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Aerodynamics and Fluid Mechanics Commons

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Study Of Differential Diffusion Using Backward Trajectories In Turbulence, Adyasha Mohanty 2018 Georgia Institute of Technology

Study Of Differential Diffusion Using Backward Trajectories In Turbulence, Adyasha Mohanty

Georgia Undergraduate Research Conference (GURC)

Molecular diffusion due to turbulent dispersion plays a crucial role in pollutant spreading and flame stabilization. Molecules in fluid flow undergo Brownian motion at a rate determined by their molecular diffusivity or Schmidt number (Sc). In this research we investigate differential diffusion of molecules for two sets of molecular pairs, one in high diffusivity regime (Sc of 0.001 and 0.01) and one in the low diffusivity regime (Sc of 100 and 1000) that provides us statistical relations between properties of each diffusing substance due to different molecular diffusivities. Direct numerical simulation with parallel computing is first used to ...


Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones 2018 Louisiana State University

Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones

LSU Master's Theses

In the testing of today’s rocket engines, both on large scale vertical test stands and smaller subscale horizontal component testing stands, it is extremely important to be able to accurately quantify and mitigate the thermal and acoustic loads the engines will generate on test stand infrastructure. Due to the large number of parameters that must be considered for many cases, development of a multi-phase computational code is under way to properly analyze and design water spray cooling systems used at NASA’s Stennis Space Center (SSC) and across other NASA centers. As such, a small-scale experiment has been conducted ...


Computational Aerodynamics And Anatomical Characterization Of Laryngotracheal Stenosis In Children, William Poynot 2018 Louisiana State University

Computational Aerodynamics And Anatomical Characterization Of Laryngotracheal Stenosis In Children, William Poynot

LSU Master's Theses

Laryngotracheal stenosis (LTS) is a health condition in which an obstruction in the upper trachea can cause breathing difficulties and increased incidence of infection, among other symptoms. Occurring most commonly due to intubation in infants, LTS often requires corrective surgery. Currently, clinical methods of assessing the blockage region are simplistic and subjective, and it is challenging to determine the most effective surgical strategy for any given patient. In the present work, a comprehensive methodology is proposed for characterizing the stenosis region both in terms of its anatomical parameters and its corresponding aerodynamic properties. The combination of computational fluid dynamics (CFD ...


Design Of A Heavy Lift Rc Aircraft - Society Of Automotive Engineers (Sae) Aero Design® West Competition Team, Jiyoung Hwang, Phillip Nielsen 2018 Embry-Riddle Aeronautical University

Design Of A Heavy Lift Rc Aircraft - Society Of Automotive Engineers (Sae) Aero Design® West Competition Team, Jiyoung Hwang, Phillip Nielsen

Undergraduate Research Symposium - Prescott

The SAE Aero West design competition challenges undergraduate students to design and build an RC aircraft that will fly with the maximum number of passengers and luggage possible. The ERAU SAE team focuses on simulation-based research and project methods such as Computational Fluid Dynamics (CFD), aircraft optimization, and Finite Element Analysis (FEA). Designing and manufacturing a well-designed heavy lift aircraft and competing with other groups will give experience in solving engineering problems. The Aerodynamics team is currently focusing on score optimization, aircraft performance and configuration. The propulsion team is constructing a test rig to test various propellers and motors to ...


The Spanwise Structure Of The Roof-Level Turbulence In A Street Canyon Flow, Tomek Jaroslawski 2018 The University of Western Ontario

The Spanwise Structure Of The Roof-Level Turbulence In A Street Canyon Flow, Tomek Jaroslawski

Electronic Thesis and Dissertation Repository

In the present work, for the first time, the spanwise organization of turbulent flow along an urban street canyon subjected to wind normal to the street axis using a boundary layer wind tunnel is systematically investigated.The effect of upstream roughness and canyon width on the turbulence in a street canyon flow is presented. Measurements in a horizontal plane were conducted at near roof-level of a street canyon using Stereoscopic Particle Image Velocimetry. Three upstream roughness arrays and two canyon width (W) to height (h) aspect ratios (AR = W / h = 1 and 3) were investigated. The results show a significant ...


Flow Measurement Using Electron Beam Flourescence, Richard Brookes, Andrew Strongrich, Anthony G Cofer, Alina Alexeenko 2018 Purdue University

Flow Measurement Using Electron Beam Flourescence, Richard Brookes, Andrew Strongrich, Anthony G Cofer, Alina Alexeenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

Low density, high-speed flows are of interest to many research areas including, spacecraft thrusters, hypersonic vehicle control, and atmospheric re-entry studies. Measurement of low-density gas flows by traditional methods such as Schlieren Photography or Particle Image Velocimetry is often not possible. In order to yield new information about gas behavior at low densities the technique of electron beam fluorescence is being re-evaluated. By recreating previous electron beam fluorescence setups used to measure density, the experiment operating parameters including beam strength and density ranges are assessed and a foundation can be built for further experimentation. Comparing intensity plots of imaged flows ...


Design Of Selectively Compliant Morphing Wind Turbine Blade Section Using Bistable Laminate For Passive Load Alleviation, Abhishek Chopra, Dr. Andres Arrieta, Janav Udani, Jose Rivas Padilla 2018 Rutgers University - New Brunswick/Piscataway

Design Of Selectively Compliant Morphing Wind Turbine Blade Section Using Bistable Laminate For Passive Load Alleviation, Abhishek Chopra, Dr. Andres Arrieta, Janav Udani, Jose Rivas Padilla

The Summer Undergraduate Research Fellowship (SURF) Symposium

The design of passively controlled compliant morphing structures for large scale wind turbine blades has been of interest due to the inherent advantages of lower mass and reduced complexity over their active counterparts. Previous studies have indicated that embedding a locally bi-stable element within the turbine blade section successfully allows for achieving passive load alleviation. The embedded bi-stable member switches from one stable state to another at a critical aerodynamic load. This local structural change results in a global shift in the aeroelastic response of the blade section. Building on these preliminary results, this research investigates a two- dimensional wind ...


Characterization Of A Turbulent Boundary Layer In Open Channel Flow Using Particle Image Velocimetry, Mathew James Stanek 2018 Coastal Carolina University

Characterization Of A Turbulent Boundary Layer In Open Channel Flow Using Particle Image Velocimetry, Mathew James Stanek

Electronic Theses and Dissertations

Turbulent boundary layers are influential in numerous applications (e.g. naval architecture, ocean engineering, sediment transport, etc.), yet considerable knowledge gaps still exist. Boundary layers are regions where transfer of mass, momentum, energy, and heat occur within the interface between a fluid and a solid, or between two fluids. Utilization of optical flow measurement techniques to measure the velocity field with high spatial resolution enables non-intrusive investigation of the complex fluid dynamics of boundary layers. In this study two-dimensional Particle Image Velocimetry was employed to investigate, primarily, the overlap layer of a turbulent boundary layer developed in the recirculating flume ...


Fuel Flow Reduction Impact Analysis Of Drag Reducing Film Applied To Aircraft Wings, Damon Resnick, Chris Donlan, Nimish Sakalle, Cody Pinkerman 2018 Southern Methodist University

Fuel Flow Reduction Impact Analysis Of Drag Reducing Film Applied To Aircraft Wings, Damon Resnick, Chris Donlan, Nimish Sakalle, Cody Pinkerman

SMU Data Science Review

In this paper, we present an analysis of flight data in order to determine whether the application of the Edge Aerodynamix Conformal Vortex Generator (CVG), applied to the wings of aircraft, reduces fuel flow during cruising conditions of flight. The CVG is a special treatment and film applied to the wings of an aircraft to protect the wings and reduce the non-laminar flow of air around the wings during flight. It is thought that by reducing the non-laminar flow or vortices around and directly behind the wings that an aircraft will move more smoothly through the air and provide a ...


Design And Performance Estimation Of A Low-Reynolds Number Unmanned Aircraft System, Sean Lauderdale King 2018 Louisiana State University

Design And Performance Estimation Of A Low-Reynolds Number Unmanned Aircraft System, Sean Lauderdale King

LSU Master's Theses

The purpose of this thesis is to conceptually design a fixed-wing unmanned aircraft systems (UAS) with a higher flight-time and top stable speed than comparable systems. The vehicle adheres to specifications derived from the client, the market, and the Federal Aviation Administration (FAA). To broadly meet these requirements, the vehicle must fly for a minimum of three hours, return to the original flight path quickly if perturbed, and must be hand-launched. The vehicle designed must also have a large potential center of gravity movement to allow for customization of the planform and client customization.

An iterative design process was used ...


A Computational Analysis Of The Aerodynamics And Aeroacoustics Of Jets With Fluid Injection, Marco Coderoni 2018 Embry-Riddle Aeronautical University

A Computational Analysis Of The Aerodynamics And Aeroacoustics Of Jets With Fluid Injection, Marco Coderoni

Dissertations and Theses

A detailed numerical analysis of fluidic injection as a tool to reduce noise emission is presented here. The noise reduction strategy, developed at the Pennsylvania State University, is based on injectors that blow air into the diverging section of the nozzle to emulate the effect of interior corrugation on the jet plume. The advantage is that the injection can be activated during takeoff and turned o_ during other phases of flight so that performance is not affected. Numerical simulations are performed on a military-style nozzle based on the GE F400-series engines, with a design Mach number of 1:65, for ...


Aerothermodynamic Analysis Of A Mars Sample Return Earth-Entry Vehicle, Daniel A. Boyd 2018 Old Dominion University

Aerothermodynamic Analysis Of A Mars Sample Return Earth-Entry Vehicle, Daniel A. Boyd

Mechanical & Aerospace Engineering Theses & Dissertations

Because of the severe quarantine constraints that must be imposed on any returned extraterrestrial samples, the Mars sample return Earth-entry vehicle must remain intact through sample recovery. Vehicles returning on a Mars-Earth trajectory will attain velocities exceeding any that have been experienced by prior space exploration missions, with velocities approaching 14 km/s. Velocities as high as these will encounter significant heating during atmospheric re-entry to Earth.

The purpose of this study has been to systematically investigate the aerothermodynamic challenges that will result from a Mars sample return, Earth-entry vehicle design. The goal was to enable efficient estimation of maximum ...


A Protocol-Based Blended Model For Fluid Mechanics Instruction, John Solomon, Eric Hamilton, Vimal Viswanathan, Chitra Nayak, Firas Akasheh 2018 Tuskegee University

A Protocol-Based Blended Model For Fluid Mechanics Instruction, John Solomon, Eric Hamilton, Vimal Viswanathan, Chitra Nayak, Firas Akasheh

Faculty Publications, Mechanical Engineering

A personalized and media-rich learning framework called “Knowledge and Curriculum Integration Ecosystem” (KACIE) has been developed and implemented in a junior level fluid mechanics course in Fall 2016 and Spring 2017. This model shares characteristics of blended instruction as well as a flipped classroom, with an overall structure that includes the application of established principles emerging from the learning sciences and from cognitive neuroscience. These principles have taken form in the KACIE model as classroom protocols or written instructions to scaffold and guide teaching and learning by faculty and students respectively. In KACIE, the course has been presented as a ...


The Design And Implementation Of A Supersonic Indraft Tube Wind Tunnel For The Demonstration Of Supersonic Flows, Daniel Kenneth Johnson 2018 California Polytechnic State University, San Luis Obispo

The Design And Implementation Of A Supersonic Indraft Tube Wind Tunnel For The Demonstration Of Supersonic Flows, Daniel Kenneth Johnson

Master's Theses and Project Reports

Historically, the endeavor of scale testing flight vehicles at supersonic Mach numbers, especially for long durations, has required the development of closed-loop wind tunnels, which are extremely expensive both to build and operate due to the high complexity and incredible power required to drive such a system. The intermittent blowdown wind tunnel, indraft tunnel, and shock tunnel have alleviated many of these cost requirements to some degree, whilst facilitating testing at very high Mach numbers and enthalpies; however, these systems require the handling of gases at pressures and temperatures that can be prohibitive for many university settings. The Ludwieg tube ...


A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise 2018 Southern Methodist University

A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise

Mechanical Engineering Research Theses and Dissertations

In this thesis, a laser velocity sensor concept based on optical microresonators is presented and the application to spacecraft atmospheric entry is explored. The concept is based on the measurement of Doppler shift of back-scattered laser light. Specifically, the Doppler shift is detected by observing the whispering gallery optical modes (WGM) of a dielectric microresonator excited by the back scattered light from particulates and gas molecules. The microresonator replaces the typical Fabry-Perot interferometer and CCD camera system, thereby significantly reducing the size and weight of the overall detection system. This thesis presents proof-of-concept results for this measurement approach. The Doppler ...


Validation Of Cfd Simulations For Hypersonic Flow Over A Yawed Cone, Julian Cecil 2018 Washington University in St. Louis

Validation Of Cfd Simulations For Hypersonic Flow Over A Yawed Cone, Julian Cecil

Engineering and Applied Science Theses & Dissertations

This study aims to numerically simulate the wind tunnel results for hypersonic flow over a circular cone of semi-apex angle of 10 degrees yawed from 0° to 20° using the commercial computational fluid dynamics software ANSYS Fluent. The ANSYS workbench is used to create the 10° semi-apex circular cone with a shock aligned structured mesh of 3.05 million cells surrounding the cone. Simulation boundary conditions for pressure and temperature in the far field correspond to Tracy’s wind tunnel experiment at Cal Tech. The six simulations cases are conducted for yaw angles of 0, 8, 12, 16, 20 and ...


The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser 2018 Linfield College

The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser

Senior Theses

There are many golf balls on the market today with varying dimple sizes, shapes, and distribution. These proprietary differences are all designed to reduce drag on the balls during flight, allowing golfers to hit the ball farther distances. There are limited published studies comparing how varying the dimples affects the reduction of drag. An experiment was developed in which golf balls were pulled through a water tank to measure the drag force acting on each ball. The water was chosen to allow for testing at slower velocities than the typical necessary speeds to cause turbulence for balls traveling in air ...


Instability Waves And Transition In Adverse-Pressure-Gradient Boundary Layers, Rikhi Bose, Tamer A. Zaki, Paul A. Durbin 2018 Iowa State University

Instability Waves And Transition In Adverse-Pressure-Gradient Boundary Layers, Rikhi Bose, Tamer A. Zaki, Paul A. Durbin

Aerospace Engineering Publications

Transition to turbulence in incompressible adverse-pressure-gradient (APG) boundary layers is investigated by direct numerical simulations. Purely two-dimensional instability waves develop on the inflectional base velocity profile. When the boundary layer is perturbed by isotropic turbulence from the free stream, streamwise elongated streaks form and may interact with the instability waves. Subsequent mechanisms that trigger transition depend on the intensity of the free-stream disturbances. All evidence from the present simulations suggest that the growth rate of instability waves is sufficiently high to couple with the streaks. Under very low levels of free-stream turbulence (∼0.1%), transition onset is highly sensitive to ...


A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi 2018 The University of Western Ontario

A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi

Electronic Thesis and Dissertation Repository

As part of the Western Cold and Flu aerosol (WeCoF) studies, the present study provides Computational Fluid Dynamics (CFD) modelling of human cough flow. The cough flow is characterized in two different aspects, the flow field and the droplets. In the study of the flow field of coughing, various dynamic characteristics, including the velocity variation, streamwise penetration and power spectral density, are examined. CFD simulations using two different approaches, the unsteady Reynolds Averaged Navier-Stokes (URANS) and the large eddy simulation (LES), are performed for comparison purposes. The numerical results are validated by the experimental data obtained from the measurements by ...


Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohamed Aldeeb, Waqar Asrar, Erwin Sulaeman 2018 International Islamic University - Malaysia

Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohamed Aldeeb, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

Experiments on the relative merits and demerits of slotted wingtips mimicking a bird’s primary feathers have been performed. The real emargination length of feather tips, their flexibility and curved shapes during cruise are considered in the present study. The experiments were performed at a Reynolds number of 3.7 x 105 on a symmetric flat plate half wing of aspect ratio 3. Lift, drag and pitching moments were measured using a six component aerodynamic balance. Four different shapes inspired by bird primary feathers have been analysed. The rigid curved tip performed the best increasing the L/D ratio ...


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