Engineering Commons^™

Foundations For Finite-State Modelling Of A Two-Dimensional Airfoil That Reverses Direction, Jake Michael Oscar Welsh

McKelvey School of Engineering Theses & Dissertations

Current 3-D finite-state wake models are incapable of simulating a maneuver in which the sign of the free-stream velocity changes direction and the rotor enters its own wake -- as might occur in the case of a helicopter which ascends and then descends. It is the purpose of this work to create a 2-D finite-state wake model which is capable of handling changes in free-stream direction as a precursor to development of a 3-D model that can do the same.

The 2-D finite-state model used for reentry modifications is an existing model created by Peters, Johnson, and Karunamoorthy. By the …

Investigating Ground Interactions Of A Rotocraft Landing Vehicle On Titan, Adam Rozman

Honors Undergraduate Theses

The exploration of celestial bodies has recently advanced from rovers to rotorcraft. This includes the recent flights of Mars Ingenuity and the upcoming Dragonfly mission to explore the terrain of Saturn’s moon Titan as part of NASA’s New Frontiers Program. Flight-based landers can travel quickly to sites kilometers apart and land in complex terrain. Although cruise conditions for these rotorcrafts are well understood, studies are necessary to understand take-off and landing. In ground effect conditions, a rotor wake impinges and reflects off the ground, creating changes in aerodynamics such as increased lift. Additionally, operating over loose surfaces, the rotors can …

Mean Pressure Gradient Effects On Flame-Flow Dynamics In A Cavity Combustor, David M. Smerina

Honors Undergraduate Theses

Pressure gradient confinement effects are experimentally investigated within a cavity combustor to analyze the flame interactions of premixed, cavity stabilized, flames in a high-speed combustor. Pressure gradient confinement effects are generated in a dual mode ramjet-scramjet (DMSR) by varying the wall geometry to form converging, diverging, and nominal configurations. The velocity field and flame position are captured temporally using simultaneous high-speed particle image velocimetry (PIV) and CH chemiluminescence. The evolution of the flow field and flame structure are analyzed, and the high temporal resolution of these measurements allows for the characterization of turbulence-flame interactions. Consideration of the combustion mode and …

Improving Quantification Of Mitral Regurgitation Through Computational Fluid Dynamics And Ex Vivo Testing, Alexandra Flowers

Electronic Theses and Dissertations

Mitral regurgitation (MR) is a prominent cardiac disease affecting more than two million people in the United States alone. In order for patients to receive proper therapy, regurgitant volume must first be quantified. As there are an array of methods to do so, the proximal isovelocity surface area (PISA) method continues to be the most accurate and clinically used method. However, there are some difficulties obtaining the necessary measurements need for this when performing transthoracic echocardiography. This study aims to evaluate and present techniques that may be used to more accurately quantify regurgitation through ex vivo testing and computational fluid …

Electric Field Induced Self-Assembly Of Mesoscale Structured Materials And Smart Fluids, Suchandra Das

Dissertations

This dissertation aims to study the forces that drive self-assembly in binary mixtures of particles suspended in liquids and on fluid-liquid interfaces when they are subjected to a uniform electric or magnetic field. Three fluid-particle systems are investigated experimentally and theoretically : (i) Suspensions of dielectric particles in dielectric liquids; (ii) Suspensions of ferromagnetic and diamagnetic particles in ferrofluids; and (iii) Dielectric particles on dielectric fluid-liquid interfaces. The results of these studies are then used to estimate the parameter values needed to assemble materials with desired mesoscale microstructures.

The first fluid-particle system studied is an electrorheological (ER) fluid formed using …

Analysis Of Fluid Flow In Redox Flow Batteries, Erfan Asadipour

McKelvey School of Engineering Theses & Dissertations

Redox flow batteries (RFB) hold great potential for large-scale stationary energy storage. However, their low energy density compared to other energy storage systems must improve for feasibility. Electrolyte flow distribution affects current density distribution and providing a uniform current density distribution is one way to improve RFB performance. Additionally, reducing the power consumption of the electrolytes’ pump as a source of energy loss in RFB systems increases their efficiency. Investigating both subjects requires analysis of the fluid dynamics in RFB cells.

