Engineering Commons^™

Aerodynamic Design And Analysis Of A Modified 2006 Mazda Miata, William N. Recher

Honors College Theses

Aerodynamic forces developed by automobiles have destabilizing effects at high speed. These forces tend to skew toward a vehicle’s rear which can present safety concerns, especially for rear-wheel-drive automobiles like the Mazda Miata. To address oversteer and high-speed instability, a vehicle’s design can be tailored to bring about aerodynamic balance and improve traction. LiDAR was used to bring the physical automobile into the digital space. Then, a splitter and diffuser were added to reduce the magnitude of the destabilizing forces. Next, the size and shape of the rear-wing required to balance the vehicle was calculated using a combination of parameters …

Experiments And Simulations Of Liquid Mass Gauging And Slosh Dynamics In Microgravity, Jedediah Morse Storey

Theses and Dissertations

Advancements in liquid propellant management science and technologies are key to increasing safety, decreasing cost, and increasing payload mass of space missions. Propellant usually comprises a large portion of the total mass of launch vehicles and spacecraft, so liquid propellant sensing, as well as predicting and controlling the motion of it, are important. Electrical Capacitance Tomography (ECT) is an emerging sensing technology that is capable of measuring the distribution of liquid anywhere inside of a tank, potentially making it useful for measuring slosh and gauging mass. An ECT-instrumented tank was successfully tested in microgravity for the first time. Basics of …

Mitigation Of Aeroacoustic Noise Of A Fixed Wing Using Passive Flow Control, Cameron L. Perry

Electronic Theses and Dissertations

As the world becomes more environmentally conscious, noise pollution is of increasing concern. In this study, shallow dimples are applied to a NACA 0012 airfoil at multiple angles of attack (AoA) with the intent of reducing aeroacoustic noise emissions. Both Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models are used for aerodynamic and aeroacoustic investigations, respectively, at a fixed Reynolds number of 4.8 x 10⁵. Altering the dimple depth to diameter ratio (d/D) from 2.5% to 15% is first investigated, with a d/D of 5% or lower resulting in the least aerodynamic impact. The transition from …

Feasibility Study Of Slotted, Natural-Laminar-Flow Airfoils For High-Lift Applications, Hector David Ortiz Melendez

Doctoral Dissertations

A computational fluid dynamics approach to evaluate the feasibility of a slotted, natural-laminar-flow airfoil designed for transonic applications, to perform as a high-lift system was developed. Reynolds-Averaged Navier-Stokes equations with a laminar-turbulent transition model for subsonic flow at representative flight conditions were used for this analysis. Baseline high-lift simulations were performed to understand the stall characteristics of the slotted, natural-laminar-flow airfoil. Maximum aerodynamic efficiency was observed with a constant slot-width. In addition, the effectiveness of the aft-element as a high-lift device was explored. Results indicate that a micro-flap is a viable option as a lift effector. These are most effective …

Fuel Injector Design Of A Hypersonic Jet Engine Using Computational Fluid Dynamics, Melissa Rose Mercado

UNLV Theses, Dissertations, Professional Papers, and Capstones

The development of hypersonic airbreathing engines, such as a supersonic combustion ramjet, or scramjet, are implemented for flight Mach numbers over 5 where combustion must occur in supersonic conditions. The advancement of scramjet propulsion has led to favored usage over rocket propulsion systems for in atmosphere applications due to their lighter weight, higher specific impulse, and greater maneuverability [1]. The combustor section of a scramjet engine houses the fuel injectors. Fuel is injected into the supersonic flow with the main objective of achieving rapid and thorough fuel-air mixing because the residence time in the combustion chamber has a timescale of …

