Aerospace Engineering Commons^™

Implementation Of An Extended Kalman Filter Using Inertial Sensor Data For Uavs During Gps Denied Applications, Sky Seliquini

Mechanical & Aerospace Engineering Theses & Dissertations

Unmanned Aerial Vehicles (UAVs) are widely used across the industry and have a strong military application for defense. As UAVs become more accessible so does the increase of their applications, now being more limited by one’s imagination as opposed to the past where micro electric components were the limiting factor. Almost all of the applications require GPS or radio guidance. For more covert and longer range missions relying solely on GPS and radio is insufficient as the Unmanned Aerial System is vulnerable to malicious encounters like GPS Jamming and GPS Spoofing. For long range mission GPS denied environments are common …

A Study Of Asymmetric Supersonic Wind Tunnel Nozzle Design, Brittany A. Davis

Mechanical & Aerospace Engineering Theses & Dissertations

Achieving higher Mach numbers for private and commercial flight is a growing interest in the aerospace community. To qualify vehicles prior to flight, tests must be run in wind tunnels. Asymmetric wind tunnel nozzles are of continuing interest to the aerospace community due to their ability to change throat geometry, allowing for a range of Mach numbers to be achieved that encompasses all of the supersonic regime. The sliding block wind tunnel at Old Dominion University (ODU) is designed for a range of Mach numbers from about 1.8 to 3.5 but is limited to an upper limit of 2.8 by …

Mechanics Of Preimpregnated Fiber Tow Deposition And Compaction, Virginia Meredith Rauch

Mechanical & Aerospace Engineering Theses & Dissertations

In additive manufacturing, such as Automated Fiber Placement (AFP), defects often develop during the deposition and compaction of preimpregnated composite material, which reduce the strength of the resultant material. It is necessary to reduce defects and have good adhesion between plies to optimize the laminate performance and reduce delamination between composite layers. The aim of this work is to study the adhesion and deformation of preimpregnated (prepreg) composite material during the deposition and compaction stage in the composite forming process and how material parameters can be used to increase laminate strength. Two types of experimentation were performed on thermoset IM7/8552 …

The State Of The Art Of Information Integration In Space Applications, Zhuming Bi, K. L. Yung, Andrew W.H. Ip., Yuk Ming Tang, Chris W.J. Zhang, Li Da Xu

Information Technology & Decision Sciences Faculty Publications

This paper aims to present a comprehensive survey on information integration (II) in space informatics. With an ever-increasing scale and dynamics of complex space systems, II has become essential in dealing with the complexity, changes, dynamics, and uncertainties of space systems. The applications of space II (SII) require addressing some distinctive functional requirements (FRs) of heterogeneity, networking, communication, security, latency, and resilience; while limited works are available to examine recent advances of SII thoroughly. This survey helps to gain the understanding of the state of the art of SII in sense that (1) technical drivers for SII are discussed and …

Model-Based Systems Engineering For A Small-Lift Launch Facility, Walter Mcgee Taraila, Sharanabasaweshwara Asundi

Mechanical & Aerospace Engineering Faculty Publications

A study of model‐based systems engineering (MBSE) applied to a small‐lift launch facility is presented. The research uses Systems Modeling Language (SysML) products and functional diagrams to document the ground systems on a launch pad servicing a small class payload (0–2 tons). With the projected growth in launch cadence of small‐lift rockets in the coming decade, there is a need to design increasingly complex launch systems with greater efficiency. The potential improvements in project communication, quality, and productivity are explored by developing a model following the ISO/IEC 15288 technical process framework and the International Council on Systems Engineering (INCOSE) Object‐Oriented …

Recent Analytic Development Of The Dynamic Q-Tensor Theory For Nematic Liquid Crystals, Xiang Xu

Mathematics & Statistics Faculty Publications

Liquid crystals are a typical type of soft matter that are intermediate between conventional crystalline solids and isotropic fluids. The nematic phase is the simplest liquid crystal phase, and has been studied the most in the mathematical community. There are various continuum models to describe liquid crystals of nematic type, and Q-tensor theory is one among them. The aim of this paper is to give a brief review of recent PDE results regarding the Q-tensor theory in dynamic configurations.

