| 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
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 | 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 ... |
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| Development of Carbon/Carbon Composites with Through-Thickness Carbon Nanotubes for Thermal and Structural Applications |
Dec-2008 |
34 pages |
| Authors:
Zhiyong (Richard) Liang; Chuck Zhang; FAMU/FSU COLL OF ENGINEERING TALLAHASSEE FL DEPT OF INDUSTRIAL ENGINEERING
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| Carbon/carbon composites offer lightweight thermal protection capable of producing excellent thermal materials. To further improve the thermal conductivity along the thickness direction and the interlaminar shear strength, we studied and demonstrated a novel method to stitch carbon nanotube yarns along the through-thickness direction of carbon fiber two-dimensional precursor felt perform to make novel 3D reinforced carbon/carbon (C/C) composites. By stitching nanotube yarns, high strength and thermal conductive CNTs were incorporated ... |
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| Comparison of Engineering Correlations for Predicting Heat Transfer in Zero-pressure-gradient Compressible Boundary Layers with CFD and Experimental Data |
Aug-2008 |
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| Authors:
K Higgins; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
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 | The aim of this report is to investigate the details and performance of several engineering correlation methods used for predicting skin friction and heat transfer rates in high-speed flows. These are the van Driest, Eckert and Spalding & Chi correlations, which, in the form presented herein, can only be used for zero-pressure-gradient flows. This limits the scope of the report to flow past flat plates, and also wedges and cones ... |
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| Investigation of the Role of Transient Growth in Roughness-Induced Transition |
31-Mar-2008 |
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| Authors:
Eli Reshotko; Edward B White; TEXAS ENGINEERING EXPERIMENT STATION COLLEGE STATION
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| A number of topics relating to transient growth are addressed. These encompass its roots in stability theory, computation of optimal transient growth characteristics for both parallel and non-parallel flow formulations, and the application of this information to multimode decomposition and roughness-induced transition. All of these are based on the spatial transient growth theory. For the important case of nosetip transition, the resulting transition relations reproduce the trends of the Reda ... |
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| Combustion of JP8 in Laminar Premixed Flames |
12 MAR 2008 |
19 pages |
| Authors:
Kalyanasundaram Seshadri; CALIFORNIA UNIV SAN DIEGO LA JOLLA
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| Experimental and numerical studies are carried out to develop a surrogate that can reproduce selected aspects of combustion of JP-8. Surrogate fuels are defined as mixtures of few hydrocarbon compounds with combustion characteristics similar to those of commercial fuels. A mixture of n-decane and trimethylbenzene, called the Aachen surrogate, and a mixture of n-dodecane, methylcyclohexane, and o-xylene called Surrogate C are selected for consideration as possible surrogates of JP-8. Experiments ... |
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| Laser Diagnostic System Validation and Ultra-Compact Combustor Characterization |
MAR 2008 |
172 pages |
| Authors:
Terry B. Hankins; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The AFIT combustion optimization and analysis laser (COAL) lab is now completely operational and is state-of-the-art in combustion diagnostics. The objective of this research is to perform a validation of a laser diagnostic system and to begin the characterization of a small-scale model of an ultra-compact combustor (UCC). Validation of the laser system was accomplished by using planar laser induced fluorescence (PLIF) on a laminar premixed hydrogen-air flame produced by ... |
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| Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel |
11 DEC 2007 |
151 pages |
| Authors:
Rodrigo Segura; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
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| Laminar-turbulent transition is a pivotal factor for the design of hypersonic vehicles but the mechanisms that induce transition are not well understood. A laser differential interferometer (LDI) is a non-intrusive optical device that measures the optical path length difference between two laser beams. The LDI is a reliable calibrated instrument to assist the study of boundary layer instability-wave growth in hypersonic flow and has high sensitivity and frequency response. An ... |
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| Autoignition and Combustion of Diesel and JP-8 |
19 JUL 2007 |
51 pages |
| Authors:
Kalyanasundaram Seshadri; CALIFORNIA UNIV SAN DIEGO LA JOLLA OFFICE OF CONTRACT AND GRANT ADMINISTRATION
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| The Department of Defense directive 4140.25 dated April 12, 2004 mandates that "primary fuel support for land-based air and ground forces in all theaters shall be accomplished using a single kerosene-based fuel, in order of precedence: JP-8, commercial jet fuel (with additive package), or commercial jet fuel (without additives)." The objective of the proposed research is to understand those key aspects of combustion of JP-8 that are required to facilitate ... |
