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An Experimental Study Of Hemispherical Vortex Generators For Separation Control Over A Naca-0012, David Joseph Ronald Tucker

Masters Theses

This is a study towards understanding hemispherical vortex generators (VGs) and their effectiveness on delaying flow separation over an airfoil. To be tested was whether these devices could generate a horseshoe vortex structure that effectively entrained higher momentum flow into the boundary layer over the surface of a NACA-0012 wing section. The experimental results are primarily from water tunnel experiments, but the clean configuration NACA-0012 airfoil was investigated by numerical methods in order to ascertain the potential for numerical modeling as a tool to accurately predict flow around the VGs, and as a guide for size and location optimization. At …

An Automated Finite Element Analysis Framework For The Probabilistic Evaluation Of Composite Lamina Properties, Jonathan Phillips Weigand

Masters Theses

This thesis outlines the development of computational modeling tools used to predict the elastic properties of composite lamina from representative volume elements (RVE) using numerical methods. The homogenization approach involves the use of Gauss’s Theorem to simply the average volumetric strain integral into a surface integral containing which is defined by surface displacements and their direction. Simulations of RVEs under specific loading conditions (longitudinal tension or shear and transverse tension or shear) are then performed in the software package ABAQUS to obtain the surface displacements. It was found that obtaining quality meshes and applying periodic boundary conditions for each RVE …

A Comparative Study Of The Gas Turbine Simulation Program (Gsp) 11 And Gasturb 11 On Their Respective Simulations For A Single-Spool Turbojet, Rayne Sung

Masters Theses

GasTurb 11 and the Gas Turbine Simulation Program (GSP) 11 are two commercially available gas turbine simulation programs used by industrial professionals and academic researchers throughout the world. The two programs use a pseudo-perfect gas assumption in their calculations, where the specific heat is taken as a function of temperature and gas composition but not pressure. This assumption allows the two programs to make more realistic calculations of gas turbine engine performance. This is in contrast to the ideal and perfect gas assumptions used in classroom calculations. In addition, GasTurb 11 and GSP 11 both utilize component maps, comprised from …

Analysis And Optimization Of Unsteady Flow Past A Circular Cylinder Using A Harmonic Balance Method, Emily Buckman Clark

Masters Theses

Two-dimensional laminar flow over a circular cylinder was investigated in this work. Three cases were considered in which the cylinder was either stationary, in constant rotation, or in periodic rotation. The purpose of this work was to investigate the effects of a rotating cylinder for lift enhancement, drag reduction, and the suppression of vortex shedding. The governing coupled nonlinear Navier-Stokes equations were solved using a finite difference discretization and Newton’s method. In this way, three flow solvers were developed for this research: a steady solver, an unsteady time-accurate solver, and an unsteady harmonic balance solver. The force coefficients were of …

An Interoperable Executive Library For Loosely Coupled Physics Systems, Andrew Austin Kail

Masters Theses

The complexity of simulating any system-wide process involving biomedical processes or thermal-fluid systems goes beyond the reach of a single computer code. In this document I present an Interoperable Executive Library (IEL) that has been designed to run, in parallel, a collection of multi-component physics simulations. The IEL is a light-weight integrator responsible for managing the distribution of data and memory, coordinating communication among parallel processes, and direct execution of a set of loosely coupled numerical and physics tasks HPC resources

Presented are two case studies utilizing the IEL. The first case simulates conjugate heat transfer coupled with a potential …

Using System Identification To Compare Global And Local Aerodynamic Modeling From Flight Data, Toby Earl Sorensen

Masters Theses

A method for identifying and comparing a longitudinal global aerodynamic model to a longitudinal local aerodynamic model for UTSI’s Piper Saratoga aircraft is explained and demonstrated. Large amplitude piloted inputs were used to estimate global nonlinear aerodynamic models from flight data. Flight derived global aerodynamic model structures, model parameter estimates, and associated uncertainties were provided for the longitudinal dimensional force and moment. The results from the global aerodynamic modeling were compared to local linear aerodynamic modeling results gathered with traditional small amplitude doublet inputs. The results from large amplitude piloted inputs compared favorably with small amplitude piloted inputs by ten …

An Experimental Study Of Supersonic Cavity Flow Control With Vertical Rods, Carolyn Leigh Thiemann

Masters Theses

Analysis of an open cavity shear layer when exposed to different leading edge pin configurations was studied experimentally, in a blow-down high speed wind tunnel run at Mach 1.84. A non-intrusive quantitative flow measurement system, Particle Image Velocimetry, was used to study velocity and vorticity fields with and without flow control implementations. The purpose of this study was to attempt to understand and explain the flow mechanisms which cause acoustic suppression obtained using different leading edge, vertical pin configurations. The cavity had an L/D of 4.89 and each pin configuration had a varied number and placement of pins, while pin …

Control Law Calculation And Verification Methods For The Variable Stability Navion In-Flight Simulation Aircraft, Joe Ming Yin Siu

Masters Theses

The University of Tennessee Space Institute’s (UTSI) variable stability research aircraft, Ryan Navion N66UT, was extensively modified by the Princeton University in the 1960’s. When UTSI acquired the aircraft from Princeton, volumes of calibration data, charts, and schematics manuals were transferred to UTSI.

