Modal Characterization And Structural Dynamic Response Of A Crane Fly Forewing, Jose E. Rubio

University of New Orleans Theses and Dissertations

This study describes a method for conducting the structural dynamic analysis of a crane fly (family Tipulidae) forewing under different airflow conditions. Wing geometry is captured via micro-computed tomography scanning. A finite element model of the forewing is developed from the reconstructed model of the scan. The finite element model is validated by comparing the natural frequencies of an elliptical membrane with similar dimensions of the crane fly forewing to its analytical solution. Furthermore, a simulation of the fluid-structure interaction of the forewing under different airflows is performed by coupling the finite element model of the wing with a …

Wind And Thermal Effects On Ground Mounted Photovoltaic (Pv) Panels, Chowdhury Mohammad Jubayer

Electronic Thesis and Dissertation Repository

A combination of Computational Fluid Dynamics (CFD) simulations and wind tunnel experiments are carried out to investigate the effects of wind on the aerodynamic loading and heat transfer of a ground mounted stand-alone photovoltaic (PV) panel with tilt angle of 25^o in open country atmospheric boundary layer. Several azimuthal wind directions are considered: Southern 0^o, Southwest 45^o, Northwest 135^o and Northern 180^o. Three dimensional Reynolds-Averaged Navier-Stokes (RANS) approaches with an unsteady solver using Shear Stress Transport (SST) k-ω turbulence closure are employed for the CFD simulations, whereas Particle Image Velocimetry (PIV) and …

Development Of An Exteroceptive Sensor Suite On Unmanned Surface Vessels For Real-Time Classification Of Navigational Markers, Christopher Lloyd Kennedy

Doctoral Dissertations and Master's Theses

This thesis presents the development of an exteroceptive sensor suite for real-time detection and classification of navigational markers on Unmanned Surface Vessels. Three sensors were used to complete this task: a 3D LIDAR and two visible light cameras. First, all LIDAR points were transformed from the sensor’s reference frame to the local frame using a Kalman filter to estimate instantaneous vehicle pose. Next, objects were chosen from the LIDAR data to be classified using either Multivariate Gaussian or Parzen Window Classifiers. Both produce 96% accuracy or better, however, multivariate Gaussian ran considerably faster than the Parzen and was simpler to …

Experiment And Simulation Of The Acoustic Signature Of Fatigued-Cracked Gears In A Two-Stage Gearbox, Matthew James Ostiguy

Master's Theses

This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy …

Mitigation Of Moving Shocks In An Expanding Duct, Veraun Chipman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inviscid flow theory governs the bulk motion of a gas at some distance away from the walls (i.e. outside the boundary layer). That is to say, there are no viscous forces in the bulk flow, which is modeled using the Euler equations. The Euler equations are simply the Navier-Stokes equations with zero viscosity terms. An ideal inviscid fluid, when brought into contact with a surface or wall, would naturally slip right past it since the fluid has no viscosity. In real life, however, a thin boundary layer forms between the wall or surface and the bulk flow. Shock wave boundary …

Lightweight, High-Temperature Radiator For In-Space Nuclear-Electric Power And Propulsion, Briana N. Tomboulian

Doctoral Dissertations

The desire to explore deep space destinations with high-power and high-speed spacecraft inspired this work. Nuclear Electric Propulsion (NEP), shown to provide orders of magnitude higher specific impulse and propulsion efficiency over traditional chemical rockets, has been identified as an enabling technology for this goal. One of large obstacle to launching an NEP vehicle is total mass. Increasing the specific power (kW/kg) of the heat radiator component is necessary to meet NASA’s mass targets. This work evaluated a novel lightweight, high-temperature carbon fiber radiator designed to meet the mass requirements of future NEP missions. The research is grouped into three …

Modeling Dynamic Stall For A Free Vortex Wake Model Of A Floating Offshore Wind Turbine, Evan M. Gaertner

Masters Theses

Floating offshore wind turbines in deep waters offer significant advantages to onshore and near-shore wind turbines. However, due to the motion of floating platforms in response to wind and wave loading, the aerodynamics are substantially more complex. Traditional aerodynamic models and design codes do not adequately account for the floating platform dynamics to assess its effect on turbine loads and performance. Turbines must therefore be over designed due to loading uncertainty and are not fully optimized for their operating conditions. Previous research at the University of Massachusetts, Amherst developed the Wake Induced Dynamics Simulator, or WInDS, a free vortex wake …

New Generator Control Algorithms For Smart-Bladed Wind Turbines To Improve Power Capture In Below Rated Conditions, Bryce B. Aquino

