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Numerical Analysis Of A Multi-Stage Elastohydrodynamic Seal For Aircraft Engines, Md Wasif Hasan

Electronic Theses and Dissertations

At present, both governmental and private aviation enterprises are trying to develop aircraft that are swifter, more lightweight, and more cost-effective in order to maintain competitiveness on both the domestic and global stage. Continuous innovation and sustainability efforts are necessary to achieve advancements in aviation systems, such as fans, compressors, combustors, and turbines, as well as sub-systems, like engine seals. Advanced engine seals exhibit considerable potential in enhancing the engine's pressure ratio and cycle temperatures, leading to reduced engine weight, increased thrust, and improved fuel economy. In this study, a novel multistage seal idea has been proposed for the supercritical …

Dynamic Mode Decomposition As A Tool For Reducing Computational Time In Numerical Simulation Of Complex Flows, Laura Amelia George

Electronic Theses and Dissertations

The length of simulation time for unsteady computational fluid dynamics (CFD) is often based on intuition or best practices, as there is no established convergence criteria to guarantee that sufficient flow time has elapsed to resolve all spatio-temporal content. Thus, these simulations are often run longer than necessary, but this increases the run time and computational resources required. This thesis first introduces an algorithm, based on dynamic mode decomposition (DMD), that can determine when continuing an unsteady CFD computation no longer yields additional spatio-temporal information. This algorithm is demonstrated on an analytical dataset as well as two CFD test cases: …

Feasibility Of Thermoplastic Extrusion Welding As A Joining Method For Vacuum-Assisted Additively Manufactured Tooling, Chase C. Flaherty

Electronic Theses and Dissertations

In recent years, additive manufacturing (AM) has been successfully utilized for the production of large-scale composite tooling. Within these endeavors, however, limited research has focused on joining methods between printed sections. This work evaluates the feasibility of thermoplastic extrusion welding as a joining method for additively manufactured tooling structures. This joining method was assessed based on industry specifications of conventional thermoset tooling for wind blade manufacturing utilizing the vacuum-assisted resin transfer molding (VARTM) process. The specifications include requirements for the mechanical strength, vacuum integrity, roughness, and hardness of the tool surface. The feasibility of this welded polymer joint was demonstrated …

Investigation Into Sintered Lunar Regolith Construction Methods And Novel Usability Evaluation, Thomas A. Cox

Electronic Theses and Dissertations

Since the Apollo missions in the late 1960's, there has been a growing interest shared by many countries around the world to return to the Moon and establish a permanent Lunar settlement. The first phase of temporary Lunar bases will be established over the next several years. For a permanent human presence on the Moon, it will be necessary to use locally available resources for the construction of Lunar habitats and other infrastructure. Sintering Lunar regolith has been shown to be a promising method for producing structural material with a variety of desirable properties from strength to radiation shielding. While …

Numerical Study Of Owls’ Leading-Edge Serrations, Asif Shahriar Nafi

Electronic Theses and Dissertations

The silent flight ability of owls is often attributed to their unique wing morphology and its interaction with their wingbeat kinematics. Among these distinctive morphological features, leading-edge serrations stand out – these are rigid, miniature, hook-like patterns located at the leading edge of the primary feathers of their wings. It had been hypothesized that these leading-edge serrations serve as a passive flow control mechanism, influencing the aerodynamic performance and potentially affecting the boundary layer development over the wing, subsequently influencing wake flow dynamics. Despite being the subject of research spanning multiple decades, a consensus regarding the aerodynamic mechanisms underpinning owls’ …

Initial Procedure For Small-Scale Extraction Of Subsurface Martian Ice, Evan Steers

Electronic Theses and Dissertations

No abstract provided.

