Engineering Commons^™

Effects Of Pulsatile Flow Rate And Shunt Ratio In Bifurcated Distal Arteries On Hemodynamic Characteristics Involved In Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study, Hang Yi, Mark Johnson, Luke C. Bramlage, Bryan Ludwig, Zifeng Yang

Mechanical and Materials Engineering Faculty Publications

The pulsatile flow rate (PFR) in the cerebral artery system and shunt ratios in bifurcated arteries are two patient-specific parameters that may affect the hemodynamic characteristics in the pathobiology of cerebral aneurysms, which needs to be identified comprehensively. Accordingly, a systematic study was employed to study the effects of pulsatile flow rate (i.e., PFR−I, PFR−II, and PFR−III) and shunt ratio (i.e., 75:25 and 64:36) in bifurcated distal arteries, and transient cardiac pulsatile waveform on hemodynamic patterns in two internal carotid artery sidewall aneurysm models using computational fluid dynamics (CFD) modeling. Numerical results indicate that larger PFRs can cause higher wall …

In-Situ Infrared Thermographic Inspection For Local Powder Layer Thickness Measurement In Laser Powder Bed Fusion, Tao Liu, Cody S. Lough, Hossein Sehhat, Yi Ming Ren, Panagiotis D. Christofides, Edward C. Kinzel, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The laser powder bed fusion (LPBF) process is strongly influenced by the characteristics of the powder layer, including its thickness and thermal transport properties. This paper investigates in-situ characterization of the powder layer using thermographic inspection. A thermal camera monitors the temperature history of the powder surface immediately after a layer of new powder is deposited by the recoating system. During this process, thermal energy diffuses from the underlying solid part, eventually raising the temperature of the above powder layer. Guided by 1D modeling of this heat-up process, experiments show how the parameterized thermal history can be correlated with powder …

Internal Energy Balance And Aerodynamic Heating Predictions For Hypersonic Turbulent Boundary Layers, Matthew Barone, Gary L. Nicholson, Lian Duan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The elemental equation governing heat transfer in aerodynamic flows is the internal energy equation. For a boundary layer flow, a double integration of the Reynolds-averaged form of this equation provides an expression of the wall heat flux in terms of the integrated effects, over the boundary layer, of various physical processes: turbulent dissipation, mean dissipation, turbulent heat flux, etc. Recently available direct numerical simulation data for a Mach 11 cold-wall turbulent boundary layer allows a comparison of the exact contributions of these terms in the energy equation to the wall heat flux with their counterparts modeled in the Reynolds-averaged Navier-Stokes …

Experimental Characterization Of Additively Manufactured Multi-Feather Wingtip Devices, Patricio Garzon

Doctoral Dissertations and Master's Theses

Soaring birds have evolved to fly for long periods of time without flapping their wings. Inspired by the flight of these birds, the proposed thesis presents an experimental investigation focused on wingtip devices designed based on biomimicry. The overarching engineering objective was to reduce the induced drag as a means to improve the fuel efficiency via these experimental wingtips. An associated secondary objective was to establish a method for manufacturing complex structures suitable for wing tunnel testing. A manufacturing technique that involved using composite weaves to reinforce additively manufactured structures was developed. This technique has the potential to reduce manufacturing …

Effect Of Spray Rails On Takeoff Performance Of Amphibian Aircraft, Soham Bahulekar

Doctoral Dissertations and Master's Theses

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and water, thus serving a myriad of purposes such as aerobatics, surveillance, and firefighting. The design of such seaplanes requires to be both aerodynamically and hydrodynamically efficient, especially during the takeoff phase. In the past, naval architects have implemented ways to make boats, yachts, and large ships more efficient; one of them being the addition of chine strips and spray rails on the hull. This thesis study explores the possibility of implementing spray rails …

Synthetic Gecko Inspired Dry Adhesive Through Two-Photon Polymerization For Space Applications, Zefu Ren

Doctoral Dissertations and Master's Theses

This work aims to develop an advanced and cost-effective fabrication process to produce a simplified gecko-inspired microstructure with two-photon polymerization and polymer molding, aimed to improve the adhesive properties of microstructures. Such adhesive microstructures can be implemented for multi-purpose adhesive grasping devices, which have recently gained significant interest in the space exploration sector. Previous gecko-inspired microstructures were reviewed, and the new gecko-inspired microstructures have been developed with the adaptation of additive manufacturing methods for facile fabrication. The examined microstructures in this thesis were the tilted mushroom-shaped and wedge-shaped designs, which could both maximize adhesion by shearing the micropillars toward the …

