| Static Stability Assessment of an ELCAS(M) Based Barge Crane |
Mar-2009 |
44 pages |
| Authors:
Erick T Huang; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
 | This effort performs an engineering assessment to quantify the lift capacity of a temporary barge crane for cargo transfer in calm water at the waterfront. The assessment addresses two basic aspects concerning the effectiveness and operational safety of a barge crane: (a) the barge capacity to accommodate a mobile crane and (b) the crane boom capacity on a floating platform. Prospective barges were assessed for their capacity against capsizing in ... |
|
| Least-Squares Finite Element Formulation for Fluid-Structure Interaction |
Mar-2009 |
276 pages |
| Authors:
Cody C Rasmussen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Fluid-structure interaction problems prove difficult due to the coupling between fluid and solid behavior. Typically, different theoretical formulations and numerical methods are used to solve fluid and structural problems separately. The least-squares finite element method is capable of accurately solving both fluid and structural problems. This capability allows for a simultaneously coupled fluid structure interaction formulation using a single variational approach to solve complex and nonlinear aeroelasticity problems. The least-squares ... |
|
| An Investigation of Shock Wave Physics via Hybrid CFD-BGK Solution Methods for Nonequilibrium Flows |
Mar-2009 |
92 pages |
| Authors:
Brook I Bentley; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The Unified Flow Solver, a hybrid continuum-rarefied code, is used to investigate the internal structure of a normal shock wave for a Mach range of 1.55 to 9.0 for Argon, and 1.53 to 3.8 for diatomic Nitrogen. Reciprocal shock thickness, density, temperature, heat flux, and the velocity distribution function are calculated for a one-dimensional shock wave and compared with experimental data from Alsmeyer and DSMC results from Bird. Using the ... |
|
| Coastal Jets and Their Interactions Along the Central California Coastline |
Mar-2009 |
85 pages |
| Authors:
Liam J Lynam; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis research focuses on the cause of strong southerly winds around the Monterey Peninsula and particularly on the effects of winter storms that produced strong southerly winds. The high-wind events from 2005 through 2008 were analyzed. During this period, 16 cases were identified that met the criteria of high winds around the Monterey Peninsula. From the 16 cases, three cases were chosen to complete a detailed analysis of the ... |
|
| Development of Non-Uniform Radiation Solution Methods for Atmospheric Re-entry Using Detailed Thermal Modeling |
Mar-2009 |
68 pages |
| Authors:
Jeffrey R Komives; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The line-by-line accurate spectral radiation solver SPRADIAN was integrated with the multi-temperature hypersonic flow-solver NH7Air for the purpose of predicting the radiation incident on the surface of a hypersonic re-entry vehicle. Atomic and molecular radiation mechanisms are considered for chemical species present in an Earth atmosphere re-entry. A new numerical method of radiation propagation is presented that is capable of accurately predicting the radiation propagation through a non-uniform radiation field. ... |
|
| Factors of Safety for Richardson Extrapolation |
Mar-2009 |
65 pages |
| Authors:
Fred Stern; Tao Xing; IOWA UNIV IOWA CITY IIHR - HYDROSCIENCE AND ENGINEERING
|
| A factor of safety (FS) method for quantitative estimates of grid/time uncertainties for CFD solutions is derived to remove the deficiencies of GCI, corrected GCI(sub C), and correction factor (CF) methods, i.e., unreasonably small uncertainty when CF 1 (estimated order of accuracy greater than theoretical) and lack of statistical analysis to prove 95% confidence for the estimated uncertainties to bound the true error. The approach follows the CF method but ... |
|
| Dynamic Channel Allocation in Wireless Networks Using Learning Automata (Preprint) |
Mar-2009 |
26 pages |
| Authors:
Behdis Eslamnour; Maciej Zawodniok; Jagannathan Sarangapani; MISSOURI UNIV-ROLLA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| Single channel based wireless networks have limited bandwidth and throughput and the bandwidth utilization decreases due to congestion and interference from other sources. In order to increase the throughput, transmission in multiple channels is considered as an option. In this paper, we propose a distributed dynamic channel allocation scheme using adaptive learning automata for wireless networks whose nodes are equipped with single radio interfaces. The proposed schemes, Adaptive Pursuit Reward-Inaction, ... |
|
| Sensors to Assess Pressure-Mediated Effects on Blast-Induced Traumatic Brain Injury |
Mar-2009 |
10 pages |
| Authors:
Mikulas Chavko; NAVAL MEDICAL RESEARCH CENTER SILVER SPRING MD
|
| This study was designed to investigate the contributions of direct impact of blast on the skull in two different orientations: face-on and side-on orientation. To assess a loading force on a target with different impact areas two piezoelectric (PCB) sensors were placed inside a shock tube in parallel and perpendicular orientations to the blast wave. Results show that the face-on pressure is much higher than the static, side-on pressure. In ... |
|
| Nonlinear Dynamics and Control of Three-Dimensional Separated Flows |
28-Feb-2009 |
6 pages |
| Authors:
George Haller; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
|
| Our objective in this project was to derive a mathematically exact theory of unsteady fluid flow separation. We have obtained analytic formulae for the location and shape of separation profiles in terms of measurable, wall-based physical quantities. These formulae can now be used to design feedback controllers that alter, destroy, or create separation. Our main achievements are as follows: (1) We have developed a mathematical theory of unsteady three-dimensional separation ... |
|
| Hybrid LES of Detonations in Reacting Multi-Phase Mixtures |
28-Feb-2009 |
166 pages |
| Authors:
Suresh Menon; Franklin Genin; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| A Large-Eddy Simulation (LES) methodology adapted to the resolution of high Reynolds number turbulent flows in supersonic conditions was proposed and developed. A novel numerical scheme was designed, that switches from a low-dissipation central scheme for turbulence resolution to a flux difference splitting scheme in regions of discontinuities. A state-of-the-art closure model was extended in order to take compressibility effects and the action of shock / turbulence interaction into account. ... |
|
| Efficient Simulation and Novel Modeling by Using Generic Three-Dimensional Exact Solutions to Analyze Transport Dynamics in Turbulent Vortices |
28-Feb-2009 |
17 pages |
| Authors:
Sukalyan Bhattacharya; TEXAS TECH UNIV LUBBOCK
|
| In this project, we have formulated an alternative boundary-layer theory. This new analysis will be able to mathematically describe flow-separation unlike the classical theory. In our research, we have partially validated the developed theory and concluded that approach has considerable potential to account for flow-separation. The effective description of separated flow can potentially lead to a fast simulation-algorithm for aerodynamic computation. Our estimate predicts that this semianalytical scheme will compute ... |
|
| Towards High-Reynolds Number Quiet Flow in Hypersonic Tunnels |
23-Feb-2009 |
17 pages |
| Authors:
Doyle D Knight; Hadassah Naiman; RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The report summarizes a research program focused on two main issues related to the achievement of high Reynolds number quiet flow in hypersonic tunnels, namely, 1) automated optimal design of quiet hypersonic tunnels, and 2) tunnel startup in the presence of blunt models. In the former case, a fully automated optimal design methodology was developed to determine the optimal shape of the supersonic nozzle to achieve laminar flow on the ... |
|
| Analysis of Near-Surface Oceanic Measurements Obtained During CBLAST-Low |
09-Feb-2009 |
|
| Authors:
Albert J Plueddemann; John H Trowbridge; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
 | Measurements obtained during the low-wind component of the Coupled Boundary Layers and Air-Sea Transfer program (CBLAST-Low) were used to elucidate the energetics of the ocean surface boundary layer. This work addressed the closure of the turbulent kinetic energy (TKE) budget, the relationship between TKE and dissipation, and the roles of wave breaking and Langmuir circulation in controlling turbulent diffusivity. The measurements occurred primarily during conditions in which shear, buoyancy and ... |
