Aerospace Engineering Commons^™

Unsteady Forces On A Spherical Particle Accelerating Or Decelerating In An Initially Stagnant Fluid, Yashas Mudlapur Phaneesh Keshav

Open Access Theses

Flows with particles play an important role in a number of engineering applications. These include trajectories of droplets in sprays in fuel-injected-reciprocating-piston and gas-turbine engines, erosion of materials due to particle impact on a surface, and deposition of materials on surfaces by impinging droplets or particles that could solidify or bond on impact. For these applications, it is important to understand the forces that act on the particles so that their trajectories could be predicted.

Considerable work has been done on understanding the forces acting on spherical particles, where the Reynolds numbers (Rep ) based on the particle …

Investigating Surface Performance Trade-Offs Of Unimpeded Taxiways, Tiffany T. Le

Open Access Theses

Optimizing usage of unimpeded taxiways is a near-term operational change to mitigate emission impact on aviation and increase efficiency at airports. An unimpeded taxiway is a path for an aircraft to taxi around an active runway. Unimpeded taxiways provide benefits such as increased departure throughput, increased safety, reduced surface congestion, more efficient taxi-in procedures, and thereby also yield environmental benefits. The goals of this work are to investigate the use of current taxiways, examine surface performance and fuel burn trade-offs, and to develop a decision-support model based on potential fuel savings of unimpeded taxiways. This study analyzes unimpeded taxiway use …

Detecting Air Traffic Controller Interventions In Recorded Air Transportation System Data, Yul Kwon

Open Access Theses

In this study, I propose a systematic method of detecting aircraft deviation due to air traffic controller (ATC) intervention. The aircraft deviations associated with ATC interventions are detected using a heuristic algorithm developed from analyzing the actual positions of an aircraft to its filed flight plan when the aircraft trajectories were identified as having an encounter in a loss-of-separation incident. An actual (closed-loop) flight trajectory of the Cleveland Air Route Traffic Control Center (ZOB ARTCC) was collected from the FlightAware database. This was compared with the corresponding planned (open-loop) trajectory dataset generated by the Microsoft© Flight Simulator X (FSX). I …

Experimental And Numerical Study Of The Air Distribution In An Airliner Cabin, Wei Liu

Open Access Theses

Nowadays, more people, including those with impaired health or who are otherwise potentially sensitive to the cabin environment, are traveling by air than ever before. The flying public demands a higher comfort level and a cleaner environment because they encounter a combination of environmental factors including low humidity, low air pressure, and sometimes, exposure to air contaminants such as ozone, carbon monoxide, various organic chemicals, and biological agents. Moreover, international air travel has increased the potential risks associated with airborne disease transmission and the release, whether accidentally or intentionally, of noxious substances during flight. Many studies suggest that the risk …

Effects Of Crossflow In An Internal-Cooling Channel On Film Cooling Of A Flat Plate Through Compound-Angle Holes, Zachary Taylor Stratton

Open Access Theses

The film-cooling holes in turbine blades are fed from an internal cooling channel. This channel imposes a crossflow at the entrance of the holes that can significantly affect the performance of the cooling jets that emanate from those holes. In this study, CFD simulations based on steady RANS with the shear-stress transport (SST) and the realizable k -ε turbulence models were performed to study film cooling of a flat plate with cooling jets issuing from eight round holes with a compound angle of 45 degrees, where the coolant channel that fed the cooling jets was oriented perpendicular to the direction …

Biaxial Shear/Tension Failure Criteria Of Spectra Single Fibers, Jianzhuo Sun

Open Access Theses

An experimental study was conducted to develop the biaxial failure surface criteria of single Spectra 130d and 100d filaments in a torsion-tension environment. The cross-sectional profiles of single Spectra fibers were investigated using scanning electron microscopy and X-ray computed tomography. A pin-gripping method to fix the ends of a polyethylene single fiber was developed. Effects of pin diameter on failure stress for both Spectra 130d and 100d were characterized. It was found that the perturbed stress field effect can be neglected when the pin diameter is larger than 0.8 mm. Additionally, the effect of the sample's gage length on fiber …