Masters Theses

With wind turbines growing in size, operation and maintenance has become a more important area of research with the goal of making wind energy more profitable. Wind turbine blades are subjected to intense fluctuating loads that can cause significant damage over time. The need for advanced methods of alleviating blade loads to extend the lifespan of wind turbines has become more important as worldwide initiatives have called for a push in renewable energy. An area of research whose goal is to reduce the fatigue damage is smart rotor control. Smart bladed wind turbines have the ability to sense aerodynamic loads …

Coupled Fluid-Thermal Analysis Of Low-Pressure Sublimation And Condensation With Application To Freeze-Drying, Arnab Ganguly

Open Access Dissertations

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of bio-pharmaceuticals for removal of solvents by sublimation. The goal of the process is to provide a stable dosage form by removing the solvent in such a way that the sensitive molecular structure of the active substance is least disturbed. The vacuum environment presents unique challenges for understanding and controlling heat and mass transfer in the process. As a result, the design of equipment and associated processes has been largely empirical, slow and inefficient.^ A comprehensive simulation framework to predict both, process and equipment performance is critical …

Studies Of Systems With Nonholonomic Constraints: The Segway And The Chaplygin Sleigh, Joseph Troy Lee Tuttle

Open Access Theses

In this thesis, two systems with nonholonomic systems are investigated: the Segway and the Chaplygin sleigh. Using Lagrangian mechanics, the constrained nonlinear equations of motion for both systems are derived. By use of the nullspace of the constraint matrices, the unconstrained equations of motion can be obtained. For the Segway, these equations are linearized about a zero equilibrium state, placed into state space form and decoupled. A feedback controller is designed about the velocity and heading angle rate reference commands. To compare to the real data from the built Segway, measurement noise was also included in the model. Experimental data …

A Computational Analysis Of The Aerodynamic And Aeromechanical Behavior Of The Purdue Multistage Compressor, David Monk

Open Access Theses

Compressor design programs are becoming more reliant on computational tools to predict and optimize aerodynamic and aeromechanical behavior within a compressor. Recent trends in compressor development continue to push for more efficient, lighter weight, and higher performance machines. To meet these demands, designers must better understand the complex nature of the inherently unsteady flow physics inside of a compressor. As physical testing can be costly and time prohibitive, CFD and other computational tools have become the workhorse during design programs.

The objectives of this research were to investigate the aerodynamic and aeromechanical behavior of the Purdue multistage compressor, as well …

Control Of A Spacecraft Using Mixed Momentum Exchange Devices, Blake J. Currie

Master's Theses

Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for …

Structural Response Analyses Of Piezoelectric Composites Using Nurbs, Vijairaj Raj

Electronic Thesis and Dissertation Repository

Variational method deduced on the basis of the minimum potential energy is an efficient method to find solutions for complex engineering problems. In structural mechanics, the potential energy comprises strain energy, kinetic energy and the work done by external actions. To obtain these, the displacement are required as a priori. This research is concerned with the development of a numerical method based on variational principles to analyze piezoelectric composite plates and solids. A Non-Uniform Rational B-Spline (NURBS) function is used for describing both the geometry and electromechanical displacement fields. Two dimensional plate models are formulated according to the first order …

Kinetics Of Aluminization And Homogenization In Wrought H-X750 Nickel-Base Superalloy, Sean Reilly

Masters Theses

In sub-millimeter sheets of wrought H-X750 Nickel-base superalloy, aluminum-rich coatings are bonded to matrix with a vapor phase aluminization process. If an appropriate amount of aluminum is bonded to matrix with homogenization treatment, the resulting diffusion couple will diffuse into coherent (g/g’) heterogeneous phases creating matrix that is both precipitation and solid solution strengthened.

The diffusional mechanisms for solid solution mass transport involved with the growth and dispersion of bonded aluminum-rich coatings in the aluminization process only differ from the no external mass flow homogenization process with annealing treatment in that the boundary conditions are different. In each case these …

Evaluation Of The Performance Of Various Turbulence Models For Accurate Numerical Simulation Of A 2d Slot Nozzle Ejector, Colin Graham

McKelvey School of Engineering Theses & Dissertations

With the development over the last several decades, accurate Computational Fluid Dynamics (CFD) modeling has now become an essential part in the analysis and design of various industrial products where the fluid flow plays an important role. The goal of this thesis is to apply the CFD technology to the analysis of a 2D slot nozzle ejector which has application in Short Take-off and Landing (STOL) aircraft and other future aerospace vehicles. In the nozzle-ejector configuration, the high speed air flow from the nozzle entrains the ambient air into a mixing chamber (ejector) as a means to create additional thrust …

Design And Fabrication Of A Low-Cost Turbine Engine Component Testbed (Tect), Joshua A. Hartman

