Thermochemistry Of Combustion In Polyvinyl Alcohol + Hydroxylammonium Nitrate,
2021
University of Alabama in Huntsville
Thermochemistry Of Combustion In Polyvinyl Alcohol + Hydroxylammonium Nitrate, James K. Baird, Robert A. Frederick Jr.
PRC-Affiliated Research
A mixture of polyvinyl alcohol (PVA) and hydroxylammoniun nitrate (HAN) forms a gummy solid known as a plastisol, which is ionically conducting. When an electrostatic potential of 200 V DC is applied across the plastisol, it ignites. Combustion ceases upon removal of the applied voltage. The products of PVA + HAN combustion are known to include the molecular gases carbon monoxide, carbon dioxide, water, nitrogen, and hydrogen. When the electric field within the plastisol is spatially uniform, combustion occurs preferentially at the anode. The fact that HAN is an ionic conductor suggests that the mechanism of combustion is electrolytic in …
Numerical Simulation Of Flow Past An Airfoil With Ice Accretion On Leading Edge,
2021
Washington University in St. Louis
Numerical Simulation Of Flow Past An Airfoil With Ice Accretion On Leading Edge, Boyu Wang
McKelvey School of Engineering Graduate Student Theses & Dissertations
The focus of this research is on aerodynamic simulation of flow past NACA 23012 airfoil with clean surface and with ice accretion on its leading edge by using the commercial CFD solver ANSYS Fluent. Reynolds-Averaged Navier-Stokes (RANS) computations are performed using Spalart-Allmaras (SA) and Wray-Agarwal (WA) turbulence models. ANSYS mesh package ICEM is used to model the geometry and generate the mesh. The computations are performed at 0, 2, 4, 6, 8, 10, and 12 degrees angle of attack which are compared with experimental data. For the case of ice accretion at the leading edge, the physical geometry becomes more …
Autonomous Optimal Trajectory Planning For Orbital Rendezvous, Satellite Inspection, And Final Approach Based On Convex Optimization,
2021
Utah State University
Autonomous Optimal Trajectory Planning For Orbital Rendezvous, Satellite Inspection, And Final Approach Based On Convex Optimization, Nicholas Ortolano, David K. Geller, Aaron Avery
Space Dynamics Laboratory Publications
Convex optimization techniques have deterministic convergence properties, are self-starting, i.e., they do not require an initial guess, and have been tested in real-time environments. These optimization techniques are applied to the trajectory planning problem for orbital rendezvous and proximity operations. Spacecraft rendezvous, inspection, and final approach trajectories are considered. Optional trajectory constraints are considered, including approach corridors, keep-out zones, and maximum thrust acceleration levels. Two linear dynamics models are investigated: Clohessy-Wiltshire dynamics to describe the relative motion in a local-horizontal local-vertical frame, and a new relative orbital motion dynamics model to describe the motion relative to a spinning or uncontrolled …
Rehology And Electrical Conductivity Of Particulate Composites In Additive Manufacturing,
2021
Southern Methodist University
Rehology And Electrical Conductivity Of Particulate Composites In Additive Manufacturing, Bin Xia
Mechanical Engineering Research Theses and Dissertations
Extrusion-based multi-functional additive manufacturing (AM) has been a rapidly developing area in AM recently. Particulate composites are widely used in this area to provide different functionalities with different types of particulate additives. However, there is no systematic understanding of the behavior of particulate composites during extrusion (especially in small nozzles) or of their properties once deposited in the build. This work investigates the properties of the type of particulate composites usually used in additive manufacturing, composed of a polymer matrix material and particulate additives within the micrometer scale. The focus is on the material rheology in the nozzle/capillary (for the …
Flying Wing Uav For Surveillance And Object Tracking,
2021
Kennesaw State University
Flying Wing Uav For Surveillance And Object Tracking, Kristen Padgett, Scott Semmelink, Jared Lasley, Paul Horne
Senior Design Project For Engineers
