Aerospace Engineering Commons^™

Hydrostatic Pressure Testing Of A Square-Cross Section Stainless Steel Propellant Tank Manufactured Using Selective Laser Sintering, Spencer Fuller

Master's Theses - Daytona Beach

The purpose of this study was to determine if parts manufactured using metal selective laser sintering (SLS) exhibit the same isotropic material properties as conventionally made metal parts. This was accomplished by performing a hydrostatic pressure test (HPT) of a metal SLS manufactured propellant tank, constructed for a nano-satellite of the cubesat class. Strain measurements from twelve strain gage locations on the propellant tank were recorded. A finite element analysis (FEA) model, which assumes isotropic material properties, was generated and a FEA analysis was ran at several pressure loads. The tanks strain data at the corresponding pressure loads from the …

Neural Network Prediction Of Ultimate Compression After Impact Loads In Graphite-Epoxy Coupons From Ultrasonic C-Scan Images, Nikolas L. Geiselman

Master's Theses - Daytona Beach

The purpose of this project was to investigate how accurately an artificial neural network could predict the ultimate compressive loads of impact damaged 24-ply graphite-epoxy coupons from ultrasonic C-scan images. The 24-ply graphite-epoxy coupons were manufactured with bidirectional preimpregnated tape and cut into 21 coupons, 4 inches by 6 inches each. The coupons were impacted at known impact energies of 10, 12, 14, 16, 18, and 20 Joules in order to create barely visible impact damage (BVID). The coupons were then scanned with an ultrasonic C-scan system to create an image of the damaged area. Each coupon was then compressed …

Development Of Multidisciplinary Design Optimization Process For A Large Scale Hybrid Composite Wind Turbine Blade, Jin Woo Lee

Master's Theses - Daytona Beach

Development of a multidisciplinary design optimization (MDO) of a large scale hybrid composite wind turbine blade is performed. Multiple objectives are considered in the MDO process to maximize annual energy production and lifetime profit, minimize weight and power production rate. A wind turbine blade is divided into regions and the layup sequences for each region are considered as design variables. The scale of wind turbine blade is also considered to find the optimum size of a wind turbine blade. Applied loads due to extreme wind conditions for rotor rotation and rotor stop condition are considered for finite element analysis (FEA) …

Effect Of Thermally Induced Deformation In A Supersonic Combustion Facility, Aditya Ajit Gupte

Master's Theses - Daytona Beach

Nastran and ANSYS finite element analysis (FEA) and Wind-US computational fluid dynamics (CFD) solvers are used to simulate the effect of thermal deformation on the reacting flow developing within the University of Virginia (UVa) Supersonic Combustion Facility (SCF). A detailed thermal-structural model is developed to resolve the temperature distribution and the resulting structural deformation taking place within the scramjet engine flowpath. The predicted thermal deformation is used to refine the CFD model and produce a new set of results for direct comparison with experiment during both ramjet and scramjet modes of operation. Improved agreement between CFD and experiment is afforded …

Investigation Of Scaling Effects For A Synthetic Jet Actuator Using High And Low Fidelity Analyses, Amandine Bourlier

Master's Theses - Daytona Beach

This research presents an investigation on the scaling effects for synthetic jet actuators using Ansys-CFX and a Lumped Element Model (LEM). Synthetic jets or zero net mass-flux devices use a vibrating diaphragm to generate an oscillatory flow through a small orifice. A synthetic jet actuator can be used on MAVs as thrust generator or fixed on an airfoil for flow separation control. A Computational Fluid Dynamics (CFD) model was created, using Ansys-CFX, to be validated against referred publications. The use of mesh adaption is discussed. This baseline model was then used to complete a scaling analysis using a set of …

Neural Network Burst Pressure Prediction In Composite Overwrapped Pressure Vessels Using Mathematically Modeled Acoustic Emission Data, Junya Iizuka

Master's Theses - Daytona Beach

The purpose of this research was to predict burst pressures in composite overwrapped pressure vessels (COPV) using mathematically modeled acoustic emission (AE) data. The AE data were collected during hydrostatic burst (hydroburst) testing often 15-inch (380 mm) diameter COP Vs. The data gathered during these tests were filtered in order to remove long duration hits, multiple hit data, and obvious outliers. Based on the duration, energy, and amplitude of the AE hits, the filtered data were classified into the various failure mechanisms of composites using a MATLAB based self-organizing map (SOM) neural network. Previous research has demonstrated that the parameters …

