Numerical Analysis Of The Interaction Between A Detonation Wave And Compressible Homogeneous Isotropic Turbulence,
2011
University of Texas at Arlington
Numerical Analysis Of The Interaction Between A Detonation Wave And Compressible Homogeneous Isotropic Turbulence, Monika Chauhan
Mechanical and Aerospace Engineering Theses - Archive
A numerical study was performed to investigate the effect of preshock turbulence on the detonation wave properties. A direct numerical simulation was performed on the chemically reactive Navier-Stokes equations using a Runge-Kutta scheme and a fifth-order WENO spatial discretization. We performed a direct numerical simulation (DNS) which belongs to the domain of Computational Fluid Dynamics (CFD), of the fluid mechanics equations in three dimensions to determine the fine scale evolution. A simple one-step chemical kinetics model was used in the study.The main objective of the research is to examine the behavior of the turbulence when subjected to a strong shock …
Airfoil-Shaped Extension-Twist-Coupled Composite Star-Beams For Rotor Blade Tip Applications,
2011
University of Texas at Arlington
Airfoil-Shaped Extension-Twist-Coupled Composite Star-Beams For Rotor Blade Tip Applications, Sthanu Mahadev
Mechanical and Aerospace Engineering Theses - Archive
Rotorcraft blade tips provide the most effective region for aerodynamic control. Rotor blade airloads are proportional to dynamic pressure and as a consequence are typically the highest in the distal blade tip region. Therefore, blade control using aerodynamic forces and moments is most effectively accomplished over the distal region of the blade. Composite materials represent the preferred material option for modern rotor blade design, especially in the field of rotorcraft and wind energy, due to superior strength-to-weight ratio, fatigue resistance and their ability to be easily tailored to incorporate different coupling (bend-twist, extension-twist, etc.) among elastic modes of deformation within …
Design Optimization Using Augmented Lagrangian Particle Swarm Optimization,
2011
University of Texas at Arlington
Design Optimization Using Augmented Lagrangian Particle Swarm Optimization, Chethan Shivappa Thenehalli
Mechanical and Aerospace Engineering Theses - Archive
Engineering optimization problems normally include multiple, non-trivial, non-linear constraints. Traditionally gradient based optimization methods were used to solve these types of problems because of their high computational efficiency. But they generally require continuity of the optimization problem and the computation of derivatives and tend to get trapped in local minima. Hence non gradient based, evolutionary algorithms (EA) which are based on heuristic and stochastic nature and do not require continuity of the design space of the optimization problem and increase the probability to find a global optimal solution, therefore are becoming a popular choice in recent years. This work uses …
Stress Analysis For A Three Phase Plate With A Concentric Circular Inclusion By Deriving An Airy Stress Function,
2011
University of Texas at Arlington
Stress Analysis For A Three Phase Plate With A Concentric Circular Inclusion By Deriving An Airy Stress Function, Abhishek Kunchala
Mechanical and Aerospace Engineering Theses - Archive
This thesis derives the Airy stress function for a three phase plate that consists of two concentric circular inclusions and a matrix phase. It incorporates the elastic property of each phase as well as the geometry of the inclusions. An Airy stress function has been derived that satisfies the continuity conditions of the displacement and traction across the phase interface precisely. The obtained results are new and could not have been possible without a computer algebra system (Mathematica).