On The Simulation Of Supersonic Flame Holder Cavities With Openfoam, Zachary Chapman

Electronic Theses and Dissertations

One of the next major advancements in the aerospace industry will be hypersonic flight. However, to achieve hypersonic flight, propulsion systems capable of reaching hypersonic speeds need to be developed. One of the more promising hypersonic propulsion systems is the scramjet engine, however, several problems still need to be explored before reliable scramjet engines can be produced, the biggest being keeping the engine ignited. This has led to the use of flame holder cavities to create a region of subsonic flow within the engine to allow combustion to occur. High experimental costs make the use of computational fluid dynamic (CFD) …

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 …

Computational And Experimental Investigation Of Mass Reduced Aircraft Wing Ribs, Charles R. Fricks Iii

Electronic Theses and Dissertations

This study seeks to develop and evaluate a novel design of mass reduced aircraft wing ribs through the topology optimization method. For comparison, the same examination is performed on ribs with normal internal geometry. The wing rib design is based on that of the Gulfstream G650 transonic jet. The rib was divided into three segments for analysis based around the positions of the two spars. Only the center section of the rib (that being between the forward and aft spars) is mass optimized, while the leading and trailing edges of the ribs (outside the spars) will be kept solid for …

Investigations Of A Surrogate Fuel Based On Fischer-Tropsch Gtl And Ctl In Cvcc, Idi And Di Compression Ignition Engines, Amanda C. Weaver

Electronic Theses and Dissertations

With the increase in availability, feedstocks, and properties of alternative fuels, compatibility issues emerge between current engine platforms often requiring a limit on the blend percentage of alternative fuel in conventional fuel or alteration to the engine platform. Two key metrics were identified, autoignition quality and lubrication characteristics, as vital for the proper function of a compression ignition engine, and if the blend of alternative fuels matches these two criteria for the diesel standard, then the resulting blend percentage can be considered as a viable alternative for complete replacement of conventional petroleum ULSD. Autoignition quality was matched using blends S-8, …

Aerodynamics And Turbulent Wake-Flow Characteristics Of Owls During Flapping Flight, Krishnamoorthy Krishnan

Electronic Theses and Dissertations

Owls exhibit unique flight capabilities in the low Reynolds number flow regime which is prone to complex viscous flow phenomena. They possess unique feather features and flexible wing structures which are postulated to help them fly nearly silently and stably at low speeds in a complex flow setting. Understanding the aerodynamics of owls could pave the way to enhance the future designs of small flying vehicles. Though it has been a focus of research over multiple decades, no conclusive agreement has been attained on the aerodynamic mechanisms associated with owl flight. Particularly, the aerodynamics of flapping owl flight is severely …

Development And Testing Of A 1:70 Scale Model Wind Turbine Of The Iea Reference 15 Mw Floating Offshore System, Amber Parker

Electronic Theses and Dissertations

This thesis presents the development of a 1/70th scale performance-matched wind turbine intended for wind and wave basin model testing of commercially viable floating wind turbine structures based off of the International Energy Agency (IEA) Wind 15 MW design. The focus of this demonstration is to test active blade pitch response controls and to provide an experimental dataset for use by modelers and industry for future turbine improvements. Future research is planned to test the turbine in conjunction with an actively damping hull to test the interactions between the two control systems.

Outlined in this thesis are the methods of …

Analysis Guidelines And Functionalities Of The Catia Native Fea Solver For Composite Materials, Mohamed Edrisy

Electronic Theses and Dissertations

The emergence of commercial FEA solvers was a significant breakthrough that boosted the accuracy and complexity of engineering design. While composite materials are special materials, their mechanical properties can be custom made by considering the needs and requirements of the design problem. Given the rapidly expanding global consumption of composite materials, access to FEA solvers capable of assigning these materials is an absolute requirement.The CATIA software is a platform for designing, analyzing, and manufacturing of parts. However, there is no meaningful documentation in the public domain exploring the finite element functionalities of CATIA software for composite materials. Isotropic materials are …

Development Of Predictive Ballistic Models For Hypervelocity Impact On Sandwich Panel Satellite Structures, Riley Carriere

