Aerospace Engineering Commons^™

Topology Optimization For Thin Walled Structures Utilizing Simp Method By Additive Manufacturing Using Optimized Conditions, Sajith Anantharaman

Mechanical and Aerospace Engineering Theses - Archive

The objective of this research is to manufacture topology optimized structure by additive manufacturing. Topology Optimization is a method of structural optimization which gives the optimum material distribution in a design domain. This material distribution is then manufactured by additive manufacturing. Additive manufacturing can manufacture complex shapes quite easily since it works by layer-by-layer. This is an on-going field of research and not many optimization algorithms make use of the advantages of additive manufacturing. Numerous researches are done in the field of optimization which are directed towards Homogenization and Solid Isotropic material with Penalization (SIMP). But most of the methods …

Autoignition Behavior Of Synthetic Alternative Jet Fuels: An Examination Of Chemical Composition Effects On Ignition Delays At Low To Intermediate Temperatures, Daniel Valco, Gerald Gentz, Casey Allen, Meredith Colket, Tim Edwards, Sandeep Gowdagiri, Matthew A. Oehlschlaeger, Elisa Toulson, Tonghun Lee

United States Air Force: Publications

The autoignition characteristics of military aviation fuels (JP-5 and JP-8), proposed camelina-derived hydroprocessed renewable jet fuel replacements (HRJ-8 and HRJ-5), Fischer–Tropsch fuels (Shell and Sasol), three Sasol isoparaffinic solvents, as well as 50/50 volumetric blends of the alternative fuels with the conventional fuels are examined. Experiments were conducted in a rapid compression machine and shock tube at compressed temperatures of 625 K ≤ Tc ≤ 1000 K, a compressed pressure of 20 bar, and under stoichiometric and lean conditions. Several implicit properties of the alternative fuels prompted a study of the influence of chemical composition on autoignition, including the influence …

Performance Oriented Adaptive Architectures With Guaranteed Bounds, Benjamin Gruenwald, Tansel Yucelen, Mario Fravolini

Mechanical and Aerospace Engineering Faculty Research & Creative Works

While adaptive control has been used in numerous applications to achieve given system stabilization or command following criteria, the ability to obtain a predictable transient performance is a challenging problem when there is no a priori knowledge about system uncertainties (e.g., their upper bounds and/or domains). In order to address this problem, a new method is presented in [1, 2] utilizing artificial basis functions in the update law of an adaptive control design. This approach is predicated on a gradient minimization procedure and achieves a predictable transient performance without inducing oscillations in the system response as the constant gain due …

Electrospray Of An Energetic Ionic Liquid Monopropellant For Multi-Mode Micropropulsion Applications, Steven P. Berg, Joshua L. Rovey, Benjamin D. Prince, Shawn W. Miller, Raymond J. Bemish

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The multi-mode chemical-electric propulsion capable energetic ionic liquid propellant [Emim][EtSO4]-HAN is electro sprayed in a 100 µm capillary emitter to test the electric-mode performance of the propellant. The ionic liquid exhibits stable electrospray emission in both cation and anion extraction modes at a nominal extraction voltage of 3400 V. Near field measurements of current and mass flow rate distribution are taken at flow rates from 0.19 nL/s to 3.06 nL/s. Total emission current, as measured by Faraday cup and integrated, increases from 754 nA to 3195 nA for cation emission and from 552 nA to 2012 nA for anion emission. …

Characterizing Noise Trends Of The Cross-Track Infrared Sounder (Cris), Bryce Walker, Mark Esplin, Ben Esplin, Deron Scott

Space Dynamics Laboratory Publications

Outline

• CrIS Summary

• Noise characterization process

• Noise trending results

• Recent Changes

• Conclusions

Dcgs: Image Processing, Screening, & Product Distribution Solution, Space Dynamics Laboratory

Space Dynamics Laboratory Publications

SCALABLE, CROSS-PLATFORM SOLUTION FOR NEAR REAL-TIME IMAGE PROCESSING, SCREENING, & PRODUCT DISTRIBUTION

SDL provides the Distributed Common Ground System (DCGS) community with a powerful image processing, screening, and product distribution solution by combining a ground station with the VANTAGE™ tactical intelligence software suite and the Sky Lynx data link interface hardware. This system's cost-effectiveness is achieved through the use of flexible and robust hardware configurations that enable the customer to scale the system to their DCGS program needs.

