Aerospace Engineering Commons^™

Numerical Modeling Of A Parallel Plate Electrowetting-On-Dielectric (Ewod) Device, Kevin Tully

Mechanical and Aerospace Engineering Theses - Archive

Numerical modeling and simulations have been performed in this study that focuses on modeling the fluid dynamics of an Electrowetting-on-Dielectric (EWOD) device. The case to be modeled in the present study is a droplet cutting problem where a droplet is sandwiched between two plates of Teflon and an electrical actuation will cause the droplet to cut or split into two smaller droplets. A finite difference method has been used to solve the Navier-Stokes equations, along with the continuity equation. An algorithm used for tracking the free surface is the Volume of Fluid (VOF) method. Along with using the VOF method …

Heat Transfer In Triangular Ducts With Axial Conduction,Containing Porous Medium, Abhishek Banerjee

Mechanical and Aerospace Engineering Theses - Archive

The objective of this study is to find a numerical solution for the velocity and temperature field in a duct of triangular cross-section area. A fully saturated porous medium is considered to be present in the duct. The study reports the contribution of axial conduction in heat transfer to flow passing through triangular porous passages. The terms in x-direction are retained in the energy equation due to the presence of axial conduction. Also, because of the geometrical asymmetry, non-orthogonal boundary conditions can exist and thus make the determination of heat transfer more difficult. The problem under consideration uses H2 boundary …

Nonlinear Finite Element Analysis Of Columns, Rajkiran Muppavarapu

Mechanical and Aerospace Engineering Theses - Archive

In many engineering applications structural components are considered to be beams or columns subjected to a range of external loads such as dead weight, wind, temperature changes etc.In this work a mathematical model has been developed for a sports lighting tower considering it to be a cantilever beam with large deformation. The concept of non-linear P-Delta analysis is applied to the column. Using this model, a tower analysis tool was developed in MATLAB. Using this tool various design alternatives can be examined to evaluate their suitability to a particular task.A number of example problems from the available literature were solved …

Stable Reference Trajectory Modification For Handling Actuator Failure In Control Systems, Ifeolu Olalekan Ogunleye

Mechanical and Aerospace Engineering Theses - Archive

The issue of rapidly reconfiguring the reference trajectory under unanticipated actuator failures in order to regain lost performance or aircraft handling qualities is explored. The failures detected in real-time are compensated for by ensuring the input to the system reflects current system conditions. This thesis will also show that only the general structure of the failed system component is needed to achieve successful failure detection and reference trajectory reconfiguration. This approach allows the nominal control structure to remain unchanged in the presence of change flight and system conditions. Acceptable system performance is recovered by detecting the actuator failures in real-time. …

Cfd Analysis Of A Uni-Directional Impulse Turbine For Wave Energy Conversion, Carlos Alberto Velez

Electronic Theses and Dissertations

Ocean energy research has grown in popularity in the past decade and has produced various designs for wave energy extraction. This thesis focuses on the performance analysis of a uni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines can produce uni-directional rotation in bi-directional flow, which makes it ideal for wave energy extraction as the motion of ocean waves are inherently bi-directional. This impulse turbine is currently in use in four of the world’s Oscillating Wave Columns (OWC). Current research to date has documented the performance of the turbine but little research has been completed to understand the flow …

Super-Adiabatic Combustion In Porous Media With Catalytic Enhancement For Thermoelectric Power Conversion, Kyle Thomas Mueller

Electronic Theses and Dissertations

The combustion of ultra-lean fuel to air mixtures provides an efficient way to convert the chemical energy of hydrocarbons into useful power. Conventional burning techniques of a mixture have defined flammability limits beyond which a flame cannot self-propagate due to heat losses. Matrix stabilized porous medium combustion is an advanced technique in which a solid porous matrix within the combustion chamber accumulates heat from the hot gaseous products and preheats incoming reactants. This heat recirculation extends the standard flammability limits and allows the burning of ultra-lean fuel mixtures, conserving energy resources, or the burning of gases of low calorific value, …

Translational And Rotational Control Of An Asteroid Orbiting Satellite, Takahiro Kuhara

Doctoral Dissertations and Master's Theses

The objective of this thesis is to analyze an effective control scheme for an asteroid orbiting satellite. The thesis first summarizes the progress made in the dynamics formulation of such satellites and then provides a theoretical framework for the control system design. The control objective is to maintain a nadir pointing attitude on a circular equatorial orbit. Using established control design techniques, feedback laws are constructed to control both rotational and translational motion of the satellite so that the control objective is achieved. Computer simulations are carried out to illustrate the effectiveness of the control laws.