Masters Theses

With gas turbine engine testing becoming very expensive because of the increasing complexity involved with the engine, engine subsystems, and test support systems, a low-cost Turbine Engine Component Testbed (TECT) is proposed. This engine build is given the designation J1-H-02. In the present study, a small augmented gas turbine engine (GTE) is constructed. The TECT engine is built with modularity as a key design consideration to allow for flame-tube patterns and augmentor sections to be changed quickly for combustion experiments that have gained impetus due to combustion anomalies/instabilities inherent with future military engine augmentors. This testbed allows for an effective …

Feedback Speed Control Of A Small Two-Stroke Internal Combustion Engine That Propels An Unmanned Aerial Vehicle, Paul D. Fjare

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unmanned aerial vehicles (UAV) require intelligent control of their power source. Small UAV are typically powered by electric motors or small two-stroke internal combustion (IC) engines. Small IC engines allow for longer flight times but are more difficult to control and cause significant ground noise. A hybrid operation that uses the engine at high altitudes and the electric motors at low altitudes is desired. This would allow for extended flight with acceptable ground noise levels. Since the engine can not be restarted in the air it must be able to remain at idle for an extended time without stalling. A …

A Small-Scale Experiment Using Microwave Interferometry To Investigate Detonation And Shock-To-Detonation Transition In Pressed Tatb, Peter John Renslow

Open Access Theses

A small-scale characterization test utilizing microwave interferometry was developed to dynamically measure detonation and run to detonation distance in explosives. The technique was demonstrated by conducting two experimental series on the well-characterized explosive triaminotrinitrobenzene (TATB). In the first experiment series, the detonation velocity was observed at varying porosity. The velocity during TATB detonation matched well with predictions made using CHEETAH and an empirical relation from the Los Alamos National Laboratory (LANL). The microwave interferometer also captured unsteady propagation of the reaction when a low density charge was near the failure diameter. In the second experiment series, Pop-plots were produced using …

Impinging Jet Spray Formation Using Non-Newtonian Liquids, Neil S. Rodrigues

Open Access Theses

Over the past two decades there has been a heightened interest in implementing gelled propellants for rocket propulsion, especially for hypergolic bi-propellants such as monomethylhydrazine (MMH) and nitrogen tetroxide oxidizer (NTO). Due to the very high level of toxicity of hypergolic liquid rocket propellants, increasing safety is an important area of need for continued space exploration and defense operations. Gelled propellants provide an attractive solution to meeting the requirements for safety, while also potentially improving performance. ^ A gelling agent can be added to liquid propellants exhibiting Newtonian behavior to transform the liquid into a non-Newtonian fluid with some solid-like …

Experimental Study Of Unsteady Heat Release In An Unstable Single Element Lean Direct Injection (Ldi) Gas Turbine Combustor, Varun S. Lakshmanan

Open Access Theses

In an effort to curb emissions from gas turbine engines, many low emission engine concepts have been developed. Among the most promising of these is the LDI (Lean Direct Injection). These systems operate at relatively low equivalence ratios close to blowout and are prone to instabilities. Combustion instabilities can reduce the life of the combustor by causing large pressure fluctuations and enhanced heat release to the walls of the combustor and reduce the efficiency of the engines. The understanding of combustion instabilities is vital to the implementation of such systems. Combustion instabilities are studied in an self-excited single element gas …

Assessment Of Noise Metrics For Application To Rotorcraft, Andrew L. Mcmullen

Open Access Theses

It is anticipated that the use of rotorcraft passenger vehicles for shorter journeys will increase because their use can reduce the time between boarding and take-off. The characteristics of rotorcraft noise are very different to that of fixed wing aircraft. There can be strong tonal components, fluctuations that can also make the noise sound impulsive, and future rotorcraft may produce proportionally more low frequency noise content. Most metrics that are used today to predict noise impact on communities around airports (e.g., L_dn) are just functions of A-weighted sound pressure level. To build a better noise annoyance model that …

Early Damage State Criterion From A Fault-Seeded Helicopter Gear Using Acoustic Emission And Neural Networks, Rudy L. Baum

Doctoral Dissertations and Master's Theses

In response to five failures since 2008 of the tail gearbox of multiple models of Sikorsky's H-60 helicopter, acoustic emission (AE) data collected from a rotating gearbox test stand at the Naval Air Station in Patuxtent River, MD, was used to monitor the initiation and propagation of a flaw from an electro-discharge machined (EDM) notch seeded on the face of a gear tooth. A period of testing was considered which spanned ~300,000 seconds or ~83 hours and culminates to a damage state such that a flaw has initiated on both ends of the EDM notch. AE data was analyzed for …

