Engineering Commons^™

Low-Velocity Impact Analysis Of Composite Repair Patches Of Different Shapes, Sarvesh Baliga

Doctoral Dissertations and Master's Theses

The area under crack for various structures can be effectively repaired by the use of composite materials. Low velocity impact can cause barely visible damage to the interior structure of laminated composite. These impacts can cause delamination in composite materials. In this study, a Finite Element Analysis was conducted using Abaqus/Explicit and the results of the analysis were compared to the experimental data from literature. E-glass/epoxy composite laminate was subjected to a low velocity impact test. To study the effect of patch repair, a composite patch was applied on a cracked laminate and a low velocity impact was then conducted …

Lagrangian Points And Jacobi Constants For A Class Of Asteroids, Tasneem Rashid

Doctoral Dissertations and Master's Theses

Asteroid Gravitational Potentials are difficult to model owing to their irregularity in shape. This thesis focuses on two approaches to model asteroid gravity fields, namely, multiple-body and spherical harmonics modeling. Computation of gravity potential serves as a first step to determine equilibrium points called Lagrangian points for a spacecraft orbiting as an asteroid. Further, Jacobi analysis is carried out to determine zero-velocity regions, i.e., inaccessible regions corresponding to the unstable Lagrangian points. Multiple sphere modeling was studied through analysis of so called Asteroid Restricted Three and Four Body Problems, providing insight into the method of modeling an asteroid as a …

Aerodynamic Trade Study Of Compound Helicopter Concepts, Julian Roche

Doctoral Dissertations and Master's Theses

The relative performance attributes of compound helicopter concepts have been examined, including their potential for meeting the requirements of several challenging mission profiles. For each concept, which included lift and/or propulsive compounding, a suite of aerodynamic performance models was developed using energy methods. In the case of a lift-compounded concept, an aerodynamic model representing the force interaction effects of the main rotor wake with the wing was also developed. Models of a conventional helicopter and of a tiltrotor were implemented as well, and the results used as a datum for comparison. In each case, the predictive capabilities of the model …

Computation Of Hypersonic Flows With Lateral Jets Using K-Ω Turbulence Model, Spatika Dasharati Iyengar

Doctoral Dissertations and Master's Theses

Thermal Protection systems (TPS) are used as shields in space vehicles which encounter high heat and temperatures at the reentry altitudes. Among them, the cooling techniques and the ablative coatings are most popular. However, they have their own weight limitations. In the recent decade, another classification of TPS called the Non-Ablative Thermal Protection systems (NaTPS) have gained significance. The spike-lateral jet method is an NaTPS concept proposed for drag and heat flux reduction in hypersonic nose cones. Numerical simulations are conducted to analyze the effectiveness of spike-lateral jet concept at re-entry altitudes. The spike attached to the hemispherical nose has …

The Three-Dimensional Turbulent Boundary Layer On A Rotating Disk, Daniel Digre

Doctoral Dissertations and Master's Theses

Three-dimensional turbulent boundary layers (3DTBL) are seen quite commonly in nature as well as in the engineering applications. Despite this, very few high Reynolds number studies have been carried out on these boundary layers, particularly focusing on eddy structure, eddy scales and their interactions. The current study focused on developing, characterizing and evaluating an experimental framework to study high Reynolds number #3DTBL on a rotating disk with the long-term goal of carrying out high-fidelity measurements. The rotating disk flow is characterized by weak centrifugal pumping which sets up the cross flow that leads to turbulence. The tangential and radial velocities …

Experimental And Computational Investigation Of Ribbed Channels For Gas Turbine Thermal Management, Yash T. Mehta

Doctoral Dissertations and Master's Theses

This study focuses on the computational benchmarking as well as validation against experimental results of a rib roughed surface in an internal channel of a stationary turbine blade. STAR-CCM+ was utilized to replace a model from a published article, and to analyze the CFD conjugate heat transfer by determining the turbulence model that best matched the published experimental values. Using those computational conditions and CFD results, an in house experimental rig was validated by comparing convective heat transfer coefficients and pressure profiles. This cooling method, when compared to a smooth channel, enhances turbulent mixing my separating and reattaching the boundary …