Beading And Dimpling Techniques To Improve The Vibration And Acoustic Characteristics Of Plate Structures, Nabeel Taiseer Alshabtat

Dissertations

A method of improving the vibroacoustic characteristics of beams and plates is presented. This method is based on creating dimples or beads on the surface of the structures. The proposed method couples the finite element method with an optimization technique based on the genetic algorithm (GA). The improvement of the vibroacoustic characteristics of beams and plates is achieved by two separate strategies. The first strategy is optimizing the natural frequencies of beams and plates. The second strategy is minimizing the sound radiation from such vibrating structures. Optimizing the natural frequencies of some types of beams and simply supported plates by …

Ductile Mode Material Removal Of Ceramics And Semiconductors, Deepak Ravindra

Dissertations

Ceramics and semiconductors are hard, strong, inert and lightweight. They also have good optical properties, wide energy bandgap and high maximum current density. This combination of properties makes them ideal candidates for tribological, semiconductor, MEMS and optoelectronic applications respectively. Manufacturing these materials without causing surface and subsurface damage is extremely challenging due to their high hardness, brittle characteristics and poor machinability. However, ductile regime machining of these materials is possible due to the high-pressure phase transformation occurring in the material caused by the high compressive stresses induced by the single point diamond tool tip. In this study, to further augment …

Balloon Borne Mars Research Platforms, Sean Michael Hancock

Mechanical & Aerospace Engineering Theses & Dissertations

Aerial platforms can fill a measurement gap between orbiters and rovers, providing planetary scale high resolution in situ measurements, access to scientifically interesting terrain that is either inaccessible or hazardous to rovers, and serve as a planet-wide delivery platforms to deploy surface probes and rovers to areas inaccessible given existing entry, descent, and landing systems. A permanent robotic outpost on the Martian surface can utilize locally-derived hydrogen as a lifting gas for balloon systems deployed from Mars. That approach can simplify the inflation and launch of aerial vehicles while allowing for a long duration deployment campaign that is not constrained …

Shock-Associated Noise Generation In Curved Coanda Turbulent Wall Jets, Caroline P. Lubert, Richard J. Shafer

Department of Mathematics and Statistics - Faculty Scholarship

Curved three-dimensional turbulent Coanda wall jets are present in a multitude of natural and engineering applications. The mechanism by which they form a shock-cell structure is poorly understood, as is the accompanying shock-associated noise (SAN) generation. This paper discusses these phenomena from both a modeling and experimental perspective. The Method of Characteristics is used to rewrite the governing hyperbolic partial differential equations as ordinary differential equations, which are then solved numerically using the Euler predictor-corrector method. The effects of complicating factors -- such as radial expansion and streamline curvature -- on the prediction of shock-cell location are then discussed. This …

X-51 Composite Airframe, Brendon J. Townshend

Aerospace Engineering

This paper gives an overview of the progress that has been made in the design build of the X-51.  The X-51 is a composite scale replica of a P-51D fuselage integrated with a P-51H wing.  Issues with the airframe as well as current action items are discussed, as well as findings so far in preliminary design.