Minimization Of The Effects Of Secondary Reactions On Turbine Film Cooling In A Fuel Rich Environment, Andrew T. Shewhart

Theses and Dissertations

The demand for increased thrust, higher engine efficiency, and reduced fuel consumption has increased the turbine inlet temperature and pressure in modern gas turbine engines. The outcome of these higher temperatures and pressures is the potential for unconsumed radical species to enter the turbine. Because modern cooling schemes for turbine blades involve injecting cool, oxygen rich air adjacent to the surface, the potential for reaction with radicals in the mainstream flow and augmented heat transfer to the blade arises. This study evaluated various configurations of multiple cylindrical rows of cooling holes in terms of both heat release and effective downstream …

Addition Of A Stanton Gauge To The Boundary Layer Data System, Brittany Reanne Kinkade

Master's Theses

The Stanton gauge technique provides an indirect method for measurement of skin friction on a smooth aerodynamic surface in which a pressure tap is available. This thesis presents the design and evaluation of a new type of skin friction measurement gauge based on the Stanton gauge concept but not requiring a surface pressure tap. This new skin friction measurement gauge, called a "Flow Tab", can therefore be used on an aerodynamic model or aircraft surface without alteration of the surface. The Flow Tab is thus particularly well-suited to use with Cal Poly's Boundary Layer Data System (BLDS), a small, self-contained …

Lightweight Uav Launcher, Ben Miller, Christian Valoria, Corinne Warnock, Jake Coutlee

Mechanical Engineering

This report discusses the design, construction, and testing of a lightweight, portable UAV launcher. There is a current need for a small team of soldiers to launch a US Marine Tier II UAV in a remote location without transport. Research was conducted into existing UAV launcher designs and the pros and cons of each were recorded. This research served as a basis for concept generation during the initial design development stage. It was required that the design weigh less than 110 lbs, occupy a smaller volume than 48" x 24" 18" in its collapsed state, be portable by a single …

A Study On The Vibrational Performance Characteristics Of An E22 Isolator After Outgassing And Bake-Out, Alma Melendez

Master's Theses

The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It …

Design Optimization Of A Composite Wing Box For High-Altitude Long-Endurance Aircraft, Philip T. Arévalo

Doctoral Dissertations and Master's Theses

A design optimization process is developed to define the wing box structure for High-Altitude Long-Endurance Aircraft (HALE). The goal of this study is to determine the best tradeoff between mass and rigidity of a HALE aircraft wing structure. A preliminary composite laminate structural design procedure is described which uses a NASTRAN-based Finite Element Analysis (FEA), and the Hierarchical Evolutionary Engineering Design System (HEEDS) MDO software to define a locus of acceptable, optimized wing box design definitions.

Neutron Imaging Of Lithium (Li) Coolants Inside High Temperature Niobium (Nb) Heat Pipes, Brad Harrison Hight

Masters Theses

Lithium (Li) behavior inside a high temperature Nb-Li leading edge heat pipe was successfully imaged under induction heating operation via neutron imaging. Startup and cool-down operations gave visual confirmation of bulk Li movement using both gravity assisted and inverted operating orientations. The pipe was imaged during an operation cycle from ambient conditions, heated to a steady state temperature of 908.8 ⁰C, and allowed to cool below 200^°C. The experiment was performed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, and at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee.

Tomographic images …

Unsteady Forces On A Spherical Particle Accelerating Or Decelerating In An Initially Stagnant Fluid, Yashas Mudlapur Phaneesh Keshav

Open Access Theses

Flows with particles play an important role in a number of engineering applications. These include trajectories of droplets in sprays in fuel-injected-reciprocating-piston and gas-turbine engines, erosion of materials due to particle impact on a surface, and deposition of materials on surfaces by impinging droplets or particles that could solidify or bond on impact. For these applications, it is important to understand the forces that act on the particles so that their trajectories could be predicted.

Considerable work has been done on understanding the forces acting on spherical particles, where the Reynolds numbers (Rep ) based on the particle …

Experimental And Numerical Study Of The Air Distribution In An Airliner Cabin, Wei Liu

Open Access Theses

Nowadays, more people, including those with impaired health or who are otherwise potentially sensitive to the cabin environment, are traveling by air than ever before. The flying public demands a higher comfort level and a cleaner environment because they encounter a combination of environmental factors including low humidity, low air pressure, and sometimes, exposure to air contaminants such as ozone, carbon monoxide, various organic chemicals, and biological agents. Moreover, international air travel has increased the potential risks associated with airborne disease transmission and the release, whether accidentally or intentionally, of noxious substances during flight. Many studies suggest that the risk …