Open Access. Powered by Scholars. Published by Universities.®

Aerospace Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

PDF

2007

Discipline
Institution
Keyword
Publication
Publication Type

Articles 1 - 30 of 185

Full-Text Articles in Aerospace Engineering

Streaming Effects In Liquid Injection Rocket Engines With Transverse Mode Oscillations, Sean Robert Fischbach Dec 2007

Streaming Effects In Liquid Injection Rocket Engines With Transverse Mode Oscillations, Sean Robert Fischbach

Doctoral Dissertations

This research is an analytical investigation of wave interactions in a simulated liquid rocket engine with uniform injection imposed at the faceplate. Of significant interest are the secondary nonlinear flows, particularly acoustic streaming, induced by transverse wave impingement over the engine injector surface. The corresponding cylindrical chamber has a small length-to-diameter ratio with respect to solid and hybrid rockets. Given their low chamber aspect ratios, liquid thrust engines are known to experience severe tangential and radial oscillation modes more often than longitudinal ones. Experimental evidence demonstrates the production of large peak-to-trough amplitude flow oscillations along with the development of a …

Go to article

A Computational Method For Flow Separation Detection And Control For Axial Compressor Airfoils, Chang Jun Meang Dec 2007

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 …

Go to article

A Cfd Investigation Of Axisymmetric Microthruster Nozzles For Use On Nano-Satellites, Michael R. O'Gara Dec 2007

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 …

Go to article

A Study Of The Beginning Boundary Layer Influence On The Flow Field About A Two-Dimensional Automotive Model, Jonathan Gabriel Ford Dec 2007

A Study Of The Beginning Boundary Layer Influence On The Flow Field About A Two-Dimensional Automotive Model, Jonathan Gabriel Ford

Masters Theses

An experimental investigation was performed to analyze the beginning boundary layer produced on the floor of a subsonic wind tunnel and its influence on the flow field about a two-dimensional automotive model. Hot film anemometer measurements were taken in the test section of the wind tunnel operating under various inlet configurations. The use of a splitter plate and modifications to the contour of the inlet to the wind tunnel were then studied to find their affects on the height of the boundary layer in the wind tunnel test section. Finally, a 2-D automotive model was constructed with pressure taps along …

Go to article

Investigation Of The Sidewall Boundary Layers In The Bidirectional Vortex Liquid Rocket Engine, Joshua W. Batterson Dec 2007

Investigation Of The Sidewall Boundary Layers In The Bidirectional Vortex Liquid Rocket Engine, Joshua W. Batterson

Masters Theses

To complement previous studies on the bidirectional vortex, we attempt to characterize viscous effects in both the axial and radial directions along the sidewall with standard asymptotic techniques. The actual boundary layer present in the chamber will be a composite of both axial and tangential shearing layers. Since the tangential velocity is completely dominant, we expect the defining characteristics of the composite boundary layer to be congruent with the tangential layer in both thickness and axial invariance. The analytic analysis is outlined first by, the formulation of the boundary layer equations via Prandtl’s method. Next, asymptotic techniques are applied to …

Go to article

Effects On Level Flight Performance Of The Optimized Wind Deflector Modification For The Md-500 Helicopter, Adam Joseph Cowan Dec 2007

Effects On Level Flight Performance Of The Optimized Wind Deflector Modification For The Md-500 Helicopter, Adam Joseph Cowan

Masters Theses

This thesis investigates the effects of personnel wind deflector devices on the level flight performance of an MD-500D helicopter configured with external passenger provisions. Numerous helicopter organizations operate with external passenger configurations. These configurations result in personnel exposure to high winds and an increase in parasite drag. Level flight performance is degraded by the increase in parasite drag caused by the external passengers. Wind deflectors were mounted on the forward portion of the fuselage to protect external passengers from the effects of wind exposure (high wind loads and wind chill factor) by deflecting the wind away from the fuselage. The …

Go to article

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 Nov 2007

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 …

Go to article

Optimal Control Of Class Of Non-Linear Plants Using Artificial Immune Systems: Application Of The Clonal Selection Algorithm, S. A. Panimadai Ramaswamy, Ganesh K. Venayagamoorthy, S. N. Balakrishnan Oct 2007