Editorial For The Special Issue On Micromachines For Non-Newtonian Microfluidics, Lanju Mei, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

In lieu of an abstract, this is an excerpt from the first page.

Microfluidics has seen a remarkable growth over the past few decades, with its extensive applications in engineering, medicine, biology, chemistry, etc [...]

On The Implementation And Further Validation Of A Time Domain Boundary Element Method Broadband Impedance Boundary Condition, Fang Q. Hu, Douglas M. Nark

Mathematics & Statistics Faculty Publications

A time domain boundary integral equation with Burton-Miller reformulation is presented for acoustic scattering by surfaces with liners in a uniform mean flow. The Ingard-Myers impedance boundary condition is implemented using a broadband multipole impedance model and converted into time domain differential equations to augment the boundary integral equation. The coupled integral-differential equations are solved numerically by a March-On-in-Time (MOT) scheme. While the Ingard-Myers condition is known to support Kelvin-Helmholtz instability due to its use of a vortex sheet interface between the flow and the liner surface, it is found that by neglecting a second derivative term in the current …

Performance Degradation Based On Importance Change And Application In Dissimilar Redundancy Actuation System, Yadong Zhang, Chao Zhang, Shaoping Wang, Rentong Chen, Mileta M. Tomovic

Engineering Technology Faculty Publications

The importance measure is a crucial method to identify and evaluate the system weak link. It is widely used in the optimization design and maintenance decision of aviation, aerospace, nuclear energy and other systems. The dissimilar redundancy actuation system (DRAS) is a key aircraft control subsystem which performs aircraft attitude and flight trajectory control. Its performance and reliability directly affect the aircraft flight quality and flight safety. This paper considers the influence of the Birnbaum importance measure (BIM) and integrated importance measure (IIM) on the reliability changes of key components in DRAS. The differences of physical fault characteristics of different …

On The Use Of High-Frequency Surface Wave Oceanographic Research Radars As Bistatic Single-Frequency Oblique Ionospheric Sounders, Stephen R. Kaeppler, Ethan S. Miller, Daniel Cole, Teresa Updyke

CCPO Publications

We demonstrate that bistatic reception of high-frequency oceanographic radars can be used as single-frequency oblique ionospheric sounders. We develop methods that are agnostic of the software-defined radio system to estimate the group range from the bistatic observations. The group range observations are used to estimate the virtual height and equivalent vertical frequency at the midpoint of the oblique propagation path. Uncertainty estimates of the virtual height and equivalent vertical frequency are presented. We apply this analysis to observations collected from two experiments run at two locations in different years, but utilizing similar software-defined radio data collection systems. In the first …

Experiences During The Implementation Of Two Different Project-Based Learning Assignments In A Fluid Mechanics Course., Orlando Ayala, Kristie Gutierrez, Francisco Cima, Julia Noginova, Min Jung Lee, Stacie Ringleb, Pilar Pazos, Krishnanand Kaipa, Jennifer Kidd

Engineering Technology Faculty Publications

There is growing evidence of the effectiveness of project-based learning (PBL) in preparing students to solve complex problems. In PBL implementations in engineering, students are treated as professional engineers facing projects centered around real-world problems, including the complexity and uncertainty that influence such problems. Not only does this help students to analyze and solve an authentic real-world task, promoting critical thinking, but also students learn from each other, learning valuable communication and teamwork skills. Faculty play an important part by assuming non-conventional roles (e.g., client, senior professional engineer, consultant) to help students throughout this instructional and learning approach. Typically in …

Ground To Air Testing Of A Fused Optical-Radar Aircraft Detection And Tracking System, Chester V. Dolph, Thomas Lombaerts, Evan Kawamura, Corey Ippolito, Vahram Stepanyan, Khan M. Iftekharuddin, George Szatkowski, Robert G. Mcswain, Chris Morris, Mahyar R. Malekpour

Electrical & Computer Engineering Faculty Publications

Onboard detection and tracking capability are integral to the sensing component in collision avoidance systems needed to safely operate autonomous urban air taxis and small Unmanned Aircraft Systems. Ground-based validation of detection and tracking systems is an important milestone towards the end goal of real-time collision avoidance using onboard sensors and algorithms. In this work, we evaluate three Extended Kalman Filter (EKF) based fusion trackers with radar and vision detection inputs, and compare them with baseline trackers for each sensor type. Performance is assessed using field collected data of ground to air test flights with the sensors co-located on a …