Optimization Of Rover Wheel Geometries For Planetary Missions, Nikita Amberkar

Doctoral Dissertations and Master's Theses

Rovers have been launched into space for exploration of the Moon and Mars to collect samples of rock and soil. To continue the explorations, the rovers need to have reliable wheels to drive around. However, due to the soil being soft, the wheels on the rover start to lose traction and the wheels sink while driving to various locations. Previous work in this field has been done experimentally or with the use of simulations. Only a few references report the effect of uncertainties in grouser simulation on the traction efficiency. The objective of this work was to (a) Understand the …

Quasi-Static Structural Analysis Of An Experimental Aircraft Wing, Scott Bender

Doctoral Dissertations and Master's Theses

In this report, a quasi-static load analysis is conducted on an experimental light sport aircraft wing via a whiffletree bending test. This report will discuss the loads present on the aircraft during straight level flight at a speed of 82 knots equivalent air speed. Flight load calculations are described along with the design of the whiffletree and mounting structures utilized for applying the distributed point loads. Initial finite element analysis is performed on the wing structure to determine critical strain locations and optimal sensor distribution. Subsequent mechanical experimentations are performed using a bending test to measure the strain at critical …

A Patient Risk Minimization Model For Post-Disaster Medical Delivery Using Unmanned Aircraft Systems, Mark J. Simpson

Doctoral Dissertations and Master's Theses

The purpose of this research was to develop a novel routing model for delivery of medical supplies using unmanned aircraft systems, improving existing vehicle routing models by using patient risk as the primary minimization variable.

The vehicle routing problem is a subset of operational research that utilizes mathematical models to identify the most efficient route between sets of points. Routing studies using unmanned aircraft systems frequently minimize time, distance, or cost as the primary objective and are powerful decision-making tools for routine delivery operations. However, the fields of emergency triage and disaster response are focused on identifying patient injury severity …

Error Estimate Of A Decoupled Numerical Scheme For The Cahn-Hilliard-Stokes-Darcy System, Wenbin Chen, Shufen Wang, Yichao Zhang, Daozhi Han, Cheng Wang, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

We analyze a fully discrete finite element numerical scheme for the Cahn-Hilliard-Stokes-Darcy system that models two-phase flows in coupled free flow and porous media. To avoid a well-known difficulty associated with the coupling between the Cahn-Hilliard equation and the fluid motion, we make use of the operator-splitting in the numerical scheme, so that these two solvers are decoupled, which in turn would greatly improve the computational efficiency. The unique solvability and the energy stability have been proved in Chen et al. (2017, Uniquely solvable and energy stable decoupled numerical schemes for the Cahn-Hilliard-Stokes-Darcy system for two-phase flows in karstic geometry. …

Exploring Passive Flow Control Techniques Applied To A Supersonic Multistream Rectangular Nozzle, Emma Dawn Gist

Dissertations - ALL

Passive control techniques are applied experimentally to examine different aspects of a supersonic multistream rectangular nozzle representing a modern airframe-integrated variable cycle engine. The flow is comprised of a core stream (M = 1.6) and bypass (M = 1.0) that merge behind a splitter plate and exit through a Single Expansion Ramp Nozzle (SERN) onto an aft-deck. Previous efforts for the nominal nozzle configuration have shown that an instability initiated at the splitter plate trailing edge (SPTE) influences the effectiveness of the third stream as a barrier for the aft-deck and persists through the entire do- main due to its …

Behavioral Intention Factors For Prescription Deliveries By Small Unmanned Aircraft In Rural Communities, Sarah M. Talley

Doctoral Dissertations and Master's Theses

Nearly half of the U.S. population regularly use and depend on prescription medications; however, pharmacy availability and access to pharmacy services are often lacking, particularly in rural communities. In an effort to meet local healthcare needs, delivery by sUAS is proposed to ensure the nearly 60 million rural residents have access to their prescription medications.

As an emerging technology with little research into home delivery applications, the successful implementation of sUAS for prescription medication delivery requires public acceptance and positive behavioral intention toward its use. At the time of the current research, no prior studies have specifically focused on the …

Propellant Optimization For A Pulsed Solid Propellant Thruster System For Small Satellites, Timothy Aaron Blackman

Theses and Dissertations

CubeSats have historically been used mostly for education, technology demonstration, remote sensing, and amateur radio relay applications. Yet with increased maneuvering capability, they can become effective tools in on-orbit servicing and space debris removal. To make this a reality, CubeSats must be enabled to perform effective rendezvous and proximity operations with non-cooperative client objects, requiring a high-thrust propulsion system. As CubeSats are inherently constrained in their volume and mass, any propulsion system must feature a high specific impulse to minimize the propellant mass requirement. As CubeSats are commonly launched as secondary payload, the use of pressurized propellant tanks is typically …

Numerical Study Of The Effects Of Injector Geometry On The Performance Of Rotating Detonation Engines, Xavier Roy

Theses and Dissertations

A study of the impact of injector geometry on the performance of rotating detonation engines is performed. A numerical scheme is developed to represent the rotating detonation engine physics. In order to simulate the interaction between the chamber and the injectors, a multizone capability is implemented inside the numerical tool. The model is calibrated to represent a hydrogen-air detonation. The rotating detonation engine annular chamber is unwrapped and studied as a two-dimensional planar domain with a periodic boundary condition. Several numerical experiments are conducted. In particular, injection parameters are examined, such as the injector inflow to channel area ratio, injection …

Electromagnetic Interference Shielding Effectiveness Of A Layered System Consisting Of A Carbon Nano-Reinforced Polymer Composite Coated With Metal Oxide And Graphite, Veronica Montserrat Serrato

Theses and Dissertations

In this study, the electromagnetic interference (EMI) shielding effectiveness (SE) of vapor grown carbon nanofiber (VGCNF) reinforced polyvinylidene difluoride (PVDF) composite and PVDF/VGCNF thermally sprayed with magnetite (Fe3O4) and graphite has been investigated. EMI SE evaluations were performed in the frequency range of 30 kHz-1.5 GHz. The developed nanocomposite (NC) system was fabricated by high shear mixing using a Banbury type mixer. The material was then subjected to compression molding. Subsequently, the films were thermally sprayed using Fe3O4/graphite powder. The NC and coated NC films had average thicknesses of 0.82 mm and 0.93 mm, respectively. The NC films were subjected …

Beyond The High Ground: A Taxonomy For Earth-Moon System Operations, Adam P. Wilmer, Robert A. Bettinger

Faculty Publications

Situational and space domain awareness in the space domain can no longer be confined to that which is found in geosynchronous orbit. International activities—commercial and military—and threats to the planet itself exist and are increasing across the entire Earth-Moon system. This reality requires a new taxonomy to accurately classify space domain awareness missions and better apply resources to and development of the same. This work presents such a taxonomy for the classification of space domain awareness regions.

Sources Of Resonant Vortices In Aero-Acoustics Resonance From Tandem Flat Plates, Atef El Khatib, Ahmad Al Miaari, Ali Hammoud

BAU Journal - Science and Technology

Aero-acoustic resonance in flows around flat plates is a major design concern in various practical applications, especially turbomachinery and heat exchangers, due to its significant effects on fatigue rates and radiated noises intensity. Although research has been intensive on the topic, there is still a lot to be understood for effective resonance prediction and control. Resonance in tandem plate systems is characterized by a double response. This study, investigates for the first time, the flow mechanisms responsible for the generation of low-velocity and high-velocity resonances of the double resonance response. Experimental testing and numerical simulation showed that low-velocity resonance vortices …

Augmenting Heads-Up Displays With Intelligent Agents: A Human Factors Approach, Grant Edward Morfitt

Theses and Dissertations

Situational awareness, both tactical and strategic, is essential for humans engaged in complex tasks in civilian and military theaters of operation. Previous work has shown that heads-up displays are effective tools for providing critical information to operators in such situations. Hitherto, heads-up displays have been designed to relay instrument and sensor information to the operator in a topical, timely, and accurate manner. There is a large body of complementary work in the area of human factors that deals with presenting information to a user without detracting from the primary mission. This thesis investigates, measures, and validates the effectiveness of a …