Correlation Of Csk2sb Photocathode Lifetime With Antimony Thickness, M. A. Mamun, C. Hernandez-Garcia, M. Poelker, A. A. Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

CsK₂Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for …

Diffusion And Elastoplastic Analyses Of Polycrystalline Magnesium For Solid State Hydrogen Storage Application, Amey Mathakari

Mechanical and Aerospace Engineering Theses - Archive

Solid state hydrogen storage can be an effective way of storing hydrogen as an energy source for mobile applications. The advantage includes high energy density, low setup cost, safe operation, abundance of metal hydrides, low maintenance, etc. Magnesium is one of the potential metals for the application. However, sluggish desorption kinetics of magnesium requiring relatively high operation temperature has hindered its practical realization. In the present study, an attempt is made to analyze effects of grain boundary on diffusion and diffusion induced stresses in polycrystalline magnesium. Grain boundaries in nanostructured magnesium can undergo severe plastic deformations during the hydrogen insertion …

Simulation And Performance Analysis Of Ejector Nozzle In A Low-Bypass Turbofan Engine Using Npss, Hatim Soeb Rangwala

Mechanical and Aerospace Engineering Theses - Archive

Nozzles for propulsive applications in airbreathing engines have long been studied to augment thrust and reduce the size of the engine. They are critical elements of the engine as they convert the internal energy into kinetic energy, thereby producing thrust. Fixed-geometry nozzles are operated optimally only at a particular set of flight conditions and are not efficient at off-design conditions. To improve off-design performance, variable geometry nozzles can be utilized which require complex mechanisms that ultimately increase weight and susceptibility to failure. Ejector nozzles provide variable geometry capability via aerodynamically varying the effective area ratios of the core and bypass …

Assessing Interlaminar Shear Stress-Strain Curves In Tape Composites Based On The Flat-Plate Torsion Method, Gary Steven Grohman

Mechanical and Aerospace Engineering Theses - Archive

Composites are attractive for structural applications in the aerospace industry for their high strength to weight ratio, stiffness, and low density. The development and implementation of composite structures has grown rapidly through the aerospace industry exceeding our ability to characterize the material properties due to costly and time consuming test methods. The ability to fully characterize the nonlinear stress-strain relationship in the 1-3 and 2-3 principal planes up to the point of failure is extremely important for predicting failures in composites. The principal directions for composites are the fiber direction, transverse direction, and the thru thickness direction, commonly referred to …

Heat Removal Analysis Using Ntu Microscopic Theory And Experimental Fluid Testing Of Radaitors, Pumps And Fans For The Thermal Management System Of Formula Sae Electric Racecar, Shahzad Shahrukh Bulsara

Mechanical and Aerospace Engineering Theses - Archive

Formula SAE at UT Arlington has always been building well engineered race cars, further being one of the top teams in The United States. However, an electric race car being first in the fleet, cooling of electric motors played a vital role. The thermal system being significantly different from combustion cars, consists of a lower heat application. It is always favorable to maintain electronics as close to ambient temperature as compared to its counter hydro-mechanical engines. To attain the objective, a complete thermal & fluid analysis was carried out using the NTU method/ microscopic theory and experimental results associated towards …

Numerical Simulations Of Surface Charging At The Lunar Terminator, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A full-particle particle-in-cell (PIC) simulation model is developed to perform fully-kinetic simulations of surface-plasma interactions at the lunar terminator region. This model uses a non-homogeneous immersed-finite-element (IFE) solver to calculate the electric field discontinuity (flux jump) at the plasma-surface interface and surface charging for realistic lunar surface terrain. The simulation includes all plasma species, including the solar wind electrons and ions, as well as photoelectrons with real proton-to-electron mass ratio so the kinetic properties in the mesothermal flow are resolved. We present simulation results of surface charging around a lunar hill at the lunar terminator region.