Post-Processing And Characterization Of Additive Manufactured Carbon Fiber Reinforced Semi-Crystalline Polymers, Patricia Revolinsky

Mechanical & Aerospace Engineering Theses & Dissertations

The aim of this work is to study the effect of post-processing on additive manufactured (AM) continuous carbon fiber reinforced plastics (CFRPs) performance. As-printed AM CFRPs do not perform as well as conventionally manufactured CFRPs with the same composition. Possible improvements to AM CFRP performance include annealing and applying uniaxial pressure with elevated temperature. Samples were subjected to pressure and temperature treatments and annealing at a constant temperature. Treated materials were subjected to three-point bending tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) to characterize and assess sample performance. Results were assessed for flexural strength, …

Empirical Modeling Of Tilt-Rotor Aerodynamic Performance, Michael C. Stratton

Mechanical & Aerospace Engineering Theses & Dissertations

There has been increasing interest into the performance of electric vertical takeoff and landing (eVTOL) aircraft. The propellers used for the eVTOL propulsion systems experience a broad range of aerodynamic conditions, not typically experienced by propellers in forward flight, that includes large incidence angles relative to the oncoming airflow. Formal experiment design and analysis techniques featuring response surface methods were applied to a subscale, tilt-rotor wind tunnel test for three, four, five, and six blade, 16-inch diameter, propeller configurations in support of development of the NASA LA-8 aircraft. Investigation of low-speed performance included a maximum speed of 12 m/s and …

High-Order Positivity-Preserving L2-Stable Spectral Collocation Schemes For The 3-D Compressible Navier-Stokes Equations, Johnathon Keith Upperman

Mathematics & Statistics Theses & Dissertations

High-order entropy stable schemes are a popular method used in simulations with the compressible Euler and Navier-Stokes equations. The strength of these methods is that they formally satisfy a discrete entropy inequality which can be used to guarantee L₂ stability of the numerical solution. However, a fundamental assumption that is explicitly or implicitly used in all entropy stability proofs available in the literature for the compressible Euler and Navier-Stokes equations is that the thermodynamic variables (e.g., density and temperature) are strictly positive in the entire space{time domain considered. Without this assumption, any entropy stability proof for a numerical scheme …

The Effect Of Through Thickness Reinforcement On Debonding Behavior Of Skin/Stringer Configuration, Yogaraja Sridhar

Mechanical & Aerospace Engineering Theses & Dissertations

Investigation of this study is to the determine the crack propagation and disbonding in the bonded region of the skin and stringer specimen. An adhesive layer has been used to bond the skin and stringer by using a heat press operation. After the bonding, a drilling method has been adopted to install the through thickness reinforcement in the specimen. The key role of the through thickness reinforcement is to increase the stiffness and strength of the panels and to prevent the crack propagation or disbonding of the panels. The reinforcement was installed in pure (Pristine) samples and in defect samples …

Development And Applications Of Adjoint-Based Aerodynamic And Aeroacoustic Multidisciplinary Optimization For Rotorcraft, Ramiz Omur Icke

Mechanical & Aerospace Engineering Theses & Dissertations

Urban Air Mobility (UAM) is one of the most popular proposed solutions for alleviating traffic problems in populated areas. In this context, the proposed types of vehicles mainly consist of rotors and propellers powered by electric motors. However, those rotary-wing components can contribute excessively to noise generation. Therefore, a significant noise concern emerges due to urban air vehicles in or around residential areas. Reducing noise emitted by air vehicles is critically important to improve public acceptance of such vehicles for operations in densely populated areas.

