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 Lift (3)
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 Coupling (1)
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Articles 1  20 of 20
FullText Articles in Engineering Science and Materials
Joint Wind And Ice Effects On Transmission Lines In Mountainous Terrain, Daniel Davalos Arriaga
Joint Wind And Ice Effects On Transmission Lines In Mountainous Terrain, Daniel Davalos Arriaga
Electronic Thesis and Dissertation Repository
Atmospheric icing on mountainous terrain can produce catastrophic damages to transmission lines when incoming particles impinge and accrete on the cable surface of the system. The first challenge in windice loading is determining joint statistics of wind and ice accretion on transmission lines. This study analyzes the weather characteristics for a specific site of study using 15 years of historical data to use as inputs for ice accretion modeling. The joint wind and ice hazard is characterized by simulating 500 years of icing events from the fitted probability distributions of ice accretion and wind on ice velocities. The second challenge ...
Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung
Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung
Theses and Dissertations
A recent research effort, sponsored by the Air Force Office of Scientific Research, numerically investigated the unsteady aerodynamic flow field around an oscillating, straked, delta wing. The study was centered on determining the importance of the unsteady aerodynamic forces acting as a driver for a nonlinear motion known as limit cycle oscillations. The current effort focused on creating a computational model to compare to the results of previous tests and modeling efforts and discover new information regarding the onset of LCO. The computational model was constructed using the Cartesian overset capabilities of the CREATEAV™ fixed wing fluid dynamics solver Kestrel ...
Influence Of Leading Edge Oscillatory Blowing On TimeAccurate Dynamic Store Separation, Ryan G. Saunders
Influence Of Leading Edge Oscillatory Blowing On TimeAccurate Dynamic Store Separation, Ryan G. Saunders
Theses and Dissertations
The primary objective of this research is to support the static and dynamic characterization and the timeaccurate dynamic load data acquisition of store separation from a cavity with leading edge oscillatory blowing. Developing an understanding of, and potentially controlling, pitch bifurcation of a store release is a motivation for this research. The apparatus and data acquisition system was used in a twopart experiment to collect both static and dynamic testing data in the AFIT low speed wind tunnel in speeds of 60, 100, and 120 mph, from Reynolds numbers varying from 5.5x10^{4} to 4.6x10^{5}, depending on ...
Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt
Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt
Theses and Dissertations
Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, timeaveraged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide timeaccurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain timeaccurate force ...
The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser
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 ...
Angle Of Attack Determination Using Inertial Navigation System Data From Flight Tests, Jack Kevin Ly
Angle Of Attack Determination Using Inertial Navigation System Data From Flight Tests, Jack Kevin Ly
Masters Theses
Engineers and pilots rely on mechanical flow angle vanes on air data probes to determine the angle of attack of the aircraft in flight. These probes, however, are costly, come with inherent measurement errors, affect the flight characteristics of the aircraft, and are potentially dangerous in envelope expansion flights. Advances in the accuracy, usability, and affordability of inertial navigation systems allow for angle of attack to be determined accurately without direct measurement of the airflow around the aircraft. Utilizing an algorithm developed from aircraft equations of motion, a postflight data review is completed as the first step in proving the ...
Dynamic Characteristics Of Biologically Inspired Hair Receptors For Unmanned Aerial Vehicles, Manohar Chidurala
Dynamic Characteristics Of Biologically Inspired Hair Receptors For Unmanned Aerial Vehicles, Manohar Chidurala
University of New Orleans Theses and Dissertations
The highly optimized performance of nature’s creations and biological assemblies has inspired the development of their engineered counter parts that can potentially outperform conventional systems. In particular, bat wings are populated with air flow hair receptors which feedback the information about airflow over their surfaces for enhanced stability and maneuverability during their flight. The hairs in the bat wing membrane play a role in the maneuverability tasks, especially during lowspeed flight. The developments of artificial hair sensors (AHS) are inspired by biological hair cells in aerodynamic feedback control designs. Current mathematical models for hair receptors are limited by strict ...
Magnus Effect In Duct Flow, Cameron W. Clarke, Jesse S. Batko, Kenneth W. Smith Jr.
Magnus Effect In Duct Flow, Cameron W. Clarke, Jesse S. Batko, Kenneth W. Smith Jr.
Williams Honors College, Honors Research Projects
The following research paper details the preliminary research carried out by this team. The project was originally conceived to determine if Magnus Lift could be utilized in an unconventional way to assist rockets during takeoff. Several conceptual designs were proposed, but the idea was scrapped when it became apparent that the team would not be able to generate the desired lift without inducing significant amounts of drag and additional weight on a rocket. Instead, the team focused on researching an interesting topic that hasn’t been previously explored: Magnus lift on a cylinder within a duct. An experimental procedure that ...
Magnus Effect In Duct Flow, Jesse S. Batko, Cameron W. Clarke, Kenneth W. Smith Jr.
Magnus Effect In Duct Flow, Jesse S. Batko, Cameron W. Clarke, Kenneth W. Smith Jr.
Williams Honors College, Honors Research Projects
The following research paper details the preliminary research carried out by this team. The project was originally conceived to determine if Magnus Lift could be utilized in an unconventional way to assist rockets during takeoff. Several conceptual designs were proposed, but the idea was scrapped when it became apparent that the team would not be able to generate the desired lift without inducing significant amounts of drag and additional weight on a rocket. Instead, the team focused on researching an interesting topic that hasn’t been previously explored: Magnus lift on a cylinder within a duct.
An experimental procedure that ...
High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang
High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang
Theses and DissertationsMechanical Engineering
A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a secondorder finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal nonequilibrium state, and a fully implicit firstorder backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of ...
NonEquilibrium Pressure Control Of The Height Of A LargeScale, GroundCoupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan
NonEquilibrium Pressure Control Of The Height Of A LargeScale, GroundCoupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan
Mechanical & Aerospace Engineering Faculty Publications
When a groundcoupled, rotating fluid column is modeled incorporating nonequilibrium pressure forces in the NavierStokes equations, a new exact solution results. The solution has been obtained in a similar manner to the classical equilibrium solution. Unlike the infiniteheight, classical solution, the nonequilibrium pressure solution yields a groundcoupled rotating fluid column of finite height. A viscous, nonequilibrium Rankine vortex velocity distribution, developed previously, was used to demonstrate how the viscous and nonequilibrium pressure gradient forces, arising in the vicinity of the velocity gradient discontinuity that is present in the classical Rankine vortex model, effectively isolate the rotating central fluid column from ...
The Influence Of Pressure Relaxation On The Structure Of An Axial Vortex, Robert L. Ash, Irfan Zardadkhan, Allan J. Zuckerwar
The Influence Of Pressure Relaxation On The Structure Of An Axial Vortex, Robert L. Ash, Irfan Zardadkhan, Allan J. Zuckerwar
Mechanical & Aerospace Engineering Faculty Publications
Governing equations including the effects of pressure relaxation have been utilized to study an incompressible, steadystate viscous axial vortex with specified farfield circulation. When sound generation is attributed to a velocity gradient tensorpressure gradient product, the modified conservation of momentum equations that result yield an exact solution for a steady, incompressible axial vortex. The vortex velocity profile has been shown to closely approximate experimental vortex measurements in air and water over a wide range of circulationbased Reynolds numbers. The influence of temperature and humidity on the pressure relaxation coefficient in air has been examined using theoretical and empirical approaches, and ...
Nonlinear Acoustics Of PistonDriven GasColumn Oscillations, Andrew William Wilson
Nonlinear Acoustics Of PistonDriven GasColumn Oscillations, Andrew William Wilson
Masters Theses
The pistondriven oscillator is traditionally modeled by directly applying boundary conditions to the acoustic wave equations; with better models rederiving the wave equations but retaining nonlinear and viscous effects. These better models are required as the acoustic solution exhibits singularity near the natural frequencies of the cavity, with an unbounded (and therefore unphysical) solution. Recently, a technique has been developed to model general pressure oscillations in propulsion systems and combustion devices. Here, it is shown that this technique applies equally well to the pistondriven gascolumn oscillator; and that the piston experiment provides strong evidence for the validity of the general ...
Understanding Practical Limits To Heavy Truck Drag Reduction, Drew Landman, Richard Wood, Whitney Seay, John Bledsoe
Understanding Practical Limits To Heavy Truck Drag Reduction, Drew Landman, Richard Wood, Whitney Seay, John Bledsoe
Mechanical & Aerospace Engineering Faculty Publications
A heavy truck wind tunnel test program is currently underway at the Langley Full Scale Tunnel (LFST). Seven passive drag reducing device configurations have been evaluated on a heavy truck model with the objective of understanding the practical limits to drag reduction achievable on a modern tractor trailer through addon devices. The configurations tested include side skirts of varying length, a full gap seal, and tapered rear panels. All configurations were evaluated over a nominal 15 degree yaw sweep to establish wind averaged drag coefficients over a broad speed range using SAE J1252. The tests were conducted by first quantifying ...
Volume Viscosity In Fluids With Multiple Dissipative Processes, Allan J. Zuckerwar, Robert L. Ash
Volume Viscosity In Fluids With Multiple Dissipative Processes, Allan J. Zuckerwar, Robert L. Ash
Mechanical & Aerospace Engineering Faculty Publications
The variational principle of Hamilton is applied to derive the volume viscosity coefficients of a reacting fluid with multiple dissipative processes. The procedure, as in the case of a single dissipative process, yields two dissipative terms in the NavierStokes equation: The first is the traditional volume viscosity term, proportional to the dilatational component of the velocity; the second term is proportional to the material time derivative of the pressure gradient. Each dissipative process is assumed to be independent of the others. In a fluid comprising a single constituent with multiple relaxation processes, the relaxation times of the multiple processes are ...
Response To "Comment On Variational Approach To The Volume Viscosity Of Fluids" [Phys. Fluids 18, 109101 (2006)], Allen J. Zuckerwar, Robert L. Ash
Response To "Comment On Variational Approach To The Volume Viscosity Of Fluids" [Phys. Fluids 18, 109101 (2006)], Allen J. Zuckerwar, Robert L. Ash
Mechanical & Aerospace Engineering Faculty Publications
We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy. (c) 2006 American Institute of Physics.
Variational Approach To The Volume Viscosity Of Fluids, Allan J. Zuckerwar, Robert L. Ash
Variational Approach To The Volume Viscosity Of Fluids, Allan J. Zuckerwar, Robert L. Ash
Mechanical & Aerospace Engineering Faculty Publications
The variational principle of Hamilton is applied to develop an analytical formulation to describe the volume viscosity in fluids. The procedure described here differs from those used in the past in that a dissipative process is represented by the chemical affinity and progress variable (sometimes called "order parameter") of a reacting species. These state variables appear in the variational integral in two places: first, in the expression for the internal energy, and second, in a subsidiary condition accounting for the conservation of the reacting species. As a result of the variational procedure, two dissipative terms appear in the NavierStokes equation ...
Large Amplitude Pitching Of Supermaneuver Delta Wings Including Flow Control, Yahia A. Abdelhamid
Large Amplitude Pitching Of Supermaneuver Delta Wings Including Flow Control, Yahia A. Abdelhamid
Mechanical & Aerospace Engineering Theses & Dissertations
The unsteady, threedimensional NavierStokes equations are solved to simulate and study the aerodynamic response of a delta wing undergoing large amplitude pitching motion up to 90° angle of attack. The primary model under consideration consists of a 76° swept, sharpedged delta wing of zero thickness, initially at zero angle of attack. The freestream Mach number and Reynolds number are 0.3 and 0.45 × 106, respectively. The governing equations are solved timeaccurately using the implicit, upwind, Roe fluxdifference splitting, finitevolume scheme. Both laminar and turbulent flow solutions are investigated. In the laminar flow solutions, validation of the computational results is ...
Efficient Dynamic Unstructured Methods And Applications For Transonic Flows And Hypersonic Stage Separation, Xiaobing Luo
Efficient Dynamic Unstructured Methods And Applications For Transonic Flows And Hypersonic Stage Separation, Xiaobing Luo
Mechanical & Aerospace Engineering Theses & Dissertations
Relativemoving boundary problems have a wide variety of applications. They appear in staging during a launch process, store separation from a military aircraft, rotorstator interaction in turbomachinery, and dynamic aeroelasticity.
The dynamic unstructured technology (DUT) is potentially a strong approach to simulate unsteady flows around relativemoving bodies, by solving timedependent governing equations. The dualtime stepping scheme is implemented to improve its efficiency while not compromising the accuracy of solutions. The validation of the implicit scheme is performed on a pitching NACA0012 airfoil and a rectangular wing with low reduced frequencies in transonic flows. All the matured accelerating techniques, including the ...
A Practical Approach To Fabricating Ideal Transducers, J J. Tiemann
A Practical Approach To Fabricating Ideal Transducers, J J. Tiemann
Review of Progress in Quantitative Nondestructive Evaluation
I was invited here to come to talk about transducers, and I'd like to tell you how that came about. It came about because the General Electric Jet Engine Dept. has been trying to perform water immersion ultrasonic inspection of engine forgings with commercially available inspection equipment and has found that this equipment is ill suited to the task. I would guess that most of these instruments were designed 5 or 10 years ago for applications in the steel industry. In any case, they do not have enough dynamic range to accommodate the large acoustic attenuation encountered in Jet ...