Structural Dynamics Of Awt-27 Wind Turbine Blade, Amr Ismaiel

Future Engineering Journal

Wind energy is one of the world’s current leading renewable energy resources. One of the major aspects of studying wind turbines is the structural dynamics for the turbine structure including blades and support structure. In the current work, the blades of the Advanced Wind Turbine (AWT-27) are investigated in a dynamic approach. Different wind fields have been generated for the study to provide different Design Load Conditions (DLCs). Three laminar wind velocities of 5 m/s, 12 m/s, and 17 m/s were simulated. Turbulent wind flow fields have also been generated at the three standard classes A, B and C of …

Schlieren Techniques For Observations Of Long Positive Sparks: Review And Application, Junjia He, Xiankang Wang, Xiangen Zhao, Juhyeong Lee, Yaping Du, Xiaopeng Liu, Quan Gan, Yang Liu, Yuqin Liao

Mechanical and Aerospace Engineering Faculty Publications

Understanding the mechanism of positive leader discharge is important in lightning protection engineering and the external insulation design in high voltage power transmission systems. During the propagation of a positive leader, some processes without light-emitting, for example, the insulation recovery process after the breakdown, cannot be observed by optical photography techniques. With the combination of the digital high-speed imaging system, the conventional Schlieren techniques offer new vistas in the long air gap discharge observation. The important features of high spatial resolution, high sensitivity, and easy arrangement make Schlieren techniques powerful and effective tools for characterising the discharge processes without light-emitting. …

Anisotropic Third-Harmonic Generation Of Exfoliated As2s3 Thin Flakes, Ravi P.N. Tripathi, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Van der Waals (vdW) materials have recently attracted significant interest in the context of orientation-dependent linear and nonlinear optical properties. Recently, arsenic trisulfide (As2S3) or orpiment is identified as a new vdW layered material having anisotropic vibrational and optomechanical responses due to the reduced in-plane crystal symmetry, but its nonlinear optical response is still not well understood yet. Herein, the anisotropic third-harmonic generation (THG) response of mechanically exfoliated As2S3 thin flakes is reported. The polarization-dependent evolution of THG emission from butterfly-shaped pattern to four-lobe pattern is comprehensively explored. Moreover, the third-order nonlinear susceptibility of As2S3 crystal is extracted by analyzing …

Preliminary Study Of Shape-Memory Alloy Torsional Tubes As Thermal Management Actuators Under Non-Ideal Conditions, Paula Sanjuan Espejo, Samuel Desloover, Devon Hardy, Mark Ricklick, Frederick Calkin, David Foutch

Publications

Shape-memory alloys (SMAs) have been used in many engineering applications because of their shape-memory effect and pseudoelasticity. SMA behavior is well understood under steady and constant temperature and loading conditions, whereas transient and non-ideal conditions effects should be further investigated. In this research, SMA torque tubes are studied for use in thermal management applications as self-regulated actuators responding to a process fluid with changes in temperature, with the goal of improved system efficiency by keeping components at an optimal temperature. When utilized in a thermal management configuration, it is likely that the SMA’s thermal environment will be different than that …

Effectiveness Of Air Pollution Mitigation Systems: Transport, Transformation, And Control Of Ozone In The Indoor Environment, Pradeep Ramasubramanian

Dissertations and Theses

Buildings are critical environments governing our collective exposure to air pollution and energy consumption. While there exist concerns regarding increases in building energy consumption due to indoor air interventions, improvements to the quality of air indoors can improve health, comfort, and productivity. Air cleaning technologies that can improve indoor air quality with minimal energy consumption have become ever more important. These technologies are utilized at various scales; from passive removal of pollutants in the air entering the indoor environment to active cleaning of air within the breathing zone. To better understand the effectiveness of active and passive ozone mitigation technologies …

A Three-Dimensional, Analytical Wind Turbine Wake Model: Flow Acceleration, Empirical Correlations, And Continuity, Zein Ahmad Sadek

Dissertations and Theses

A new, three-dimensional, analytical, steady state wake model is presented which includes local flow acceleration near the rotor improving wake description compared to existing models. Wake structures such as the momentum deficit and regions of accelerated flow are concisely described with compound and normal Gaussian functions. Large-eddy simulations (LES) are used as training data to develop the model using two, inline turbines under various inflow conditions parameterized by hub height wind speed and turbulence intensity. Mass conservation is considered by fixing two components of the wake velocity model and optimizing the third to best satisfy continuity; after which, the model …