|
| User's Manual for the Navy Coastal Ocean Model (NCOM) Version 4.0 |
06-Feb-2009 |
73 pages |
| Authors:
Clark Rowley; Paul J Martin; Charlie N Barron; Lucy F Smedstad; TImothy J Campbell; Alan J Wallcraft; Robert C Rhodes; Tamara L Townsend; Suzanne N Carroll; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEAN DYNAMICS AND PREDICTION BRANCH
|
| The version 4 series of the Navy Coastal Ocean Model (NCOM) has been developed at the Naval Research Laboratory (NRL) and transitioned to the Navy Oceanographic Office. New capabilities include a general vertical coordinate (GVC) option in addition to the sigma-z coordinate vertical grid, Earth System Modeling Framework (ESMF) compliance, and several other compile time options that increase the flexibility of the model code. NRL has also begun maintaining NCOM ... |
|
| Experimental/Computational Approach to Accommodation Coefficients and its Application to Noble Gases on Aluminum Surface (Preprint) |
03-Feb-2009 |
26 pages |
| Authors:
Andrew Ketsdever; Sergey F Gimelshein; Nathaniel Selden; Natalie E Gimelshein; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A technique is proposed to assess gas-surface accommodation coefficients. The technique utilizes the fact that radiometric forces exerted on heated objects immersed in rarefied gases are governed by the interaction of gas molecules with the surface. In the present implementation, it connects measurements of radiometric forces on a heated vane in the transitional flow regime with the kinetic modeling of the flow, and derives the accommodation coefficients through the successive ... |
|
| Stochastic Analysis and Control of Transonic Helicopter Aerodynamics and Supersonic Projectiles |
02-Feb-2009 |
6 pages |
| Authors:
Sivaguru S Sritharan; WYOMING UNIV LARAMIE
|
| The main goal of this project is to develop a systematic mathematical theory for the robust real time feedback control and stochastic analysis of unsteady transonic aerodynamics of helicopter rotor blades, supersonic ballistic projectiles and propagation of blast waves in the presence of adverse external disturbances. The proposed work builds upon similar scientific advances by the principal investigator in the context of incompressible fluid dynamics, magneto-hydrodynamics and combustion models during ... |
|
| Eddy-Mean Flow Interactions in Western Boundary Current Jets |
Feb-2009 |
|
| Authors:
Stephanie N Waterman; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| This thesis examines eddy-mean flow interactions in western boundary current jets via theoretical studies of eddy-mean flow interactions in idealized configurations and an observational analysis to characterize eddy-mean flow interactions in the Kuroshio Extension. Theoretical studies are made of the mechanism by which eddies drive recirculation gyres through nonlinear rectification, and the role that eddies play in the downstream evolution of a baroclinic jet subject to mixed instabilities. The observational ... |
|
| Mathematical Fluid Dynamics of Plasma Flow Control Over High Speed Wings |
Feb-2009 |
42 pages |
| Authors:
David Marshall; Alexander V Fedorov; Victor R Soloviev; V M Krivtsov; V G Soudakov; TELEDYNE SCIENTIFIC AND IMAGING LLC THOUSAND OAKS CA
|
| Develop theoretical models and computational tools for SDBD flow control applications. |
|
| West Adriatic Coastal Water Excursions into the East Adriatic |
15 Jan 2009 |
26 pages |
| Authors:
Ivica Vilibic; Jeffrey W Book; Gordana B Paktar; Mirko Orlic; Vlado Dadic; Martina Tudor; Paul J Martin; Miroslava Pasaric; Branka Grbec; Frano Matic; Hrvoje Mihanovic; Mira Morovic; INSTITUTE OF OCEANOGRAPHY AND FISHERIES SPLIT (CROATIA)
|
| A pool of less saline surface water was observed in late June 2006 at the northern edge of the South Adriatic Pit (SAP). Three possible sources were considered: (1) Albanian rivers, (2) local Croatian rivers, or (3) relatively fresh West Adriatic Current (WAC) waters. Available CTD and ADCP data, together with satellite images indicate that WAC waters are the most likely source. This requires an excursion of WAC water across ... |
|
| Experimental and Numerical Analysis of Radiometric Forces on a Heated Circular Vane in Argon (Preprint) |
13-Jan-2009 |
16 pages |
| Authors:
N Gimelshein; S Gimelshein; N Selden; C Ngalande; A Ketsdever; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Radiometric force on a 0.12m circular vane is studied experimentally and numerically over a wide range of pressures that cover the flow regimes from near free molecular to near continuum. In the experiment, the vane is resistively heated to about 419 K on one side and 394 K on the other side, and immersed in a rarefied argon gas. The radiometric force is then measured on a nano- Newton thrust ... |
|
| Integrated Computational/Experimental Study of Turbulence Modification and Mixing Enhancement in Swirling Jets |
07-Jan-2009 |
30 pages |
| Authors:
J Naughton; D Stanescu; S Heinz; R Semaan; M Stoellinger; C Zemtsop; WYOMING UNIV LARAMIE
|
| Swirling jet flows have been studied experimentally and computationally and the results have been compared with theory. Three-component Laser Doppler Anemometry (LDA) measurements have been carried out for swirling jets of various strengths and swirl distributions. Radial profiles of velocity have been obtained from the jet exit to 50 diameters downstream. The experimental results are consistent with previous results and with similarity theory for weakly swirling turbulent jets. However, the ... |
|
| Stochastic Nonlinear Aeroelasticity |
Jan-2009 |
41 pages |
| Authors:
Philip S Beran; Ned J Lindsley; Jose Camberos; Mohammad Kurdi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report documents the culmination of in-house work in the area of uncertainty quantification and probabilistic techniques for aeroelasticity. The work was divided into different project areas, including: accurate analysis of limit-cycle oscillations for simple aeroelastic systems with variability; probabilistic prediction of flutter in systems with distributed variability (random fields); optimization of nonlinear dynamic systems (deterministic with intent to transition to risk-quantified optimization), and incorporation of sensitivities into probabilistic analyses. ... |
|
| Detection of Rossby Waves in Multi-Parameters in Multi-Mission Satellite Observations and HYCOM Simulations in the Indian Ocean |
Jan-2009 |
12 pages |
| Authors:
Jay F Shriver; Bulusu Subrahmanyam; David M Heffner; David Cromwell; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Rossby waves are difficult to detect with in situ methods. However, as we show in this paper, they can be clearly identified in multi-parameters in multi-mission satellite observations of sea surface height (SSH), sea surface temperature (SST) and ocean color observations of chlorophyll-a (chl-a), as well as 1/12-deg global HYbrid Coordinate Ocean Model (HYCOM) simulations of SSH, SST and sea surface salinity (SSS) in the Indian Ocean. While the surface ... |
|
| Summary Diagrams for Coupled Hydrodynamic-Ecosystem Model Skill Assessment |
Jan-2009 |
22 pages |
| Authors:
Bradley Penta; Robert Helber; Jason K Jolliff; Igor G Shulman; John C Kindle; Robert A Arnone; Marjorie A M Friedrichs; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| The increasing complexity of coupled hydrodynamic-ecosystem models may require skill assessment methods that both quantify various aspects of model performance and visually summarize these aspects within compact diagrams. Hence summary diagrams, such as the Taylor diagram (Taylor, 2001. Journal of Geophysical Research. 106. D7. 7183-7192). may meet this requirement by exploiting mathematical relationships between widely known statistical quantities in order to succinctly display a suite of model skill metrics in ... |
|
| Dynamic Length-Scale Characterization and Nonequilibrium Statistical Mechanics of Transport in Open-Cell Foams |
Jan-2009 |
5 pages |
| Authors:
Tyler R Brosten; Sarah L Codd; Robert S Maier; Joseph D Seymour; MONTANA STATE UNIV BOZEMAN DEPT OF MECHANICAL ENGINEERING
|
| Nuclear magnetic resonance measurements of scale dependent dynamics in a random solid open-cell foam reveal a characteristic length scale for transport processes in this novel type of porous medium. These measurements and lattice Boltzmann simulations for a model foam structure indicate dynamical behavior analogous to lower porosity consolidated granular porous media, despite extremely high porosity in solid cellular foams. Scaling by the measured characteristic length collapses data for different foam ... |
|
| Laboratory and Numerical Studies of Hydrodynamics Near Jetties |