Finite Element Based Stability Constrained Weight Minimization Of Sandwich Composite Ducts For Airship Applications,
2011
University of Texas at Arlington
Finite Element Based Stability Constrained Weight Minimization Of Sandwich Composite Ducts For Airship Applications, Urmi B. Khode
Mechanical and Aerospace Engineering Theses - Archive
High Altitude Long Endurance (HALE) airships are platform of interest due to their persistent observation and persistent communication capabilities. A novel HALE airship design configuration incorporates a composite sandwich propulsive hull duct between the front and the back of the hull for significant drag reduction via blown wake effects. The sandwich composite shell duct is subjected to hull pressure on its outer walls and flow suction on its inner walls which result in in-plane wall compressive stress, which may cause duct buckling. An approach based upon finite element stability analysis combined with a ply layup and foam thickness determination weight …
Preliminary Design Of Mesoscale Turbocompressor And Rotordynamics Tests Of Rotor Bearing System,
2011
University of Texas at Arlington
Preliminary Design Of Mesoscale Turbocompressor And Rotordynamics Tests Of Rotor Bearing System, Md Saddam Hossain
Mechanical and Aerospace Engineering Theses - Archive
A mesoscale turbocompressor spinning above 500,000 RPM is evolutionary technology for micro turbochargers, turbo blowers, turbo compressors, micro-gas turbines, auxiliary power units, etc for automotive, aerospace, and fuel cell industries. Objectives of this work are:1) to evaluate different air foil bearings designed for the intended applications, and 2) to design & perform CFD analysis of a micro-compressor. CFD analysis of shrouded 3-D micro compressor was conducted using Ansys Bladegen as blade generation tool, ICEM CFD as mesh generation tool, and CFS as main solver for different design and off design cases and also for different number of blades. Comprehensive experimental …
Adaptation Of Digital Datcom Into A Conceptual Design Process,
2011
University of Texas at Arlington
Adaptation Of Digital Datcom Into A Conceptual Design Process, Brandon Watters
Mechanical and Aerospace Engineering Theses - Archive
As implied with open-ended `design decision-making' there are multiple prospective conventional and unconventional aircraft solution concepts able to satisfy a given mission specification. The task of defining, assessing and selecting prospective options for the mission at hand is the primary purpose of the aircraft conceptual design (CD) phase. In addition, conceptual design tends to be fast paced and an iterative process structure that requires a quick design-response. This leads the aircraft designer to simplified analysis techniques that focus on the impact (trends and sensitivities) of a new technology on the design. Correctly predicting these trends and sensitivities can be difficult. …
Vehicle Suspension Optimization For Stochastic Inputs,
2011
University of Texas at Arlington
Vehicle Suspension Optimization For Stochastic Inputs, Kailas Vijay Inamdar
Mechanical and Aerospace Engineering Theses - Archive
In the present thesis, a simulation based numerical method has been proposed for optimization of vehicle suspension system for stochastic inputs from random road surface profiles. Road surfaces are classified in based upon the power spectral density functions. The road surface is considered as a stationary stochastic process in time domain assuming constant vehicle speed. Using Fourier transforms, it is possible to generate the road surface elevations as a function of time. Time domain responses of the output of the suspension system are obtained using transfer function techniques. Optimum values of the damper constant are computed by simulation of the …
Feasibility Study Of T700 Rotorcraft Engine Rotor Supported By Hybrid Air Foil Bearings,
2011
University of Texas at Arlington
Feasibility Study Of T700 Rotorcraft Engine Rotor Supported By Hybrid Air Foil Bearings, Mahesh Kumar Varrey
Mechanical and Aerospace Engineering Theses - Archive
A potential solution towards light weighted and simple structured turbomachinery lies in elimination of oil-lubrication system. These promising benefits of oil-free turbomachinery have demanded extensive research in the field of small turbomachinery, leading to the development of different types of oil free bearings. Air foil bearings (AFBs) are one of the oil-free bearings with many advantages over others. AFBs have simple construction, greater service life and reduced maintenance. Their superior dynamic performance compared to traditional rigid surface bearings is an added advantage. Implementation of these foil bearings in the rotorcraft propulsion system decreases the total weight of the engine setup, …
Analysis Of Laminated Tubular Structure Under Torsion,
2011
University of Texas at Arlington
Analysis Of Laminated Tubular Structure Under Torsion, Thana Chomtid