Optimal Control Of Class Of Non-Linear Plants Using Artificial Immune Systems: Application Of The Clonal Selection Algorithm, S. A. Panimadai Ramaswamy, Ganesh K. Venayagamoorthy, S. N. Balakrishnan

Electrical and Computer Engineering Faculty Research & Creative Works

The function of natural immune system is to protect the living organisms against invaders/pathogens. Artificial Immune System (AIS) is a computational intelligence paradigm inspired by the natural immune system. Diverse engineering problems have been solved in the recent past using AIS. Clonal selection is one of the few algorithms that belong to the family of AIS techniques. Clonal selection algorithm is the computational implementation of the clonal selection principle. The process of affinity maturation of the immune system is explicitly incorporated in this algorithm. This paper presents the application of AIS for the optimal control of a class of non-linear …

Go to article

Flightlines, Vol. 15, No. 1, Jeffrey A. Johnson Oct 2007

Flightlines, Vol. 15, No. 1, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Go to article

Study Of Contra-Rotating Coaxial Rotors In Hover, A Performance Model Based On Blade Element Theory Including Swirl Velocity, Florent Lucas Oct 2007

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 …

Go to article

Presenting Science And Engineering Careers In A Unique And Appealing Way., Nihad E. Daidzic, Vojin R. Nikolic Sep 2007

Presenting Science And Engineering Careers In A Unique And Appealing Way., Nihad E. Daidzic, Vojin R. Nikolic

Aviation Department Publications

An original summer camp activity in the areas of aerospace/aeronautical engineering and aviation has been developed. A pilot version of the program was completed successfully in June 2007 at Minnesota State University, Mankato. The main objective of the program was to increase the awareness and interest among high school students for science and engineering careers. Through a series of short lectures and extensive hands-on demonstrations the attending students have been familiarized with the fundamental concepts and relationships of science and engineering in general, and of aerospace engineering and aviation, in particular. Two major team projects have been completed and tested. …

Go to article

Final Assembly, Testing And Processing Of The Rigidizable Inflatable Get-Away-Special Experiment (Rigex) For Spaceflight Qualification, Jeremy J. Owens Sep 2007

Final Assembly, Testing And Processing Of The Rigidizable Inflatable Get-Away-Special Experiment (Rigex) For Spaceflight Qualification, Jeremy J. Owens

Theses and Dissertations

The purpose of this research is to complete the building, testing, verification, and qualification of the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX) for spaceflight. The process of qualifying a payload for spaceflight is discussed, specifically addressing the issues of operability and survivability verification of a general payload. The spaceflight qualification process is then applied to the RIGEX payload at the Air Force Institute of Technology (AFIT) and at the Johnson Spaceflight Center (JSC) in Houston, TX, capstoning the work of 12 masters students and 3 summer interns that has already gone into the RIGEX project over the last 7 years. The …

Go to article

Optimal Control Strategies For Constrained Relative Orbits, David J. Irvin Jr. Sep 2007

Optimal Control Strategies For Constrained Relative Orbits, David J. Irvin Jr.

Theses and Dissertations

The US Air Force's ability to protect space assets is enhanced by a proficiency in satellite proximity operations and Space Situational Awareness (SSA). In pursuit of that proficiency, this research develops a key capability of interest to mission planners; the ability of a deputy satellite to "hover" within a defined volume fixed in the vicinity of a chief satellite for an extended period of time. This research finds optimal trajectories, produced with discrete-thrusts, that minimize fuel spent per unit time and stay within the user-defined volume, thus providing a practical hover capability in the vicinity of the chief. The work …

Go to article

Raman Scattering Study Of Supercritical Bi-Component Mixtures Injected Into A Subcritical Environment, Young Man An Sep 2007

Raman Scattering Study Of Supercritical Bi-Component Mixtures Injected Into A Subcritical Environment, Young Man An