Two main objectives of the present dissertation are: (1) to expand the multidisciplinary optimization to …

Analysis Of A Non-Equilibrium Vortex Pair As Aircraft Trailing Vortices, Manuel Ayala

Mechanical & Aerospace Engineering Theses & Dissertations

Shortly after the roll-up evolution of the vortex sheet behind the wings of an aircraft, a coherent counter-rotating vortex pair emerges. Presence of this vortex pair in the downstream of an aircraft, creates unsafe conditions for other aircraft, especially near airport runways. Fundamental knowledge of the physics that govern the formation, duration and dissipation of aircraft wake vortices is desirable in order to improve aircraft operational safety. This study uses non-equilibrium pressure theory to develop an accurate model describing the physical behavior of the vortex pair created by an aircraft in the early to mid-field vortex regime. An isolated aircraft …

A Digital One Degree Of Freedom Model Of An Electromagnetic Position Sensor, Michelle Elizabeth Weinmann

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of this project was to improve an existing system currently in use by NASA Langley Research Center (LaRC). The 6-inch Magnetic Suspension and Balance System (MSBS) built at MIT is operational with control in three degrees of freedom, with two additional degrees of freedom exhibiting passive stability. The means for measuring model displacement within the magnetic environment is an Electromagnetic Position Sensor (EPS), consisting of excitation coils at 20 kHz and multiple sets of pickup coils. The pickup coil voltages are proportional to model displacement in each degree of freedom. However, the EPS electronic signal processing system is …

Computational Aerodynamics Of A Wing Mounted Propeller, Sarah Agam

College of Engineering & Technology (Batten) Posters

Computational fluid dynamics (CFD) is a vital component in aerospace engineering. A major use of CFD is analyzing the flow properties to determine outputs like aerodynamic lift and drag over an airfoil or compute engine efficiency. It is more practical to conduct a CFD analysis first before doing experimental work as CFD allows for rapid and diverse testing of propeller shapes at a lower cost. CFD also allows for a wider range of testing parameters; for example, an airfoil can be subjected to steady, unsteady, incompressible, or high velocity flows.

Propellers are extensively used in the aircraft industry, especially in …

A Model-Based Systems Engineering Approach To E-Vtol Aircraft And Airspace Infrastructure Design For Urban Air Mobility, Heidi Selina Glaudel

Mechanical & Aerospace Engineering Theses & Dissertations

This paper serves to contribute to Model-Based Systems Engineering (MBSE) by following the NASA Systems Engineering Handbook framework for a Systems Engineering (SE) design approach to an Electric Vertical Takeoff and Landing (e-VTOL) aircraft and the incorporating airspace infrastructure. The focus of this study is, by using the MBSE model created, to capture the technical requirements definition and design intent of the vehicle and airspace inclusive of community specific knowledge derived from the Federal Aviation Administration (FAA) NextGen Urban Air Mobility (UAM) Concept of Operations (ConOps) version 1.0. The stakeholder requirements derived from the FAA UAM NextGen ConOps will form …

A New Method For Estimating The Physical Characteristics Of Martian Dust Devils, Shelly Cahoon Mann

Mechanical & Aerospace Engineering Theses & Dissertations

Critical to the future exploration of Mars is having a detailed understanding of the atmospheric environment and its potential dangers. The dust devil is one of these potential dangers. The transport of dust through saltation is believed to be the driving mechanism responsible for Martian weather patterns. The two primary mechanisms for dust transport are dust storms and dust devils. Dust devils on Mars are a frequent occurrence with one in five so called giant dust devils being large enough to leave scars on the surface that are visible from space. Due to the thin atmosphere, winds of 60 mph …

Improved Strain Gage Instrumentation Strategies For Rotorcraft Blade Measurements, Timothy S. Davis

Mechanical & Aerospace Engineering Theses & Dissertations

In this work, a new strategy is presented to wire, calibrate, and measure strain gages for rotor blade testing that will provide more information and is robust to individual gage loss. The additional information can be used in several ways. including reducing redundancy, offering rapid identification of damage locations, and in some cases reducing risk allowing tests to continue to collect calibrated data after one or more sensors have failed. This strategy replaces the classical four-gage full Wheatstone bridge with four separately wired quarter bridges that are combined into a full bridge in the data acquisition system using a calculated …

Hybrid Models As Transdisciplinary Research Enablers, Andreas Tolk, Alison Harper, Navonil Mustafee

Computational Modeling & Simulation Engineering Faculty Publications

Modelling and simulation (M&S) techniques are frequently used in Operations Research (OR) to aid decision-making. With growing complexity of systems to be modelled, an increasing number of studies now apply multiple M&S techniques or hybrid simulation (HS) to represent the underlying system of interest. A parallel but related theme of research is extending the HS approach to include the development of hybrid models (HM). HM extends the M&S discipline by combining theories, methods and tools from across disciplines and applying multidisciplinary, interdisciplinary and transdisciplinary solutions to practice. In the broader OR literature, there are numerous examples of cross-disciplinary approaches in …

Spacecraft Informatics, K. L. Yung, Lida Xu, Chris Zhang

Information Technology & Decision Sciences Faculty Publications

No abstract provided.