Feasibility Analysis Of Large Length-Scale Thermocapillary Flow Experiment For The International Space Station, Samantha Jean Alberts

Open Access Theses

The investigation of microgravity fluid dynamics emerged out of necessity with the advent of space exploration. In particular, capillary research took a leap forward in the 1960s with regards to liquid settling and interfacial dynamics. Due to inherent temperature variations in large spacecraft liquid systems, such as fuel tanks, forces develop on gas-liquid interfaces which induce thermocapillary flows. To date, thermocapillary flows have been studied in small, idealized research geometries usually under terrestrial conditions. The 1 to 3m lengths in current and future large tanks and hardware are designed based on hardware rather than research, which leaves spaceflight systems designers …

Blast Energy Mitigation In Porous Rocks, Brittany Corinne Essink

Open Access Theses

Geo-materials are commonly used and sought after for blast mitigation applications due to their wide availability and low cost compared to industry trademarked materials. Characterization of these natural geo-materials such as volcanic rocks is of paramount importance in determining their blast mitigation capabilities. While there is a large amount of information available for materials such as concrete or sand blasts, information on the properties of volcanic rocks is far more scarce. This lack of data is due to the wide range of existing natural volcanic rocks and the variation in the minerals and pore structures of the rocks.

In this …

Scalable Autonomous Operations Of Unmanned Assets, Sunghun Jung

Open Access Dissertations

Although there have been great theoretical advances in the region of Unmanned Aerial Vehicle (UAV) autonomy, applications of those theories into real world are still hesitated due to unexpected disturbances. Most of UAVs which are currently used are mainly, strictly speaking, Remotely Piloted Vehicles (RPA) since most works related with the flight control, sensor data analysis, and decision makings are done by human operators. To increase the degree of autonomy, many researches are focused on developing Unmanned Autonomous Aerial Vehicle (UAAV) which can takeoff, fly to the interested area by avoiding unexpected obstacles, perform various missions with decision makings, come …

The Comparison Of Composite Aircraft Field Repair Method (Cafrm) With Traditional Aircraft Repair Technologies, Peng Hao Wang

Open Access Dissertations

In the aviation industry, manufacturers made the transition from aluminum to composite materials for the majority of their primary structures over the last few decades. While the design and manufacturing techniques have consistently evolved, field repair methods were consistently overlooked. In this study, specimens fabricated using some of the common repair methods such as the autoclave repair method, and Double Vacuum Debulk (DVD) repair method were tested against the Composite Aircraft Field Repair Method (CAFRM) proposed by the researcher. Specimens were tested with microscopy, acid digestion, short beam shear, and mode I fracture tests. The researcher was able to determine …

Design, Development, And Testing Of A Conformal Power Control Interface For Thrust Vectoring Aircraft, David Rozovski

Open Access Dissertations

Over the last five years, a new power control inceptor for tiltrotor aircraft, known as the Rotational Throttle Interface (RTI) was designed and built. Prior to the RTI, no tiltrotor inceptor had been able to simultaneously indicate both the direction and magnitude of thrust conformally. The purpose of the RTI is to provide an interface that maps to the intended vehicle response throughout ALL ranges of operation. Doing so is expected to reduce confusion that may have contributed to several tiltrotor accidents

Two tests were conducted with the RTI, one at the NASA Vertical Motion Simulator, and one at Canada's …

Spacecraft Orbit Design In The Circular Restricted Three-Body Problem Using Higher-Dimensional Poincaré Maps, Christopher D. Geisel

Open Access Dissertations

Strategies for designing three-dimensional spacecraft trajectories in a multi-body dynamical environment are investigated using four-dimensional Poincaré maps. Unlike the planar circular restricted three-body problem, where a two-dimensional map provides a simplified view of a portion of the vast and often chaotic design space, the spatial problem requires a four-dimensional map to achieve an equivalent perspective. Such higher-dimensional maps present a visualization challenge. Furthermore, a spacecraft in the spatial problem can exhibit fundamentally more diverse and complex behavior than in the planar problem. A novel approach to four-dimensional-map-based design in the spatial circular restricted three-body problem is developed and applied to …