Estimation Of Air Flow Angles Derived From An Inertial Navigation System, Brett Douglas Mather

Master's Theses - Daytona Beach

The purpose of this study is to explore the use of an Inertial Navigation System as a primary method for measuring aircraft air flow angles in flight testing. The traditional methods used to measure air flow angles consist of sensors external to the aircraft, such as an air data boom or an angle of attack probe. The advantage of using INS to measure air flow angles would be in the simplicity of the instrumentation. All components could be fixed internally, leaving minimal external modifications to the aircraft necessary for instrumentation. This would reduce costs and instrumentation time and enable air …

Extension To Multiple Species Of A Two-Equation Turbulence Model For High Speed Flows, Martin Horvath

Master's Theses - Daytona Beach

The Wilcox (2006) k-co turbulence model has been extended to multiple species and implemented in a CFD code for high speed flows using the Steger-Warming flux-vector splitting scheme. The model was chosen because compressibility corrections are not required, nor are viscous damping factors or wall functions to produce the law of the wall, and it has previously been validated for approximately one hundred test cases ranging from incompressible to hypersonic flow regimes. Initial validation cases using first-order accuracy have been performed, including a Mach 2.5 flow past a backward-facing step and a Mach 2.85 flow into a 24° compression corner. …

Numerical Simulation Of A Liquid Jet Atomization And Break-Up Using Ansys-Cfx 12.0, Yash Akhil Bhatt

Master's Theses - Daytona Beach

Break-up and atomization characteristics of JetA liquid fuel were investigated numerically. The results have been compared to various experimental results to evaluate the accuracy of the numerical model. The CFD code ANSYS-CFX 12.0 was used to carry out the steady state analysis at different time scales. A comparison between the atomization characteristics of a pressure jet atomizer and an air-blast atomizer is shown. By employing a Lagrangian particle tracking method to track the path of the liquid particles, the liquid jet/spray phenomena was studied in light of low and high back pressure environments. The 'BLOB' primary atomization model and the …

Neural Network Fatigue Life Prediction In Notched Aluminum Specimens From Acoustic Emission Data, Muhammed Arif Okur

Master's Theses - Daytona Beach

This purpose of this research was to identify fatigue crack growth and predict failure for 7075-T6 aluminum notched bars under uniaxial tensile loading using acoustic emission (AE) data. The experiments performed in this study extend the results obtained by previous researchers who used maximum cyclic loads of 4,000, 3,000, and 2,000 pounds at a stress ratio of R = 0.0 and a frequency of 1 Hz to perform the fatigue tests. For this research the cyclic load remained at 2,000 pounds, but an additional ten specimens were tested in order to increase the amount of AE data available to the …

Effect Of Time Pressure And Task Uncertainty On Human Operator Performance And Workload For Autonomous Aerial Vehicle Missions, Trevor Peterson

Master's Theses - Daytona Beach

Unmanned aircraft systems (UAS) are being utilized at an increasing rate for a number of military applications. The potential for their use in the national airspace is also of interest to the Federal Aviation Administration, but there are some concerns about the safety of flying unmanned aircraft. The role of a UAS operator differs from that of a pilot in a manned aircraft, and this new role creates a need for a shift in interface and task design in order to take advantage of the full potential of these systems. This study examined the effect of time pressure and task …

Parametric Viscous Analysis Of Gust Interaction With Stationary And Elastically Mounted Airfoil, Timothy M. Hollenshade Jr.

