From A Single Grain To Microstructure: How Explosive Grains Interact Under Shock Compression,
2023
Missouri University of Science and Technology
From A Single Grain To Microstructure: How Explosive Grains Interact Under Shock Compression, Lawrence Salvati, Siva Kumar Valluri, Dana D. Dlott
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We studied the effect of varying the HMX concentration in a plastic-bonded explosive (PBX) by analyzing the time-dependent thermal emission with short (4 ns) duration shocks that produced pressures of about 20 GPa. We found that the HMX tended to aggregate even at the lowest concentrations. Once the cluster size reached about 15 μm, at 30 wt.%, the cluster size started increasing more dramatically, but energy release during deflagration reached a plateau. These observations are consistent with the idea that the clusters act as a limiting factor for hot spot criticality, possibly due to heat loss mechanisms such as conduction …
Porosity: The Key To Initiating Metallic Composite Particles Under Shock Compression,
2023
Missouri University of Science and Technology
Porosity: The Key To Initiating Metallic Composite Particles Under Shock Compression, Siva Kumar Valluri, Edward L. Dreizin, Dana D. Dlott
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The use of metallic composites as additives can potentially improve the energy density of explosives. Before employing them as additives it is imperative to design composites with physically separated metal fuel and oxidizer that can combust on short time scales, tens of nanoseconds, similar to high-performance molecular explosives. Towards that end, sensitizing composite powder particles to shock compression is crucial. In the current work, particle porosity is explored as means to induce hotspot formation within the particle through pore-collapse. Particles of two porous powders, Al-MoO3-KNO3 (equivalence ratio 3) and Al-CuO (equivalence ratio 4) prepared by arrested reactive milling with emulsion …
Seeing Inside Shocked Plastic-Bonded Explosives,
2023
Missouri University of Science and Technology
Seeing Inside Shocked Plastic-Bonded Explosives, Dhanalakshmi Sellan, Lawrence Salvati, Siva Kumar Valluri, Dana D. Dlott, Xuan Zhou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A new method is described to study how microstructures within a plastic-bonded explosive (PBX) interact with shock waves to produce hot spots, and to identify the critical hot spots that grow into a deflagration. A unique feature of this method is that it allows us to see every crystal in the PBX during the shock. We used an HMX-based PBX fabricated into a wafer about one crystal thick so there are no crystals hidden from view. The wafer is embedded in a transparent polymer in a traveling wave geometry, and a microscope with a laser flyer launcher and a nanosecond …
A New Empirical Law For The Prediction Of The Zero-Lift Pitching Moment Coefficient Of Swept And Tapered Wings,
2023
Ecole d’aviation de Borj El Amri, Tunisia
A New Empirical Law For The Prediction Of The Zero-Lift Pitching Moment Coefficient Of Swept And Tapered Wings, Mondher Yahyaoui
Journal of Aviation Technology and Engineering
A new empirical law for the prediction of the zero-lift pitching moment coefficient of trapezoidal wings with linear twist and constant taper and sweep in subsonic flow is introduced. This law is quite general in that it does not rely on the use of charts and spans the normal range of values of taper ratio, aspect ratio, and sweep for subsonic aircraft. It does not, however, accommodate different airfoils along the wingspan and only positive sweep has been considered. The empirical law was first derived for the incompressible regime and then an additional empirical law for the compressibility effect has …
Risks From Spacecraft Breakup Events In Near Rectilinear Halo Orbits,
2023
Air Force Research Laboratory
Risks From Spacecraft Breakup Events In Near Rectilinear Halo Orbits, Nathan R. Boone, Robert A. Bettinger, Bryan D. Little
Faculty Publications
Spacecraft breakup events were simulated in the vicinity of the Lunar Gateway’s Near Rectilinear Halo Orbit to evaluate the risk of debris collision with the station. The Monte Carlo simulations model the breakup of an object shortly after deployment from the Gateway, and using the propagated trajectories of over a million particles across 5,000 random breakup events, the likelihood of collision with the Gateway is statistically evaluated. Approaches within 10 km were observed for only 2.4% of the breakup events, suggesting a low risk of collision, but approaches at larger distances that might still generate a debris avoidance maneuver were …
An Analysis Of Aerodynamic Design Issues Of Box-Wing Aircraft,
2023
Air Force Institute of Technology, Kaduna Nigeria
An Analysis Of Aerodynamic Design Issues Of Box-Wing Aircraft, Paul Jemitola, Paul Okonkwo
Journal of Aviation Technology and Engineering
The potential of the joined/box-wing aircraft as an environmentally friendly airliner that is capable of meeting current and future emission thresholds led to the investigation of this concept. This study reviews the evolution and current trends in the aerodynamic design of the box-wing aircraft with specific emphasis on box-wing theory, airfoil characteristics, and aerodynamic issues of the box-wing aircraft. The study was undertaken to highlight the distinct features of the box-wing configuration which make it very attractive for future airliners. The study reveals that the box-wing aircraft possesses a significant aerodynamic advantage over conventional aircraft. The box-wing aircraft configuration is …
Introduction To Using Generative Ai In Research Literature Review For Graduate Students,
2023
University of North Dakota
Introduction To Using Generative Ai In Research Literature Review For Graduate Students, Joseph Vacek
AI Assignment Library
Information literacy is a skill set that new graduate students need to learn and practice, and the inclusion of generative AI, including its limitations, is worthy of exploration.