In this thesis, a novel, computationally cost-effective hydraulic-electrical analogous model (HEAM) was developed to study fluid dynamics by implementing …

Benchmarking Of A Mobile Phone Particle Image Velocimetry System, David Armijo

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

One of the most important tools in a fluid dynamics laboratory is a particle image velocimetry (PIV) system. This system can measure the speed of a fluid flow simply by taking high-speed images of the motion of the fluid, then applying PIV cross-correlation software to calculate speed from the resulting images. The mI-PIV project is in the process of designing a new method of performing PIV by putting the cross-correlation software on a mobile phone application, called mobile Instructional PIV (mI-PIV). This system is an innovative stepping stone in making PIV systems more widely available. It is designed to be …

Fluted Films Caused By Gravity Driven Water Drainage From Vertical Tubes, Matthew B. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

When a stationary mass of water in a vertical tube is suddenly released, it creates a variety of artistic shapes and behaviors as it escapes the tube exit. As the descending water accelerates in the tube, friction along the tube wall slows the outer radius, resulting in a moving film entrained on the tube that trails the main body of water. When this film exits the tube, surface tension, gravity, and inertia interact to cause the film to create a wide variety of shapes, including jets, tubes, water bells, champagne glasses, and bubbles; rich forms that appear in other natural …

Characterization Of Single- And Multi-Phase Shock-Accelerated Flows, Patrick John Wayne

Mechanical Engineering ETDs

Experiments conducted in the Shock Tube Facility at the University of New Mexico are focused on characterization of shock-accelerated flows. Single-phase (gaseous) initial conditions consist of a heavy gas column of sulfur hexafluoride seeded with approximately 11% acetone gas by mass. Visualization of the image plane for gaseous initial conditions is accomplished via planar laser-induced fluorescence (PLIF) with a high-powered Nd:YAG ultraviolet laser and an Apogee Alta U-42 monochrome CCD camera, with a quantum efficiency > 90%. Multi-phase (gas-solid) initial conditions consist of glass micro-beads deposited on small 1-cm diameter discs of specific surface chemistry, mounted flush with the bottom wall …

A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc, Nicholas Stegmeier

Electronic Theses and Dissertations

The importance of computing in the natural sciences continues to grow as scientists strive to analyze complex phenomena. The dynamics of turbulence, astrophysics simulations, and climate change are just a few examples where computing is critical. These problems are computationally intractable on all computing platforms except supercomputers, necessitating the continued development of efficient algorithms and methodologies in parallel computing. This thesis investigates the use of parallel computing and mathematical modeling in the natural sciences through several applications, namely computational fluid dynamics for impinging jets in mechanical engineering, simulation of biofilms in an aqueous environment in mathematical biology, and the solution …

Investigations Into The Airside Cooling Of A Heat Exchanger, David Vallet

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this study we investigate the air-side cooling of a flat-plate fin and tube heat transfer condenser with numerical simulations. A new design is proposed which utilises vortex generators to direct the flow in such a way as to remove some of the stagnant heated air that collects in the wake of the pipes. A comparative study of the proposed design and a standard tube and fin condenser is conducted by varying the air side entrance velocities. The Shear Stress Tension, SST $\kappa - \omega$ 2-equation turbulent model is used to solve the RANS model in ANSYS Fluent 18. The …

Large Length Scale Capillary Fluidics: From Jumping Bubbles To Drinking In Space, Andrew Paul Wollman

Dissertations and Theses

In orbit, finding the "bottom" of your coffee cup is a non-trivial task. Subtle forces often masked by gravity influence the containment and transport of fluids aboard spacecraft, often in surprising non-intuitive ways. Terrestrial experience with capillary forces is typically relegated to the micro-scale, but engineering community exposure to large length scale capillary fluidics critical to spacecraft fluid management design is low indeed. Low-cost drop towers and fast-to-flight International Space Station (ISS) experiments are increasing designer exposure to this fresh field of study. This work first provides a wide variety of drop tower tests that demonstrate fundamental and applied capillary …

Developing And Testing An Anguilliform Robot Swimming With Theoretically High Hydrodynamic Efficiency, John B. Potts Iii

University of New Orleans Theses and Dissertations

An anguilliform swimming robot replicating an idealized motion is a complex marine vehicle necessitating both a theoretical and experimental analysis to completely understand its propulsion characteristics. The ideal anguilliform motion within is theorized to produce ``wakeless'' swimming (Vorus, 2011), a reactive swimming technique that produces thrust by accelerations of the added mass in the vicinity of the body. The net circulation for the unsteady motion is theorized to be eliminated.

The robot was designed to replicate the desired, theoretical motion by applying control theory methods. Independent joint control was used due to hardware limitations. The fluid velocity vectors in the …

Computational Fluid Dynamics Validation Of Buoyant Turbulent Flow Heat Transfer, Jared M. Iverson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Computational fluid dynamics (CFD) is commonly used to visualize and understand complicated fluid flow and heat transfer in many industries. It is imperative to validate the CFD computer models in order to avoid costly design choices where experimentation cannot be used to ratify the predictions of computer models. Assessments of CFD computer models in the literature conclude that significant errors occur in computer model predictions of fluid flow influenced by buoyancy forces.

