Aerospace Engineering Commons^™

Role Of Surface Chemistry In Nanoscale Electrokinetic Transport, Secuk Atalay

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation work presents the efforts to study the electrofluidics phenomena, with a focus on surface charge properties in nanoscale systems with the potential applications in imaging, energy conversion, ultrafiltration, DNA analysis/sequencing, DNA and protein transport, drug delivery, biological/chemical agent detection and micro/nano chip sensors.

Since the ion or molecular or particle transport and also liquid confinement in nano-structures are strongly dominated by the surface charge properties, in regards of the fundamental understanding of electrofluidics at nanoscale, we have used surface charge chemistry properties based on 2-pK charging mechanism. Using this mechanism, we theoretically and analytically showed the surface charge …

Experimental Investigation Of Mist Film Cooling And Feasibility Study Of Mist Transport In Gas Turbines, Reda M. Ragab

LSU New Orleans Theses and Dissertations

In the modern advanced gas turbines, the turbine inlet temperature may exceed 1500°C as a requirement to increase power output and thermal efficiency. Therefore, it is imperative that the blades and vanes are cooled so they can withstand these extreme temperatures. Film cooling is a cooling technique widely used in high-performance gas turbines. However, the film cooling effectiveness has almost reached plateau, resulting in a bottleneck for continuous improvement of gas turbines' efficiency.

In this study, an innovative cooling scheme, mist film cooling is investigated through experiments. A small amount of tiny water droplets with an average diameter about 10-15 …

Buckling, Postbuckling And Imperfection Sensitivity Analysis Of Different Type Of Cylindrical Shells By Hui's Postbuckling Method, Hailan Xu

LSU New Orleans Theses and Dissertations

Hui and Chen (1986) were the first to show that the well-known Koiter’s General Theory of Elastic Stability of 1945 can be significantly improved by evaluating the postbuckling b coefficient at the actual applied load, rather than at the classical buckling load. Such improvement method was demonstrated to be (1) very simple to apply with no tedious algebra, (2) significant reduction in imperfection sensitivity and (3) although it is still asymptotically valid, there exists a significant extension of the range of validity involving larger imperfection amplitudes. Strictly speaking, Koiter’s theory of 1945 is valid only for vanishingly small imperfection amplitudes. …

A Wedge Impact Theory Used To Predict Bow Slamming Forces, Ashok Benjamin Basil Attumaly

LSU New Orleans Theses and Dissertations

The pressures and impact forces acting on a hull while experiencing bow wave slamming is analyzed using Vorus' Impact Theory. The theory extends the hydrodynamic analysis of planing hulls from simple wedges to irregular shapes using a Boundary Element Method. A Fortran-based code developed by the Author is used to analyze hullforms. Linear strip theory is used to extend the analysis over a three dimensional hull. Post-processing of output data gives hull pressure distributions at different time steps and is visually presentable.

Impact pressure, Impact force, Planing, Wave slamming, Bow impact, Vorus' theory, Boundary Element Method, Linear strip theory

Adaptive Control Techniques For Transition-To-Hover Flight Of Fixed-Wing Uavs, Brian Decimo Marchini

Master's Theses

Fixed-wing unmanned aerial vehicles (UAVs) with the ability to hover combine the speed and endurance of traditional fixed-wing fight with the stable hovering and vertical takeoff and landing (VTOL) capabilities of helicopters and quadrotors. This combination of abilities can provide strategic advantages for UAV operators, especially when operating in urban environments where the airspace may be crowded with obstacles. Traditionally, fixed-wing UAVs with hovering capabilities had to be custom designed for specific payloads and missions, often requiring custom autopilots and unconventional airframe configurations. With recent government spending cuts, UAV operators like the military and law enforcement agencies have been urging …

Investigation Into The Mitigation Of The Effects Of Uncertain Optical Degradation On An Interplanetary Solar Sail Mission Using A Single Model Update, Jordan Smiroldo

Master's Theses

The renewed academic interest in using solar sails as a source of spacecraft propulsion has been accompanied by a recent fervor of investigations into non-ideal and off-nominal sail performance considerations. One of the most influential considerations, uncertain optical degradation, has been shown to present significant trajectory design difficulties. This paper investigates the potential of using a mid-course degradation model update to mitigate the risk of missing the target destination in a sample 300 day Earth-Venus trajectory. Using a range of potential degradation profiles, it is shown that correcting in the first half of the mission is highly likely to result …

Analysis Of An Inflatable Gossamer Device To Efficiently De-Orbit Cubesats, Robert A. Hawkins Jr.