Unmanned aerial vehicles (UAV) have become ubiquitous in recent years due to their adaptability and ease of use. Surveillance UAVs in particular have seen increased interest and usage by law enforcement, civilian security, surveying, and federal services. The increased interest has led to the development of UAVs with increased endurance and payload capacity. Further as many of the applications of surveillance drones involve heightened security requirements, an aircraft of domestic make is preferential to many organizations. With this demand in mind, Inspired Products, LLC put forth a request for assistance in the design and testing of a surveillance UAV. More …
Effect Of Galvanic Corrosion On Crack Propagation Of Cold Expanded Holes In Aa2024-T3,
2021
Embry-Riddle Aeronautical University
Effect Of Galvanic Corrosion On Crack Propagation Of Cold Expanded Holes In Aa2024-T3, Ken Shishino
Doctoral Dissertations and Master's Theses
A search for the balance between weight reduction and durability of a structure has always been a popular topic within the aerospace industry. Among numerous researches to improve a structure’s fatigue life, processes on mechanically fastened joints have been a topic of focus as it is naturally a discontinuity in the material leading to a local stress concentration under loading. Cold expansion is a well-known technique with a wide range of applications in both new and repaired structures. The benefits include the extension of fatigue life and a delay in crack growth without addition of weight. However, localized galvanic corrosion …
Rocket Flight Simulation With Monte Carlo Uncertainty Analysis,
2021
University of Alabama in Huntsville
Rocket Flight Simulation With Monte Carlo Uncertainty Analysis, Jonathan Wallace Drake
Honors Capstone Projects and Theses
No abstract provided.
Cybersecurity Considerations With The Increasing Uses Of Small Unmanned Aircraft Systems (Suas) Or Drones,
2021
Bergen Technical High School
Cybersecurity Considerations With The Increasing Uses Of Small Unmanned Aircraft Systems (Suas) Or Drones, Matthew Kucharek, Stanley Mierzwa
Center for Cybersecurity
The effort to produce this information resource results from a collaborative effort between the Bergen County Technical Schools (high school), through the advisor Andrea Buccino, and a cybersecurity expert mentor. High school senior members of this learning partnership are provided with an interactive learning experience. They gain an increase and knowledge in a particular area of study while under the topical guidance of a mentor. In this example, the high school senior is pursuing coursework in Aerospace Engineering, and this was combined with the focus of cybersecurity to expand the students’ cross-discipline knowledge. This collaborative work was done virtually, given …
Real-Time Material State Assessment Of Composites Using Artificial Intelligence And Its Challenges,
2021
University of Texas at Arlington
Real-Time Material State Assessment Of Composites Using Artificial Intelligence And Its Challenges, Muthu Ram Prabhu Elenchezhian
Mechanical and Aerospace Engineering Dissertations - Archive
Over several decades of careful experimental investigation and exhaustive development of discrete damage analysis methods including integrated computational mechanics methods, our community knows a great deal about how discrete defects such as matrix cracks and defect growth (e.g. delamination) can be predicted in structural composites. For many practical situations controlled by laminated multiaxial composite structures, the loss of performance and “sudden death” end of life is controlled by defect coupling which becomes a precursor to fracture plane development. These interaction sequences are highly dependent on local details of manufacture, design configurations, and loading for a given application material and influenced …
Cooling Efficiency Improvement Of A Data Center Using Optimized Cabinet Design And Hybrid Cooling With High Inlet Conditions Of Single-Phase Coolant And Air,
2021
University of Texas at Arlington
Cooling Efficiency Improvement Of A Data Center Using Optimized Cabinet Design And Hybrid Cooling With High Inlet Conditions Of Single-Phase Coolant And Air, Uschas Chowdhury
Mechanical and Aerospace Engineering Dissertations - Archive