Master's Theses - Daytona Beach

This thesis details the development and implementation of a module within a high-accuracy numerical viscous analysis code to simulate the nonlinear interaction of SD7003 airfoil with non-uniform, unsteady incoming flow. The study is focused on the low-Re number unsteady flows typical of MAV applications in which a gust encounter can induce a particularly significant aerodynamic and aeroelastic response. Efficient source models are developed to introduce sharp-edge and time-harmonic gust perturbations with specified amplitude, frequency and duration inside the computational domain through the source terms in the governing momentum equations. Parametric analysis of gust-airfoil interactions for different steady airfoil loads is …

Removal Of Biofilm Through Controlled Cavitation, Mathew Chackalackal Mathew

Master's Theses - Daytona Beach

Human kind is poised to take the next "giant step" in space exploration, the manned mission to Mars, among other things. But before any plans for such long term habitation on an alien planet, there has to be consideration towards prevention and removal of bacterial contamination. Bacterial contamination or rather degradation of materials was considered of negligible importance. Bacterial degradation can be serious for long-term manned space mission, more so because there is no way to obtain quick replacements. For such conditions, a new innovative way of bacterial removal has been proposed wherein the bacteria is removed with no damage …

Numerical Simulation Of Mode Transition In A Hydrogen-Fueled Scramjet, Manan Ajay Vyas

Master's Theses - Daytona Beach

The Wind-US computational fluid dynamics (CFD) flow solver was used to simulate dual-mode direct-connect ramjet/scramjet engine flowpath tests conducted in the University of Virginia (UVa) Supersonic Combustion Facility (SCF). The objective was to develop a computational capability within Wind-US to aid current hypersonic research and provide insight to flow as well as chemistry details that are not resolved by instruments available. Computational results are compared with experimental data to validate the accuracy of the numerical modeling. These results include two fuel-off non-reacting and eight fuel-on reacting cases with different equivalence ratios, split between one set with a clean (non-vitiated) air …

An Analytical Investigation Of Natural Frequency For A Symmetric Composite Box-Beam With Thermal Effects, Lakshmi Narayana Sanjeev Chitikela

Master's Theses - Daytona Beach

The main purpose of the following analysis is to develop an analytical method for determining the natural frequency of a symmetric composite box-beam subjected to temperature gradient. A set of coupled partial differential equations of motion is obtained by means of small defection theory and D'Alembert's method. The Smith and Chopra stiffness matrix is used in the governing equations of motion and an appropriate MATLAB® code has been written to solve for the stiffness matrix elements of the box-beam. The resulting governing equations of motion are solved to obtain the natural frequencies of the box-beam in flap and lag directions …

Compression After Impact Load Prediction In Graphite/Epoxy Laminates Using Acoustic Emission And Artificial Neural Networks, Anthony Michael Gunasekera

Master's Theses - Daytona Beach

The purpose of this research was to investigate the effectiveness of artificial neural networks (ANNs) in predicting the compression after impact (CAI) load of graphite/epoxy laminates from acoustic emission (AE) nondestructive testing (NDT) data. Thirty-four 24-ply bidirectional woven cloth laminate coupons were constructed and impacted at various energy levels ranging from 8 to 20 Joules, generating barely visible impact damage (BVID). Acoustic emission data were acquired as the coupons were compressed to failure. Not having been analyzed by previous experimenters, several noise tests were also performed to determine the impact of external noise on acoustic emission data during testing. Once …

Determination Of Stability And Control Derivatives For A Modern Light Composite Twin Engine Airplane, Monica M. Londono

Master's Theses - Daytona Beach

To develop and compare full envelope stability and control derivatives and their associated errors for a modern light composite twin engine airplane from flight test data and digital DATCOM (Data Compendium). This development is to serve three purposes 1) to provide data for validation of newer analytical techniques such as Computational Fluid Dynamics (CFD), 2) to provide public domain static and dynamic stability and control derivatives for a modern twin engine airplane, 3) to analyze the relationship between test design and error for both output error and equation error methods.

A flight test program was conducted on a Diamond Twin …

The Effect Of Pilot And Air Traffic Control Experiences & Automation Management Strategies On Uas Mission Task Performance, Christopher J. Reynolds

Master's Theses - Daytona Beach

Unmanned aircraft are relied on now more than ever to save lives and support the troops in the recent Operation Enduring Freedom and Operation Iraqi Freedom. The demands for UAS capabilities are rapidly increasing in the civilian sector. However, UAS operations will not be carried out in the NAS until safety concerns are alleviated. Among these concerns is determining the appropriate level of automation in conjunction with a suitable pilot who exhibits the necessary knowledge, skills, and abilities to safely operate these systems.

