| Supercritical and Transcritical Shear Flows in Microgravity: Experiments and Direct Numerical Simulations |
AUG 2006 |
314 pages |
| Authors:
Dustin W. Davis; Bruce Chehroudi; Douglas G. Talley; Josette Bellan; Nora Okong'o; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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 | Experiments and direct numerical simulations (DNS) were conducted on shear layers at subcritical to supercritical pressures. The experiments were performed on single-component coaxial jets, where the slower inner flow was liquid nitrogen, the faster outer flow was cold gaseous nitrogen, and the environment was room temperature gaseous nitrogen. The experiments were performed with and without the effects of transverse acoustic waves. Careful attention was given to measuring all the initial ... |
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| Reactive Flow Control of Delta Wing Vortex (Postprint) |
AUG 2006 |
27 pages |
| Authors:
Yong Liu; Ming Mu; Jim Zhu; Douglas A. Lawrence; Ephraim J. Gutmark; James H. Myatt; Cameron A. May; OHIO UNIV ATHENS DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| In this paper, the reactive flow control of delta wing leading edge vortices using along-core pulse width modulation (PWM) flow injection is presented. Leading edge vortices on the upper surface of a delta wing can augment lift. Manipulating breakdown points of leading edge vortices can effectively change the delta wing's lift and drag and generate attitude control torque. In this paper, a dynamic model of active flow control of vortex ... |
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| Structural Design and Analysis of Initial Extended Area Protection and Survivability (EAPS) Projectile Configurations |
AUG 2006 |
36 pages |
| Authors:
Michael M. Chen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A mission program named Extended Area Protection and Survivability was initiated at the U.S. Army Research Laboratory to demonstrate guided ammunition technologies to defend the battle space against any presented targets, such as mortars, rockets, and artillery. This report introduces the first step in the development of the guided ammunition system. It presents high-level physics-based simulations of a 60-mm projectile system. The topology of the initial projectile was developed on ... |
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| Stochastic Spectral/HP Element Methods for CFD and MHD Simulations |
31 JUL 2006 |
7 pages |
| Authors:
George Karniadakis; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
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| Multi-Element Polynomial Chaos: Generalized polynomial chaos (gPC) or Wiener-Askey expansions is a method developed by the PI and his students. This method is similar to spectral techniques - but in high-dimensions - so both Galerkin and collocation projections can be employed to produce the algebraic equations from the partial differential equations. |
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| Meso and Micro Scale Propulsion Concepts for Small Spacecraft |
28 JUL 2006 |
28 pages |
| Authors:
R. A. Yetter; V. Yang; I. A. Aksay; F. L. Dryer; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MECHANICAL AND NUCLEAR ENGINEERING
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| Combustion of liquid nitromethane and RK315A was experimentally studied in a meso-scale combustor with a volume of 108 cubic mm and diameter of 5 mm. The meso-scale combustor utilized a vortex combustion concept, which has been demonstrated to be useful for stabilizing combustion of gaseous hydrocarbon air mixtures in small volumes. The monopropellants were injected tangentially from the backend of the cylindrical combustor and the combustion products exited the chamber ... |
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| Aircraft Measurements of Turbulence in the Stably Stratified Atmosphere: Analysis of Cliff-Ramp Patterns, Refractive Turbulence and Waves in the Troposphere and Boundary Layer |
27 JUL 2006 |
45 pages |
| Authors:
Jorg Hacker; Donald Wroblewski; FLINDERS UNIV OF SOUTH AUSTRALIA SALISBURY AIRBORNE RESEARCH AUSTRALIA
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| This slide presentation is the final report of a project to measure turbulence in several high altitude formations over Southern Australia. Aircraft Measurements of Turbulence in the Stably Stratified Atmosphere: Analysis of Cliff-Ramp Patterns, Refractive Turbulence and Waves in the Troposphere and Boundary Layer |
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| Model-Based Feedback Control of Cavity Resonance: An Experimental and Computational Approach |
24 JUL 2006 |
59 pages |
| Authors:
Clarence W. Rowley; David R. Williams; ILLINOIS INST OF TECH CHICAGO DEPT OF MECHANICS MECHANICAL AND AEROSPACE ENGINEERING
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| This report presents results of experiments and numerical simulations studying closed-loop feedback control of oscillations in the compressible flow past a rectangular cavity. When weapons bays are exposed to high flow speeds, extremely large pressure fluctuations result, and are often large enough to cause structural damage to the aircraft and internal stores. The goal of this work is to design an implement a model-based feedback controller to suppress oscillations in ... |
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| Optimization of a Stabinger Viscometric Method to Maximize Sample Throughput: Balancing the Competing Interests of Speed, Cost, and Data Quality |
10 JUL 2006 |
28 pages |
| Authors:
Edward T. Urbansky; John C. Axley; JOINT OIL ANALYSIS PROGRAM PENSACOLA FL TECHNICAL SUPPORT CENTER
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| The U.S. Army Oil Analysis Program has sought to purchase automated viscometers (with autosamplers) for its centralized laboratories. The Army OAP has a sample throughput requirement of at least 40 samples per hour. In principle, this is within reach of the Anton Paar SVM3000 Stabinger viscometer. In addition, anecdotal evidence in our laboratory had led to disagreement regarding flush volume and measurement time requirements for optimal and sufficient performance of ... |
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| A Rocket-Like Coaxial Injector in an Acoustic Field Under Sub- and Supercritical Conditions |
03 JUL 2006 |
9 pages |
| Authors:
D. W. Davis; Bruce Chehroudi; Douglas G. Talley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental investigation was undertaken under non-reacting condition to gain a physical understanding of the interaction of acoustic waves and a coaxial-jet injector similar to those used in cryogenic liquid rockets. Liquid nitrogen (the round inner jet) and gaseous nitrogen (the annular outer jet) were used under subcritical, near critical, and supercritical chamber pressures, with and without presence of an external acoustic field. High-speed imaging provided information on the dynamic ... |
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| Performance of Pylons Upstream of a Cavity-Based Flameholder in Non-Reacting Supersonic Flow (Postprint) |
01-Jul-2006 |
22 pages |
| Authors:
Mark R Gruber; Lane C Haubelt; Paul I King; Campbell C Carter; Kuang-Yu M Hsu; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION SCIENCES BRANCH
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| Cavity-based fuel injection and flame holding, typically found in hydrocarbon-fueled scramjet applications, are of current interest for use in supersonic combustors. The Air Force Research Lab (AFRL) and the Air Force Institute of Technology (AFlT) are investigating the enhancement of fuel-air mixing with small pylons that project into the supersonic flow upstream of a flame holder. The pylons were of three sizes and were shaped as a thin triangular wedge ... |
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| 2005 Program of Study: Fast Times and Fine Scales |
JUL 2006 |
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| Authors:
Oliver Buhler; Charles Doering; Joseph Keller; George C. Papanicolaou; Eric V. Eijnden; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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 | The 2005 GFD program was entitled "Fast Times and Fine Scales" with a focus on asymptotic and stochastic modeling methods that exploit a physical scale separation of some kind. An extremely strong application pool resulted in the appointment of the unusually large class of eleven GFD Fellows for the summer. The first week consisted of principal lectures from Joe Keller on waves in fluids, ray methods, and a variety of ... |
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| Experimental and Analytical Study of the Hydroacoustics of Propellers in Rigid Ducts |
JUL 2006 |
62 pages |
| Authors:
Scott C. Morris; Thomas Mueller; NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| This report describes the results of a detailed study of the fluid dynamics and acoustic signature of a rotor operating in a rigid duct. The study focused on the separation of the acoustic source functions and the system response, or transfer function. A new algorithm was developed and quantified to separate these functions from radiated sound measurements. Measurements of the approach flow turbulence and propeller wake turbulence provided insight into ... |
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| Quantum Simulation and Communication Games |
JUL 2006 |
3 pages |
| Authors:
David Meyer; CALIFORNIA UNIV SAN DIEGO LA JOLLA
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| Progress was made toward classification of different algorithmic schemes in quantum image processing. Goal one is to identify quantum versions of isotropic and anisotropic diffusion processing. Secondly, novel quantum transforms for feature extraction were sought. Finally, image classification in the quantum domain was to be investigated. |
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| Rotational Dynamics of Small Molecules in Quantum Solids and Liquids (Briefing Charts) |
JUL 2006 |
16 pages |
| Authors:
Mario E. Fajardo; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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| High resolution Infrared (IR) absorption spectra of diatomic dopants in solid pH2 provide rigorous tests of theories describing molecular rotations in solids. Leading candidate theories cannot explain strong linear correlation. |
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| Moments on a Coning M864 by a Liquid Payload: The Candlestick Problem and Porous Media |
JUL 2006 |
26 pages |
| Authors:
Gene R. Cooper; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Moments that are caused by a payload assumed to be an inviscid liquid flowing in a coning projectile are predicted. This payload is contained in a uniform sequence of end-to-end cylinders stacked in columns along and off the symmetry axis of the projectile. A theoretical model is used to analyze inertial waves passing through the liquid, which are generated by the coning motion. This analysis continues by considering a single ... |
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| White Sands Missile Range Urban Study: Flow and Stability Around a Single Building Part 1: Background and Overview |
JUL 2006 |
50 pages |
| Authors:
Gail Vaucher; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| The U.S. Army Research Laboratory (ARL) serves the Army Soldier by providing research tools and resources. The atmospheric boundary layer (ABL), an area which begins at the surface and extends vertically to 1-2 km above ground level, is one of the ARL research areas. The lowest 10% of the ABL (a.k.a., surface layer) is the primary work environment for an Army Soldier. Characterizing this atmospheric surface layer was the focus ... |
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| Hydraulic Design of Channels Conveying Supercritical Flow |
JUL 2006 |
40 pages |
| Authors:
Richard L. Stockstill; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| This is a review of the Hydrologic Criteria and Drainage Design Manual (Clark County Regional Flood Control District 1999) of the Clark County Regional Flood Control District (CCRFCD). Areas of needed research relative to channels conveying supercritical flow and corresponding channel appurtenances have been identified. The extension of features common to supercritical channel flow is presented. A case is made that extension of hydraulic design guidance of supercritical confluences (trapezoidal ... |
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| Design of A Microgravity Spray Cooling Experiment |
JUL 2006 |
14 pages |
| Authors:
Kerri M. Basinger; Kirk L. Yerkes; Travis E. Michalak; Richard J. Harris; John McQuillen; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| An analytical and experimental study was conducted for the application of spray cooling in a micro gravity and high-g environment. Experiments were carried out aboard the NASA KC-135 reduced gravity aircraft, which provided both the microgravity and high-g environments. In reduced gravity, surface tension flow was observed around the spray nozzle, due to unconstrained liquid in the test chamber and flow reversal at the heat source. A transient analytical model ... |
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| Reduced Order Modeling for Aero-Elastic Simulations |
JUL 2006 |
11 pages |
| Authors:
Mark Balas; WYOMING UNIV LARAMIE DEPT OF ELECTRICAL ENGINEERING
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| Control of systems described by large-order models typically requires construction and use of reduced order models (ROM's) for the purpose of feedback controller design and implementation. However, controllers based on these ROM's can have deleterious interactions with un-modeled modes, and some sort of stability compensation is needed, such as Residual Mode Filters (RMF's). In this report we summarize our work on exponential closed loop stability using RMF's for Aero-Elastic Simulations. ... |
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| Computational Hypersonics and Plasmadynamics |
JUL 2006 |
9 pages |
| Authors:
Datta V. Gaitonde; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
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| Several independent efforts addressing simulation capability development and high-speed flow control application were pursued by team members during the reporting period. Control of laminar and turbulent shock/boundary layer and shock/shock interactions was explored with active and passive techniques. Unsteady plasma actuators and laser-based volumetric heat deposition were introduced in ramp and Edney interactions to mitigate integrated and localized heat loads. Separately, porous walls were shown to reduce separation and enhance ... |
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| Multidisciplinary Computational Research |
JUL 2006 |
10 pages |
| Authors:
Miguel R. Visbal; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
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| The purpose of this work is to develop advanced multidisciplinary numerical simulation capabilities for aerospace vehicles with emphasis on highly accurate, massively parallel computational methods for Direct and Large-Eddy simulation of turbulence, flow control, aero-acoustics and nonlinear fluid/structure interactions. These technical objectives directly support AFRL Air Vehicles Directorate's Capability Focused Tech Investment in persistent ISR, Strike and Multi-Role Mobility thrusts. |
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| Surface Roughness Effects in Low Reynolds Number Channel Flows (POSTPRINT) |
JUL 2006 |
9 pages |
| Authors:
N. Gimelshein; J. Duncan; T. Lilly; S. Gimelshein; A. Ketsdever; I. Wysong; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| Rarefied helium and nitrogen flow expanding into vacuum through 150 micron high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness ... |
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| O+HCI Cross Sections and Reaction Probabilities in DSMC |
28 JUN 2006 |
7 pages |
| Authors:
Takashi Ozawa; D. A. Levin; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A chemical reaction model, suitable for use in the Direct Simulation Monte Carlo (DSMC) method, is developed to simulate hypervelocity collisions of an important reaction in atmospheric-jet interactions ? O(3P)+HCI(1Σ+) → OH(2Π)+C1(2P). The model utilizes the Quasi-Classical Trajectory (QCT) method with two potential energy surfaces (PES), new benchmark triple A″ and A′ surfaces [1] and London-Eyring-Polanyi-Sato (LEPS) PES.[2] The sensitivity of the flow to the fidelity of the chemical model ... |
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| An Improved Weighted Essentially Non-Oscillatory Scheme for Hyperbolic Conservation Laws |
23 JUN 2006 |
16 pages |
| Authors:
Rafael Borges; Bruno Costa; Wai S. Don; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
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| We develop in this article an improved version of the fifth-order weighted essentially non-oscillatory (WENO) scheme. Through the novel use of higher order information already present in the framework of the classical scheme, new smoothness indicators are devised and we obtain a new WENO scheme with less dissipation than the classical WENO of Jiang and Shu, with the same computational cost, and a slightly better performance than the improved mapped ... |
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| Near Wall Velocity and Vorticity Measurements, In A Very High R(theta) Turbulent Boundary Layer |
15 JUN 2006 |
87 pages |
| Authors:
Scott C. Treat; John F. Foss; MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING
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| Velocity and vorticity measurements have been obtained at two y+ values: 810 and 2,150, in the very high R(theta)(O 10(exp 6)) turbulent boundary layer at the SLTEST site, Dugway Proving Grounds, Utah. Detailed descriptions of the experimental procedures are reported in order to allow the processed results to be evaluated. The research focus is on the velocity-vorticity products that appear in the formal statement of the vertical gradient of the ... |
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| The Ins and Outs of Keeping US Service Jobs at Work |
14 JUN 2006 |
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| Authors:
Eric D. Gorney; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| The purpose of this research is to discuss employment in the United States (US) service sector. The main concern is not pinpointing numerical estimates, but instead identifying trends which lead to job growth or job loss. Like manufacturing jobs that have been lost to offshore locations or productivity mains, so too are service jobs at risk. Off shoring the outsourcing of business functions overseas and automation have the same effect ... |
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| Quasi-2D Unsteady Flow Solver Module for Rocket Engine and Propulsion System Simulations |
14 JUN 2006 |
12 pages |
| Authors:
Bryan T. Campell; Roger L. Davis; AEROJET SACRAMENTO CA
|
| A new quasi-two-dimensional procedure is presented for the transient solution of real-fluid flows in lines and volumes including heat transfer effects. The solver is targeted to the commercial dynamic simulation software package Simulink(Registered) for integration into a larger suite of modules developed for simulating rocket engines and propulsion systems. A Fortran95 code using more conventional solution procedures is being developed in parallel to provide verification test cases. The solution procedure ... |
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| Surface Roughness Effects in Low Reynolds Number Channel Flows |
12 JUN 2006 |
9 pages |
| Authors:
N. Gimelsheim; J. Duncan; T. Lilly; S. Gimelshein; A. Ketsdever; I. Wysong; ERC INTERNATIONAL INC SAN DIEGO CA
|
| Rarefied helium and nitrogen flow expanding into vacuum through 150 micrometers high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness ... |
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| Multifunctional Carbon Nanotube Damping Films |
06 JUN 2006 |
49 pages |
| Authors:
Nikhil Koratkar; Prabhat Hajela; Pulickel Ajayan; RENSSELAER POLYTECHNIC INST TROY NY
|
| The objective of this project was to quantify the energy dissipation that occurs when the interfacial slip of nanoscale fillers is activated in a host matrix material. We consider both polymer (such as polycarbonate, PEO, PEG) and epoxy matrices. The nanoscale fillers considered are carbon nanotubes (both singlewalled as well as multi-walled) as well as fullerenes. The nano-composites are fabricated by using a solution mixing technique with tetra-hydro-furan as the ... |
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| Dynamics of Eastern Boundary Currents and Their Effects on Sound Speed Structure |
01 JUN 2006 |
91 pages |
| Authors:
Vanessa M. Guthrie; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Identifying the influence of eastern boundary current (EBC) dynamical processes on sound speed structure can provide better ocean models for acoustic predictions in littoral regions. This study will explore the effects of currents, wind and eddies on the sound speed structure of two different EBC models, the North Canary Current System (NCCS) and the Leeuwin Current System (LCS). These systems represent classical features of EBCs as well as regional anomalies. ... |
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| Reattachment of a Separated Boundary Layer on a Flat Plate in a Highly Adverse Pressure Gradient Using a Plasma Actuator (Postprint) |
01-Jun-2006 |
12 pages |
| Authors:
Issac G Boxx; Richard B Rivir; Jeffery M Newcamp; Nathan M Woods; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH TURBINE ENGINE DIV
|
| An experimental study was performed to examine the phase-dependent response characteristics of a dielectric barrier discharge plasma flow control actuator. The actuator was investigated on a fully separated flat plate boundary layer with an adverse freestream pressure gradient distribution. The actuator was positioned downstream of the boundary layer separation. Phase-locked particle image velocimetry (PIV) was used to obtain two-dimensional velocity field measurements at thirty equally spaced phase-angles along the sinusoidal ... |
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| ADH Sediment Module Testing |
JUN 2006 |
15 pages |
| Authors:
Jennifer N. Tate; R. C. Berger; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
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| The Kate Aubrey reach of the Mississippi River, located north of Memphis, TN, was used as a test domain for the ADaptive Hydraulics (ADH) sediment transport routines. This 27.4 km (17-mile) stretch of river experiences times of wetting and drying and contains several nonerodable dike structures and revetments. This reach is a good test condition for a model since there are two dike configurations in its history, one that did ... |
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| Streamwise Fluctuations of Vortex Breakdown at High Reynolds Numbers |
JUN 2006 |
49 pages |
| Authors:
Jonathan S. Connelly; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL AND ASTRONAUTICAL ENGINEERING
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| This thesis deals with the characterization of the dependence on the flow geometry of the stream wise fluctuations of the stagnation point of vortex breakdown in axisymmetric tubes and over delta wing aircraft. The statistical analysis presented herein shows that in an axisymmetric tube the 'darting' about the mean stagnation point are distributed normally for the two Reynolds numbers: Re(D) 230,000 and 300,000 (independently of the Reynolds number in the ... |
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| High Cycle Fatigue Prediction for Mistuned Bladed Disks with Fully Coupled Fluid-Structural Interaction |
JUN 2006 |
138 pages |
| Authors:
Ge-Chenga Zha; Ming-Ta Yang; Fariba Fahroo; MIAMI UNIV CORAL GABLES FL DEPT OF MECHANICAL ENGINEERING
|
| During the period from April 2003 to March 2006, this research had been progressing well as planned toward the ultimate goal of simulating the mistuned rotor with fully-coupled fluid structure interaction. This is multidisciplinary comprehensive project that needs components from both fluid and structure dynamics. |
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| Experiments in Numerical Studies of Low Density and Real Gas Effects on Regions of Shock Wave/Boundary Layer Interaction in Hypervelocity Flows |
JUN 2006 |
69 pages |
| Authors:
Michael S. Holden; Timothy P. Wadhams; Matthew MacLean; Ronald A. Parker; CALSPAN UB RESEARCH CENTER BUFFALO NY
|
| Experiments with extensive numerical simulations were conducted examining effects of low density flows and real gas effects on aerothermal characteristics of flows in hypervelocity facilities and in simple and complex flowfields in hypervelocity flows. These studies demonstrated that in the absence of real gas effects the DSMC and Navier-Stokes solutions accounting for slip effects were in excellent agreement with measurements. An extensive series of calibration and validation studies were done ... |
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| An Analysis of Nonlinear Elastic Deformations for a Homogeneous Beam at Varying Tip Loads and Pitch Angles |
JUN 2006 |
106 pages |
| Authors:
Robert J. McGraw; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The Princeton beam experiments of 1975 were performed in hopes of producing viable data for beam nonlinear elastic deformation models in hopes of improving helicopter main beam designs. The recorded data, specifically for homogeneous beams of 7075 aluminum, have been referenced as a baseline for the past thirty years to validate numerous computer models and theories in an effort to build beams capable of withstanding aeroelastic, static, and dynamic loading. ... |
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| Characterizing a Co-Flow Nozzle for use in a Filtered Rayleigh Scattering System |
JUN 2006 |
138 pages |
| Authors:
David S. Miceli; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Research was conducted on the flow field exiting a co-annular flow nozzle for use in filtered Rayleigh scattering flow visualizations. More specifically, the flow visualizations were of the flow field exiting a coflow nozzle and illuminated by a tunable, nominal 4.2 watt narrow line width Argon laser operating at 514.5nm. ND:YAG lasers are typically used in this application, but some of the properties of a tunable Argon laser make it ... |
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| Assessing Convergence in Predictions of Periodic-Unsteady Flowfields |
JUN 2006 |
13 pages |
| Authors:
J. P. Clark; E. A. Grover; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Here we report on a method developed to determine the level of convergence in a predicted flowfield that is characterized by periodic-unsteadiness. The method relies on fundamental concepts from digital signal processing including the discrete Fourier transform, cross-correlation, and Parseval's theorem. Often in predictions of vane-blade interaction in turbomachines, the period of the unsteady fluctuations is expected. In this method, the development of time-mean quantities, Fourier components (both magnitude and ... |
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| Simulating Macrosegregation in Var Ingots of Titanium Alloy During Solidification |
JUN 2006 |
46 pages |
| Authors:
D. R. Poirier; P. K. Sung; ARIZONA UNIV TUCSON DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Simulations of VAR-ingots of Ti-6A1-4V, with emphasis on predicting macrosegregation of oxygen, are presented. MULTIA simulations showed that segregation patterns in the ingots result largely from the strong convection in the melt pool. Permeabilities in the mushy zones were less important. Simulations revealed more details in the macrosegregation patterns when the element-size selected for the calculation was reduced to 7.2 mm x 10.8 mm. the extent of the segregation, as ... |
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| Optimization of a Low Heat Load Turbine Inlet Vane |
JUN 2006 |
25 pages |
| Authors:
Jaime J. Johnson; Paul I. King; John P. Clark; Michael J. Flanagan; Ryan P. Lemaire; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Often there is a distinction between the design of turbomachinery airfoils for aerodynamic performance and durability. However, future aero-engine systems require ever increasing levels of turbine inlet temperature causing the durability and reliability of components to be an ever more important design concern. As a result, the need to incorporate heat transfer predictions into traditional aerodynamic design and optimization systems presents itself. Here, an effort to design an airfoil with ... |
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| Digital Holographic Spray Analyzer(POSTPRINT) |
JUN 2006 |
8 pages |
| Authors:
B. Miller; K. A. Sallam; K. C. Lin; C. Carter; OKLAHOMA STATE UNIV STILLWATER
|
| Advanced spray diagnostics are needed for studying the formation of drops in a variety of natural and technological spray processes, e.g. water falls, bow waves of ships, and many types of commercial spray atomizers, among others. Of interest is the dense-spray near-injector region which is typically opaque for spray diagnostics such as phase Doppler particle analyzers (PDPA). This is unfortunate because primary breakup processes that control spray size and velocity ... |
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| Reattachment of a Separated Boundary Layer on a Flat Plate in a Highly Adverse Pressure Gradient Using a Plasma Actuator(POSTPRINT) |
JUN 2006 |
12 pages |
| Authors:
Isaac G. Boxx; Richard B. Rivir; Jeffrey M. Newcamp; Nathan M. Woods; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| An experimental study was performed to examine the phase-dependent response characteristics of a dielectric barrier discharge plasma flow control actuator. The actuator was investigated on a fully separated flat plate boundary layer with an adverse freestream pressure gradient distribution. The actuator was positioned downstream of the boundary layer separation. Phase-locked particle image velocimetry (PIV) was used to obtain two-dimensional velocity field measurements at thirty equally spaced phase-angles along the sinusoidal ... |
|
| Wind Tunnel Renovation, Flow Verification and Flapping Wing Analysis |
JUN 2006 |
95 pages |
| Authors:
Curtis Hickle; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The Naval Postgraduate School (NPS) Micro-Air Vehicle (MAV) wind tunnel was refurbished in this study. This wind tunnel has a 61 by 38 centimeter test section with a contraction ratio of 6.75, and testing speeds up to 9 meters per second (m/s). The objectives of this work were to create a high quality, customized facility for further MAV study, and to fully characterize the wake of the MAV at a ... |
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| Effect of Span Variation on the Performance of a Cross Flow Fan |
JUN 2006 |
65 pages |
| Authors:
Charla W. Schreiber; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Over the past few decades, advances in aeronautic and control technologies have established a new vision for future air transportation systems. NASA has initiated the motion with several programs supporting the "highway of the sky," a system of launch pads and air pathways enabling smaller and more easily piloted aircraft to travel the open space above instead of busy freeways and crowded city streets. Previous investigations into crossflow fan technology ... |
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| Modeling Fluid Flow by Exploring Different Flow Geometries and Effect of Weak Compressibility |
JUN 2006 |
71 pages |
| Authors:
James J. Sopko; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Atmospheric mixing is a problem of exceptional importance and difficult to study. The anelastic approximation is the accepted fluid system governing the atmosphere over large vertical scales (about 8 km). The anelastic equations, unlike the Navier-Stokes equations, incorporate a nontrivial spatial divergence constraint on the velocity field. This yields a weakly compressible fluid flow. The basis of this study is to use numerical analysis to explore the effects of weak ... |
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| Loss Measurements in the Endwall Region of a Cascade of Compressor Blades at Stall |
JUN 2006 |
117 pages |
| Authors:
Marlies C. Urban; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Flow around second-generation controlled-diffusion blades in cascade at stall was investigated using five-hole probe surveys. Wake pressure surveys were conducted at various locations between the cascade centerline and endwall region. Corresponding inlet pressure surveys were also performed to allow the total pressure loss distribution to be calculated across the blades. A fully automated traverse mechanism was implemented for the probe surveys ahead of and aft of the cascade blades. The ... |
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| Effect of Pressure and Temperature On Oil Mist Sprays Used for Blade Excitation in High Cycle Fatigue Testing |
JUN 2006 |
151 pages |
| Authors:
Andrew P. Thompson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The flow patterns of two oil mist nozzles used in rotor blade excitation experiments were characterized using a Laser Doppler Velocimeter (LDV). Both nozzles were operated in a vacuum test chamber and velocity measurements were taken at three axial distances from the nozzle exit, at three or four different pressures, at three different temperatures. The 4 gallon per hour mini-mist nozzle produced a referenced velocity consistent with a hollow cone ... |
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| A New Class of Hybrid Schemes Based on Large Eddy Simulation and Low-Dimensional Stochastic Models |
JUN 2006 |
43 pages |
| Authors:
Tarek Echekki; NORTH CAROLINA STATE UNIV AT RALEIGH
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| A hybrid approach for large-eddy simulations (LES) of turbulent combustion with the One-Dimensional Turbulence (ODT) model is developed. The need for a structure-based approach can address some of the key challenges arising in the prediction of non-linear physics on the sub-grid scale. The implementation involves hybrid solutions of 3-D LES with 1-D solutions based on the ODT, with ODT elements embedded within the LES computational domain. The solutions require the ... |
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| Aerodynamic Analysis of Body-Strake Configurations |
JUN 2006 |
52 pages |
| Authors:
Asher Sigal; TECHNION - ISRAEL INST OF TECH HAIFA
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| This report results from a contract tasking Technion - Israel Institute of Science and Technology as follows: The Grantee will investigate methods to improve the rapid aerodynamic prediction of configurations that feature strakes instead of conventional wings. The longitudinal characteristics of body-strake configurations will be estimated using a hybrid approach that will consider two contributions. (1) The linear (potential) contribution will be estimated; (2) The nonlinear contribution of the whole ... |
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| A Rapid and Inexpensive PCR-Based STR Genotyping Method for Identifying Forensic Specimens |
JUN 2006 |
18 pages |
| Authors:
Doris M. Kupfer; Mark Huggins; Brandt Cassidy; Nicole Vu; Dennis Burian; Dennis V. Canfield1; FEDERAL AVIATION ADMINISTRATION OKLAHOMA CITY OK CIVIL AEROMEDICAL INST
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| Situations arise where forensic samples can be inadvertently misidentified during field collection. Samples identified in the field as being from the same person that return conflicting toxicological results may suggest such misidentification. Polymerase chain reaction (PCR)-based human identity testing provides a reliable and independent method to confirm sample identification. In the study presented here, the Federal Bureau of Investigation's human Combined DNA Identity System (CODIS) loci were used on a ... |
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Fluid Mechanics