Jan-2009 |
34 pages |
| Authors:
Zeki Demirbilek; Lihwa Lin; Hajime Mase; Jinhai Zheng; William C Seabergh; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
|
| Numerical and physical modeling studies were performed by the Coastal Inlets Research Program (CIRP) of the U.S. Army Corps of Engineers to investigate the spatial and temporal behavior of waves and wave-induced currents near jetties of an idealized coastal inlet. Hydrodynamics were examined in the vicinity of two extreme types of jetty structure: a highly absorbing jetty (resembling fairly porous rock rubble structure) and a fully reflective jetty (resembling a ... |
|
| Equivalent Roughness Height for Plane Bed Under Oscillatory Flow |
Jan-2009 |
15 pages |
| Authors:
Magnus Larson; Benoit Camenen; Atilla Bayram; CEMAGREF LYON (FRANCE)
|
| A new relationship between the roughness height and the main hydrodynamic and sediment parameters for plane beds under oscillatory conditions is presented. In order to derive such a relationship, a large data base encompassing plane-bed experiments was compiled from previous investigations and analyzed. Different methods to estimate the roughness height were investigated. Comparisons between the data and different existing predictive formulas for the bed roughness obtained from the literature were ... |
|
| High SST Variability South of Martha's Vineyard: Observation and Modeling Study |
Jan 2009 |
19 pages |
| Authors:
Xiaodong Hong; Paul J Martin; Shouping Wang; Clark Rowley; NAVAL RESEARCH LAB MONTEREY CA
|
| High, small-scale SST variability (6 deg C over 5-10 km) observed South of Martha's Vineyard during the low wind component of the Coupled Boundary Layers Air-Sea Transfer (CBLAST-Low) oceanographic field program in August 2003 is investigated using the Navy Coastal Ocean Model (NCOM), with atmospheric forcing provided by the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS(Registered)). 1 The ocean model includes tidal boundary forcing by the eight major tidal constituents, which ... |
|
| Samplers for Evaluation and Quantification of Ultra-Low Volume Space Sprays |
Jan 2009 |
5 pages |
| Authors:
M Farooq; W C Hoffmann; T W Walker; V L Smith; C A Robinson; J C Dunford; I W Sutherland; NAVY ENTOMOLOGY CENTER OF EXCELLENCE JACKSONVILLE FL
|
| A field study was conducted to explore the suitability of 5 pesticide deposition samplers for airborne spray and ground deposits from ultra-low-volume (ULV) space sprays. Samplers included horizontally stretched stationary cotton ribbons at 2 heights, rotating ribbon, rotating Teflon slides, and filter paper. Slides were also used for droplet-size analysis. A set of 7 samplers of each type was placed at 1, 7, 15, 25, 40, 65, and 90 m ... |
|
| The Effects of Laser Energy Deposition on Supersonic Cavity Flow |
Jan 2009 |
9 pages |
| Authors:
Selin Aradag; Hong Yan; Doyle Knight; TOBB UNIV OF ECONOMICS AND TECHNOLOGY ANKARA (TURKEY)
|
| The study examines the capability for reduction of the resonant pressure fluctuations in supersonic flow over an open rectangular cavity using repetitively pulsed energy deposition, computationally. The simulations are performed for the cases both with and without energy deposition for the unsteady flow over a three-dimensional cavity at a free stream Mach number of 1.5. The Reynolds-averaged compressible time dependent Navier Stokes equations in three dimensions are solved using the ... |
|
| Blending Chem-Bio Dispersion Forecasts and Sensor Data |
31 Dec 2008 |
204 pages |
| Authors:
Tarunraj Singh; Peter Scott; Puneet Singla; Yang Cheng; Uma Konda; Gabriel Terejanu; Alex James; Sue E Haupt; George Young; Anke Beyer-Lout; Kerrie Long; CUBRC INC BUFFALO NY
|
| In a chemical release incident, two important questions in hazard prediction and assessment are: Where are the sources located? and, What is the plumes dispersion profile? This report details the development, and testing of algorithms to address the two questions. SCIPUFF is the model of choice for forecasting the dispersion which is used in conjunction with sensor data and meteorological data for improving the forecast and the identification of the ... |
|
| An Investigation of a Gas Laser Pressure Recovery System Diffuser |
19-Dec-2008 |
10 pages |
| Authors:
Carrie A Noren; Theodore Ortiz; Michael Wilkinson; Wade Klennert; Timothy J Madden; Richard W Chan; H W Behrens; Robert Walter; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A diffuser, with the purpose of efficiently recovering pressure from a gas laser system, was designed and studied. A diffuser, as part of a pressure recovery system, is used in a gas laser system to transition the laser cavity's low pressure to the ambient pressure outside the device. The diffuser studied here is made up of a constant-area supersonic section and a diverging subsonic section. The diffuser is studied experimentally ... |
|
| Transition Delay in Hypervelocity Boundary Layers by Means of CO2/Acoustic Instability Interactions |
08-Dec-2008 |
52 pages |
| Authors:
Graham Candler; Ivett A Leyva; Stuart Laurence; Amy W Beierholm; Hans G Hornung; Ross Wagnild; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A novel method to delay transition in hypervelocity flows over slender bodies by injecting CO2 into the boundary layer of interest is investigated. The results presented here consist of both experimental and computational data. The experimental data was obtained at Caltech's T5 reflected shock tunnel, while the computational data was obtained at the University of Minnesota. The experimental model was a 5 degree sharp cone, chosen because of its relevance ... |
|
| Measurements of the Effectiveness of Concave Spherical Dimples for Enhancement of Hot-gas Side Heat Transfer (Preprint) |
04-Dec-2008 |
10 pages |
| Authors:
Stephen A Danczyk; Edward B Coy; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Measurements of the heat transfer enhancement effects of concave spherical dimples have been performed under hydrogenoxygen hot-fire conditions in a subscale combustion chamber. Seven configurations were tested with a range of area densities from 15-70% and depth to diameter ratios of 0.111 to 0.333. (Additional quantitiative results will included in the form of heat transfer coefficients and Stanton number.) Enhancements of 15-82% relative to a smooth surface were measured. Reynolds ... |
|
| Simulation of Flow Past a Sphere using the Fluent Code |
Dec-2008 |
35 pages |
| Authors:
D A Jones; D B Clarke; DEFENSE SCIENCE AND TECHNOLOGY ORGANIZATION VICTORIA (AUSTRALIA) MARITIME PLATFORMS DIV
|
| We use the commercial computational fluid dynamics code Fluent to simulate the flow around a sphere in several different flow regimes; steady-state laminar flow at a Reynolds number (Re) of 100, time-dependent laminar flow at Re = 300, and turbulent flow at Re = 10,000 and Re = 1,000,000. These simulations provide a test of the ability of the code to accurately reproduce typical flow structures observed in generic bluff ... |
|
| A Computational Framework Based on Variational LES Method for the Multi-Disciplinary Analysis of MAVS With Flapping Wings |
Dec-2008 |
8 pages |
| Authors:
Charbel Farhat; Ajaykumar Rajasekharan; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
|
| In this paper the three level formulation of a variational multi-scale (VMS) large eddy simulation (LES) method for compressible flow computations is extended for applications involving moving/deforming grids. A consistent method to improve the VMS-LES constant dynamically as the flow develops (dynamic VMS-LES) is also extended for dynamic grid applications. Two applications of VMS-LES for the simulation of separated flow over moving NACA-0012 extruded airfoil is then presented. The first ... |
|
| Modeling Combustion Chamber Dynamics of Impinging Stream Vortex Engines Fueled With Hydrazine-Alternative Hypergols |
Dec-2008 |
9 pages |
| Authors:
C C Chen; M J Nusca; M J McQuaid; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| To advance the development of Impinging Stream Vortex Engines (ISVEs) for tactical missile propulsion system applications, a computational fluid dynamics (CFD) modeling capability has been developed and employed to simulate the combustion chamber dynamics of various ISVE designs. Simulations of firstgeneration ISVE configurations fueled with monomethylhydrazine/ red fuming nitric acid (MMH/RFNA) led to insights that inspired a combustion chamber design change, and simulations of an ISVE with the new feature ... |
|
| A Shock Tube for Downselecting Material Concepts for Blast Protection. Part I: Description of the Shock Tube and a Comparison of Flush Mounted and Recess Mounted Pressure Sensors |
Dec-2008 |
27 pages |
| Authors:
Ronald A Segars; Marina G Carboni; ARMY NATICK SOLDIER RESEARCH DEVELOPMENT AND ENGINEERING CENTER MA
|
| This report documents Part I of a study on the interaction between shock waves and material systems as part of a U.S. Army initiative to better protect individual Soldiers against novel blast threats. The research was conducted using a shock tube fabricated at the U.S. Army Natick Soldier Research, Development and Engineering Center (NSRDEC). The shock tube was used because it is less expensive than explosive blasts, allows many tests ... |
|
| User's Manual for the Polar Ice Prediction System (PIPS) Version 3.0 |
05-Nov-2008 |
84 pages |
| Authors:
E J Metzger; Lucy F Smedstad; Suzanne N Carroll; Pamela G Posey; Ruth H Preller; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| The Polar Ice Prediction System (PIPS) Version 3.0 is a dynamic sea-ice model that forecasts conditions in all sea-ice covered areas in the northern hemisphere (down to 30 degrees north in latitude). It has a horizontal resolution of approximately 9 km. The vertical resolution in the model has been set at 45 levels so that Arctic shelves, continental slopes, and submarine ridges are accurately represented. Currently, the domain includes the ... |
|
| Dynamically Resolved Simulation of Atmospheric Features and Turbulence Using Advanced Models and Adaptive Algorithms |
30-Oct-2008 |
36 pages |
| Authors:
Xudong Xiao; D S McRae; Hassan A Hassan; Yih-Pin Liew; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| In order to resolve atmospheric features, such as gravity waves to the degree necessary for accurate optical turbulence prediction, we developed an adaptive version of MM5 that incorporates the NCSU Dynamic Solution Adaptive Grid Algorithm (DSAGA) and a new four-equation hybrid LES/RANS turbulence model that provides a new approach for the calculation of the index of refraction structure function Cn2, a quantitative measure of atmospheric optical turbulence. These four equations ... |
|
| Transition Delay in a Hypervelocity Boundary Layer using Nonequilibrium CO2 Injection |
28-Oct-2008 |
132 pages |
| Authors:
Amy K Beierholm; Ivett Leyva; S J Laurence; J Jewel; H G Hornung; CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
|
| A new technique to delay transition to turbulence in hypervelocity air flows is introduced and investigated in this work. The main motivation for such a technique is the pressing need to reduce aerodynamic heating rates on hypersonic vehicles. Turbulent heat transfer rates can be an order of magnitude higher than laminar rates at hypersonic Mach numbers. Hence, schemes to delay transition to turbulence could provide an important means to reduce ... |
|
| Integration of Microwave Plasma Ignition Into a Multi-Fuel Engine |
Oct-2008 |
14 pages |
| Authors:
James Smith; WEST VIRGINIA UNIV MORGANTOWN
|
| The purpose of this effort was to demonstrate the successful integration of a Quarter-Wave Coaxial Cavity Resonator Plasma Igniter into a multi-fuel engine. The grantee successfully accomplished the objective by demonstrating successful engine operation with both gasoline and jet fuel. Microwave frequency stimulation of the highly ionized combustion mixture, and generation of reactive oxygen species can potentially result in more complete combustion, preventing in-cylinder build-up of deposits and achieving improved ... |
|
| HyPAq: Software for the Transient Analysis of Hypersonic Vehicles in Abaqus |
Oct-2008 |
|
| Authors:
Nigel S Smith; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
|
| The Defence Science and Technology Organisation (DSTO) has embarked upon a research and development program fro air breathing hypersonic vehicles. Part of this program involves the selection and development of software tools useful in the aerothermo-structural design of these vehicles. HyPAq is a hypersonic package for Abaqus - a set of programs and subroutines to be used in conjunction with that particular finite element analysis code. HyPAq interpolates pressures and ... |
|
| Rotorcraft Downwash Flow Field Study to Understand the Aerodynamics of Helicopter Brownout |
Oct-2008 |
28 pages |
| Authors:
Mark Potsdam; Alan J Wadcock; Lindsay A Ewing; Eduardo Solis; Ganesh Rajagopalan; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
|
| Rotorcraft brownout is caused by the entrainment of dust and sand particles in helicopter downwash, resulting in reduced pilot visibility during low, slow flight and landing. Recently, brownout has become a high-priority problem for military operations because of the risk to both pilot and equipment. Mitigation of this problem has focused on flight controls and landing maneuvers, but current knowledge and experimental data describing the aerodynamic contribution to brownout are ... |
|
| A Framework for Uncertainty Quantification in Nonlinear Multi-Body System Dynamics |
22-Sep-2008 |
9 pages |
| Authors:
D Negrut; M Datar; D Gorsich; D Lamb; WISCONSIN UNIV-MADISON DEPT OF MECHANICAL ENGINEERING
|
| This paper outlines a methodology for determining the statistics associated with the time evolution of a nonlinear multi-body dynamic system operated under input uncertainty. The focus is on the dynamics of ground vehicle systems in environments characterized by multiple sources of uncertainty: road topography, friction coefficient at the road/tire interface and aerodynamic force loading. Drawing on parametric maximum likelihood estimation, the methodology outlined is general and can be applied to ... |
|
| FY07 NRL DoD High Performance Computing Modernization Program Annual Reports |
05-Sep-2008 |
109 pages |
| Authors:
Portia A Shingler; Beth A Howell; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL SCIENCE
|
| These reports summarize the accomplishments of the NRL Principal Investigators who received computer allocations on the DoD High Performance Computing Modernization Program Shared Resource Center in FY07. |
|
| RDHWT/MARIAH II Hypersonic Wind Tunnel Research Program |
01-Sep-2008 |
165 pages |
| Authors:
M L Laster; C C Limbaugh; J L Jordan; AEROSPACE TESTING ALLIANCE (ATA) ARNOLD AFB TN
|
| The U.S. Air Force sponsored and the USAF Arnold Engineering Development Center directed the Radiantly Driven Hypersonic Wind Tunnel (RDHWT)/ Magnetohydrodynamic Accelerator Research Into Advanced Hypersonics (MARIAH II) Program. This report primarily covers the research for the period from January 2001 through July 2004. The scope of the research program was to develop enabling technologies for a medium-scale hypersonic wind tunnel (MSHWT) that would provide a Mach 8 to 15 ... |
|
| Morphing Aircraft Structures: Research in AFRL/RB |
01-Sep-2008 |
35 pages |
| Authors:
Brian Sanders; Shiv Joshi; Jayanth Kudva; Geoffrey J Frank; Franklin E Eastep; Bryan Cannon; Matthew P Snyder; Jason C Bowman; Gregory W Reich; Terrence Weisshaar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report reviews research in several different areas related to morphing aircraft structures undertaken in AFRL/RBSA. The first is an aeroelastic analysis of a folding-wing vehicle to determine the flutter boundaries of the wing at different fold angles. The second is the development of a simulation tool to study both the flight stability of a morphing vehicle during the morphing process, and the kinematic stability of the morphing mechanism subject ... |
|
| Mechanical Response of an Al-PTFE Composite to Uniaxial Compression Over a Range of Strain Rates and Temperatures |
01-Sep-2008 |
28 pages |
| Authors:
Daniel T Casem; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Compressive stress-strain curves were generated for a pressed and sintered mixture of polytetrafluoroethylene and aluminum powders. Experiments were performed at strain rates ranging from 0.001 to 8000/s using a servo-hydraulic load frame and a split Hopkinson pressure bar. High-rate experiments were also performed over a temperature range of 22-78 C. The data is fit to the Johnson-Cook and Modified Johnson-Cook constitutive equations and also to a Zerilli-Armstrong equation adapted for ... |
|
| The Key Role of Surface Tension in the Theory of Bubble-Assisted Explosion/Combustion Triggering |
01-Sep-2008 |
20 pages |
| Authors:
Michael Grinfeld; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| We have revised the classical and widely accepted theory of (Bowden, F. P.; Yoffe, A. D. The Initiation and Growth of Explosion in Liquids and Solids; Cambridge University Press: New York, NY, 1952) explaining the initiation of explosion/combustion by means of adiabatic compression of the dissolved gaseous bubbles within condensed liquid substances. The main thrust of our study is to explore the role of surface tension at the interface liquid ... |
|
Fluid Mechanics