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| CFD Investigation of Effect of Depth to Diameter Ratio on Dimple Flow Dynamics |
JUN 2007 |
83 pages |
| Authors:
Robert B. Etter; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This study aimed to further the understanding of laminar flow through a dimple with the goal of mitigating flow separation. Dimples of various depth to diameter ratios (0.05, 0.15) were examined for three different dimple diameters and chordwise locations, corresponding to diameter based (ReD) and chordwise location based (Rex) Reynolds number combinations of ReD 20500\Rex 5000, ReD 20500 Rex 77000, and ReD 9000 Rex 21000. For the last combination, a ... |
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| High-Speed Digital-Image Data Acquisition, Processing, and Visualization System for Turbulent Mixing and Combustion |
25 MAY 2007 |
13 pages |
| Authors:
Paul E. Dimotakis; CALIFORNIA INST OF TECH PASADENA DEPT OF AERONAUTICS
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| This report summarizes an equipment and instrumentation system for high-speed digital image data acquisition and processing. The research program targets the physics of turbulence, mixing, and combustion, focusing on high-speed environments. The system includes components for Planar Laser Induced Fluorescence (PLIF), flame-speed, and ignition and extinction measurements of laminar flames at variable pressure; tracking flow structures in a high-speed mixing layer using high-speed color schlieren; laser-beam manipulation and volume scanning ... |
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| Rapid, Femtomolar Bioassays in Complex Matrices ComBining Microfluidics and Magnetoelectronics |
22 MAR 2007 |
32 pages |
| Authors:
S. P. Mulvaney; C. L. Cole; M. D. Kniller; M. Malito; C. R. Tamanaha; J. C. Rife; M. W. Stanton; L. J. Whitman; NAVAL RESEARCH LAB WASHINGTON DC
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| A significant challenge for all biosensor systems is to achieve high assay sensitivity and specificity while minimizing sample preparation requirements, operational complexity, and sample-to-answer time. We have achieved multiplexed, unamplified, femtomolar detection of both DNA and proteins in complex matrices "including whole blood, serum, plasma, and milk" in minutes using as few as two reagents by labeling conventional assay schemes with micrometerscale magnetic beads, and applying fluidic force discrimination "FFD". ... |
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| Advancing Detached-Eddy Simulation |
2007 |
110 pages |
| Authors:
Kyle D. Squires; ARIZONA STATE UNIV TEMPE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| Measurements show that the flow over the Aerospatiale A-airfoil experiences a laminar separation in the vicinity of the leading edge region, just downstream of the peak negative pressure along the suction side. Transition occurs in the separated shear layer with the reattached turbulent boundary layer evolving further along the suction side prior to a subsequent separation near the trailing edge. The laminar separation and transition is accounted for using the ... |
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| Experimental Studies of Transitional Boundary Layer Shock Wave Interactions |
DEC 2006 |
14 pages |
| Authors:
N. T. Clemens; D. S. Dolling; Z. R. Murphree; K. B. Yueceil; TEXAS UNIV AT AUSTIN CENTER FOR AEROMECHANICS RESEARCH
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| Transitional shock wave/boundary layer interactions are studied with planar imaging techniques. The interaction is generated by a cylinder mounted on a flat plate in a Mach 5 flow. Planar laser scattering (PLS) and particle image velocimetry (PIV) are used to visualize the flow structure. Images are obtained in streamwise-spanwise planes (plan view). Earlier work focused on investigating similar interactions with tripped boundary layers, whereas the current work focuses on the ... |
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| Experimental and Detailed Numerical Studies of Fundamental Flame Properties of Gaseous and Liquid Fuels |
DEC 2006 |
120 pages |
| Authors:
Fokion N. Egolfopoulos; CALIFORNIA UNIV LOS ANGELES
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| The dynamic behavior of laminar flames was studied for a wide range of conditions. The parameters considered included the fuel type, reactant composition, flame temperature, and combustion mode. Both gaseous and liquid fuels, including jet fuels and their surrogates, were considered. Flame ignition and extinction limits were determined experimentally and numerically for fuels and reaction conditions that have not been considered previously. For both low and high molecular weight fuels, ... |
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| Experimental Investigation of Pitch Control Enhancement to the Flapping Wing Micro Air Vehicle |
DEC 2006 |
135 pages |
| Authors:
Chin C. Kian; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The mechanical pitching characteristic of the NPS flapping-wing Micro Air Vehicle (MAV) developed by Professor Kevin D. Jones are studied experimentally through the use of constant temperature anemometry and force balance techniques. The MAV without the main fixed-wing is placed in a laminar flow field within a low speed wind tunnel with the wake after the flapping wings characterized with a constant temperature anemometer and thrust generation measured by a ... |
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| Measurements and Modeling of SiCl(4) Combustion in a Low-Pressure H2/O2 Flame |
10 NOV 2006 |
28 pages |
| Authors:
T. Moore; B. Brady; L. R. Martin; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