Pattern-Of-Life Modeling With Automatic Dependent Surveillance-Broadcast (Ads-B),
2023
Air Force Institute of Technology
Pattern-Of-Life Modeling With Automatic Dependent Surveillance-Broadcast (Ads-B), Sarah J. Bolton
Theses and Dissertations
This dissertation and research were sponsored by the Air Force Research Laboratory Layered Sensing Exploitation Branch (AFRL/RYA) to investigate the utility of using the data found within aircraft secondary radar to make predictions about aircraft characteristics and intent. The research focuses on making predictions on aircraft characteristics using only the kinetic data within one type of secondary radar, Automatic Dependent Surveillance-Broadcast (ADS-B), as a surrogate for primary radar. The results from this research provide a means to reduce the reliance on a type of aircraft tracking that is vulnerable to cyber attack and other integrity concerns.
Selection Of Materials For A Nuclear Rocket Engine,
2023
University of North Dakota
Selection Of Materials For A Nuclear Rocket Engine, Marcos Fernandez-Tous
AI Assignment Library
Selection of materials which will be used in the construct of a nuclear reactor for a space rocket.
A Framework And Approach For Leveraging Unsteady Response In Turbocompressor Flowfields,
2023
Dartmouth College
A Framework And Approach For Leveraging Unsteady Response In Turbocompressor Flowfields, Eric M. Krivitzky
Dartmouth College Ph.D Dissertations
Turbomachinery is an essential technology in the transfer of mechanical work to or from a fluid stream. Forming a cornerstone component in nearly all electrical energy production and air transportation propulsion systems, turbomachinery also accounts for significant en- ergy transfer due to its omnipresence in fluid handling, including water pumping and pro- cess machinery. As system designers look towards optimized arrangements that enhance system flexibility to highly variable conditions, increase the density of energy transfer, and reduce the amount of lost work, the performance and operability demands on turbomachin- ery components continue to increase. For turbocompressors, a turbomachinery subtype that …
Skyqube V2,
2023
Morehead State University
Skyqube V2, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Professor Bob Twiggs titled "SkyQube V2" from August 19, 2023.
Trajectory Design Optimization Using Coupled Radial Basis Functions (Crbfs),
2023
University of Central Florida
Trajectory Design Optimization Using Coupled Radial Basis Functions (Crbfs), Kyler Roy
Electronic Theses and Dissertations, 2020-2023
Optimal trajectory design has been extensively studied across multiple disciplines adopting different techniques for implementation and execution. It has been utilized in past space trajectory missions to either optimize the amount of fuel spent or minimize the time of flight to meet mission requirements. Coupled Radial Basis Functions (CRBFs) are a new way to solve these optimal control problems, and this thesis applies CRBFs to spacecraft trajectory optimization design problems. CRBFs are real-valued radial basis functions (RBFs) that utilize a conical spline while also not being affected by the value of the shape parameter. The CRBF approach is applied to …
The Performance Of A Liquid-Fueled High Pressure Igniter For Scramjets,
2023
University of Central Florida
The Performance Of A Liquid-Fueled High Pressure Igniter For Scramjets, Gerardo Rodriguez
Electronic Theses and Dissertations, 2020-2023
Ignition systems within scramjet combust ors remain a trending topic of research because of the essential role they play in the engine's operation. An alternative to currently researched ignition systems is investigated in this study with the main goal of u tilizing the same liquid fuel as the mai n combustion chamber for the ignition system itself. In this case, JetA fuel was injected in a liquid jet in crossflow configuration with air to atomize the fuel. To characterize this ignition system, metrics such as combustion chamber pressure rise, pulse frequency, and jet penetration were used to validate possible utilization …
A High-Pressure Shock Tube Study Of Hydrogen And Ammonia Addition To Natural Gas For Reduced Carbon Emissions In Power Generation Gas Turbines,
2023
University of Central Florida
A High-Pressure Shock Tube Study Of Hydrogen And Ammonia Addition To Natural Gas For Reduced Carbon Emissions In Power Generation Gas Turbines, Michael Pierro
Electronic Theses and Dissertations, 2020-2023
Ignition delay times from undiluted mixtures of natural gas (NG)/H2/Air and NG/NH3/Air were measured using a high-pressure shock tube at the University of Central Florida. The combustion temperatures were experimentally tested between 1000-1500 K near a constant pressure of 25 bar. Mixtures were kept undiluted to replicate the same chemistry pathways seen in gas turbine combustion chambers. Recorded combustion pressures exceeded 200 bar due to the large energy release, hence why these were performed at the high-pressure shock tube facility. The data is compared to the predictions of the NUIGMech 1.1 mechanism for chemical kinetic model validation and refinement. An …
Flow Induced Vibration In Corrugated Metal Flexhoses,
2023
University of Central Florida
Flow Induced Vibration In Corrugated Metal Flexhoses, Patrick Tran
Electronic Theses and Dissertations, 2020-2023
