range of motion. This includes astronauts who need to counteract muscle atrophy and bone loss during prolonged spaceflight. The lightweight PMA driven by pressurized air does not need gravity to produce resistance, making it an attractive option for a microgravity exercise device.

The control system developed is based on an inverse three-element phenomenological model and adaptive nonlinear control. The system operates as a type of haptic controller, automatically adjusting resistance to assist a simulated neuromuscular actuator in maintaining the desired velocity. A human quadriceps dynamic simulator (HQDS) was developed so that control effectiveness and accommodation could be tested prior to human implementation. A motor, which produces torque analogous to quadriceps' torque production about the knee, is used in conjunction with the HQDS to simulate neuromuscular actuation. Tracking error results for motor shaft position (simulated joint angle), velocity (simulated lower leg angular velocity), and PMA displacement indicate that the control system is effective at producing PMA displacement and resistance necessary for a scaled, simulated neuromuscular actuator to maintain low-velocity isokinetic movement during simulated concentric and eccentric knee extension. This work is an important step towards human implementation of PMA produced resistance for isokinetic strength training and rehabilitation.

Committee:

Chandler Phillips, MD,PE (Advisor); David Reynolds, PhD (Committee Member); Stanley Mohler, MD (Committee Member); Dana Rogers, PhD (Committee Member); Raymond Hill, PhD (Committee Member)

Subjects:

Biomedical Engineering; Engineering; Rehabilitation

Keywords:

PMA control; aerospace exercise; microgravity resistive training; rehabilitation; biomimetic actuator

Shakiba-Herfeh, MohammadModeling and Nonlinear Control of a 6-DOF Hypersonic Vehicle
Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering
In the past two decades, there has been a renewed and sustained effort devoted to modeling the dynamics of air-breathing hypersonic vehicles, for both simulation and control design purposes. The highly nonlinear characteristics of flight dynamics in hypersonic regimes and the consequent significance variability of the response with the operating conditions requires the development of innovative flight control solutions, hence the development of suitable model of the vehicle dynamics that are amenable to design, validation and rapid calibration of control algorithms. In this dissertation, a control-oriented and a simulation model of a generic hypersonic vehicle were derived to support the design and calibration of model-based flight controllers. A nonlinear robust adaptive controller was developed on the basis of the control-oriented model, that was shown to provide stable trajectory tracking in higher fidelity computer simulations. The first stage of this research was the development of a control design model (CDM) for the 6-degree-of-freedom dynamics of an air-breathing hypersonic aircraft based on an available high-fidelity first principle model. A method that incorporates the theory of compressible fluid dynamics and system identification methods, was proposed and implemented. The development of the CDM is based on curve fit approximation of the forces and moments acting on the vehicle, making the model suitable for control design. Kriging and Least Squares methods were used to find the most appropriate curve-fitted model of the aerodynamic forces for both the control design and the control simulation models. It was shown that the 6-DOF model can be both categorized as an under-actuated mechanical system, as well as an over-actuated system with respect to a chosen in- put/output pair of interest. An important contribution of this work is the development of a nonlinear adaptive controller for the 6-DOF control design model. The controller was endowed with a modular structure, comprised of an adaptive inner-loop attitude controller and a robust nonlinear outer-loop controller of fixed structure. The purpose of the outer- loop controller is to avoid the typical complexity of solutions derived from adaptive backstepping methods. A noticeable feature of the outer-loop controller is the presence of an internal model unit that generates the reference for the angle-of-attack, in spite of parametric model uncertainty. Airspeed, lateral velocity, vehicle’s heading and altitude were considered as regulated outputs of the system. Simulation results on the control simulation model show the effectiveness of the developed controller in spite of significant variation in the flight parameters.

Committee:

Andrea Serrani (Advisor); Vadim Utkin (Committee Member); Kevin Passino (Committee Member); Can Koksal (Committee Member)

Subjects:

Electrical Engineering

Keywords:

Nonlinear Control; Aerospace; 6DOF; Hypersonic; Control

Young, Paul SModeling and Analysis for Atmospheric Galvanic Corrosion of Fasteners in Aluminum
Master of Science in Engineering, University of Akron, 2015, Chemical Engineering
Corrosion at fasteners in aluminum presents a high risk and challenge to corrosion mitigation strategies. The objective is to model atmospheric galvanic corrosion and determine the stages of damage evolution for 2024-T3 around fasteners. The synthesis of three test methods, exposure testing, laboratory measurements, and software modeling, are used to increase understanding of corrosion modes and damage evolution in order to help mitigate risk for atmospheric galvanic corrosion from fasteners in aluminum. An exposure study in Daytona Beach, Florida consisted of coupling aluminum coupons to metal fasteners for 24 months. Fastener metals used are 316L stainless steel, cadmium-plated low carbon 1018 steel, and cadmium-plated fasteners with Cd partially removed to simulate damaged plating. The corrosion damage modes at each stage are identified, and the impact of galvanic action is determined. A sequence of corrosion damage stages is developed and the transition through the stages is related to corrosion processes and their controlling factors. The results are related to corrosion mitigation for fasteners in Al. Galvanic corrosion is studied in the lab through Mixed Electrode Theory and through analytical modeling. Data quantifies the impact of galvanic action from fastener metal on the corrosion of aluminum. The models provide visual and quantitative data to identify galvanic couples of higher risk. Models predictions are at time zero and without the influence of damage evolution or changing environments. Laboratory testing allows for samples to be damaged so corrosion modes can be identified. The combination of modeling for quantifying the galvanic impact and damage evolution from lab tests allow for more effective corrosion mitigation methods to be employed. Models are becoming a valuable tool as user knowledge increases about the sensitivity of parameter inputs. Fasteners in aluminum, comparable to Daytona exposure tests, are used as examples for model applications. The effects of model inputs on the predictions of model outputs are analyzed for all inputs through quantified data. Models produce 3-D diagrams that highlight corrosion damage, making results easy to comprehend for non-subject experts and providing the ability to increase the effectiveness of material selection. Knowledge pertaining to atmospheric galvanic corrosion from fasteners in aluminum is increased. Laboratory tests and software models correlated very well due to the controlling input parameter (polarization curves) for software modeling being generated from laboratory data. Exposure tested aluminum coupons go through a series of corrosion stages that include pitting, intergranular corrosion and stress corrosion cracking. A synergistic effect is generated when the three test methods, exposure testing, lab testing, and software modeling, are used in combination.