Non-Equilibrium Behavior Of Large-Scale Axial Vortex Cores, Robert L. Ash, Irfan R. Zardadkhan

Mechanical & Aerospace Engineering Faculty Publications

A logical basis for incorporating pressure non-equilibrium and turbulent eddy viscosity in an incompressible vortex model is presented. The infrasonic acoustic source implied in our earlier work has been examined. Finally, this non-equilibrium turbulent vortex core is shown to dissipate mechanical energy more slowly than a Burgers vortex, helping us to explain the persistence of axial vortices in nature. Recent molecular dynamics simulations replicate aspects of this non-equilibrium pressure behavior.

Evaluation Of Murrell’S Ekf-Based Attitude Estimation Algorithm For Exploiting Multiple Attitude Sensor Configurations, Sharanabasaweshwara Asundi, Norman Fitz-Coy, Haniph Latchman

Mechanical & Aerospace Engineering Faculty Publications

Pico- and nano-satellites, due to their form factor and size, are limited in accommodating multiple or redundant attitude sensors. For such satellites, Murrell's implementation of the extended Kalman filter (EKF) can be exploited to accommodate multiple sensor configurations from a set of non redundant attitude sensors. The paper describes such an implementation involving a sun sensor suite and a magnetometer as attitude sensors. The implementation exploits Murrell's EKF to enable three sensor configurations, which can be operationally commanded, for satellite attitude estimation. Among the three attitude estimation schemes, (i) sun sensor suite and magnetometer, (ii) magnetic field vector and its …

Influence Of The Inherent Safety Principles On Quantitative Risk In Process Industry: Application Of Genetic Algorithm Process Optimization (Gapo), Mehdi Jahangiri, Abolfazl Moghadasi, Mojtaba Kamalinia, Farid Sadeghianjahromi, Sean Banaee

Community & Environmental Health Faculty Publications

Inherent safety (IS) refers to a set of measures that enhance the safety level of processes and equipment, rendering additional equipment and/or add-ons. The early design phase of processes is suited best for implementation of IS strategies as some of such strategies either are impossible to be implemented at the operation phase or substantially increase costs. The purpose of this study is to present a new approach called genetic algorithm process optimization (GAPO), by which processes can be made inherently safer even at the operation phase. This study simulates the IS principle, assessing its impact on quantitative risk and the …

Time Domain Boundary Element Method Prediction Of Noise Shielding By A Naca 0012 Airfoil, Douglas M. Nark, Fang Q. Hu

Mathematics & Statistics Faculty Publications

As aircraft noise constraints become more stringent and the number/mixture of aircraft configurations grows, it becomes more important to understand the interaction of individual aircraft noise sources with nearby aircraft structures. Understanding these interactions and exploring possible approaches to mitigate or exploit their acoustic impact is essential for overcoming key noise barriers. This paper describes the further validation of a time domain boundary element approach for the prediction of the interactions between incident noise sources and nearby aircraft structures. Predictions were completed for multiple source locations and comparisons of these results with measured data are presented. Overall, very good agreement …

Fluid-Wall Interactions In Pseudopotential Lattice Boltzmann Models, Cheng Peng, Luis F. Ayala, Orlando M. Ayala

Engineering Technology Faculty Publications

Designing proper fluid-wall interaction forces to achieve proper wetting conditions is an important area of interest in pseudopotential lattice Boltzmann models. In this paper, we propose a modified fluid-wall interaction force that applies for pseudopotential models of both single-component fluids and partially miscible multicomponent fluids, such as hydrocarbon mixtures. A reliable correlation that predicts the resulting liquid contact angle on a flat solid surface is also proposed. This correlation works well over a wide variety of pseudopotential lattice Boltzmann models and thermodynamic conditions.