New Advances In Fluid–Structure Interaction, Wenli Chen, Zifeng Yang, Gang Hu, Haiquan Jing, Junlei Wang

Mechanical and Materials Engineering Faculty Publications

Fluid–structure interactions (FSI) play a crucial role in the design, construction, service and maintenance of many engineering applications, e.g., aircraft, towers, pipes, offshore platforms and long-span bridges. The old Tacoma Narrows Bridge (1940) is probably one of the most infamous examples of serious accidents due to the action of FSI. Aircraft wings and wind-turbine blades can break because of FSI-induced oscillations. To alleviate or eliminate these unfavorable effects, FSI must be dealt with in ocean, coastal, offshore and marine engineering to design safe and sustainable engineering structures. In addition, the act of wind on plants and its resultant wind-induced motions …

Spacecraft Trajectory Optimization Suite: Fly-Bys With Impulsive Thrust Engines (Stops-Flite), Aaron H. Li

Master's Theses

Spacecraft trajectory optimization is a near-infinite problem space with a wide variety of models and optimizers. As trajectory complexity increases, so too must the capabilities of modern optimizers. Common objective cost functions for these optimizers include the propellant utilized by the spacecraft and the time the spacecraft spends in flight. One effective method of minimizing these costs is the utilization of one or multiple gravity assists. Due to the phenomenon known as the Oberth effect, fuel burned at a high velocity results in a larger change in orbital energy than fuel burned at a low velocity. Since a spacecraft is …

The Effects Of Atomic Oxygen On Silicone And Carbon-Based Contamination, Mayana W. Gordon

Master's Theses

Understanding the space environment and contamination concerns of a spacecraft is critical in designing a successful mission. The ability for a spacecraft to meet its science objectives relies on systems functioning as intended. A concern for maintain- ing performance while on orbit is molecular contamination. Silicones have previously been shown to form a silica layer on their surfaces when exposed to atomic oxygen. For silicone contamination, this translates to a silica film on the contaminated surface. Missions such as Long Duration Exposure Facility and Evaluation of Oxygen Interactions with Materials III have indicated that the silica film can trap deposits …

An Improved Method To Estimate Savings From Thermal Comfort Control In Residences From Smart Wi-Fi Thermostat Data, Abdulelah D. Alhamayani, Qiancheng Sun, Kevin P. Hallinan

Mechanical and Aerospace Engineering Faculty Publications

The net-zero global carbon target for 2050 needs both expansion of renewable energy and substantive energy consumption reduction. Many of the solutions needed are expensive. Controlling HVAC systems in buildings based upon thermal comfort, not just temperature, uniquely offers a means for deep savings at virtually no cost. In this study, a more accurate means to quantify the savings potential in any building in which smart WiFi thermostats are present is developed. Prior research by Alhamayani et al. leveraging such data for individual residences predicted cooling energy savings in the range from 33 to 47%, but this research was based …

Aerodynamics And Aeroacoustics Optimization Of Vehicle’S Side Mirror Base And Exhaust Pipe, Moath Nayef Mohamed Zaareer

Theses

This thesis is concerned with studying two different vehicle parts in terms of aerodynamics and aeroacoustics. Two main factors determine the efficiency and luxury of the vehicle, the low aerodynamic forces and low noise emission. The aerodynamic drag coefficient is concerned with how easy a vehicle can travel through the air; the lower the value, the less fuel is needed to move the vehicle forward and less air resistance the vehicle faces. The aerodynamic lift coefficient is related to vehicle ground stability, and the more negative the value is, the higher the vehicle's stability. Moreover, the aeroacoustics is concerned with …

Static Testing Of Hybrid Rocket Engine Using Biomass Waste, Saleh Mohammed Musaed Badi

Theses

This work investigates experimentally for the first time the performance of two solid biomass wastes as propellants for a Hybrid Rocket Motor based on the combustion and propulsion parameters such as combustion chamber pressure, thrust force, chamber temperature, combustion characteristics, and flame length generated. The main objective of this study is to examine the performance of the proposed biomass fuels (Date stone powder and Jojoba waste powder) in comparison with typical hydrocarbon fuels. To make an accurate comparison, Paraffin Wax-based propellant was used in this study as a reference fuel to compare with biomass performance using the same testing facility …