Electronic Theses and Dissertations

Sandwich panels are widely used in the design of uninhabited satellites and, in addition to having a structural function can often serve as shielding, protecting the satellites’ equipment from hypervelocity impacts (HVI) of orbital debris, and micrometeoroids. This thesis aims to provide: a comprehensive review of HVI experimental studies for honeycomb- and open-cell foam-cores; an examination of available predictive models used to assess the panels’ ballistic limits; as well as signify the influence of honeycomb-core parameters, such as cell size and foil thickness, as well as core material, on the ballistic performance of honeycomb-core sandwich panels (HCSP) when subject to …

Design, Development, And Testing Of Near-Optimal Satellite Attitude Control Strategies, Giovanni Lavezzi

Electronic Theses and Dissertations

Advances in space technology and interest toward remote sensing mission have grown in the recent years, requiring the attitude control subsystems of observation satellites to increase their performances in terms of pointing accuracy and on-board implementability. Moreover, an increased interest in small satellite missions and the recent technological developments related to the CubeSats standard have drastically reduced the cost of producing and flying a satellite mission. In this context, the proposed research aims to improve the state of the art for satellite attitude control methodologies by proposing a near-optimal attitude control strategy, simulated in a high-fidelity environment. Two strategies are …

A Non-Reacting Passive Scalar Comparison Of Starccm And Openfoam In A Supersonic Cavity Flame Holder, Thomas Nuese

Electronic Theses and Dissertations

The scramjet engine equipped with a modern-day airliner would allow for very quick travel across the United States. The major problem is that designing such an engine and testing it to make sure it is safe would cost millions if not billions of dollars. Computational fluid dynamics allows for complex designs to be tested but can still take many days, weeks, or even months to complete. With the use of computational fluid dynamics (CFD), the scramjet engine can be analyzed to determine a quicker way to test and develop a reliable configuration in addition to analyzing the effects of different …

Comparative Analysis Of Winglet Efficiency On Supercritical Versus Traditionally Cambered Airfoils, Evan Cathers

Electronic Theses and Dissertations

This study serves to define the performance of several industry-recognized and exploratory wing tip devices on aircraft wings utilizing contemporary supercritical airfoil geometry. For comparison, the same examination is performed on a wing comprised of traditionally cambered airfoils, the platform upon which winglets were initially developed. The supercritical wing design is based on that of the Airbus A320, while the conventional airfoil is based upon the Boeing 737-800 platform. Tip devices selected for analysis include blended, raked, split scimitar, fence, and spiroid winglets, as well as tip sails, characterized by the spreading of a bird’s primary flight feathers. Methodology for …

Investigations Of The Low Temperature Combustion Regions And Emissions Characteristics Of Aerospace F24 In A Constant Volume Combustion Chamber And A Common Rail Direct Injection Ci Engine, Richard C. Smith Iii

Electronic Theses and Dissertations

A study was conducted to investigate the low temperature combustion (LTC) regions of aerospace F24 and ULSD in the static setting of a CVCC and the dynamic setting of a CRDI research engine. This research is conducted to reduce in-cylinder emissions by understanding and implementing a technique to achieve an extended LTC. Emissions data for this study were collected during the operation of the CRDI research engine with a MKS 2030 FTIR and an AVL Microsoot 483. The parameters researched within the static setting of the CVCC included the determinations of the cool flames and NTC regions within the LTHR …

Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan

Electronic Theses and Dissertations

In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep …

Reaction Wheels Fault Isolation Onboard 3-Axis Controlled Satellite Using Enhanced Random Forest With Multidomain Features, Mofiyinoluwa Oluwatobi Folami