This research examined two levels of automation: Management by Consent (MBC) and Management by Exception (MBE). User …

Flight Regime And Maneuver Recognition For Complex Maneuvers, Jerome H. Travert

Master's Theses - Daytona Beach

The purpose of this study is to demonstrate capability of flight regime recognition during complex maneuvers flown in a fixed wing airplane using measured data from an Inertial Measurement Unit (IMU). Flight Regime Recognition (FRR) is required for numerous applications in the aerospace and aviation industry, including the determination of loads for stress and strain analysis. It can also be used in recreational aviation for maneuver recognition, for example in aerobatics.

This study uses a flight simulator to generate representative flight data that is parsed by a specifically developed algorithm into appropriate flight regimes. This algorithm is a filter technique …

An Intelligible Software (Cfa) Approach For Fiber-Reinforced Laminate Failure Analysis Including A Piecewise Representation Of The Tsai-Wu Failure Criterion Using Excel And Matlab, Ryan C. Schmidt

Master's Theses - Daytona Beach

Present generations rely heavily on the use of petroleum as their primary means of transportation. As the cost of petroleum continues to escalate, the need for lightweight structures for vehicle applications becomes more evident. The ability to engineer materials so that they possess desired application specific properties and characteristics has made tremendous progress in the past century. Consequently, the use of these composite materials for aircraft weight reduction has been investigated for decades.

The aerospace industry often uses composite materials to make a laminated composite structure where each constituent ply of the laminate has its own material properties. This anisotropic …

Magnetic Stabilization Of Nadir-Pointing Small Satellites, Chau Ton

Master's Theses - Daytona Beach

Since magnetic control systems are relatively lightweight, require low power and are inexpensive, they are attractive for small, inexpensive satellites in low Earth orbits. In this thesis we present averaging-based feedback control laws that achieve three-axis stabilized nadir-pointing attitude. Two types of nonlinear feedback control laws are proposed: full-state feedback and passivity-based feedback. Full-state feedback uses the attitude and angular velocity measurements to regulate the spacecrafts dynamics. Passivity-based feedback uses the attitude measurement and doesn’t require the rate sensors. The control laws are tested using two magnetic field models: the tilted dipole model and the International Geomagnetic Reference Field (IGRF) …

The Effects Of Elasticity In The Foundation On The Flutter Of A Metallic High Aspect Ratio Wing, Horacio Esteban Sepic Kriskovich

Master's Theses - Daytona Beach

The goal of this thesis is to study the flutter characteristics of a metallic high-aspect ratio wing, with linearly varying chord across the semis-span, and a simulated elastic foundation. The general planform of the wing is similar to the one found in a High- Altitude Long-Endurance Uninhabited Aerial Surveillance Vehicle (HALE USAV).

The problem is studied using a simplified aerodynamic loading based on thin-airfoil theory, which is then combined with a Lagrangian formulation to solve the system as stationary. The wing has no control surfaces or external stores, and is modeled as a uniform beam with known mechanical properties, being …

Design, Implementation And Validation Of An Attitude Determination Subsystem For Nanosatellites, Mathieu Naslin

Master's Theses - Daytona Beach

The purpose of this study is to design and analyze the accuracy of an attitude determination subsystem for a satellite of the CubeSat class by using low cost sensors. CubeSats are nanosatellites that complies a certain amount of layout criterions described by the California Polytechnic State University. A 3-axis attitude determination platform has been designed with emphasis on the use of low cost, off the shelf sensors. This platform features a sun sensor, a magnetometer and an earth sensor. The principles of observation and the description of the acquisition method are explained. The interfacing of the software package and real …

Modular Multi-Stage Axial Compressor Design, Christopher S. Hemerly

Master's Theses - Daytona Beach

Increasingly, companies are becoming more interested in reducing cost. Recent studies indicate that up to 80% of the Lifecycle costs (LCC) has been embedded in the engine's DNA at the end of the development and design phase. One concept to aid in the cost reduction is the modular design of expensive and development-intensive components, such as multi-stage axial compressors. It is the objective of this approach to utilize a "core" module in all the compressors, thus maximizing commonality and minimizing all relevant development, design, manufacture, procurement, and service costs; these reductions in cost are projected to increase affordability by five-fold. …