The objective of this study is to improve and optimize the cooling efficiency of liquid and air cooling from server to room level while applying best practices in the industry. The effect of increased air and coolant temperature has been explored through a literature survey and studies are conducted from device level to room level for air and liquid cooling. Three major aspects are considered. A closed-form air cooling solution is proposed for high-powered racks in a modular data center equipped with in-row coolers. Direct-to-chip liquid cooling technology is extensively studied at the server level for raised air and coolant …
Impact Of Material Models On Immersion Cooled Electronics Packages And Reliability Assessment For Chip-Package Interaction,
2021
University of Texas at Arlington
Impact Of Material Models On Immersion Cooled Electronics Packages And Reliability Assessment For Chip-Package Interaction, Tushar Jashvantbhai Chauhan
Mechanical and Aerospace Engineering Dissertations - Archive
The immersion cooling for IT equipment has been around for decades. From thermal energy management perspective, immersion cooling is better than traditional cooling technology. However, there is need for more work in open literature when it comes to impact of immersion cooling on the reliability of IT equipment to make it commercially implemented. Detailed study of material compatibility of the various electronics packaging materials for immersion cooling is essential to understand their failure modes and reliability. The stiffness and thermal expansion are critical material properties for electronics mechanical design. This part of the study mainly focuses on two things. The …
Development Of A Test Method For Characterizing An Indirect Evaporative Cooling Module For Data Center Cooling Application,
2021
University of Texas at Arlington
Development Of A Test Method For Characterizing An Indirect Evaporative Cooling Module For Data Center Cooling Application, Abhijit Rajendra Bhosale
Mechanical and Aerospace Engineering Theses - Archive
Evaporative cooling is a smarter way of maintaining optimum operating conditions in data centers. Indirect Evaporative Cooling (IEC) provides the advantage of cooling without changing the humidity of the Data Center (DC) air. We analyze and develop a method of testing to help build IEC modules at larger scales with improved characterization that is intended to help DC engineers achieve stringent Power Utilization Efficiency (PUE) targets by expending minimum power. We study the design parameters pertinent to sizing an IEC module used in DC cooling and develop a test method while technically selecting the components involved. The module is planned …
Sensitivity Study Of Calibrated Data Center Models To Minimize Site Survey Time Using Cfd,
2021
University of Texas at Arlington
Sensitivity Study Of Calibrated Data Center Models To Minimize Site Survey Time Using Cfd, Saurabh Singh
Mechanical and Aerospace Engineering Theses - Archive
Data center (DC) consists of components like cooling pipes, data cables, power conduits, etc. To analyze the thermal behavior of DC using computational fluid dynamics, virtual model of DC is required. To build this virtual model, data is required regarding the different components like size, location and defining parameters. Site surveys are required to collect this data. Data collection is important to build an accurate model. There is lack of guidance with respect to which components are crucial to achieve level of accuracy in computational model. Sensitivity study can be used to determine accuracy achieved by introducing simplification in component …
Effectiveness Of Closed-Loop Inverse-Kinematic Landmark Navigation Method On Drifting And Heading Errors Of Imprecise Multi-Legged Robots,
2021
University of Texas at Arlington
Effectiveness Of Closed-Loop Inverse-Kinematic Landmark Navigation Method On Drifting And Heading Errors Of Imprecise Multi-Legged Robots, Thong Quang Nguyen
Mechanical and Aerospace Engineering Theses - Archive
This work addresses the effectiveness of a closed-loop inverse-kinematic control methodology on alleviating drifting and heading errors in the walking and turning of a hexapod robot. Most work in this area focuses on stability, hardware design, and control. This work is aimed at controlling imprecise hardware on unknown structured environments. The proposed controller uses a camera and an ultrasonic sensor as sensory feedback. It also uses the well-known tripod gait for locomotion, implemented with the closed-loop inverse-kinematic method. Experimental results show the effectiveness of this approach in walking and turning the hexapod on an unknown surface.