An Approach To Automotive Electrification And Testing, Christopher Rowe

Doctoral Dissertations and Master's Theses

In order to compete in the EcoCAR 2 competition, Embry-Riddle Aeronautical University has redesigned the Powertrain of a 2013 Chevrolet Malibu into a plug-in hybrid electric vehicle. This endeavor was made possible by the EcoCAR 2 competition sponsored by the Department of Energy, General Motors, and Argonne National Laboratory. The Powertrain was changed from a conventional internal combustion engine with a start/stop capability, to a fully electric Powertrain, with a diesel generator, and plug in charging capability. This paper will cover the electrical work performed on the vehicle during the summer prior to year three of the competition, EcoCAR 2 …

Numerical Study Of Synthetic-Jet Actuation Effect On Airfoil Trailing Edge Noise, Marco Sansone

Doctoral Dissertations and Master's Theses

The current study conducts numerical simulations to assess the possibility of employing Synthetic Jet Actuators (SJAs) as active noise control devices for reduction of airfoil acoustic radiation. High-accuracy numerical efforts employ a sixth-order accurate Navier-Strokes solver implementing a low-pass filtering of poorly resolved high-frequency solution content to retain numerical accuracy and stability over the range of transitional flow regimes. In the adopted numerical procedure, the actuator is modeled without its resonator cavity through imposing a simple fluctuating-velocity boundary condition at the bottom orifice of the actuator. The orifice cavity with the properly defined boundary condition is embedded into the airfoil …

Aircraft Detection And Tracking Using Uav-Mounted Vision System, Yan Zhang

Doctoral Dissertations and Master's Theses

For unmanned aerial vehicles (UAVs) to operate safely in the national airspace where non-collaborating flying objects, such as general aviation (GA) aircraft without automatic dependent surveillance-broadcast (ADS-B), exist, the UAVs' capability of “seeing" these objects is especially important. This “seeing", or sensing, can be implemented via various means, such as Radar or Lidar. Here we consider using cameras mounted on UAVs only, which has the advantage of light weight and low power. For the visual system to work well, it is required that the camera-based sensing capability should be at the level equal to or exceeding that of human pilots. …

Direct Adaptive Control For Stability And Command Augmentation System Of An Air-Breathing Hypersonic Vehicle, Ron Aditya

Doctoral Dissertations and Master's Theses

In this paper we explore a Direct Adaptive Control scheme for stabilizing a non-linear, physics based model of the longitudinal dynamics for an air breathing hypersonic vehicle. The model, derived from first principles, captures the complex interactions between the propulsion system, aerodynamics, and structural dynamics. The linearized aircraft dynamics show unstable and non-minimum phase behavior. It also shows a strong short period coupling with the fuselage-bending mode. The value added by direct adaptive control and the theoretical requirements for stable convergent operation is displayed. One of the main benefits of the Directive Adaptive Control is that it can be implemented …

Design, Fabrication, And Testing Of A Proprioceptive Electroadhesion Pad For Space Applications, Walter Saravia

Doctoral Dissertations and Master's Theses

The purpose of this study is to design, analyze, and fabricate an electroadhesion mechanism with the goal of providing controlled electrostatic adhesion to objects with little known surface finish, of varying curvature, and different materials. The main purpose of the mechanism is that of ensuring a soft docking, controlled in closed loop, for attachment to large pieces of orbital debris. Other envisaged purposes for the mechanism are sample collection and manipulation in free-fall and in-situ analysis of cohesive forces in regolith at small bodies, such as asteroids or comets. Electrostatic finite element analysis was performed on various electroadhesion pad designs …

An Investigation Of Cooling Configurations In Gas Turbine Engines Using Jet Impingement, Bhushan Upalkar

Doctoral Dissertations and Master's Theses

A numerical investigation for predicting the heat transfer effects of turbulence was conducted by making a scaled-up model of a section in a jet impingement channel. Different turbulence models were run and the results were compared to experimental data. Experimental comparisons were made for impingement channels between a baseline case, which is a rectangular array of jets of 20 rows and 3 jets per row, and different hole spacing configurations. The heat transfer was measured using Temperature Sensitive Paint. The turbulence model v²-f gave the most accurate prediction with an error of about 17% with the EB k-E, with an …

Identifying Secondary Crashes By Using Geographic Information System (Gis) And Determining The Secondary Crashes Characteristics, Yuan Tian

Doctoral Dissertations and Master's Theses

As the nation’s transportation infrastructure expands, traffic incidents led to more than 25% of traffic congestion in the United States (FHWA, 2014). The risk of the occurrence of secondary crashes can be six times higher in the presence of a primary crash than that at a normal traffic condition (Yang et al., 2013 and Tedesco, 1994). The purpose of this study is 1) to develop a method to identify the secondary crashes with the primary incidents in Geographic Information Systems (GIS) under different spatial-temporal criteria, and 2) to determine the impacts of spatial-temporal criteria on the secondary crash characteristics in …

Development And Prototype Validation Of An Additive Manufactured Cubesat Propulsion Tank, Geovanni A. Solorzano

Doctoral Dissertations and Master's Theses

The purpose of this study is to determine if a cubesat propellant tank using the additive manufacturing technology of direct metal laser sintering meets the requirements, and material properties of a conventionally manufactured tank. Additionally, to see if additive manufactured parts are a viable option to be used in cubesat applications. This was accomplished by designing a model which will be used by the ARAPAIMA cubesat that meets all the Air Force's University Nanosatellite Program (UNP), NASA's and Department of Defense's requirements for pressurized vessels and material properties. A finite element analysis study was conducted to determine where and when …

An Experimental Method To Calculate Coefficient Of Friction In Mecanum Wheel Rollers And Cost Analysis Using Dfma Techniques, Nishant Sonawane

Doctoral Dissertations and Master's Theses

Mecanum wheel is a special kind of omni-directional wheel which is designed for robot vehicles. The purpose of this thesis is to work on geometry and working of Mecanum wheel rollers and to conduct experiments on these rollers to find its values of coefficient of friction in different conditions. This thesis also includes the work conducted to formulate the equations which can be used to find different parameters of roller for its motion, kinematics, rolling, friction and overall impact with respect to the working of a robot. The work is tested in experiments and the values are compared with previous …

Lumped Parameter Model For A Self Powered Fontan Palliation Of The Hypoplastic Left Heart Syndrome, Jang Ho Park

Doctoral Dissertations and Master's Theses

Out of all newborn infants with congenital heart disease (CHD), 8% have a single functioning ventricle. The Fontan surgical procedure, where the superior and inferior venous returns are connected directly to the pulmonary arteries to allow the single functioning ventricle to perfuse the systemic circulation, has been around for decades, yet the patients who undergo this operation suffer from chronic illnesses and their survivability is less than 50% by adulthood [1-10]. Some suggest that the Fontan operation can be improved by implanting a synthetic pump. However, synthetic pumps also present some complications due to mechanical failure, risk of stroke, and …

Random Actuation Pattern Optimization By Genetic Algorithm For Ultrasonic Structural Health Monitoring Of Plates, Pierrot R. Derjany

Doctoral Dissertations and Master's Theses

The objective of this research is to investigate an optimized two-dimensional random pattern of uniformly excited points using the Genetic Algorithm (GA) technique for structural health monitoring. The point excitations generate ultrasonic waves in both isotropic and anisotropic materials that can be effective in diagnosing structural defects. The formed ultrasonic waves can constructively interfere and send out an intense wave beam to a predetermined target. The constructed wave beams can be steered to different directions with variable target distances. In the GA, the cost function is constructed to reduce main lobe beamwidth, eliminate grating lobes and suppress sidelobes’ levels. Mathematical …

Similarity Analysis Of A Swirling Counter-Flow, Jitesh Rane

Doctoral Dissertations and Master's Theses

Swirling counter-flows are used in numerous engineering applications, like combustion, heat exchangers, cyclonic separation and mixing, etc. These swirling counter-flows produce complex flow fields. It is important to study these types of flows in order to use them properly in many applications.

The present work provides insight into the flowfield inside a swirling counter-flow when the fluid is injected tangentially in a cylindrical container. A semi-analytical solution is developed by starting with the full Navier-Stokes equation and using a similarity analysis. A decaying swirl along the axis of the cylinder is assumed, which reduces the Navier-Stokes equations to first order …

Design And Validation Of Hardware-In-The-Loop Testbed For Proximity Operations Payloads, Kristia K. Harris

Doctoral Dissertations and Master's Theses

The research presented here is a new testbed design for CubeSat and payload testing and development. This research demonstrates a low-cost, hardware-in-the-loop testing apparatus for use with university CubeSat programs for testing throughout the different levels of the development process. The average university CubeSat program undergoes very little hardware-in-the-loop testing. Most of the focus is the targeted towards performance testing and environmental testing which occur after completion the development process. This research shows that, for minimal schedule and cost impact, testing can occur early in the development process. The testbed presented here demonstrates suitable accuracy to be used for advanced …

Design Of Synthetic Jet Actuator For Flight Control Of Small Uav, Priyanka Pagadala

Doctoral Dissertations and Master's Theses

The main idea of this project is to develop a prototype SJA - Synthetic Jet Actuator to embed into a small UAV with modified Glauert wing cross-section for Active Flow Control. Apart from lift enhancement, drag reduction, or separation control, etc; LCO suppression might be possible by modifying the boundary layer through the use of these actuators. For initial investigation, a wing section with span of 12.4 cm and chord of 14 cm was fabricated and tests were conducted in the subsonic wind tunnel at the free stream velocities of 5 and 10 m / s. From these experiments, lift …

Sensor Fusion And Obstacle Avoidance For An Unmanned Ground Vehicle, Gurasis Singh

Doctoral Dissertations and Master's Theses

In recent years, the capabilities and potential value of unmanned autonomous systems (UAS) to perform an extensive variety of missions have significantly increased. It is well comprehended that there are various challenges associated with the realization of autonomous operations in complex urban environments. These difficulties include the requirement for precision guidance and control in conceivably GPS-denied conditions as well as the need to sense and avoid stationary and moving obstructions within the scene. The small size of some of these vehicles restricts the size, weight and power consumption of the sensor payload and onboard computational processing that can accommodated by …

Modeling And Simulation Of Radiation From Electronic Transitions In Hypersonic Atmospheric Reentry Flow, Curtis Scholz

Doctoral Dissertations and Master's Theses

A capability for higher accuracy heat transfer modeling in CFD for hypersonic re-entry flows, via inclusion of thermal radiation, is sought. With temperatures reaching tens of thousands of degrees, radiation is known to be significant to chemical reaction rates and thermal boundary layer development, hence surface heat transfer and thermal ablation both to the heat shield and the backshell region of re-entry vehicles. Two current NASA solicitations seek such an improved capability relative to the Mars and Earth entry problems, as uncertainty typically leads to overdesign and excess weight. The present research develops a first physics-based “building block,” which computes …

Aerodynamic And Structural Design Of A Winglet For Enhanced Performance Of A Business Jet, Nicolas El Haddad

Doctoral Dissertations and Master's Theses

The preliminary design of a winglet to improve the range and fuel burn of the Falcon 10 business jet is presented. Twelve candidate geometries were studied varying the cant angle and the span. The configuration offering the best compromise between induced drag reduction, profile drag increase and weight increase due to the winglet structure and necessary wing structural reinforcement was selected. More refined analysis was performed for that winglet with Reynolds averaged Navier-Stokes computational fluid dynamics and finite element analysis. Range and fuel burn were finally calculated for a typical mission using these refined results. The selected winglet, with a …

Design And Manufacturing Of A Mecanum Wheel For The Magnetic Climbing Robot, Shruti Deepak Kamdar

Doctoral Dissertations and Master's Theses

An AndyMark Mecanum Wheel has been re-designed for better performance and utilization by Helical Robotics. Mecanum Wheel is a complex "Omni-Directional" wheel that currently contains several drawbacks. The drawbacks include design, usage of hobby grade material, bumps in rollers, etc. A comprehensive design of the Mecanum wheel is being presented using Computer Aid Software, CAD and analysis tools, such as Finite Element Analysis, FEA. The different concepts were hand sketched using various parameters and then implemented in a CAD software-- CATIA. The Mecanum Wheel's feasibility was thoroughly studied through ANSYS software. Load analysis was performed using various materials and several …

Phased Array Beamsteering In Composite Laminates For Guided Wave Structural Health Monitoring, Peter Osterc

Doctoral Dissertations and Master's Theses

In this study a guided wave phased array beamsteering approach is applied to composite laminates. Current beamsteering algorithms derived for isotropic materials assume omnidirectional wave propagation. Due to inherent anisotropy in composites, guided wave propagation varies with direction and wavefronts no longer have perfect circular shapes.