A Study Of Asymmetric Supersonic Wind Tunnel Nozzle Design, Brittany A. Davis

Mechanical & Aerospace Engineering Theses & Dissertations

Achieving higher Mach numbers for private and commercial flight is a growing interest in the aerospace community. To qualify vehicles prior to flight, tests must be run in wind tunnels. Asymmetric wind tunnel nozzles are of continuing interest to the aerospace community due to their ability to change throat geometry, allowing for a range of Mach numbers to be achieved that encompasses all of the supersonic regime. The sliding block wind tunnel at Old Dominion University (ODU) is designed for a range of Mach numbers from about 1.8 to 3.5 but is limited to an upper limit of 2.8 by …

A Computational Fluid Dynamics-Based Surrogate Wind Turbine Blade Aerodynamic Model For Hybrid Simulation, Eric Lalonde

Electronic Thesis and Dissertation Repository

Hybrid simulation (HS) is a promising technique for studying wind turbines due to the presence of scaling errors in wind tunnel testing. However, HS of wind-loaded structures is limited by the current practice of using lower-accuracy, "pre-calculated" aerodynamic loads, which uncouple the aerodynamic loading from the structural response. This thesis presents six stand-alone studies that collectively build towards a novel HS framework that employs a computational fluid dynamics (CFD) based surrogate model to generate higher-accuracy aerodynamic loads within the HS loop. An experimentally-validated residential wind turbine model equipped with an external damping system was used to illustrate the proposed framework. …

Simulating The Effects Of Floating Platforms, Tilted Rotors, And Breaking Waves For Offshore Wind Turbines, Hannah Johlas

Doctoral Dissertations

Offshore wind energy is a rapidly expanding source of renewable energy worldwide, but many aspects of offshore wind turbine behavior are still poorly understood and are not accurately captured by low-cost engineering models used in the design process. To help improve these models, computational fluid dynamics (CFD) can provide valuable insight into the complex fluid flows that affect offshore wind turbine power generation and structural loads. This research uses CFD simulations to examine three main topics important to future offshore wind development: how breaking waves affect structural loads for fixed-bottom wind turbines; how platform motions affect power generation, wake characteristics, …

Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke

Mechanical & Aerospace Engineering Theses & Dissertations

Urban Air Mobility (UAM) is one of the most popular proposed solutions for alleviating traffic problems in populated areas. In this context, the proposed types of vehicles mainly consist of rotors and propellers powered by electric motors. However, those rotary-wing components can contribute excessively to noise generation. Therefore, a significant noise concern emerges due to urban air vehicles in or around residential areas. Reducing noise emitted by air vehicles is critically important to improve public acceptance of such vehicles for operations in densely populated areas.

Two main objectives of the present dissertation are: (1) to expand the multidisciplinary optimization to …

Optimizing Design Parameters For Active Flow Control Boundary-Layer Fence Performance Enhancement On A Delta Wing, Nathan L. Tedder

Theses and Dissertations

Utilizing computational fluid dynamic (CFD) simulations, the presented study is able to further the investigation of replicating and improving upon the performance of a NACA 0012 cropped half-span delta-wing at high angles-of-attack with an active flow control fluidic fence via wall-normal, steady blowing from an optimized single chordwise slot located at z/b = 70%,. The data is generated using CREATE-AV Kestrel v10.1rc5 CFD software on the Department of Defense High Performance Computing systems. The flight regime is held constant at a Mach number of 0.18 and a Reynolds number (Re) of 5.0 x 10⁵, based on the root …

Helios And Tenasi Results For The Workshop For Integrated Propeller Prediction, Aaron Crawford

Honors Theses

Beginning in 2018, the AIAA began the workshop for integrated propeller prediction. This effort was intended to bolster the CFD prediction capabilities of the aerospace community due to a resurgent interest in propeller driven vehicles for electric applications. The test bed for this workshop is the NASA X-57, a model of which was experimentally tested in the Lockheed Martin Low Speed Wind Tunnel in January 2019. Using the 3D scanned geometry provided by the workshop a mesh was created and all priority one simulations were performed using two flow solvers. The flow solvers used were Helios, developed by the ADD …

