Aerospace Engineering Commons^™

Faa Letter In Response To White House Letter Regarding Faa Changes To Air Traffic Control Specialist Hiring Process, Tim Brady, Gregory Mcguirk

Publications

On July 18, 2014, you submitted a letter to President Obama regarding the Federal Aviation Administration's (FAA) recent changes to the Air Traffic Control Specialist (ATCS) hiring process. You expressed concern with the FAA's decision to implement a single all sources hiring strategy and, as a result, you feel that it has disadvantaged graduates who successfully completed the Air Traffic Collegiate Training Initiative (AT-CTI) program, such as xxx. You also expressed concern with the implementation of the Biographical Assessment. Your letter was forwarded by the White House to our agency to address your concerns.

Aerodynamic Optimization Of Box Wing – A Case Study, Adeel Khalid, Parth Kumar

International Journal of Aviation, Aeronautics, and Aerospace

The optimization of a possible medium range box wing commercial airliner is presented in three stages. Preliminary research is used to determine various parameters for a potential box wing model, and a baseline model is designed in Autodesk Inventor, based upon the cantilever Airbus A330-200, an aircraft of a similar role. The Computational Fluid Dynamics (CFD) software used in this project is Dassault Systèmes SolidWorks, which is validated through comparing the NACA 0009 airfoil lift and drag polars with published results. The first stage of optimization is performed on the airfoil shape, with 8 different designs being tested against the …

To Study The Effect Of Catalyst On The Physical Parameters Of Carbon Spheres, Tejas Shailesh Mehta

Doctoral Dissertations and Master's Theses

The discovery of fullerenes has opened up modern studies in carbon materials. Carbon nanoparticles have a large surface area and demonstrate good conductivity. Their unique properties has gained attention in many areas such as water filtration, hydrogen storage and battery electrodes. In this research, carbon spheres with high specific area and uniformity were grown using the Chemical Vapor Deposition (CVD) process with silicon substrates, ethylene (C2H4) as a carbon precursor and argon as the inert gas. We observe that the morphology of carbon spheres largely depend on the experimental conditions, including CVD time duration, temperature, catalyst and flow of gases. …

A Continuous/Discontinuous Fe Method For The 3d Incompressible Flow Equations, Nikolaos Kyriazis

Doctoral Dissertations and Master's Theses

A projection scheme for the numerical solution of the incompressible Navier-Strokes equation is presented. Finite element discontinuous Galerkin (dG) discretization for the velocity in the momentum equations is employed. The incompressibility constraint is enforced by numerically solving the Poisson equation for pressure using a continuous Galerkin (cG) discretization. The main advantage of the method is that is does not require the velocity and pressure approximation spaces to satisfy the usual inf-sup condition, thus equal order finite element approximations for both velocity and pressure can be used. Furthermore, by using cG discretization for the Poisson equation, no auxiliary equations are needed …

Exploration Of A Computational Fluid Dynamics Integrated Design Methodology For Potential Application To A Wind Turbine Blade, Gaurav Kapoor

Doctoral Dissertations and Master's Theses

The main purpose of this thesis is to conduct a parametric sensitivity study on the blade design of AOC 15/50 wind turbine based on a CFD approach and optimize the blade design for maximizing the power output. The ANSYS® Fluent® flow solver using the k-ω SST turbulence model was validated by simulating the flow over two dimensional airfoils comprising the AOC 15/50 wind turbine blade. The CFD results have shown a considerable agreement with the experimental data for the airfoils. Parametric correlation study and sensitivity analysis were conducted by performing actual flow simulations over the turbine blade using ANSYS® Fluent®. …

A Cfd Investigation Of The Hydrodynamic Characteristics Of Fluid Flow Through An Impeller And Multi-Objective Design Optimization Of A Centrifugal Pump, Mohammed Khammat Sagban