Committee:

Joe Payer, Dr. (Advisor); Hongbo Cong, Dr. (Committee Member); Chelsea Monty, Dr. (Committee Member); Rajeev Kumar Gupta, Dr. (Committee Member)

Subjects:

Aerospace Engineering; Aerospace Materials; Chemical Engineering; Engineering; Materials Science; Metallurgy; Naval Engineering; Science Education

Keywords:

Atmospheric galvanic corrosion, intergranular corrosion, stress corrosion cracking, mixed electrode theory, modeling, exposure testing, wedging, aluminum, 2024-T3, finite elemental analysis, coulometric reduction, rust, aerospace alloys

Mooney, Ryan E.Guiding “Big Science:” Competing Agency of Scientists and Funding Organizations in American Cold War Research
Master of Arts in History, Youngstown State University, 2015, Department of History
This research project aims to evaluate the agency of scientists participating in American Cold War research initiatives funded by the government. The aim will be to weigh the internal direction of scientific programs versus the external pressures faced from patron organizations such as the Department of Defense. The project utilizes secondary sources supported by governmental documentation as well as written and oral accounts of scientific and technical personnel involved in select research efforts. The two initiatives examined were aerospace research and its eventual adaptation to the space program, as well as nuclear testing and the national laboratories which supported it. Sources strongly suggested significant internal direction on the part of rank-and-file laboratory and technical personnel and very little pressure to orient research toward defense-related activities, despite some cooperative overlap.

Committee:

Brian Bonhomme, PhD (Advisor); Donna DeBlasio, PhD (Committee Member); Daniel Ayana, PhD (Committee Member)

Subjects:

Aerospace Engineering; American History; Military Studies; Philosophy of Science

Keywords:

history of science;history of space program;history of nuclear testing;history of aerospace research

Leque, NicholasDevelopment of an Experimental Methodology for Evaluation of Gear Contact Fatigue under High-Power and High-Temperature Conditions
Master of Science, The Ohio State University, 2011, Mechanical Engineering
Contact fatigue failures in the form of pitting or micro-pitting have been a perennial problem in power transmission applications. These failures are dictated by a large number of parameters including loading conditions, gear geometry and tooth modifications, kinematics (rolling and sliding velocities), lubricant parameters (viscosity, pressure-viscosity behavior), and material parameters (material type, hardness, case depth, residual stresses). As such, theoretical treatment of contact fatigue failures has been rather challenging, directing the focus to the experimental investigation of the problem. Most of the experimental gear pitting studies to date were limited to low-speed and low-temperature operating conditions. This study aims at developing a methodology for evaluating the contact fatigue lives of gears under high-speed (pitch-line velocities up to 50 m/s), high-stress (contact stresses up to 2 GPa) and high-temperature (oil inlet temperatures up to 150C). Specifications of a test machine concept that meets these requirements are defined and two test machines are designed and procured for this purpose. Gear test specimens that result in pits consistently are developed with the other competing failures (wear, scuffing, tooth breakage), as well as the high vibration conditions, avoided. Preliminary high-speed tests are presented at the end, representing both automotive and aerospace conditions to show that pitting and micro-pitting failures can be produced with the proposed methodology.

Committee:

Ahmet Kahraman, PhD (Advisor); Carlos Castro, PhD (Committee Member)

Subjects:

Engineering; Mechanical Engineering

Keywords:

Gears; fatigue life; pitting; micro-pitting; high-speed; high-temperature; aerospace; automotive

Stickney, Frank AlexanderThe authority perception of the program manager in the aerospace industry /
Doctor of Philosophy, The Ohio State University, 1969, Graduate School

Committee:

Not Provided (Other)

Subjects:

Business Administration

Keywords:

Project management;Aerospace industries

GANGWAR, ASHUTOSHSource Term Modeling of Rectangular Flow Cavities
MS, University of Cincinnati, 2001, Engineering : Aerospace Engineering
The presence of small cavities has an effect on the primary fluid flow and should be modeled properly. The goal of this research is to develop a source term module that models the effect of these cavities for gas-path only simulations. In this approach the unsteady effect of the cavity in the solution is modeled by adding source terms to the right hand side of the Navier-Stokes equation without actually having to resolve the complex cavity geometry. This idea increases considerably the numerical efficiency of the scheme by avoiding the computation of small-scale fluid dynamic structures and complex geometric details of the cavity. Unsteady flow phenomena governing both subsonic and supersonic cavity oscillations were studied. The exact cycle for both cases has been presented and compared with those presented by other researchers. These unsteady solutions have been used to determine deterministic source terms. Source terms were then inserted in steady solutions and used to demonstrate that they can be used to model accurately cavity unsteadiness. Also two methods to model these source terms were briefly reviewed.

Committee:

Dr.Paul Orkwis (Advisor)

Subjects:

Engineering, Aerospace

Keywords:

CFD/CAVITY; SUPERSONIC; AEROSPACE

Next Page