Mechanical and Aerospace Engineering Theses - Archive
Laminated composite shells in particular are prominent in bearing various types of loads and are hence used in many engineering structures. The analysis of laminated composites is quite complicated since the material behavior is anisotropic, which gets further intensified in the analysis of complex structures like tubular structures. Finite element method is a useful method for evaluating and conducting the behavior of thin laminated tubular structure subjected to torsion. In this study, the behavior of shear stress versus angle along the laminated tubular structure cross section was conducted in varies radius ratio which are 1, 0.8, 0.6, 0.4, and 0.2 …
Static And Dynamic Calibration Of A Multi-Component Sidewall Force Balance For A Transonic Ludwieg Tube Wind Tunnel,
2011
University of Texas at Arlington
Static And Dynamic Calibration Of A Multi-Component Sidewall Force Balance For A Transonic Ludwieg Tube Wind Tunnel, Michael Gerard Werling
Mechanical and Aerospace Engineering Theses - Archive
Experimentation involving transonic flow requires replicating not only the Mach number but also the Reynolds number. Improper matching of the Reynolds number affects the interaction between the shocks and boundary layer on the surface of an airfoil, moving the position of the shock and altering the downstream flow field. Both Mach and Reynolds numbers have a large influence on the lift and drag characteristics of airfoils, amongst other aerodynamic effects, within the transonic regime of flight. A strain-based, multi-component, sidewall force balance was purchased in 1989 specifically for the transonic Ludwieg tunnel at the University of Texas-Arlington, but proper calibration …
Evaporative Cooling Performance Of A Brazed Microporous Coating On An Aluminum Surface,
2011
University of Texas at Arlington
Evaporative Cooling Performance Of A Brazed Microporous Coating On An Aluminum Surface, Ryan M. King
Mechanical and Aerospace Engineering Theses - Archive
The effect of an aluminum microporous coating on evaporative cooling performance was studied using distilled water as the working fluid. The aluminum microporous coating was fabricated by brazing aluminum particles to an aluminum substrate. Microporous coating thicknesses of 175 µm ± 20 µm, 270 µm ± 20 µm, and 900 µm ± 90 µm, and average aluminum particle sizes of 27 µm, 70 µm and 114 µm were used in a parametric study to determine the optimum aluminum microporous coating. A hot water treatment maximized the wickability of the microporous coating. Wickability was measured by vertical dipping of the coating. …
Algebraic Solution To The Planar Rigid Body Impact Problem,
2011
University of Texas at Arlington
Algebraic Solution To The Planar Rigid Body Impact Problem, Drew Morgan
Mechanical and Aerospace Engineering Theses - Archive
For systems of rigid bodies that undergo impacts, a series of closed-form equations are developed to solve for post-impact velocities which simulate a real-world (energy-consistent) interaction. The analysis is based in the impulse domain, and requires that the surface interaction be characterizable by Coulomb friction and an energetic coefficient of restitution. No iteration, optimization, or numerical methods are used.
Performance Optimization Of Multi-Core Processors Using Core Hopping - Thermal And Structural,
2011
University of Texas at Arlington
Performance Optimization Of Multi-Core Processors Using Core Hopping - Thermal And Structural, Sunil Lingampalli
Mechanical and Aerospace Engineering Theses - Archive
As the work load on the single core processor increases, it's processing speed increases resulting in increased power densities and die temperatures. The increase in die temperature results in decreased performance and reliability and increased leakage currents and cooling costs. In order to decrease the work load and the cooling cost on the single core processor, multi-core processors have been implemented. Multicore Processors also known as Chip Multi Processors (CMP's) are the processors which contain two or more independent cores on a chip. In CMPs, if one core reaches its critical temperature, the workload is transferred to the other. This …
Estimation Of Aircraft States And Wind Exposure In Aerial Refueling,
2011
University of Texas at Arlington
Estimation Of Aircraft States And Wind Exposure In Aerial Refueling, Je Hyeon Lee
Mechanical and Aerospace Engineering Dissertations - Archive
When a tanker and receiver aircraft fly in tight formation in an aerial refueling operation, they are exposed to various sources of wind with varying magnitude and direction. The tanker and the receiver aircraft experience prevailing wind and turbulence. The receiver aircraft is also subject to an additional wind field induced by the wake of the tanker.The receiver aircraft is required to fly in a precise trajectory relative to the tanker. Especially, the receiver aircraft should stay at a position with small tolerances for the fuel transfer operation while the tanker aircraft flies straight level and makes constant altitude turns. …
Fabrication Of Micropatterns On 3d Surfaces And Generation Of Linked Zno Nanowires,
2011
University of Texas at Arlington
Fabrication Of Micropatterns On 3d Surfaces And Generation Of Linked Zno Nanowires, Hui Wang
Mechanical and Aerospace Engineering Dissertations - Archive
Conventional lithographic approaches are good at fabricating structures on the top surfaces of substrates. They are not suited for 3D surface patterning due to the fact that vertical radiation exposure is employed to transfer patterns. In the meanwhile, patterns generated on 3D surfaces, such as the vertical sidewalls of silicon channels and the irregular surfaces of glass micropipettes may provide valuable applications in microfluidics, 3D circuits, bioengineering and so on. In this work, we developed new approaches to produce metal micropatterns on the vertical sidewalls of silicon channels as well as to fabricate two separated metal microlines on the tips …
Development Of An Experimental And Analytical Model Of An Active Cooling Method For High-Power Three-Dimensional Integrated Circuit (3d-Ic) Utilizing A Multidimensional Configured Thermoelectric Modules,
2011
University of Texas at Arlington
Development Of An Experimental And Analytical Model Of An Active Cooling Method For High-Power Three-Dimensional Integrated Circuit (3d-Ic) Utilizing A Multidimensional Configured Thermoelectric Modules, Huy Phan
Mechanical and Aerospace Engineering Dissertations - Archive
An increase in demand for more functionality and capacity of microelectronic components within the same logistic footprint drives the growth of three-dimensional integrated circuit (3D-IC) packaging technologies in recent years. However, the reduction in size and an increase in transistors density also intensified the heat flux of stacked-dice, which introduces many thermal challenges at both the package and cooling levels. Traditional passive cooling system such as forced air convection cooling, phase change materials and passive or active heat sinks will become inadequate to cool future processors and cannot accommodate the demand of future sub-ambient cooling of 3D-ICs. Within the past …
Hybrid Dynamic Simulation For Performance Optimization Of Legged Mechanisms,
2011
University of Texas at Arlington
Hybrid Dynamic Simulation For Performance Optimization Of Legged Mechanisms, Daniel Montrallo Flickinger
Mechanical and Aerospace Engineering Dissertations - Archive
Agile locomotion is needed for mobile robots to efficiently navigate challenging terrain. The ability of an agile legged mobile robot to abruptly change trajectory allows it toquickly react to obstacles and successfully operate in environments usually more suited forlegged animals. The research presented herein aims to increase the agility and performanceof legged robots.Using hybrid dynamic simulation, novel methods are developed to model the inter-action of a legged robot with the ground. In considering robot agility, an accurate model ofthe events that occur while in contact is needed. Methods are developed to model groundinteraction where oblique angled impacts occur, and to …
Design And Modeling Techniques For Cooling Of Telecommunication Systems,
2011
University of Texas at Arlington
Design And Modeling Techniques For Cooling Of Telecommunication Systems, Naveen Kannan
Mechanical and Aerospace Engineering Theses - Archive
Conventional data centers are extremely large buildings that have complex power distribution and cooling systems. These traditional brick and mortar data centers employ relatively expensive cooling systems and are inefficient. It has in turn led to an increase in construction and operational costs. These inefficiencies of traditional data centers can be overcome by partitioning the server load into modular sections which can be deployed, powered and cooled depending on availability and requirement. Furthermore, improvements in efficiency and operational costs can be achieved by employing "free cooling" to cool the IT equipment. Free cooling involves the introduction of outside air through …
Design Optimization Of A Wind Turbine Blade,
2011
University of Texas at Arlington
Design Optimization Of A Wind Turbine Blade, Bharath Koratagere Srinivasa Raju
Mechanical and Aerospace Engineering Theses - Archive
This work focuses on designing a blade of 45 meters in length that produces a power of 1.6 MW. The design of the blade was done using the Blade Element Momentum theory and the Prandtl's tip loss factor was used. The aerodynamic loads and differential power at are tabulated and plotted.The finite element method for analysis of the blade is used. As the chord lengths vary decreasingly along the blade radii in order to use the simple beam theory the breath and height of the blade is considered as a function of the chord length, hence the analysis is done …