The Experimental Fluid Dynamics Laboratory at Utah State University constructed a wind tunnel with which to perform experiments on buoyancy induced fluid flow. The experiments measured the heat …

Modeling, Numerical Analysis, And Predictions For The Detonation Of Multi-Component Energetic Solids, Michael Wayne Crochet

LSU Doctoral Dissertations

Metal powders are often used as an additive to conventional high explosives to enhance the post-detonation blast wave. Piston-impact simulations are commonly utilized to predict performance metrics such as detonation speed and strength, as well as assessing the impact and shock sensitivity of these materials. The system response is strongly influenced by the initial particle size distribution and material composition. Multiphase continuum models have been routinely applied at the macroscale to characterize the detonation of solid high explosives over engineering length scales. Current models lack a description of the physically permissible constitutive relations for mass transfer due to general chemical …

Vortex Shedding Dynamics In Long Aspect-Ratio Aerodynamics Bodies, Liu Chen

Dissertations, Master's Theses and Master's Reports - Open

The focus of the current dissertation is to study qualitatively the underlying physics of vortex-shedding and wake dynamics in long aspect-ratio aerodynamics in incompressible viscous flow through the use of the KLE method. We carried out a long series of numerical experiments in the cases of flow around the cylinder at low Reynolds numbers. The study of flow at low Reynolds numbers provides an insight in the fluid physics and also plays a critical role when applying to stalled turbine rotors. Many of the conclusions about the qualitative nature of the physical mechanisms characterizing vortex formation, shedding and further interaction …

Cfd Study On Aerodynamic Effects Of A Rear Wing/Spoiler On A Passenger Vehicle, Mustafa Cakir

Mechanical Engineering Master's Theses

Aerodynamic characteristics of a racing car are of significant interest in reducing car-racing accidents due to wind loading and in reducing the fuel consumption. At the present, modified car racing becomes more popular around the world. Sports cars are most commonly seen with spoilers, such as Ford Mustang, Subaru Impreza, and Chevrolet Corvette. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high-speed maneuverability, a spoiler can still be beneficial. One of the design goals of a spoiler is to reduce drag and increase fuel efficiency. Many vehicles have a fairly steep …

Purge And Secondary Flow Interaction Control By Means Of Platform Circumferential Contouring, Melissa Harris

Electronic Theses and Dissertations

This study presents an attempt to reduce the losses produced by the purge flow in a turbine stage by incorporating circumferential platform contouring. Two contours are proposed and compared against a baseline at different levels of swirl. The computational simulations were performed using a RANS three-dimensional Computational Fluid Dynamics code with the Shear Stress Transport turbulence model. The results of steady simulations demonstrate that for the first contour, when the flow is swirled to 50% of the rim speed, the purge flow exits the cavity with less cross flow. This in turn reduces the strength of the passage vortex. However, …

Heat Transfer In A Coupled Impingement-Effusion Cooling System, Mark W. Miller

Electronic Theses and Dissertations

Gas turbine engines are prevalent in the today’s aviation and power generation industries. The majority of commercial aircraft use a turbofan gas turbine engines. Gas turbines used for power generation can achieve thermodynamic efficiencies as high as 60% when coupled with a steam turbine as part of a combined cycle. The success of gas turbines is a direct result of a half century’s development of the technology necessary to create such efficient, powerful, and reliable machines. One key area of technical advancement is the turbine cooling system. In short, increasing the turbine inlet temperature leads to a rise in cycle …

Computational Fluid Dynamic Optimization And Design For The Airborne Laser System, Matthew James Opgenorth

Electronic Theses and Dissertations

The Airborne Laser (ABL) was designed to destroy any ballistic missile shortly after launch that could be a threat to the United States and its allies. The ABL uses several lasers to accomplish the destruction of the ballistic missile, most notably the high powered Chemical Oxygen Iodine Laser (COIL). The COIL is a complex device that could be improved upon in several areas that will result in overall weight reduction, refinement of beam quality, and increased magazine capacity.