By examining slowness, velocity and wave curves, as well as amplitude variation with direction for a given composite laminate, the wavefront from a single source can be described as a function of the angle of propagation and distance from origin. Using this approach, a more general delay and sum beamforming algorithm for composite laminates …

Investigation Of Mountain Waves In The Mesosphere Over The Andes Mountains, Jaime Aguilar Guerrero

Doctoral Dissertations and Master's Theses

An image processing algorithm has been developed to analyze data from a NIR All-Sky Imager of OH airglow emission (from about 87 km altitude), located in the Andes, with the purpose of investigating the atmospheric gravity waves generated when low level wind blows over the high mountains (referred to as Mountain Waves). These types of waves are a special case of atmospheric gravity waves, which carry significant momentum and exert strong forcing to the background upper atmosphere. The imager is located at the Andes Lidar Observatory (ALO) at Cerro Pachón, Chile (30°S, 71°W), which also houses a Na Doppler Lidar …

Attitude Determination & Control System Design And Implementation For A 6u Cubesat Proximity Operations Mission, Francisco J. Franquiz

Doctoral Dissertations and Master's Theses

The purpose of this work is to discuss the attitude determination and control system (ADCS) design process and implementation for a 12 kg, 6U (36.6 cm x 23.9 cm x 27.97 cm) CubeSat class nano-satellite. The design is based on the requirements and capabilities of the Application for Resident Space Object Proximity Analysis and IMAging (ARAPAIMA) proximity operations mission. The satellite is equipped with a cold gas propulsion system capable of exerting 2.5 mN m torques in both directions about each body axis. The attitude sensors include an angular rate gyro and star tracker (STR), supplemented by the payload optical …

Supersonic Retro-Propulsion Computational Fluid Dynamics Analysis Applied To Future Mars Mission, Margarita Nataly Brandt

Doctoral Dissertations and Master's Theses

Supersonic Retro-Propulsion is one of the most promising emerging technologies being considered by NASA for use in future Mars missions. This new form of Entry Descent Landing has the potential to help increase the allowable payload mass currently constraining many science instruments and operations. Computational Fluid Dynamics was used to show the feasibility of supersonic retro - propulsion in Mars atmospheric conditions. The results presented show the SRP will be able to perform satisfactory using the same conditions that the Curiosity Rover was exposed to during its landing sequence. The plume expansion was analyzed for various cases, moving from free …

Surface Structure And Its Effect On Reducing Drag, Ragini Ramachandran

Doctoral Dissertations and Master's Theses

A miniature subsonic open return wind tunnel was designed and fabricated to measure drag on small test models at low Reynolds numbers. The wind tunnel featured a sensitive strain gauge type load cell. The average drag coefficient of sphere and cube test models were used to validate the miniature wind tunnel, and the values obtained were consistent with published results over the range of Reynolds numbers tested. These initial results gave confidence that the tunnel could be used to study the effects of surface finish on the drag of various models. Several fabrics with differing ribbed surface structures, including a …

Scalloped Leading Edge Vaned Diffuser Analysis For A Compact High Pressure Ratio Centrifugal Compressor, Vinod Poonamchand Gehlot

Doctoral Dissertations and Master's Theses

Microturbines and small gas turbines are often an attractive option for turbo-hybryd application research in aviation due to their simple design and high power to weight ratio. However, the low operating pressure ratios of microturbines leads to low thermal efficiency, which results in very high fuel consumption. Higher operating pressure ratios in microturbines could vastly improve their current fuel efficiency. This thesis focuses on developing a compact, single stage 8:1 pressure ratio centrifugal compressor stage designed to meet the high-pressure ratio requirements of microturbines and small gas turbine engines in turbo hybrid-electric propulsion applications. The first stage vaned diffuser was …