Master's Theses

There is an increased need for spacecraft to quickly and efficiently de-orbit themselves as the amount of debris in orbit around Earth grows. Defunct spacecraft pose a significant threat to the LEO environment due to their risk of fragmentation. If these spacecraft are de-orbited at the end of their useful life their risk to future spacecraft is greatly lessened. A proposed method of efficiently de-orbiting spacecraft is to use an inflatable thin-film envelope to increase the body's area to mass ratio and thusly shortening its orbital lifetime. The system and analysis presented in this project is sized for use on …

Numerical Flow Field Analysis Of An Air Augmented Rocket Using The Axisymmetric Method Of Characteristics, Jeffrey Massman

Master's Theses

An Axisymmetric Rocket Ejector Simulation (ARES) was developed to numerically analyze various configurations of an air augmented rocket. Primary and secondary flow field visualizations are presented and performance predictions are tabulated. A parametric study on ejector geometry is obtained following a validation of the flow fields and performance values.

The primary flow is calculated using a quasi-2D, irrotational Method of Characteristics and the secondary flow is found using isentropic relations. Primary calculations begin at the throat and extend through the nozzle to the location of the first Mach Disk. Combustion properties are tabulated before analysis to allow for propellant property …

Waveguiding Of Surface Phonon Polariton, Franklin Manene, Brian A. Lail, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Metal losses lead to unacceptably low propagation lengths in THz and LWIR waveguides. While SPP based waveguides provide relatively good confinement and attenuation in the near-IR and visible these are insufficiently bound to the surface in the THz and LWIR. We study using surface phonon polaritons for waveguiding at these frequencies. An eigenmode approach was applied to model a hybrid waveguide structure at λ=10.6 μm. The results show that phonon-coupled hybrid waveguide of silicon carbide BCB and gold exhibit enhanced propagation length and confinement at LWIR. © 2013 IEEE.

Experimental Investigation Of The Active Flow Control On A Two-Dimensional Wind Turbine Airfoil, Guannan Wang

Dissertations - ALL

Wind turbine blades experience unsteady aerodynamic loading under various off-design conditions. The fatigue loading reduces the operational time of the wind turbine hence leads to an increase in the Cost of Energy (CoE) of the wind power. In this study, active flow control with unsteady blowing actuators was applied to a two-dimensional wind turbine airfoil to alleviate the unsteady aerodynamic loading and improve the aerodynamic performance, particularly under large scale freestream disturbances. A low speed, open jet aeroacoustic wind tunnel was designed and constructed based on an existing anechoic chamber for this investigation. A theoretical analysis based on a Blade …

Pyrolysis Of Acrylonitrile-Butadiene-Styrene (Abs) Under High Heat Flux Conditions, James R. Wilson

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Acrylonitrile-butadiene-styrene (ABS) is a common industrial plastic that is widely used for structural and piping applications. Additionally, within the past decade ABS has become the most popular material used in a type of rapid prototyping known as fused- deposition modeling (FDM). Within the past three years, ABS plastic blends have also been investigated as a potential fuel for hybrid- and solid-propelled rocket systems, exhibiting promising results. Because the use of ABS as a rocket propellant is very recent, a pyrolysis database, describing how ABS will burn, at the temperatures and heating rates experienced by rocket systems does not exist. Previous …

Single Case Research Designs: An Effective And Efficient Methodology For Applied Aviation Research, Geoffrey R. Whitehurst

Dissertations

The purpose of this three-paper dissertation is to examine the potential of single case research designs (SCDs) as an appropriate and efficient experimental design for use in applied aviation research. In the current environment of dwindling resources, funding for experiments requiring large sample sizes, a normal requirement for between-group designs, is becoming difficult to find. However, the need to improve safety within the aviation industry is an ongoing requirement, especially as advances in technology continue have an impact on how the industry operates. SCDs are experimental designs that require very few participants and therefore have the potential to save time …

Remote/Autonomous Sentry Gun Platform, Angelo Gagliardi, Dante Gagliardi

Electrical Engineering

This senior project involves the complete system design and construction of a "Nerf" sentry gun to replace an armed guard. We aimed to develop a compact and highly mobile defense system that allows operational flexibility. The sentry gun can autonomously track and shoot at moving targets, while also allowing a user to remotely access and control the gun via computer. The mobility, hardiness, and functionality of this system allows a reliable replacement for human beings in harsh and hostile environments; ultimately sparing a life.