Doctoral Dissertations and Master's Theses

In this thesis, the first part is conducting an investigation of the hydrodynamic characteristics (pressure and velocity) of fluid flow (water) through an impeller of a centrifugal pump. To illustrate a one-dimensional model is used to identify an impeller of a GDM 10 x 12 HD centrifugal pump using Vista CPD design and BladeGen tool. A three-dimensional model is then built with a commercial software package ANSYS Blade Modeler. The structured mesh of the impeller blade is obtained by using TurboGrid system. The volute of the centrifugal pump is built in ANSYS geometry, and an unstructured mesh is accomplished by …

Improving Airplane Touchdown Control By Utilizing The Adverse Elevator Effect, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

The main objective of this original research article is to understand the short-term dynamic behavior of the transport-category airplane during landing flare elevator control application. Increasing the pitch angle to arrest the sink rate, the elevator will have to produce negative lift to rotate the airplane’s nose upward. This has an immediate adverse effect of initially accelerating airplane downward. A mathematical model of landing flare based on the flat-Earth longitudinal dynamics of rigid airplane was developed which is realistic only on very short time-scales as pitch stiffness and damping were neglected. Pilot control scenarios using impulse and step elevator pull-up …

Investigation Of Pulse Detonation Engine Flow Conditions For Turbomachinery Integration, Luis Estefano Ferrer-Vidal EspañA-Heredia

Doctoral Dissertations and Master's Theses

Pressure gain combustion has been known to be more thermodynamically efficient than its constant pressure counterpart, which employs deflagration. Integration of pressure gain combustors into gas turbine engines has been and still is one of the most important challenges facing the gas turbine industry. Pressure gain combustion devices are inherently unsteady. This unsteadiness affects turbomachinery components designed using steady operation assumptions, and results in mechanical inefficiencies which could outweigh the thermal efficiency benefits. Understanding of turbine components specifically made to operate in the exhaust conditions provided by a pressure gain combustor may yield new turbine design paradigms. As a first …

Reduction Of Secondary Flow Losses In A Turbine For Use In Man-Portable Power Generation, Andrew J. Yatsko

Doctoral Dissertations and Master's Theses

As the world has moved into a more energy-demanding environment, there has been the push for higher energy density in a smaller package. One of the potential solutions is through the application of a gas turbine engine; yet the challenge is extracting the energy efficiently through the small components. The focus of the research is on the turbine components and how the secondary flow losses from the generated airfoil shapes can be reduced to improve component performance. One of the secondary flow loss items to be addressed is the generation of the Horseshoe Vortex. The Horseshoe Vortex is an aerodynamic …

The Effects Of Rewards On The Ability Of An Autonomous Uav Controlled By A Reinforcement Learning Agent To Accomplish A Target Localization Task, Hemali Dinesh Virani

Doctoral Dissertations and Master's Theses

The need for Unmanned Aerial System (UASs) is increasing in the fields of science, security, military and others. With an increasing number of challenges faced by mankind the need for system with advance autonomous and intelligent capabilities is growing rapidly. The required intelligent behavior can be achieved in an unmanned system with machine learning methods such as Reinforcement Learning (RL) theory. This theory presents algorithms which have the capability to learn how to adapt to its environment. Using RL methods, autonomous systems have the ability to use past experiences to improve future mission performance. In this research, the effects of …

Characterization And Low-Dimensional Modeling Of Urban Fluid Flow, Dietmar Rempfer, Candace Wark, Bruno Monnier, Sriharsha Kandala

Publications

This report describes work that was done under AFOSR Contract Number FA9550-11-1-0056, studying the structure of a model urban boundary layer flow. The model geometry consisted of a set of plexiglass blocks, and the flow around this geometry was studied both experimentally as well as computationally. For the experiment, a Stereoscopic Particle Image Velocimetry (SPIV) method was developed that allows for a three-dimensional description of this urban flow, and helps gain insight into the characteristic flow structures in the streets and canyons of our model urban geometry. On the computational side, a new spectral-element code was developed that was demonstrated …

On Uav Robust Nonlinear Control In Presence Of Parametric Uncertainties, Vladimir V. Golubev, William Mackunis