Based on the study and research of available Princeton documents, methods of calculating flight control laws were “reverse-engineered”. The Variable Stability Navion employs an implicit model following structure to achieve in-flight simulation of other aircraft’s flying quality. Mathematical formulas were derived to calculate stability derivative potentiometer settings, for the analog response feedback flight controls system. MATLAB scripts …

Broncoblade: An Open Source Wind Turbine Blade Analysis Tool, Alex R. Quinlan

Masters Theses

This thesis reports the development and validation of BroncoBlade, a horizontal axis wind turbine analysis tool. BroncoBlade prepares finite element models and integrates them with an aeroelastic simulator. Analysis results for the SNL100-00 baseline blade are evaluated against reference results published by Sandia National Laboratories. Variations on the SNL100-00 blade incorporating carbon fiber are compared to the baseline blade.

Development Of Cfd Models For The Purposes Of Exploring Free Surface Wave Phenomena, Leonard P. Stoehr

Masters Theses

With the push for finding alternative, green energy sources, the harnessing of energy from ocean and lake waves is becoming a more researched field. To fully understand the behavior of wave interactions and optimize designs to extract this energy, it is necessary to develop computer models that can accurately replicate this behavior. A case is presented in which previous work done using the wave tank found in the Western Michigan University fluids lab is examined. The case involves harnessing the energy generated by ocean waves through the usage of plates of different shapes resting horizontally on the water’s surface. The …

Manual Modification And Plasma Exposure Of Boron Nitride Ceramic To Study Hall Effect Thruster Plasma Channel Material Erosion, Alexander J. Satonik

Masters Theses

"Worn Hall effect thrusters (HET) show a variety of unique microstructures and elemental compositions in the boron nitride thruster channel walls. Worn thruster channels are typically created by running test thrusters in vacuum chambers for hundreds of hours. Studies were undertaken to manually modify samples of boron nitride without the use of a hall effect thruster. Samples were manually abraded with an abrasive blaster and sandpaper, in addition to a vacuum heater. Some of these samples were further exposed to a xenon plasma in a magnetron sputter device. Sandpaper and abrasive blaster tests were used to modify surface roughness values …

A Computational Study Of Driven Micro-Cavities In Supersonic Flat Plate Flow, Thomas Ryan Rehmeier

Masters Theses

"Driven micro-cavities embedded in the wall beneath turbulent supersonic boundary layers are analyzed using two-dimensional computational fluid dynamics. This concept is a passive flow control technique in which very small cavities formed by arrays of thin vertical walls are oriented transverse to the flow direction and underlie the boundary layer. The purpose is to reduce or eliminate skin friction drag. Various micro-cavity configurations were analyzed at locations (0.1 m and 1 m) downstream of the leading edges of flat plates, for free-stream Mach numbers of 1.2, 2.0, and 3.0. Results focus on net drag reduction achieved, cavity flow-field effects, perforation …

Libration Point Orbits Near Small Bodies In The Elliptic Restricted Three-Body Problem, Bharat Mahajan

Masters Theses

"In this study, the feasibility of using libration point orbits to explore small solar system bodies, including asteroids and comets, is considered. A novel design for a small body mission is proposed that makes use of libration point orbits as "parking" orbits. In considering a human exploration mission to asteroids or comets, these "parking" orbits may provide benefits including a safe vantage point for staging/observation, reduced perturbation effects from the nonuniform gravitational field of the body, fewer communication blackouts, ease of guidance and control of a lander on the surface, etc. Because small solar system bodies have extremely low mass …

Dynamic Mechanical Analysis And Computer Simulation Of Polyurea Aerogels, Victoria Ann Prokopf

Masters Theses

"Historically, the use of aerogels has been limited due to their poor mechanical properties. However, polyurea aerogels have proven to be mechanically strong under quasi-static conditions. Polyurea aerogels can be created by filling molds of the desired shape with a liquid solution that then creates a solid gel filled with liquid. The liquid can be removed from the gel by supercritical drying. This thesis outlines dynamic testing as well as simulation for polyurea aerogels.

Testing has been conducted in dynamic tension and bending for densities of polyurea aerogels ranging from 0.12 g/cm³ to 0.31 g/cm³. In most …

Modeling Of Fracture And Durability Of Paste-Bonded Composite Joints Subjected To Hygro-Thermal-Mechanical Loading, David Lee Harris

Masters Theses

"The objective of the research is to characterize the behavior of composite/composite joints with paste adhesive using both experimental testing and analytical modeling. In comparison with the conventional tape adhesive, joining composites using paste adhesive provides several advantages. The carbon fiber laminate material systems employed in this study included IM7 carbon fibers and 977-3 epoxy matrix assembled in prepreg tape, and AS4 carbon fibers and 977-3 epoxy matrix as a five-harness satin weave. The adhesive employed was EA 9394 epoxy. All laminates and test specimens were fabricated and inspected by Boeing using their standard propriety procedures. Three types of test …

Effects Of Machining Parameters And Cooling Strategies On Cutting Forces And Surface Integrity In High-Speed Slot End-Milling Of Titanium Alloy, Emenike Chukwuma

Masters Theses

“Paper 1 presents the results of the investigations of the effects of cooling strategies [Emulsion cooling, Minimum Quantity Lubrication (MQL) and Liquid Nitrogen (LN₂)] and machining parameters (feed rate and spindle speed) on cutting force components, cutting temperature and tool wear during slot end-milling of titanium Ti-6Al-4V workpiece. All machining experiments were conducted using four-flute 0.5 inch diameter uncoated solid carbide end-mill on Cincinnati Milacron, Sabre 750 vertical machining center equipped with Acramatic 2100 controller. Cutting force components were acquired and tool wear was indirectly measured from maximum cutting force variation per slot from the first pass to …