Robust Image-Based Visual Servo Control Of An Uncertain Missile Airframe, Murat Tunca Aygun

Doctoral Dissertations and Master's Theses

A nonlinear vision-based guidance law is presented for a missile-target scenario in the presence of model uncertainty and unknown target evasive maneuvers. To ease the readability of this thesis, detailed explanations of any relevant mathematical tools are provided, including stability definitions, the procedure of Lyapunov-based stability analysis, sliding mode control fundamentals, basics on visual servo control, and other basic nonlinear control tools. To develop the vision-based guidance law, projective geometric relationships are utilized to combine the image kinematics with the missile dynamics in an integrated visual dynamic system. The guidance law is designed using an image-based visual servo control method …

Molecular Dynamics Model Of Carbon Nanotubes In Epon 862/Detda Polymer, Guttormur Arnar Ingvason

Doctoral Dissertations and Master's Theses

The aerospace industry is interested in increasing the strength while reducing the weight of carbon fiber composite materials. Adding single walled carbon nanotubes (SWCNT) to a polymer matrix can achieve that goal by improving delamination properties of the composite. Due to the complexity of polymer molecules and the curing process, few 3-D Molecular Dynamics simulations of a polymer-SWCNT composite have been run. Our model runs on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a COMPASS (Condensed phase Optimized Molecular Potential for Atomistic Simulations Studies) potential to represent the interactions between the atoms of the polymer and the SWCNT. This …

Investigation Into The Effects Of Wire Mesh On Tensile And Impact Properties Of Fiber Metal Laminates, Shivani A. Rudradat

Doctoral Dissertations and Master's Theses

An investigational study was conducted into the tensile and impact behavior of Fiber Metal Laminates by combining 5052 aluminum mesh or2024-T3 aluminum sheets,2.47 N (8.9 oz) or 6.67 N (24 az) ShieldStand^® S fiberglass, and Hysol EA 9313 epoxy. Testing was performed under the guidelines of ASTM D3039-00 utilizing an lnstron 8802 Servohydraulic Materials Testing Instrument for tensile tests and ASTM D3763-06 utilizing an Inston 9250 HV Dynatup Impulse Impact Testing System for impact tests. Samples were strained at arate of 2 mrn/min for tensile tests and impacted with enetgies of 10 to 40 J in l0 J increments …

Hollow Plume Mitigation Of A High-Efficiency Multistage Plasma Thruster, Scott Alan Mcgrail

Master's Theses

Since 2000, a relatively new electric thruster concept has been in research, development, and production at Thales Electron Devices in Germany. This High Efficiency Multistage Plasma Thruster, or HEMPT, has promising lifetime capabilities due to its plasma confinement system. However, the permanent magnet system that offers this and other benefits also creates a hollow plume, where ions are accelerated at angles rather than up the thruster centerline, causing a dip in ion current along the centerline. A laboratory model, built at JPL, was run at Cal Poly to characterize this plume shape and implement a shield to restore a conical …

Mode I Fracture Toughness Of Eight-Harness-Satin Carbon Cloth Weaves For Co-Cured And Post-Bonded Laminates, Josh E. Smith

Master's Theses

Mode I interlaminar fracture of 3k 8-Harness-Satin Carbon cloth, with identical fill and weft yarns, pre-impregnated with Newport 307 resin was investigated through the DCB test (ASTM D5528). Crack propagations along both the fill and weft yarns were considered for both post-bonded (co-bonded) and co-cured laminates. A patent-pending delamination insertion method was compared to the standard Teflon film option to assess its applicability to mode I fracture testing. The Modified Beam Theory, Compliance Calibration method, and Modified Compliance Calibration method were used for comparative purposes for these investigations and to evaluate the validity of the proposed Equivalent Stiffness (EQS) method. …

Experimental Study On The Effect Of Air Flow On Soap Bubble Formation, John M. Davidson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Soap bubbles are a common interfacial fluid dynamics phenomenon having applications such as buoyant hollow spherical fillers and flow visualization of large scale airflows. In contrast to the dynamics of liquid drops in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented, possibly because soap bubbles have gas-liquid-gas interfaces. Having the thin-liquid-film interface seems to alter the characteristics of the bubble/drop creation process. Thus, the main objective of this study is to experimentally examine how airflow develops and interacts with the soap liquid film as the film stretches and finally collapses to pinch-off. …

Aerodynamic Performance And Particle Image Velocimetery Of Piezo Actuated Biomimetic Manduca Sexta Engineered Wings Towards The Design And Application Of A Flapping Wing Flight Vehicle, Anthony M. Deluca

Theses and Dissertations

Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing element model (BEM). An …