Electronic Theses and Dissertations

With the increasing number of satellite launches throughout the years, it is only natural that an interest in the safety and monitoring of these systems would increase as well. However, as a system becomes more complex it becomes difficult to generate a high-fidelity model that accurately describes all the system components. With such constraints using data-driven approaches becomes a more feasible option. One of the most commonly used actuators in spacecraft is known as the reaction wheel. If these reaction wheels are not maintained or monitored, it could result in mission failure and unwarranted costs. That is why fault detection …

Multilateration Index., Chip Lynch

Electronic Theses and Dissertations

We present an alternative method for pre-processing and storing point data, particularly for Geospatial points, by storing multilateration distances to fixed points rather than coordinates such as Latitude and Longitude. We explore the use of this data to improve query performance for some distance related queries such as nearest neighbor and query-within-radius (i.e. “find all points in a set P within distance d of query point q”). Further, we discuss the problem of “Network Adequacy” common to medical and communications businesses, to analyze questions such as “are at least 90% of patients living within 50 miles of a covered emergency …

Flight Trajectory Prediction For Aeronautical Communications., Nathan T Schimpf

Electronic Theses and Dissertations

The development of future technologies for the National Airspace System (NAS) will be reliant on a new communications infrastructure capable of managing a limited spectrum among aircraft and ground systems. Emerging approaches to this spectrum allocation task mostly consider machine learning techniques reliant on aircraft and Air Traffic Control (ATC) sector data. Much of this data, however, is not directly available. This thesis considers the development of two such data products: the 4D trajectory (latitude, longitude, altitude, and time) of aircraft, and the anticipated airspace utilization and communication demand within an ATC sector. Data predictions are treated as a time …

Interfacial Heat Transfer In Squeeze Casting Of Cast Al Alloy A380 And Mg Alloy Az91 And Wrought Alloy Az31, Luyang Ren

Electronic Theses and Dissertations

The weight reduction of vehicles and airplanes in the automotive and aerospace industries is urgently needed due to the government regulation and market demand. To satisfy engineering performance of lightweight auto and aero components, high strength light alloys such as aluminum (Al) or magnesium (Mg) alloys are usually adopted. This study was intended to explore a solution for casting high strength cast and wrought Al and Mg alloys. Before light alloys can be utilized for mass production, critical processing parameters need to be accurately determined. The interfacial heat transfer coefficient is one of the most important factors in casting processes. …

Development Of Triangular And Tetrahedral Finite Elements For Solutions To Thermoelastic Instabilities Using Hotspotter, Cortney Samuel Leneave

Electronic Theses and Dissertations

The objective of the work presented in this thesis is to develop first-order triangular and tetrahedral elements for solutions to Thermoelastic Instabilities (TEI) regarding sliding friction systems in Hotspotter.

Hotspotter software uses a finite element method and an eigenvalue method and is an important tool because currently no other commercial software exists which solves the TEI problem for critical velocities and wave numbers of a system. Hotspotter currently uses quadrilateral and hexahedral elements for two and three dimensional analysis, respectively. Typically, tri and tet elements are used in industry when doing static and dynamic stress analysis. Therefore, the Hotspotter user …

Experimental And Numerical Investigation Of Naca Airfoil Wing With Winglets, Courtney Danielle Bachmann

Electronic Theses and Dissertations

This research was performed in order to study wingtip devices and, in particular, winglets. Winglets are attached to commercial aircraft for the purpose of reducing induced drag caused by wake vortices on the wingtip. A winglet device can save an aircraft anywhere from 3-7% in fuel consumption. Over the course of a year, this can add up to hundreds of thousands of dollars saved. This research consisted of two parts: one part experiment and one part equipment design. The latter phase of this research examined various methods of testing in a subsonic wind tunnel laboratory setting. Experimental results found with …

Mechanical Properties Of Nanomodified Hybrid Gfrp Composite Materials, Micah Rop Kimutai