Theses and Dissertations

This research studies the species distribution profiles of methane/ethylene bi-components at downstream locations filled with subcritical nitrogen in a closed chamber. Unique thermodynamic and transport properties of supercritical fluids along with phase transition phenomena during fuel injection process can significantly change combustion characteristics inside a scramjet combustor. Plume properties of supercritical jets are of great interests to the studies of fuel/air mixing and subsequent combustion. The primary goal of this research is to help to clarify whether there is any preferential condensation within the condensed jets. The Raman Scattering technique is used to quantify spatial distribution of injected methane and …

Go to article

Validation Of The Afit Small Scale Combustion Facility And Oh Laser-Induced Fluorescence Of An Atmospheric Laminar Premiext Ed Flame, Stephen J. Koether Sep 2007

Validation Of The Afit Small Scale Combustion Facility And Oh Laser-Induced Fluorescence Of An Atmospheric Laminar Premiext Ed Flame, Stephen J. Koether

Theses and Dissertations

Construction in the AFIT combustion facility is complete and the objective of this report is to explain the steps taken to make the laboratory operational. The infinite radius Ultra-Compact Combustor (UCC) sectional model has been delivered and is fully installed with all fuel, air and instrument lines. Every major system in the lab has been tested and is functioning properly. Laboratory operating procedure has been established to ensure both safety and continuity in experimental results. Finally, the lab has been certified through official safety channels and combustion experiments are underway. The unique capability of the AFIT combustion laboratory is the …

Go to article

Cyclic Creep And Recovery Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200° C In Air And Steam Environments, Bridgett A. Whiting Sep 2007

Cyclic Creep And Recovery Behavior Of Nextel™ 720/Alumina Ceramic Matrix Composite At 1200° C In Air And Steam Environments, Bridgett A. Whiting

Theses and Dissertations

The cyclic creep and recovery behaviors of the N720/Al2O3 composite were investigated in this research. The ceramic matrix composite (CMC) contains a porous alumina matrix with laminated, woven mullite/alumina (NextelTM 720) fibers. The composite does not have an interface between the fiber and matrix. The CMC relies on the porous nature for flaw tolerance. The objective of this study the influences of monotonic creep and cyclic creep loading histories on the creep lifetime, creep strain rate, accumulated creep strain as well as on the recovery of creep strain at near zero stress. The cyclic creep and …

Go to article

Radar Orbit Analsis Tool Using Least Squares Estimator, Sandra M. Rashash Sep 2007

Radar Orbit Analsis Tool Using Least Squares Estimator, Sandra M. Rashash

Theses and Dissertations

Most objects tracked in space follow a regular Keplerian orbit; unfortunately, non-Keplerian objects such as maneuvering satellites, tethered systems, and thrusting ballistic missiles are becoming more common. It is important to be able to distinguish between Keplerian and non-Keplerian objects due to the potential risk of a tethered satellite being mistaken for an object on re-entry. This research focused on creating a computer model that can detect the non-gravitational acceleration present in non-Keplerian orbits. A 3rd order Taylor series expansion was used to model the dynamics and to produce simulated radar data. Linear least squares estimation was used to estimate …

Go to article

Common Aero Vehicle Autonomous Reentry Trajectory Optimization Satisfying Waypoint And No-Fly Zone Constraints, Timothy R. Jorris Sep 2007

Common Aero Vehicle Autonomous Reentry Trajectory Optimization Satisfying Waypoint And No-Fly Zone Constraints, Timothy R. Jorris

Theses and Dissertations

To support the Global Strike mission, an autonomous trajectory optimization technique is presented to minimize the flight time, satisfy terminal and intermediate constraints, and remain within the specified vehicle heating and control limitations. "Waypoints" are specified for reconnaissance or multiple payload deployments and "no-fly zones" are specified for geopolitical restrictions or threat avoidance. The Hypersonic Cruise Vehicle (HCV) is used as a simplified two-dimensional platform to compare multiple solution techniques. The solution techniques include a unique geometric approach, an analytical dynamic optimization technique, and a numerical approach. This numerical technique is a direct solution method involving pseudospectral methods and nonlinear …

Go to article

Comparative Study Of Aerodynamic Interference During Aft Dispense Of Munitions, Matthew G. Burkinshaw Sep 2007