Publications

We examine a new robust nonlinear flight control technology that employs an array of synthetic-jet micro-actuators embedded in UAV wing design in order to completely eliminate moving parts (such as ailerons) thus greatly enhancing maneuverability required for small fixed-wing air vehicles operating, e.g., in tight urban environments. Estimated fast response times are critical in mitigating gust effects while greatly improving flight stability and control. The new controller design is particularly advantageous for high levels of uncertainty and nonlinearity present both in the unsteady flowpath environment and in the embedded actuator’s response. The current work focuses on a benchmark case of …

Evaluation And Flight Assessment Of A Scale Glider, Alvydas Anthony Civinskas

Doctoral Dissertations and Master's Theses

The objective of this project is to do a flight assessment of a Phoenix K8B radio controlled glider to see what process is needed to verify its glide slope and stability characteristics. The flight test analysis, plus a computational fluid dynamics analysis, and an industry-like component build-up aerodynamic analysis were done to provide comparable estimates for the aircraft glide slope. A stability and control derivative analysis was also completed and compared using SURFACES, USAF Datcom, and MIT AVL software. The glide slope estimate and stability and control derivatives obtained from flight test data showed considerable range and uncertainty. Potential sources …

Unsteady Viscous Cavity Flow Using Computational Fluid Dynamics, Chandramouli Vadlamudi

Doctoral Dissertations and Master's Theses

The problem of unsteady viscous incompressible flow in a two-dimensional cavity is treated using the unsteady incompressible Navier-Stokes equations with various initial and boundary conditions. First the case of a square cavity with one inlet and one outlet is treated in steady and unsteady flows. The software package ANSYS FLUENT was used in the CFD simulations. This approach captures the appearance of separation bubbles and vortex formation inside the cavity. Steady state flows are also obtained from the unsteady simulations after convergence of the time dependent solutions. Then the case of a cavity with a synthetic jet and two outlets …

Axial Compressor Design With Counter-Rotation And Variable Rpm For Stall Mitigation, Madhur Tiwari

Doctoral Dissertations and Master's Theses

Compressor Stall, an aerodynamic instability due to abnormal air flow in the compressor resulting in loss of total pressure and compressor performance. One of the reasons of compressor stall is due to rise in static back pressure at compressor exit which may result from an imbalance of incidence angle at the rotor and stator and rotational speed. The paper presents the results of a new axial compressor design with counter rotation and variable RPM. Counter-Rotation is used to push compressor performance during stall by moving the operating point away from surge line with a higher pressure ratio rise. Initially an …

Overview Of Instruments For Investigating Dust Interactions On Small Solar System Bodies By Landers And Rovers, Ryan L. Kobrick, Jeffrey A. Hoffman, Kenneth W. Street Jr., Douglas L. Rickman

Publications

Small Solar System bodies such as asteroids, comets and Mars' moons Phobos and Deimos have relatively unknown regolith environments. It is hypothesized that dust preserved in the regolith on the surfaces will have similar mechanical properties to lunar dust because of similar formation processes from micrometeoric bombardment, low relative gravity for slow settling times, and virtually no weathering because there is no atmosphere.

Early Damage State Criterion From A Fault-Seeded Helicopter Gear Using Acoustic Emission And Neural Networks, Rudy L. Baum

Doctoral Dissertations and Master's Theses

In response to five failures since 2008 of the tail gearbox of multiple models of Sikorsky's H-60 helicopter, acoustic emission (AE) data collected from a rotating gearbox test stand at the Naval Air Station in Patuxtent River, MD, was used to monitor the initiation and propagation of a flaw from an electro-discharge machined (EDM) notch seeded on the face of a gear tooth. A period of testing was considered which spanned ~300,000 seconds or ~83 hours and culminates to a damage state such that a flaw has initiated on both ends of the EDM notch. AE data was analyzed for …

Space Shuttle Case Studies: Challenger And Columbia, Scott L. Post

Publications

The two Space Shuttle tragedies, Challenger and Columbia, have led to many papers on case studies on engineering ethics. The Challenger disaster in particular is often discussed due to the infamous teleconference that took place the night before the launch in which some engineers tried to postpone the launch. However, the space shuttle program itself is worthy of study as it relates to the engineering design process, and the details of the Challenger and Columbia disasters are worthy of discussion as they relate to a variety of sub-disciplines, including material science, thermodynamics, fluid mechanics, and heat transfer. This paper summarizes …