Numerical Simulation Of Uva Ramjet/Scramjet Hypersonic Engine With Hydrogen-Air Combustion Using Wind-Us, Vishal Anand Bhagwandin

Master's Theses - Daytona Beach

The internal flowpath of University of Virginia's Mach 5, direct-connect, dual-mode scramjet engine was simulated using Wind-US, a density-based Reynolds-Averaged Navier-Stokes flow solver. Detailed flowfield simulation results are directly compared to experimental data to evaluate the accuracy of the numerical model and to provide insight into the flowfield behavior. Four hydrogen-air reaction mechanisms were initially assessed using the Burrows-Kurkov case. An Evans-Schexnayder, 7-specie, 8-reaction set with third body efficiencies was then selected for the scramjet simulations. The scramjet simulations included one fuel-off case and two reacting cases with different equivalence ratios, all with clean, non-vitiated air supply. The strong sensitivity …

Study Of The Influence Of Nacelle And Pylon On Aerodynamics Of A New Vu Design, Romain Larose

Master's Theses - Daytona Beach

The purpose of this thesis was to illustrate the influence of the nacelle and pylon on aerodynamics of a new Very Light Jet design, using Computational Fluid Dynamics.

The objective of the first phase was to repair the existing CATIA model in order to facilitate the meshing process.

The second and third phase was to create two meshes: a mesh for the complete model (aircraft with nacelle and pylon), and a second for the aircraft alone.

The two problems have been solved at cruise conditions using Navier-Stokes equations with a second order accuracy.

The model complying with theory, the results …

Design And Numerical Evaluation Of A Counter- Rotating Compressor In The Absence Of Boundary Layer Control: Part I, Naiara Petralanda

Master's Theses - Daytona Beach

The purpose of this thesis was to design and evaluate a three stage counter-rotating compressor that employed well established design principles and technologies using a phased approach. The objective of the first phase was to generate the preliminary annulus shape and estimate the major parameters by modeling the flow as inviscid and time independent. The second and third phases refined the design approximating the flow using Euler's equations and the Navier-Stokes equations respectively.

The performance predictions decreased as the design move forward and more accurate flow and loss models were used. The final three dimensional analysis, which was limited to …

Modeling And Parameter Estimation Of Spacecraft Lateral Fuel Slosh, Yadira Rodriguez Chatman

Master's Theses - Daytona Beach

Predicting the effect of fuel slosh on spacecraft and launch vehicle attitude control systems has been a very important and challenging task and has been the subject of considerable research over the past years. Analytic determination of the slosh analog parameters has been met with mixed success and is made more difficult by the introduction of propellant management devices such as elastomeric diaphragms. The experimental set-up in this research incorporates a diaphragm in a simulated spacecraft fuel tank subjected to lateral slosh behavior. This research focuses on the parameter estimation of a SimMechanics model of the simulated spacecraft propellant tank …

Modeling, Analysis And Testing Of A Semi-Active Control System For Landing Gear Applications, David James Majko

Master's Theses - Daytona Beach

There have been several recent studies on the potential benefits of controllable dampers. Controllable dampers can use a fluid with controllable properties, such as Magneto - Rheological fluid (MR fluid), or control the damping force by changing orifice size. For this project, controllable dampers were created using MR fluid. When exposed to a magnetic fluid, the viscosity of MR fluid can change significantly. By replacing the standard damper oil in an aircraft landing gear and exposing the system to an appropriate magnetic field, the damping coefficients of the system can be changed almost instantaneously to accommodate nearly any situation. This …

Application Of Kalman Filtering To Real-Time Flight Regime Recognition Algorithms In A Helicopter Health And Usage Monitoring System, Rachel Elizabeth Rajnicek

Master's Theses - Daytona Beach

The purpose of this study is the application of Kalman filters to real-time Flight Regime Recognition (FRR) algorithms to identify the regime flown and observe transitions between flight regimes. Rotor fault identification, a technique that is somewhat similar to flight regime recognition, successfully used Kalman filters to determine fault types and damage locations. Recently developed FRR algorithms successfully applied Hidden Markov Models, which are similar to Kalman filters. The selected regime set for this study derives from a study performed by Bell Helicopter Textron, Inc. The selected parameter set for this study is modified from the Schweizer 300 Flight Test …