Mapping Galileo's Trajectory, Mark Woods

Aerospace Engineering

The NASA Galileo mission was mapped out using a patched conics approximation.  Galileo launched from Earth, underwent a gravity assist from Venus back to Earth for another gravity assist.  Galileo then came back to Earth for one more gravity assist to propel it to Jupiter.  A simulation ignoring all perturbations (i.e. third body effects, zonal (harmonics, solar wind, drag) was carried out.  The simulation was able to make it to the final Earth flyby before diverging from the actual trajectory.  The simulated and actual flyby dates all differed by less than 5 hours, and the simulated and actual flyby altitudes …

Analysis Of Surface Augmentation Of Airfoil Sections Via Flow Visualization Techniques, John Louis Vento

Aerospace Engineering

This report details an experiment done to verify the effectiveness of two passive flow control systems on two-dimensional airfoil sections. The flow control was tested on two types of airfoils: a symmetric NACA 0011, intended to represent an airplane in cruise, and a NACA16611, intended to represent an aircraft with flaps extended.  Two types of passive systems were employed, a dimple surface augmentation, similar to a golf ball, and a grit system located at 20% chord. Airfoils without either augmentation were tested as a control case. Using a water tunnel and dye to perform flow visualization, the effects of each …

Flight Testing In A Simulation Based Environment, David W. Babka

Aerospace Engineering

Over the past two decades performance flight testing of full scale aircraft has transferred some of the testing workload to simulation based systems.  Flight testing full scale aircraft in the real world environment has always been expensive, especially now with the rise in aviation fuel costs. Additionally, new emerging technologies require extensive testing and doing so in the full scale environment is cost prohibitive.  A cheaper alternative is to test systems in a simulation based environment.  Not only can aircraft be simulated via a computer, but all the aircrafts systems can be modeled in the simulation.  Furthermore, most of the …

Dynamic Ergonomic Analysis And Simulation Of Fastening Operation, Akul Joshi

Doctoral Dissertations

"Operator performing fastening operation with powered hand-tools at awkward postures is subjected to external forces that may pose a risk of developing ergonomic injuries. For design of safe workplaces and selection of tools it is necessary to identify the probable causes of discomfort by simulating the work conditions and quantifying the risk factors. An ergonomic simulator is developed to simulate the fastening operation and quantify the effects of posture and force in fastening operation. The effect of dynamic forces is analyzed using two approaches. The first approach analyzes the effect of tool vibration while the second analyzes the hand-arm system …

Space Mission Engineering: The New Smad, James R. Wertz, David F. Everett, Jeffery J. Puschell

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by James Wertz, David Everett, and Jeffery J. Puschell on "Space Mission Engineering: The New SMAD" in 2011.

The Effect Of Mmod Porosity On Crater Depth After Hypervelocity Impact, David Ledesma

Open Access Theses & Dissertations

A significant amount of research has been conducted in the last decades on the design of spacecraft shielding for the impacts of Micro Meteoroid and Orbital Debris (MMOD). Through the use of hydrocodes, empirical data, and physical testing, researchers have been successful in studying a wide range of shielding configurations. However, a very limited amount of research has been conducted to understand the effect that the porosity and irregular shape of MMOD has on the damage they create on spacecraft components.

The work presented in this thesis addresses the modeling of MMDO porosity by using the CTH hydrocode to investigate …

Use Of Bio Ethanol The Key Solution For A More Sustainable Road Transport, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Life Cycle Analysis (LCA) of alternative transportation fuels clearly shows the advantages of reducing the use of nonrenewable fossil fuels vs. renewable synthetic and biologic novel fuels to reduce the emissions of carbon dioxide. Being based on the natural or synthetic recycle of carbon dioxide through the use of renewable energy sources, use of these renewable fuels does not imply depletion of natural resources and is therefore sustainable in the long term. Renewable fuels and advanced internal combustion engines and powertrains are the technologies that in addition to be the most likely to produce benefits in term of carbon balance …

Magnetometer-Only Attitude Determination With Application To The M-Sat Mission, Jason D. Searcy

Masters Theses

"The topic of this thesis focuses on attitude determination for small satellites. The method described uses only a magnetometer to resolve the three-axis attitude of the satellite. The primary challenge is that magnetometers only instantaneously resolve two axes of a satellite's attitude. Typically, magnetometers are used in conjunction with other sensors to resolve all three axes. However, by using a filter over an adequately long orbit arc, the magnetometer data can yield all the information necessary. The magnetic field data are filtered to obtain the magnetic field derivative vector, which are combined with the magnetic field vector to fully resolve …