A Comparative Study Of The Low Speed Performance Of Two Fixed Planforms Versus A Variable Geometry Planform For A Supersonic Business Jet, Aaron C. Smelsky

Doctoral Dissertations and Master's Theses

A numerical investigation of the effects of high lift devices on the low-speed performance of a generic swept wing and a delta wing was conducted. The two fixed planforms were initially sized to achieve the same high speed performance as the baseline variable geometry wing. Following a review of high lift devices a detailed analysis of their use was conducted with the aid of vortex lattice method and empirical formulations. The slat and Fowler flap combination proved to be the best mechanical solution. In comparison with the initially sized delta planform, the final delta planform required a 26% increase in …

Effect Of 406 Mhz Elts And Cospas-Sarsat Cessation Of 121.5 Mhz Elt Monitoring On Search And Rescue Duration For General Aviation Aircraft Accidents In The Contiguous United States, Ryan J. Wallace, Todd P. Hubbard

International Journal of Aviation, Aeronautics, and Aerospace

Emergency Locator Transmitters (ELTs) are credited with saving hundreds of lives every year in the United States. Following an aircraft accident, these devices transmit an emergency beacon signal to the COSPAS-SARSAT satellite network, directing search and rescue forces to the crash site. In recent years, this constellation has been plagued by ELT false alarms, propagating a technology transition to new 406 MHz ELT systems. In 2009, the group ceased monitoring of 121.5 MHz ELTs, degrading search and rescue capability for legacy ELTs. The Federal Communications Commission twice attempted to enact regulations to mandate industry-wide transition to 406 MHz ELTs, however, …

The Role Of Unmanned Aircraft Systems (Uas) In Disaster Response And Recovery Efforts: Historical, Current And Future, Dennis Vincenzi, David C. Ison, Brent A. Terwilliger

Publications

A wide range of legislation has been proposed or put into place that restricts the use of unmanned systems. These actions by legislators and regulators will stifle the growth of this technology and the associated surrounding industry. The largest obstacle to the proliferation of UAS in the U.S. is the FAA. The FAA has designated the location of six test sites that are anticipated to allow for less restrictive and formative research to assess the technologies that the FAA has claimed need to exist in order to integrate UAS into the NAS. Further complicating the adoption of UAS for beneficent …

Design Optimization Of A Composite Wing Box For High-Altitude Long-Endurance Aircraft, Philip T. Arévalo

Doctoral Dissertations and Master's Theses

A design optimization process is developed to define the wing box structure for High-Altitude Long-Endurance Aircraft (HALE). The goal of this study is to determine the best tradeoff between mass and rigidity of a HALE aircraft wing structure. A preliminary composite laminate structural design procedure is described which uses a NASTRAN-based Finite Element Analysis (FEA), and the Hierarchical Evolutionary Engineering Design System (HEEDS) MDO software to define a locus of acceptable, optimized wing box design definitions.

The Effect Of The 2-Dimensional Magnetic Field Profile In Hall Thrusters, Megan Lewis Harvey

Doctoral Dissertations and Master's Theses

Electric propulsion engines, in particular Hall thrusters, provide the possibility of long-distance, low-cost space travel. The geometrical details of the Hall thrusters, especially the magnetic field prole, are crucial to improving their efficiency. The effect of the magnetic field structure was investigated using a simple, two-dimensional model, assuming axial symmetry. The previous one-dimensional conclusion, namely that the details of the shape of the magnetic field are unimportant, was confirmed. This result has implications for the design of future Hall thruster engines, with an eye toward maximizing their efficiency.