This study on flow-induced vibration provides valuable insights into the fundamental dynamics of fluid-structure interactions. The findings contribute to the development of predictive models and design guidelines for engineering systems susceptible to flow-induced vibration. By improving our understanding of this phenomenon, engineers can enhance the safety and reliability of various structures subjected to fluid flow, such as pipelines, flexhoses, and bellows. Flowinduced vibration is a phenomenon that occurs when fluid flow interacts with a structure, leading to oscillations and potentially causing mechanical damage. Understanding the underlying mechanisms and predicting the vibration characteristics is crucial for the design and safe operation …
A Study Of The Influence Of Heat Flux On Aerodynamics In Hypersonic Flow,
2023
University of Central Florida
A Study Of The Influence Of Heat Flux On Aerodynamics In Hypersonic Flow, Kristina Pionessa
Electronic Theses and Dissertations, 2020-2023
This study investigates the utilization of computational fluid dynamics (CFD) to simulate aerodynamic heating effects in support of research and design endeavors. The initial investigation demonstrates the effectiveness of a computational approach in analyzing different geometries and flow conditions. Specifically, CFD is employed to analyze the aerodynamics of a blunt cone, double cone, and hypersonic leading edge experiencing a changing heat source across the flow/body boundary. At the stagnation point, maximum thermal loading occurs as previously found; therefore, boundary layer thickness and shock standoff distance is measured at that position to compare the results of each case. Characteristics such as …
A Study Of The Performance Of Wind Turbines Fitted With Sprayed Liquid Flaps,
2023
University of Central Florida
A Study Of The Performance Of Wind Turbines Fitted With Sprayed Liquid Flaps, Alexander Spitzer
Electronic Theses and Dissertations, 2020-2023
Lift generating technologies are often considered a potential solution to increased power generation and reliability within wind turbine design. The Sprayed Liquid Flap (SLF) is a novel active control method that has shown success in providing lift generation on aircraft wings, but its application in the context of rotating flows is unexplored. This research aims to understand the effects of the SLF on a wind turbine and provide a pathway for future exploration of its aerodynamic impacts on rotating flows. Computational Fluid Dynamics with an Euler-Euler multiphase approach is employed to assess the influence of the SLF on a wind …
Stochastic Modeling Of Physical Drag Coefficient – Its Impact On Orbit Prediction And Space Traffic Management,
2023
Missouri University of Science and Technology
Stochastic Modeling Of Physical Drag Coefficient – Its Impact On Orbit Prediction And Space Traffic Management, Smriti Nandan Paul, Phillip Logan Sheridan, Richard J. Licata, Piyush M. Mehta
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Ambitious satellite constellation projects by commercial entities and the ease of access to space in recent times have led to a dramatic proliferation of low-Earth space traffic. It jeopardizes space safety and long-term sustainability, necessitating better space domain awareness (SDA). Correct modeling of uncertainties in force models and orbital states, among other things, is an essential part of SDA. For objects in the low-Earth orbit (LEO) region, the uncertainty in the orbital dynamics mainly emanate from limited knowledge of the atmospheric drag-related parameters and variables. In this paper, which extends the work by Paul et al. (2021), we develop a …
The Effects Of Microgravity On The Development Of Osteoporosis,
2023
University of Central Florida
The Effects Of Microgravity On The Development Of Osteoporosis, Jackson Asiatico
Electronic Theses and Dissertations, 2020-2023
Previous research has identified a potential link between microgravity conditions and the onset of osteoporosis, a connection that stems from altered fluidic pathways crucial in nutrient dispersion and cell stimulation. Specifically, the absence of mechanical loading in space environments reduces fluid shear stress, thereby disrupting the normal flow of interstitial fluid in trabecular bone. This disruption greatly impacts the functionality of osteoblasts and osteoclasts, the vital cells responsible for maintaining healthy bones. The focus of this study aims to explore the impact of microgravity on bone loss in astronauts, establishing the connection between the lack of mechanical loading and the …
Gas Permeability Of 3d Stitched Composites For Cryogenic Applications,
2023
Mississippi State University
Gas Permeability Of 3d Stitched Composites For Cryogenic Applications, Shuvam Saha
Theses and Dissertations
This research aims to investigate the influence of 3D through-thickness stitching on the gas permeability and transverse microcracking of cryogenically cycled carbon/epoxy composites. 3D through-thickness stitching can be used to improve the interlaminar properties of polymer matrix composites (PMCs) and produce lightweight, unitized structures for cryogenic storage tanks. To fully utilize stitched composite structures for these applications, their inherent gas permeability challenges must be understood. Therefore, in this study, the stitched composites' damage evolution and gas permeability was experimentally characterized under a) pure thermal stress, b) thermal and uniaxial mechanical stress, and c) thermal and biaxial mechanical stress. Helium gas …