Comparative Study Of Aerodynamic Interference During Aft Dispense Of Munitions, Matthew G. Burkinshaw

Theses and Dissertations

Based on forthcoming USAF needs, an investigation was launched to further the understanding of aft dispense of munitions in a high-speed environment. A computational fluid dynamics (CFD) study was performed followed by a wind tunnel experiment. The study consisted of a strut-mounted cone simulating a parent vehicle and a sting mounted cone-cylinder store situated directly behind the cone. The CFD modeled the test objects inside a supersonic wind tunnel in which the experiments took place. The CFD study consisted of evaluating a new strut designed to reduce asymmetry in the airflow aft of the cone. The CFD study also included …

Go to article

Finite Element Analysis Of Lamb Waves Acting Within A Thin Aluminum Plate, Sejin Han Sep 2007

Finite Element Analysis Of Lamb Waves Acting Within A Thin Aluminum Plate, Sejin Han

Theses and Dissertations

Structural health monitoring (SHM) is an emerging technology that can be used to identify, locate and quantify structural damages before failure. Among SHM techniques, Lamb waves have become widely used since they can cover large areas from one single location. Due to the development of various structural simulation programs, there is increasing interest in whether SHM data obtained from the simulation can be verified by experimentation. The objective of this thesis is to determine Lamb wave responses using SHM models in ABAQUS CAE(a Finite Element Analysis(FEA) program). These results are then compared to experimental results and theoretical predictions under isothermal …

Go to article

Navigation Using Orthogonal Frequency Division Multiplexed Signals Of Opportunity, Jamie S. Velotta Sep 2007

Navigation Using Orthogonal Frequency Division Multiplexed Signals Of Opportunity, Jamie S. Velotta

Theses and Dissertations

The global positioning system (GPS) provides high-accuracy position measurements anywhere in the world. However, a limitation of this system is that a line of sight to multiple satellites is required; therefore, it is unsuitable to use indoors or in urban canyons. Also, in the presence of radio-frequency interference or jamming, GPS may be unavailable. Alternative methods of navigation and positioning are need to either compliment GPS as a backup or for use in areas unreachable by satellites. This research analyzes a feature-based correlation approach for determining reception differences between two Orthogonal Frequency Division receivers for the purpose of TDOA calculations. …

Go to article

Flight Dynamic Response Of Hale Aircraft To Kc-135 Flowfield, Amanda J. Devuono Sep 2007

Flight Dynamic Response Of Hale Aircraft To Kc-135 Flowfield, Amanda J. Devuono

Theses and Dissertations

This research effort examines the static effects of a KC-135 flowfield on a flexible winged Sensorcraft model. The KC-135 flowfield data is generated by a vortex lattice code and integrated into Sensorcraft model for analysis. Building on previous research, a refueling situation was modeled to note the effects of the Sensorcraft at varying locations within the flowfield. The Sensorcraft model was analyzed for both rigid and flexible wings as a means of comparision. Flowfield locations of interest were determined and trimmed conditions were computed for each flowfield location. Utilizing the trimmed condition and flowfield locations, the nonlinear set of EOM's …

Go to article

Investigation Of Non-Conventional Bio-Derived Fuels For Hybrid Rocket Motors, Scott Grayson Putnam Aug 2007

Investigation Of Non-Conventional Bio-Derived Fuels For Hybrid Rocket Motors, Scott Grayson Putnam

Doctoral Dissertations

Non-conventional bio-derived fuels have been evaluated for use in hybrid rocket motors. Tests were conducted at combustion pressures in the range of 100 – 220 psig and thrust levels of 40 – 170 newtons. Beeswax was tested with oxygen as the oxidizer and showed a regression rate at least three times as high as traditional hybrid propellant combinations such as hydroxyl-terminated polybutadiene (HTPB) and liquid oxygen (LOX). This provides the promise of a high thrust hybrid rocket motor using a simple, single port geometry and overcomes the main weakness of traditional hybrid rocket motor propellants, which are low regression rates. …

Go to article

Applying Human Factors Principles In Aviation Displays: A Transition From Analog To Digital Cockpit Displays In The Cp140 Aurora Aircraft, Ryan C. Palmer Aug 2007