Applicability Of Continuum Fracture Mechanics In Atomistic Systems, Shao-Huan Cheng

Open Access Dissertations

By quantitating the amplitude of the unbounded stress, the continuum fracture mechanics defines the stress intensity factor K to characterize the stress and displacement fields in the vicinity of the crack tip, thereby developing the relation between the stress singularity and surface energy (energy release rate G). This G-K relation, assigning physical meaning to the stress intensity factor, makes these two fracture parameters widely used in predicting the onset of crack propagation. However, due to the discrete nature of the atomistic structures without stress singularity, there might be discrepancy between the failure prediction and the reality of nanostructured materials. Defining …

Analysis Of Cyberattacks On Unmanned Aerial Systems, Andrew Morris Shull

Open Access Theses

With the increasing power and convenience offered by the use of embedded systems in control applications, such systems will undoubtedly continue to be developed and deployed. Recently, however, a focus on data-centric systems and developing network-enabled control systems has emerged, allowing for greater performance, safety, and resource allocation in systems such as smart power grids and unmanned military aircraft. However, this increase in connectivity also introduces vulnerabilities into these systems, potentially providing access to malicious parties seeking to disrupt the operation of those systems or to cause damage. Given the high potential cost of a failure in these systems in …

Flow And Heat Transfer In An L-Shaped Cooling Passage With Ribs And Pin Fins For The Trailing Edge Of A Gas-Turbine Vane And Blade, Irsha Ashok Pardeshi

Open Access Theses

Efficient and effective cooling of the trailing edges of gas-turbine vanes and blades is challenging because there is very little space to work with. In this study, CFD simulations based on steady RANS closed by the shear-stress transport turbulence model were performed to study the flow and heat transfer in an L-shaped duct for the trailing edge under two operating conditions. One operating condition, referred to as the laboratory condition, where experimental measurements were made, has a Reynolds number at the duct inlet of Re_D = 15,000, coolant inlet temperature of T_inlet = 300 K, wall temperature of …

Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku

Open Access Dissertations

The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty given by the probability density function (PDF). As even collision events with very low probability are important, accurate prediction of collisions require the representation of the full PDF of the random orbit state. Through representing the full PDF …

Flexible Circuits For Aerospace Applications With Special Emphasis On Rf Connectors, Abhishek Nareshraj Singh

Graduate Theses and Dissertations

The current work focused on the study of flexible electronic circuits for use in aerospace applications with emphasis on RF Connectors. The electrical and mechanical performance of the flexible circuits was studied and compared to a standard coaxial cable for feasibility study in avionics space. Also, Anisotropic Conductive Films (ACF) are studied for connecting the flexible RF connectors and their performance studied for electrical and mechanical behavior with change in bonding parameters.

The Influence Of Non-Equilibrium Pressure On Rotating Flows, Irfan Rashid Zardadkhan

Mechanical & Aerospace Engineering Theses & Dissertations

This study was undertaken to investigate the influence of pressure relaxation on steady, incompressible flows with strong streamline curvature. In the early part of this dissertation research, the significance of non-equilibrium pressure forces in controlling the structure of a steady, two dimensional axial vortex was demonstrated. In order to extend the study of pressure relaxation influences on more complex rotating flows, this dissertation has examined other rotating flow features that can be associated with hurricanes, tornadoes and dust devils. To model these flows, modified boundary layer equations were developed for a fluid column rotating near a solid plane including the …

Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark

Graduate Theses and Dissertations

Recent advances within the field of cube satellite technology has allowed for the possible development of a maneuver that utilizes a satellite's Low Earth Orbit (LEO) and increased atmospheric density to effectively use lift and drag to implement a noncoplanar orbital maneuver. Noncoplanar maneuvers typically require large quantities of propellant due to the large delta-v that is required. However, similar maneuvers using perturbing forces require little or no propellant to create the delta-v required. This research reported here studied on the effects of lift on orbital changes, those of noncoplanar types in particular, for small satellites without orbital maneuvering thrusters. …