Thermal Design Analysis Of Server Chassis Manifolds For Liquid Cooled Servers Using Cfd,
2021
University of Texas at Arlington
Thermal Design Analysis Of Server Chassis Manifolds For Liquid Cooled Servers Using Cfd, Kaustubh Kantilal Adsul
Mechanical and Aerospace Engineering Theses - Archive
Direct-to-chip liquid cooling is one of the most popular methods in data center thermal management when it comes to cooling high chip power densities. A cold plate-based liquid cooling system contains various components such as pumps, data center room, and rack-level manifolds, and server chassis-level manifold. Efficient coolant distribution to the heat-dissipating cold plates plays an important role in both the thermal and hydraulic performance of the server. It is, thus, very important to design and manufacture server chassis manifold geometry that can perform efficiently under the anticipated heat loads and coolant flow rates. In the present thesis, two such …
Design And Cfd Analysis Of A Tank Solution For Natural Convection Based Single-Phase Immersion Cooling Of Servers,
2021
University of Texas at Arlington
Design And Cfd Analysis Of A Tank Solution For Natural Convection Based Single-Phase Immersion Cooling Of Servers, Siddhesh Manohar Khanvilkar
Mechanical and Aerospace Engineering Theses - Archive
The issue of thermal management of data centers is becoming even more challenging with increasing chip power densities. This has been primarily driven by increasing demands in artificial intelligence and machine learning-based applications, increased usage of cloud-based services, and high-performance computing. The development of these applications has led to a corresponding increment in high performance and high power density CPUs and GPUs. Liquid cooling technologies are outperforming the traditional air cooling approach in dissipating high heat fluxes. Out of these technologies, single-phase immersion cooling offers advantages like substantially lower PUE values, simplified data center infrastructure, ease of deployment for edge …
Design, Development, And Characterization Of A Flow Control Device For Dynamic Cooling Liquid-Cooled Servers,
2021
University of Texas at Arlington
Design, Development, And Characterization Of A Flow Control Device For Dynamic Cooling Liquid-Cooled Servers, Hardik Yashwant Hurnekar
Mechanical and Aerospace Engineering Theses - Archive
Since the early ’60s, based on Moore’s law, transistor density has been doubling every generation resulting in increased power density. Eventually, in the early ’90s, we moved from constant voltage to constant electric field and corresponding constant power for a given area during technology changes. Dennard’s model of voltage scaling and corresponding constant power ceased, ending improved performance gains in the early 2000s that again required techniques to mitigate increased power and corresponding temperature. The performance gain is being achieved by using multi-core processors, leading to non-uniform power distribution and localized high temperatures making cooling very challenging. Direct cold plate-based …
Evaluating The Thermal Performance Of Topology Optimized Low-Cost 3d Printed Heat Sink Made Of Copper,
2021
University of Texas at Arlington
Evaluating The Thermal Performance Of Topology Optimized Low-Cost 3d Printed Heat Sink Made Of Copper, Bilal Taha
Mechanical and Aerospace Engineering Theses - Archive
The performance of a heat sink is highly dependent on the overall surface area available for heat transfer. Designing heat sinks with greater surface areas meant bigger size, weight, and volume of heat-exchanger thus making it unfeasible to produce. Design and manufacture of compact-sized heat sinks is a difficult task, as it would require the use of complex surface modeling and complex surface cutting. But with the advent of 3D printing technology, it has become easier to manufacture heat sinks having complex designs producing larger surface areas as they add material layer by layer rather than cutting it away. The …
Investigation On Microstructure And Mechanical Properties Of Porous Structures Processed By Laser Powder Bed Fusion,
2021
University of Texas at Arlington
Investigation On Microstructure And Mechanical Properties Of Porous Structures Processed By Laser Powder Bed Fusion, Samarth Ramachandra
Mechanical and Aerospace Engineering Theses - Archive
Inconel 718 (i.e., IN718) is a prominent nickel-based, precipitation-hardening superalloy which exhibits exceptionally stable mechanical and corrosion resistant properties, even at temperature range of 650ºC to 700ºC, making it suitable for a wide range of applications such as aerospace, nuclear reactors, tooling, turbines, oil and gas applications. The high toughness and work hardening offered by this superalloy, however, greatly limits the choice of machinability. The presence of low levels of aluminum permits good weldability which further allows the use of laser-based additive manufacturing (AM) to efficiently fabricate IN718 parts without the limitations associated with conventional manufacturing methods. Thanks to AM …
Investigation Of The Microstructural And Mechanical Properties Of Selectively Laser Melted In718 Overhangs Fabricated Without Support Structures,
2021
University of Texas at Arlington
Investigation Of The Microstructural And Mechanical Properties Of Selectively Laser Melted In718 Overhangs Fabricated Without Support Structures, Manjunath Hanumantha
Mechanical and Aerospace Engineering Theses - Archive
Additive manufacturing is a new manufacturing technology that allows for extreme design freedom as well as the simultaneous production of many parts with high complexities. IN718 is a high-strength, corrosion-resistant super alloy of nickel and chromium. It is ideal for high-end applications such as rocket nozzles and turbines because it can handle exceptionally high pressure and heat. Because of its high stiffness qualities, conventional manufacturing of complex IN718 geometries is challenging. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) because of its potential to produce near-perfect parts at a low cost when working …