This dissertation presents novel design and optimization techniques coupled with fluid dynamics to improve the performance of the COIL system. The focus …

Analysis Of The Flow Through A Francis' Turbine Runner Using Computational Fluid Dynamics, William Anthony

Archived Theses and Dissertations

This study investigates the fluid flow through the runner of an exceptionally low specific speed Francis’ turbine using computational fluid dynamics (CFD) to predict some performance characteristic of the runner, and to determine the effect of cavitation on the flow features within the turbine. It employs FLUENT CFD codes for the analysis. The study was carried out under steady conditions in two- dimensional analysis, primarily using the RNG k-ε turbulence model. It is mainly on single phase analysis; however a single case of two-phase cavitation modeling was performed in order to evaluate cavitation effects. The hydraulic losses were much dependent …

Developing Dns Tools To Study Channel Flow Over Realistic Plaque Morphology, Ryan M. Beaumont

Electronic Theses and Dissertations

In a normal coronary artery, the flow is laminar and the velocity is parabolic in nature. Over time, plaques deposit along the artery wall, narrowing the artery and creating an obstruction, a stenosis. As the stenosis grows, the characteristics of the flow change and transition occurs, resulting in turbulent flow distal to the stenosis. To date, direct numerical simulation (DNS) of turbulent flow has been performed in a number of studies to understand how stenosis modifies flow dynamics. However, the effect of the actual shape and size of the obstruction has been disregarded in these DNS studies. An ideal approach …

Design And Numerical Simulation Of Two Dimensional Ultra Compact Combustor Model Sections For Experimental Observation Of Cavity-Vane Flow Interactions, David S. Moenter

Theses and Dissertations

An improved computational fluid dynamics (CFD) model was developed for numerical simulation of the Ultra Compact Combustor (UCC) concept to enhance turbulent flow characterization of the circumferentially traveling, centrifugal-force enhanced combustion, cavity flow into the engine main flow passage via a radial cavity in the turbine axial guide vanes. The CFD model uses a dense grid on a 60° periodic, axisymmetric combustor section, with the RNG κ-ε turbulence model to resolve turbulent flow details. An overall analysis and performance evaluation of the experimentally tested UCC configuration and an axially shortened cavity baseline configuration was conducted at various experimentally documented operating …

Dynamic Unstructured Method For Prescribed And Aerodynamically Determined Relative Moving Boundary Problems, Kamakhya Prasad Singh

Mechanical & Aerospace Engineering Theses & Dissertations

A new methodology is developed to simulate unsteady flows about prescribed and aerodynamically determined moving boundary problems. The method couples the fluid dynamics and rigid-body dynamics equations to capture the time-dependent interference between stationary and moving boundaries. The unsteady, compressible, inviscid (Euler) equations are solved on dynamic, unstructured grids by an explicit, finite-volume, upwind method. For efficiency, the grid adaptation is performed within a window around the moving object. The Eulerian equations of the rigid-body dynamics are solved by a Runge-Kutta method in a non-inertial frame of reference. The two-dimensional flow solver is validated by computing the flow past a …

An Adaptive Remeshing Finite Element Method For High-Speed Compressible Flows Using Quadrilateral And Triangular Elements, Gururaja R. Vemaganti

Mechanical & Aerospace Engineering Theses & Dissertations

In this study a new adaptive remeshing method for high speed compressible flow analysis is presented. The method uses quadrilateral elements where possible, and triangles are introduced as needed. The primary goal of this study is to develop a remeshing method which uses both the concepts of unstructured and structured meshes for the finite element analysis to predict accurate aerodynamic heating in problems related to high speed viscous flows. The remeshing method uses a solution based on an old mesh to create a new mesh based on an advancing front technique. In the present implementation, a structured mesh of quadrilaterals …

Application Of The Finite Element Method Using The Method Of Weighted Residuals To Two Dimensional Newtonian Steady Flow With Constant Fluid Properties, Mien Ray Chi

Theses and Dissertations

In this thesis we will be concerned with the two-dimensional steady laminar Newtonian fluid flow with constant fluid properties in Cartesian coordinate system. More precisely, we will consider a flow for which the interesting dependent variables, for example, velocity, vorticity, stream function, etc., are expressible as functions of two independent Cartesian coordinates.

Transition From Laminar To Turbulent Flow For A Two-Phase Mixture, Mohammed Sharief Qureshi

Theses and Dissertations

A phase is simply one of the states of matter. Multiphase flow is the simultaneous flow of several phases. Two-phase flow is the simplest case of multiphase flow.

A Numerical Solution To The Problem Of Rotation Near The Ground, David D. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

No abstract.

Developing Turbulent Flow In An Annulus, Dwight H. Kelly

Theses and Dissertations

Turbulent flows are encountered in nearly every case where fluid motion is involved. Since turbulent flow through relatively short annular sections occurs frequently in practical applications, e.g., flow through heat exchangers, axial flow turbomachinery and jet aircraft engines, there is a need for detailed information on this subject.

The Development Of Turbulent Flow In The Inlet Region Of Smooth Pipe, Forrest C. Smith

Theses and Dissertations

Turbulent flows are encountered in nearly every case where fluid motion is involved. Turbulent flow in pipes is of great practical interest, and the problem of flow in the entry region is of special importance since the great majority of applications are in the realm of developing flow.