Icao Aviation System Block Upgrades: A Method For Identifying Training Needs, Rebecca K. Lutte

Aviation Institute Faculty Publications

Since the mid-1970s, air traffic growth has expanded two-fold once every fifteen years (ICAO, 2013). The ICAO Global Air Navigation Plan (GANP) is a roadmap to achieve a “vision of an integrated, harmonized, and globally interoperable air traffic management (ATM) system” (ICAO, 2012, p. 1). A component of the GANP is the Aviation System Block Upgrades (ASBU), a framework for achieving that vision. A collaborative approach led by ICAO between public and private organizations and member states resulted in the development of the ASBU framework. However, obstacles exist for successful implementation. One area of concern is the need for training …

Analysis Of Thin-Walled Cylindrical Composite Shell Structures Subject To Axial And Bending Loads: Concept Development, Analytical Modeling And Experimental Verification, Sthanu Mahadev

Mechanical and Aerospace Engineering Dissertations - Archive

Several studies have focused on the modeling and response characterization of composite structural members, with particular emphasis on thin-walled cylindrical composite shells. This class of shell configurations is explored to determine their mechanical response in primary aerospace structural members. The present work is focused on formulating a modified composite shell theory prognosis methodology for investigating the structural response of thin-walled cylindrical shell type composite configurations under axial and bending loads, respectively. The prime motivation to develop this theory arises from its capability to generate simple yet accurate closed-form analytical results that can efficiently charecterize cylindrical composite shell constructions. This work …

Design Of Next Generation Antenna Mounts In Telecommunication Towers With Low Effective Projected Area, Ruben Gregory Puthota Dominic Savio

Mechanical and Aerospace Engineering Theses - Archive

Design of new antenna mount with low effective projected area (EPA) and high load carrying capacity for telecommunication towers is the purpose of this thesis. The main aim is to reduce the EPA of the mount against the wind pressure direction at the desired elevation from ground by reducing the mount frame structure parts compared to the previous mount designs used in the market. The model in itself has to withstand its dead weight, operator’s weight along with five antenna-radio units. The new model has been designed with a single horizontal frame and four supporting structure for EPA reduction and …

Characterization Of Flapping Wing Aerodynamics And Flight Dynamics Analysis Using Computational Methods, Alok Ashok Rege

Mechanical and Aerospace Engineering Dissertations - Archive

Insect flight comes with a lot of intricacies that cannot be explained by conventional aerodynamics. Even with their small-size, insects have the ability to generate the required aerodynamic forces using high frequency flapping motion of their wings to perform different maneuvers. The maneuverability obtained by these flyers using flapping motion belies the classical aerodynamics theory and calls for a new approach to study this highly unsteady aerodynamics. Research is on to find new ways to realize the flight capabilities of these insects and engineer a micro-flyer which would have various applications, ranging from autonomous pollination of crop fields and oil …

Comprehensive Design Analysis Of Thick Fr-4 Qfn Assemblies For Enhanced Board Level Reliability, Abhishek Nitin Deshpande

Mechanical and Aerospace Engineering Theses - Archive

Quad Flat No-lead package (QFN) is one of the most cutting-edge technologies emerged in the market, exhibiting high performance and efficiency with unparalleled cost effectiveness. QFN, a leadless package, is an ideal choice for applications where size, weight thermal and electrical characteristics are critical, particularly in mobile and handheld devices. Applications like automotive, defense and high current circuits require the package to be mounted on thick printed circuit boards (PCB). But using thick PCBs (>3mm) is detrimental to the package reliability. The motivation of this work is to understand the effect of several package parameters affecting reliability and optimize …

Experimental Investigation Of Wall Shear Stress Modifications Due To Turbulent Flow Over An Ablative Thermal Protection System Analog Surface, Jacob Helvey

Theses and Dissertations--Mechanical and Aerospace Engineering

Modifications were made to the turbulent channel flow facility to allow for fully developed rough quasi-2D Poiseuille flow with flow injection through one surface and flow suction through the opposing surface. The combination of roughness and flow injection is designed to be analogous to the flow field over a thermal protection system which produces ablative pyrolysis gases during ablation. It was found that the additional momentum through the surface acted to reduce skin friction to a point below smooth-wall behavior. This effect was less significant with increasing Reynolds number. It was also found that the momentum injection modified the wake …

Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri

Theses and Dissertations--Mechanical and Aerospace Engineering

Space vehicles, while entering the planetary atmosphere, experience high loads of heat. Ablative materials are commonly used for a thermal protection system, which undergo mass removal mechanisms to counter the heat rates. Spallation is one of the ablative processes, which is characterized by the ejection of solid particles from the material into the flow. Numerical codes that are used in designing the heat shields ignore this phenomenon. Hence, to evaluate the effectiveness of spallation phenomenon, a numerical model is developed to compute the dynamics and chemistry of the particles. The code is one-way coupled to a CFD code that models …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …