Engineering Commons^™

A Computational Method For Flow Separation Detection And Control For Axial Compressor Airfoils, Chang Jun Meang

Master's Theses - Daytona Beach

Conducting full annulus experiments on multistage compressors is costly and time consuming due to the complexity of the experimental processes. To reduce complexity, Computational Fluid Dynamics (CFD) methods are applied to turbomachinery and other applications in recent analysis of such cases. CFD methods are widely used within the aerospace industry and are increasingly demonstrating their reliability. For axial compressors, it is known that highly staggered compressor stators will increase the aerodynamic loading on the stator, which directly relates to the compressor stall and efficiency. In this work, compressor stators stagger angle is increased 4 ° to induce separation on the …

A Cfd Investigation Of Axisymmetric Microthruster Nozzles For Use On Nano-Satellites, Michael R. O'Gara

Master's Theses - Daytona Beach

The performance of microthruster nozzles (^ 0.1 N thrust) depending on nozzle contour, propellant and surroundings, destined for use in nanosatellite missions, is investigated via a numerical approach using the Wind-US flow solver. An experimental apparatus designed to measure microthruster performance in atmospheric or vacuum conditions used to aid numerical simulations is also presented. Comparing the numerical and experimental results show an approximate 25% drop in efficiency for unknown reasons. An evaluation of favorable nozzle contours suggested by previous researchers is conducted, and the results demonstrate the need for a more rigorous treatment of the nozzle flow at the exit …

Moral Development In Pilot Populations, Erica Anne Diels

Doctoral Dissertations and Master's Theses

Ethical issues are becoming more commonplace in society today and while most industries are taking steps to improve poor ethical decisions through ethics education, aviation is lagging behind in both understanding of ethical issues inherent to the industry and ethics education. In this study three groups of pilots (students, instructors, and faculty) at Embry-Riddle Aeronautical University are examined in an effort to determine moral development level in terms of P score on the Defining Issues Test 2 (DIT2) and two domain specific additional questions. It was hypothesized that differences would be found between the groups and that the moral development …

Assessment Of The Thermal Improvements Awarded By Horseshoe Vortex Elimination On A Turbine Stator Blade In Computational Fluid Dynamics And Conjugate Heat Transfer, Laurent Lachmann

Master's Theses - Daytona Beach

The present work looks at an advanced turbine stator blade design and evaluates its thermal performance relative to a standard design. A new turbine stator blade is designed to eliminate the horseshoe vortex appearing at the leading edge. The new design is characterized by an extension of the leading edge at the hub and at the tip of about 30% of chord. By comparing this new design to an ordinary one (featuring straight leading edge), the present thesis verifies the horseshoe vortex elimination, and compares the thermal attributes of the fluid. The fluid is three-dimensional, viscous and turbulent. The analysis …

Study Of Contra-Rotating Coaxial Rotors In Hover, A Performance Model Based On Blade Element Theory Including Swirl Velocity, Florent Lucas

Master's Theses - Daytona Beach

The purpose of this study is to create a simple model to evaluate the performance of a counter-rotating coaxial rotor system. As it is based on the blade element theory, it could be used as a design tool where the engineer can modify all parameters - rotor radius, blade pitch distribution, tip velocity, rotor spacing, number of blades, blade chord, and airfoil's shape through its lift coefficient versus angle of attack slope. Different blade pitch distributions are tried and are assessed based on the power required to hover at the same weight. Also, the impact of the swirl velocity induced …

Quantifying The Cognitive, Symptomatic And Neuroendocrine Impact Of The Coriolis Illusion; A Countermeasure For Motion Sickness, Catherine Grandizio

Master's Theses - Daytona Beach

When pilots are unable to accurately perceive the position and motion of their bodies, they are spatially disoriented. Spatial disorientation is often induced by aviation illusions, and its consequences include dizziness, confusion, nausea and fatigue. The present research evaluated the severity of cognitive, neuroendocrine and subjective symptoms of the Coriolis illusion, induced by a spatial disorientation flight training device. Also, the research examined the effectiveness of a mild, ground-based countermeasure, similar to the Coriolis illusion, in reducing the occurrence and severity of symptoms. In the early stages of data analysis, there appeared to be a significant impact of the Coriolis …

Microthruster Experimental Analysis, Amy Denise Richards

Master's Theses - Daytona Beach

The purpose of this study was to design an experimental apparatus that could accurately test and measure the thrust efficiency of conical shaped microthrusters with varying divergence half angles. The experimental apparatus measured the thrust of micronozzles for various feed pressures in vacuum (to duplicate in space operation) as well as ambient. Calibration experiments confirmed the force measurement accuracy of the setup while gas thrust experiments were used to help determine the most efficient divergence half angle. Thrust results were compared to findings from two separate scientific studies that sought to optimize microthruster nozzles using CFD software.

The Effects Of Foreign Accent And Language On Reaction Time And Accuracy In An Air Traffic Control Task, Rosabelle Suarez

Master's Theses - Daytona Beach

The present study examines the effect of foreign accent interference with the ability to execute commands presented in speech format. The objective of this study was to demonstrate that a foreign accent influences performance. Participants were between 18 and 40 years of age. Half of the participants were native speakers of Spanish who began learning English as a second language via the classroom setting. The other half were native English-speaking with little or no exposure to the Spanish language. The experimental design was similar to an aviation scenario where participants listened to simulated ATC procedural commands and execute them on …

Voluntary And Confidential Reporting Systems As A Means Of Reducing The Accident Rate In Shadow 200 Flight Operations, William Lawrence Jagnow

Master's Theses - Daytona Beach

Although effective, the United States Army's Shadow 200 Unmanned Aerial Vehicle has suffered an unacceptably high accident rate. Errors committed by operators have significantly contributed to this accident rate. The voluntary and confidential Aviation Safety Reporting System and Aviation Safety Action Program have been successful in identifying and addressing errors committed by air carrier pilots. This study has explored the implementation of voluntary and confidential reporting systems in Shadow 200 flight operations. Mixed methods research combined quantitative survey data and qualitative interview data as a means of determining attitudes relevant to the implementation of such systems. Identified deficiencies included: (a) …

Prediction Of Fatigue Life In 7075-T6 Aluminum From Neural Network Analysis Of Acoustic Emission Data, Nicholas S. Spivey

Master's Theses - Daytona Beach

Through the use of an acoustic emission (AE) data acquisition system, a Kohonen self-organizing map, and a back-propagation neural network, AE data from 7075-T6 aluminum specimens were used to classify failure mechanisms and predict the number of fatigue cycles to failure. AE waveforms were captured from 40 notched tensile specimens during the low-cycle fatiguing process. A Kohonen self-organizing map and initial data filters were used to classify the data into two distinct failure mechanisms, plane strain and plane stress fracture, plus a third less prevalent mechanism. These results were employed to construct a back-propagation neural network to predict the number …

The Effect Of Display Design On Pilot Performance In Controlled Flight Into Terrain Scenarios, Jeremy Charles Smith

Doctoral Dissertations and Master's Theses

New technologies are being developed to prevent the continuing problem of Controlled Flight into Terrain (CFIT) accidents. One such technology, the Synthetic Vision System, seems to hold the solution. While it is readily adapted to the commercial aviation instrument environment, it may not be intuitive enough for the General Aviation private pilot with minimal instrument training. This experiment attempted to examine how pilots of every experience level use and interpret the depiction of synthetic terrain to recognize and avoid potential CFIT situations. The outcome of CFIT was measured against pilot experience and display condition.

Investigation Of Magnetic Field Profile Effects In Hall Thrusters, Oren Kornberg

Master's Theses - Daytona Beach

The purpose of this study was to show the relationship of different magnetic field profiles to the acceleration region length of a Hall thruster. The general transport equations were simplified and solved using a one-dimensional analysis. Some of the model assumptions include quasineutrality, Maxwellian electrons, and negligible thruster wall effects. The solved equation kept magnetic field as an input to the model for the analysis. The magnetic field was altered by changing the shape through the thruster, while keeping the maximum point fixed, and by shifting the profile, while keeping the shape fixed. Results indicate a strong correlation between the …

Fabrication And Compressive Behavior Of Corrugated Aramid-Epoxy Cellular Solids, Jeffrey Arthur Schneider

Master's Theses - Daytona Beach

Cellular solids are materials whose base material does not always occupy the entire solid fraction available. A number of cellular solids can provide blast protection and absorb impact energy, but few perform well resisting blunt object (ballistic) penetration. In this thesis, a method is proposed for fabricating cellular solids from aramid-epoxy composites that can absorb impact energy and resist blunt object penetration. The aramid-epoxy samples were fabricated using wet-layup techniques, with two different styles of Kevlar 49 woven fabric in a variety of orientations. Test sample density ranged from 0.08 0.23 g/cm3. Different lamination orientations, assembly techniques, and bonding adhesives …

Control System Design And Simulation Of Spacecraft Formations Via Virtual Formation Approach, Pavan Donepudi

Master's Theses - Daytona Beach

The problem of formation control of multiple spacecraft using the virtual structure approach is studied. The thesis first summarizes the progress made in the area of spacecraft formation control and then provides an overview of the virtual structure method. Modifying earlier established control design techniques, new feedback laws are constructed to control both the rotational and translational motion of a group of spacecraft. Several computer simulations are performed to illustrate the effectiveness of the modified control laws. The ephemeris and attitude data files generated via Matlab are exported to Satellite Tool Kit (STK) to create 3D animations. Various formation scenarios …

Validation Of Conjugate Heat-Transfer Capability For Water- Cooled High-Speed Flows, Bruno R. Fletcher

Master's Theses - Daytona Beach

A FORTRAN conduction/convection heat transfer module named FOGO (meaning fire in Portuguese) has been developed to perform the conjugate heat transfer analyses with existing flow solvers. In this work, FOGO is coupled with TBD and WIND-US flow solvers. WIND-US is a well validated flow solver developed by NASA, AEDC, and Boeing. TBD is a new flow solver developed at ERAU. TBD is verified for laminar stagnation point heat transfer prediction and turbulent flowfield protection. The FOGO module is verified against an exact solution for transient one-dimensional heat flow in a semi-infinite solid

The coupled TBD-FOGO and WIND-FOGO conjugate heat-transfer solvers …

Distance Learning For Instrument Flight: Evaluating The Effectiveness Of A Virtual Mentor, Andrew S. Mendolia

Master's Theses - Daytona Beach

PC-based flight simulators are sometimes used as an alternative to traditional forms of instrument training. This type of training typically requires an instructor to be present with the student in order to facilitate training. Flight instructors play many important roles in aviation training, one of which is the role of mentor. The premise of this study was to examine the use of synchronous web-based instruction for instrument flight via Microsoft Flight Simulator’s (10.0) “shared-cockpit” feature, where the instructors serves as a mentor from a distance. The results indicate that web-based instruction is no more effective than practice without instruction. Although …