Electronic Theses and Dissertations

The mechanical behavior of the nanomodified hybrid epoxy matrix was investigated in glass fiber reinforced plastics (GFRP). In this study, five nanocomposites enriched with as received halloysite, nanomer I.28E, HNT-APTES, and the hybrid combinations of the two HNTs with the nanomer I.28E were successfully fabricated. To evaluate the effects and morphological characteristics of the individual fillers and the hybrid configurations on the epoxy resin matrix, TGA, DSC, and DMA were analyzed. To understand the effect of the five configurations on the neat GFRP laminate, mode I interlaminar fracture toughness, tensile, and vibration properties were investigated. Electron microscopy testing techniques were …

The Design And Validation Of A Uav Propeller Intended For Extremely Low Reynolds Number Environments, Benjamin Hebert

Electronic Theses and Dissertations

Mars exploration and UAV development have both advanced significantly over the past century, and are now being considered in tandem. Currently needed are UAV propellers that can operate in the Martian atmosphere. Flow will be in the range of Re < 20,000, creating extreme conditions not typically examined. A Blade Element Momentum Theory (BEMT) algorithm is developed using a variety of corrections designed specifically for low Reynolds number and rotational flows. Due to both the simplicity of the basic BEMT formulation, corrections are easy to put in place and often necessary to achieve accurate estimates. Aerodynamic coefficients are determined from XFOIL code, and have questionable accuracy in this regime. To account for this, a correction model is developed by comparing XFOIL results to experimental results of airfoils at low Re. This is all tested against a previous low Re propeller experiment. The results of this comparison are used to adjust the values in the correction, to produce more accurate results for theoretical design.

From here, a design philosophy for the propeller is developed using established methods and previous experimental data. High thrust is prioritized, with efficiency being a secondary concern. A hard mach limit of 0.7 is set to avoid major drag penalties, limiting the usable ranges of RPM and radius. Airfoil designs are then examined, based on previous designs, theoretical intuition, and …

Uav 6dof Simulation And Kalman Filter For Localizing Radioactive Sources, John G. Goulet

Electronic Theses and Dissertations

Unmanned Aerial Vehicles (UAVs) expand the available mission-space for a wide range of budgets. Using MATLAB, this project has developed a six degree of freedom (6DOF) simulation of UAV flight, an Extended Kalman Filter (EKF), and an algorithm for localizing radioactive sources using low-cost hardware. The EKF uses simulated low-cost instruments in an effort to estimate the UAV state throughout simulated flight.

The 6DOF simulates aerodynamics, physics, and controls throughout the flight and provides outputs for each time step. Additionally, the 6DOF simulation offers the ability to control UAV flight via preset waypoints or in realtime via keyboard input.

Using …

Satellite Constellation Deployment And Management, Joseph Ryan Kopacz

Electronic Theses and Dissertations

This paper will review results and discuss a new method to address the deployment and management of a satellite constellation. The first two chapters will explorer the use of small satellites, and some of the advances in technology that have enabled small spacecraft to maintain modern performance requirements in incredibly small packages.

The third chapter will address the multiple-objective optimization problem for a global persistent coverage constellation of communications spacecraft in Low Earth Orbit. A genetic algorithm was implemented in MATLAB to explore the design space – 288 trillion possibilities – utilizing the Satellite Tool Kit (STK) software developers kit. …

Characterization Of Directed Energy Deposition Additively Manufactured Grcop-42 Alloy, Scott Landes

Electronic Theses and Dissertations

GRCop is an alloy family constructed of copper, chromium, and niobium and was developed by NASA for high heat flux applications. The first of its kind, GRCop-84, was specifically designed for the environments seen by channel cooled main combustion chamber liners. To further increase thermal conductivity while maintaining material strength characteristics, the percentage of alloying elements were cut in half and GRCop- 42 was developed. In recent years, NASA has successfully additively manufactured GRCop with comparable material characteristics to wrought GRCop using a Laser Powder Bed Fusion (L-PBF) process. Benefits of this process include fabrication of intricate cooling channels as …