Winglet Performance Evaluation Through The Vortex Lattice Method, Phil R. Rademacher

Doctoral Dissertations and Master's Theses

The purpose of the study was to assess the possibility of retrofitting winglets to the Dassault Falcon 10 small size business jet using the vortex lattice method solver program SURFACES© by GreatOWL Publishing. The winglet geometric parameters investigated were the winglet span, cant angle, sweep and taper ratio in terms of their influence on drag, range, fuel burn, as well as wing root bending moments. The results of the research show that winglet span and cant angle offer the highest gains in terms of performance while taper ratio and sweep angle have a minor contribution. In general, all winglets provided …

Separation Bubbles And Vortex Formation In Cavity Flows, Kartheek Ravulapati

Doctoral Dissertations and Master's Theses

This research is a computational fluid dynamic study of the formation of vortices and separation bubbles in a square cavity as well as in a cylindrical cavity. Whereas there has been previous research work on the problem of a free stream over different types of cavities, like open and closed cavities or lid driven cavities, this research on an inlet induced flow inside a square cavity lead to unusual and interesting basic fluid dynamical phenomena. The flow in a square cavity and in a cylindrical cavity is simulated over a range of Reynolds numbers and the appearance of separation bubbles …

Cti White Paper, Tim Brady, Gregory Mcguirk

Publications

The FAA Air Traffic Collegiate Training Initiative (AT-CTI) Program has 36 partner institutions across the United States which offer a variety of accredited academic degrees and actively promote a multicultural and diverse collegiate environment.

Performance Improvement Through Velocity Triangle Optimization-Driven Redesign For Mitigating The Horseshoe Vortex In Axial Turbines, Vladislav Shulman

Doctoral Dissertations and Master's Theses

Momentum differences between the neighboring streamlines at the end wall/primary flow interaction region of an axial turbine stage induce three-dimensional vortical flow structures, such as the leading edge horseshoe vortex, resulting in significant aerodynamic performance deterioration. Reducing the effect of such flow instabilities requires turbine blade modification to discourage boundary layer roll-up, but traditional structural modification design systems can be prohibitively complex and time-intensive.

To address this problem, this study contributes a blade modification method involving airfoil shape optimization, designed to adjust the leading edge airfoil shape in horseshoe vortex-affected turbine applications. The key insight is that airfoil design (treated …

Bio-Inspired Mechanism For Aircraft Assessment Under Upset Conditions, Israel A. Moguel

Doctoral Dissertations and Master's Theses

Based on the artificial immune systems paradigm and a hierarchical multi-self strategy, a set of algorithms for aircraft sub-systems failure detection, identification, evaluation and flight envelope estimation has been developed and implemented. Data from a six degrees-of-freedom flight simulator were used to define a large set of 2-dimensional self/non-self projections as well as for the generation of antibodies and identifiers designated for health assessment of an aircraft under upset conditions. The methodology presented in this paper classifies and quantifies the type and severity of a broad number of aircraft actuators, sensors, engine and structural component failures. In addition, the impact …

Flow Separation Control Using Synthetic Jets On A Flat Plate, Karunakaran Saambavi

Doctoral Dissertations and Master's Theses

The primary goal of this thesis is to assess the effect of synthetic jets on flow separation. CFD simulation is conducted for laminar flow over a flat plate using the commercial software ANSYS FLUENT. The oscillating zero mass jet flow is simulated by imposing a harmonically varying boundary condition on the wall surface.

In this work, the effect of synthetic jets for different angles of attack and different frequencies ranging from 200 Hz to 800 Hz was assessed. The application of the synthetic jet actuators is based in their ability to energize the boundary layer, thereby providing significant increase in …

Slosh Damping With Floating Magnetoactive Micro-Baffles, Vijay Santhanam

Doctoral Dissertations and Master's Theses

Liquid sloshing within propellant tanks of launch vehicles and other major vehicles has been a major concern. Various methods have been utilized for the damping of slosh through Propellant Management Devices (PMD) accomplishing a wide range of results. Exploratory research conducted at the Embry-Riddle Aeronautical University Fuel Slosh Test Facility in development of an innovative PMD is presented. Embedding floating micro-baffles with a magnetoactive material such that the baffle can be manipulated when exposed to a magnetic field preserves the benefits of both floating and static baffle designs. Activated micro-baffles form a rigid layer at the free surface and provide …