A Numerical Investigation Of Microgravity Evaporation, Daniel Peter Ringle

Dissertations and Theses

Evaporation is important to myriad engineering processes such as cooling, distillation, thin film deposition, and others. In fact, NASA has renewed interest in using cabin air pressure evaporation as a means to recycle waste water in space. As one example, NASA recently conducted experiments aboard the International Space Station (ISS) to measure evaporation rates in microgravity and to determine the impacts of porous structure on the process. It has long been assumed that differences in evaporation rates between 1-g₀ and microgravity are small. However, discrepancies by as much as 40% have been observed in practice. The assumption now …

Rough Airfoil Simulation For Wind Turbine Applications, Nathaniel B. Develder

Doctoral Dissertations

As a result of insects or other environmental fouling, surface roughness on wind turbine blades can reduce power output significantly. Superhydrophobic surfaces, though possibly a passive, cost-saving, answer to the problem of ice accretion on wind turbine rotors in cold climates, may alter turbulence development in the blade boundary layer similar to environmental roughness. This work uses an equivalent sand grain extension to the Turbulent Potential model to computationally assess the aerodynamic effects of surface roughness on the s809 airfoil, including a representational superhydrophobic surface. Rough surface boundary layer theory, application of the equivalent sand grain method, roughness parameter correlation, …

Design And Analysis Of A Disk-Oriented Engine Combustor, Bennett M. Staton

Theses and Dissertations

In a novel approach to gas-turbine power production, an engine was designed and analyzed to use both a single-stage centrifugal compressor and single-stage radial in- ow turbine configured back-to-back. This air path reduced the axial length of the engine up to 60%, providing additional modularity in a gas-turbine engine that could be used to improve mobility of ground-based power units or increase the survivability of aircraft through the use of distributive propulsion. This increased modularity was made possible by the use of a circumferential ow combustor that substantially decreased the axial length of the burner and negated the need to …

Development Of A Computationally Inexpensive Method Of Simulating Primary Droplet Breakup, Brendon A. Cavainolo

Honors Undergraduate Theses

Liquid droplet impingement on aircraft can be problematic as it leads to ice accretion. There have been many incidents of aircraft disasters involving ice accretion, such as American Eagle Flight 4184. Understanding liquid droplet impingement is critical in designing aircraft that can mitigate the damages caused by icing. However, the FAA's regulations are only specified for "Appendix C" droplets; thus, aircraft designs may not be safe when accounting for droplets such as Supercooled Large Droplets. The assumptions of many models, such as the Taylor-Analogy Breakup (TAB) model, are no longer accurate for Supercooled Large Droplets, and the physics of those …

Numerical Study Of Spacer Grid Geometry In A 5 X 5 Nuclear Fuel Rod Bundle, Wan Chuan Fan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reactor fuel rod bundles serve as the primary heat source in light water reactors (LWRs), commonly found in the aforementioned PWR plants. The fuel rod bundles’ structure consists of a collection of fuel rods put into a parallel grid configuration. The bundles also include fuel rod spacers, which hold the fuel rods in place, in accordance with the grid. Repeating structures of the fuel bundles create the meta-structure in the reactor. In other words, the grid configuration repeats until it fills the entire space of the reactor. This results in reactor fuel rods suspended in the working fluid domain, oriented …

Investigating The Effect Of An Upstream Spheroid On Tandem Hydrofoils, Joel Tynan Guerra

Master's Theses

This thesis documents a series of three dimensional unsteady Reynolds Averaged Navier-Stokes CFD simulations used to investigate the influence of an upstream prolate spheroid body on tandem pitching hydrofoils. The model is validated by performing separate CFD simulations on the body and pitching hydrofoils and comparing results to existing experimental data. The simulations were run for a range of Strouhal numbers (0.2-0.5) and phase differences (0-π). Results were compared to identical simulations without an upstream body to determine how the body affects thrust generation and the unsteady flow field.