Applying Human Factors Principles In Aviation Displays: A Transition From Analog To Digital Cockpit Displays In The Cp140 Aurora Aircraft, Ryan C. Palmer

Masters Theses

A flight test program that evaluated the results of a CP140 Aurora cockpit modernization project was conducted between May 2004 and October 2005. This paper uses the results of that test program to show how basic human factors principles were violated which led to the identification of multiple design deficiencies. This paper proposes that the failure to apply good human factors principles when designing aircraft displays can lead to unacceptable deficiencies. The result can be poor modal awareness, confusion in the cockpit, and often negative training for the pilots. In particular, four major deficiencies were analyzed to determine the specific …

Go to article

Active Vibration Control Using Optimized Piezoelectric Topologies, Matthew James Parsons Aug 2007

Active Vibration Control Using Optimized Piezoelectric Topologies, Matthew James Parsons

Masters Theses

This work investigates the optimal topology of an actively controlled piezoelectric actuator bonded to an elastic cantilever beam under steady-state harmonic loading near the first natural frequency of the beam. The actuator is discretized using finite elements, and control is applied to the actuator based on the sensor’s degrees of freedom using proportional control. This study investigates the optimal distribution of actuator material for one and five layers of finite elements. The optimized actuator topology shows substantial improvement over initial piezoelectric topologies and over traditional actuator placement. This study has two main topics, material homogenization and topology optimization. The piezoelectric …

Go to article

Space Suit Concepts And Vehicle Interfaces For The Constellation Program, D. M. Klaus, J. Metts, R. Kobrick, M. Mesloh, T. Monk, Et Al. Jul 2007

Space Suit Concepts And Vehicle Interfaces For The Constellation Program, D. M. Klaus, J. Metts, R. Kobrick, M. Mesloh, T. Monk, Et Al.

Publications

In carrying out NASA’s Vision for Space Exploration, a number of different environments will be encountered that will require the crew to wear a protective space suit. Specifically, four suited mission phases are identified as Launch, Entry & Abort profiles, Contingency 0g (orbital) Extravehicular Activity (EVA), Lunar Surface EVA and Martian Surface EVA. This study presents conceptual design solutions based on a previous architecture assessment that defined space suit operational requirements for four proposed space suit configuration options. In addition, a subset of vehicle interface requirements are defined for enabling umbilical and physical connections between the suits and the various …

Go to article

Microthruster Experimental Analysis, Amy Denise Richards Jul 2007

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.

Go to article

The Effects Of Foreign Accent And Language On Reaction Time And Accuracy In An Air Traffic Control Task, Rosabelle Suarez Jul 2007

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 …

Go to article

Reinforcement Learning Based Output-Feedback Control Of Nonlinear Nonstrict Feedback Discrete-Time Systems With Application To Engines, Peter Shih, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier Jul 2007

Reinforcement Learning Based Output-Feedback Control Of Nonlinear Nonstrict Feedback Discrete-Time Systems With Application To Engines, Peter Shih, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The controller includes an observer for estimating states and the outputs, critic, and two action NNs for generating virtual, and actual control inputs. The critic approximates certain strategic utility function and the action NNs are used to minimize both the strategic utility function and their outputs. All NN weights adapt online towards minimization of a performance index, utilizing gradient-descent based rule. …

Go to article

Cooperative Uav Formation Flying With Obstacle/Collision Avoidance, Xiaohua Wang, Vivek Yadav, S. N. Balakrishnan Jul 2007

Cooperative Uav Formation Flying With Obstacle/Collision Avoidance, Xiaohua Wang, Vivek Yadav, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Navigation problems of unmanned air vehicles (UAVs) flying in a formation in a free and an obstacle-laden environment are investigated in this brief. when static obstacles popup during the flight, the UAVs are required to steer around them and also avoid collisions between each other. In order to achieve these goals, a new dual-mode control strategy is proposed: a “safe mode” is defined as an operation in an obstacle-free environment and a “danger mode” is activated when there is a chance of collision or when there are obstacles in the path. Safe mode achieves global optimization because the dynamics of …

Go to article

Next Last