The combined time-averaged thrust increases with Strouhal number, and is highest …

Thermochemical Non-Equilibrium Models For Weakly Ionized Hypersonic Flows With Application To Slender-Body Wakes, Matthew P. Clarey

Theses and Dissertations

The current resurgence of interest in hypersonic technologies has warranted an inquiry into the commonly employed thermochemical non-equilibrium models within computational fluid dynamic (CFD) simulations. Additionally, research has historically focused on forebody flowfields, while studies of the complex wake structure have remained elusive. Although the forebody is of significance for vehicle analysis, the wake presents many exploitative characteristics. This dissertation aimed to address these two deficits. First, two three-temperature non-equilibrium models were developed, increasing the fidelity of hypersonic solutions above that of the legacy two-temperature model. The models were then investigated via zero-dimensional simulations, to detail the non-equilibrium processes, and …

Control, Characterization, And Cooling Of An Ultra-Compact Combustor, Kevin J. Demarco

Theses and Dissertations

An Ultra-Compact Combustor (UCC) is novel alternative to axial flow combustors commonly used in gas turbine engines. The UCC offers multiple benefits to engine design. First, the UCC aims to increase the thrust-to-weight ratio of an aircraft gas turbine engine by decreasing the size, and thus weight, of the engine's combustor. This is done by utilizing a Circumferential Cavity (CC) wrapped around the main core flow which hosts the combustion event, allowing a shortened combustor length. Second, within the CC, the combusting mixture is subjected to a high centrifugal loading which aids combustion by improving both flame propagation and residence …

Computational Investigation Using Bleed As A Method Of Shock Stabilization, Dayle L. Chang

Theses and Dissertations

Shock-wave/boundary layer interactions (SWBLI) produce undesirable dynamic loads and separated unsteady flows, adversely impacting the performance and structural integrity of supersonic vehicles. Computational fluid dynamics (CFD) is a successful tool in experimental planning and shows promise as a critical tool in understanding and mitigating negative effects of SWBLI. The goal of this research is to demonstrate the effect of bleed holes on shock stability using the OVERFLOW CFD solver to inform the planning of an Air Force Research Laboratory (AFRL) SWBLI wind tunnel experiment. First, a two-dimensional, flat plate, single-hole configuration was developed. Massflow discrepancies of 14.8% were initially observed …

Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar

Theses and Dissertations--Mining Engineering

Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone, …

Development Of A Cfd Model Of The Catalytic Combustion Of A Microtube Multi-Mode Propulsion System, Andrew Paul Taylor

Masters Theses

"This thesis presents the process and results of the development of a computational fluid dynamics (CFD) model in ANSYS Fluent 18.1 on the catalytic decomposition of a novel liquid monopropellant in a microtube in order to gain deeper insights than what is available through the experimental data. The CFD model was created using the Euler- Euler Multiphase model in conjunction with the Heterogeneous Reaction submodel. Such a choice of modeling setting was backed up by theory and benchmark computations on multiphase and compressible flow, shown in Section 3 and Appendix A. It was found that the previously determined one-step reaction …

Aerodynamic Design And Analysis Of A Large-Scale Stall-Regulated H-Type Vertical Axis Wind Turbine For An Offshire Floating Installation, Brian Peter Hand

PhDs

Wind energy has witnessed a consistent expansion over the past decade, especially with the move to offshore installation. There is an increasing need to further exploit superior offshore wind resources, which is pushing multi-megawatt wind turbines into deeper water locations where the current popular horizontal axis wind turbine configuration is not entirely suitable. In particular, there has been a renewed interest in the vertical axis wind turbine (VAWT) configuration due to its inherent design attributes for an offshore floating application and also its potential to provide a significant reduction in the system cost of energy. However, challenges still remain as …

Design And Computational Fluid Dynamics Analysis Of An Idealized Modern Wingsuit, Maria E. Ferguson

McKelvey School of Engineering Theses & Dissertations

The aerodynamics of a modern wingsuit has been the subject of very few detailed scientific studies to date. The prevailing design process remains the dangerous “sew and fly” method, in which designs are tested when they are first flown. This study utilizes Computational Fluid Dynamics (CFD) tools to analyze the flow field and aerodynamics of an idealized wingsuit, which is designed using Computer-Aided Design (CAD) modeling. The 3D CAD software Autodesk Inventor is used to create the wingsuit model, which is designed with a Gottingen 228 airfoil cross-section and a relatively large planform of aspect ratio 1.3. The commercial flow …

Liquid Fuel Film Cooling: A Cfd Analysis With Hydrocarbon Fuel, Jacob D. Bills

Theses and Dissertations

Cooling of liquid rocket engine combustion chambers and nozzles is a critical component to liquid rocket engine design. A common method of cooling is liquid fuel film cooling. Liquid fuel is injected along the surface of the wall to act as a barrier against the core combustion gases. A numerical model is developed for simulating liquid fuel _lm cooling in a rocket engine using a hydrocarbon fuel. The model incorporates turbulent multiphase ow with species transport within the commercial ANSYS® Fluent CFD software. Conjugate heat transfer is simulated through walls containing embedded cooling channels. A novel User Defined Function is …

Hot Streak Characterization In Serpentine Exhaust Nozzles, Darrell S. Crowe

Theses and Dissertations

Modern aircraft of the United States Air Force face increasingly demanding cost, weight, and survivability requirements. Serpentine exhaust nozzles within an embedded engine allow a weapon system to fulfill mission survivability requirements by providing denial of direct line-of-sight into the high-temperature components of the engine. Recently, aircraft have experienced material degradation and failure along the aft deck due to extreme thermal loading. Failure has occurred in specific regions along the aft deck where concentrations of hot gas have come in contact with the surface causing hot streaks. The prevention of these failures will be aided by the accurate prediction of …

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 …

Turbulence Modeling For Subsonic Separated Flows Over 2-D Airfoils And 3-D Wings, Aaron Michael Rosen

Open Access Theses

Accurate predictions of turbulent boundary layers and flow separation through computational fluid dynamics (CFD) are becoming more and more essential for the prediction of loads in the design of aerodynamic flight components. Standard eddy viscosity models used in many commercial codes today do not capture the nonequilibrium effects seen in a separated flow and thus do not generally make accurate separation predictions. Part of the reason for this is that under nonequilibrium conditions such as a strong adverse pressure gradient, the history effects of the flow play an important role in the growth and decay of turbulence. More recent turbulence …

Freedrop Testing And Cfd Simulation Of Ice Models From A Cavity Into Supersonic Flow, Thomas J. Flora

Theses and Dissertations

Weapon release at supersonic speeds from an internal bay is highly advantageous. For this reason, both experimental and numerical methods were used to investigate store separation from a cavity (L=D=4.5) into Mach 2.94 flow. The experiment used a piezoresistive pressure transducer, Schlieren and high-speed photography for data acquisition. The computational solution used the OVERFLOW solver. A sphere and a Mk-82, scaled to 1:20, were formed using frozen tap water. The sphere model was freedrop tested experimentally and computationally, while the sub-scale store shaped model was freedrop tested experimentally. The total pressure was varied to alter the dynamic response of the …

Numerical Investigation Of Highly Curved Turbulent Flows In Centrifugal Compressors And In A Simplified Geometry, Kevin J. Elliott

Electronic Thesis and Dissertation Repository

Curvature effects are investigated in terms of a recently developed curvature corrected turbulence model in turbomachinery applications. Two centrifugal compressor stages and a curved geometry modelled after a centrifugal impeller are simulated using the curvature corrected SST (SST-CC) turbulence model. This work improves the understanding of how the SST-CC model predicts curvature effects. An analysis of the SST-CC production multiplier in both centrifugal cases reveals that the model is appropriately accounting for curvature effects, showing increased production near concave surfaces and decreased production near convex surfaces. This correlates well with the simplified geometry results and demonstrates that the simplified geometry …