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| Laser-Induced Fluorescence (LIF) was used to measure temperature and OH concentration profiles as a function of distance from a McKenna-style burner in premixed, one-dimensional, low-pressure H2/O2/Ar SiCl4-doped flames. The addition of SiCl4 was shown to affect the flame temperature and OH concentration profiles. A gas-phase chemical kinetics mechanism for the combustion of SiCl in an H2/O2/Ar flame was proposed, and experimental results were compared with predictions for a premixed, one-dimensional ... |
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| Nonlinear Wave Interaction with Submerged and Surface-Piercing Porous Structures |
SEP 2006 |
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| Authors:
Okey Nwogu; Zeki Demirbilek; MICHIGAN UNIV ANN ARBOR DEPT OF NAVAL ARCHITECTURE AND MARINE ENGINEERING
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| A coupled Boussinesq-boundary integral method is developed to simulate nonlinear water wave interaction with structures consisting of multiple layers with different physical and hydraulic characteristics. The flow field in the water region is modeled with a modified set of Boussinesq-type equations, with additional terms to account for the flow of water into/out of the porous region. The equations of motion for the porous regions include an empirical Forchheimer-type term for ... |
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| Robust Controller for Turbulent and Convective Boundary Layers |
01 AUG 2006 |
69 pages |
| Authors:
Jason L. Speyer; J. John Kim; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| Linear feedback controllers and estimators have been designed from the governing equations of a channel flow, linearized about the laminar mean flow, and a layer of heated fluid, linearized about the no-motion state. Spectral decomposition involving a two-dimensional Fourier expansion and a Chebyshev-Galerkin projection cast these linearized equations into state-space form that decoupled to independent Fourier wavenumber sub-systems. The control law are designed by applying Linear Quadratic Gaussian (LQG) synthesis ... |
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| Proper Orthogonal Decomposition (POD)/Response Surface Methodology (RSM) Methodology for Low Reynolds Number Aerodynamics on Micro Aerial Vehicle (MAV) |
JUL 2006 |
49 pages |
| Authors:
Danny Liu; Lei Tang; ZONA TECHNOLOGY INC SCOTTSDALE AZ
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| This report was developed under a SBIR contract. The phase I project results in two major accomplishments that will facilitate the follow-on MAV design/analysis procedures. These are: a new computational (CFD) approach in the treatment of the low Reynolds number (low-Re) aerodynamics for airfoils and a proper orthogonal decomposition (POD) technique that is essential in providing a rapid CFD solution retrieval/reconstruction procedure for evaluations of forces, and moments for 3D ... |
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| Performance of a Liquid Flow Ultra-Compact Heat Exchanger |
JUN 2006 |
65 pages |
| Authors:
Michael A. Sammataro; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A numerical analysis of the performance of compact pin-fin array heat exchangers was carried out using water and JP-4 fuel as the working fluids. Three different configurations were used with hydraulic diameters ranging from 0.137 to 0.777 mm and volumetric area densities varying between 4.5 and 14.5 mm2/mm3. Numerical simulations were carried out to determine the performance of each heat exchanger over a series of Reynolds numbers in both the ... |
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| Numerical Prediction of Laminar Shock/Shock Interactions in Hypersonic Flow |
01 JAN 2006 |
11 pages |
| Authors:
Domenic D'Ambrosio; POLITECNICO DI TORINO (ITALY) DEPT DI INGEGNERIA AERONAUTICA E SPAZIALE
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| The results of a series of numerical simulations are presented of experiments conducted at the ONERA Chalais-Meudon Research Center and at the CALSPAN-University at Buffalo Research Center on shock-shock interactions. The flow-field characteristics are described with the aid of the numerical predictions and the computed values of surface pressure and heat transfer are compared with the experimental measurements for purposes of verification and validation. A preliminary grid refinement study is ... |
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| CFD Validation of Shock-Shock Interaction Flow Fields |
01 JAN 2006 |
27 pages |
| Authors:
S. Walker; J. D. Schmisseur; AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ARLINGTON VA
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| Current capabilities for numerical simulation of laminar shock-shock interactions are examined. Two fundamental configurations are considered: the Edney IV shock-shock interaction and the crossing oblique-shock interaction generated by a double wedge configuration. Two cases for each configuration were examined by a distinguished group of international researchers using the Reynolds-averaged Navier-Stokes (RANS) equations and Direct Simulation Monte Carlo (DSMC) methods. The report presents an extensive comparison of the submitted computations and ... |
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| Evaluation of Microphone Windscreen Performance in a Wind Tunnel |
DEC 2005 |
32 pages |
| Authors:
Tung-Duong Tran-Luu; Latasha Solomon; ARMY RESEARCH LAB ADELPHI MD
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| Turbulent wind noise can severely degrade acoustic signals often making it difficult to detect classify and/or track signals of interest. Windscreens are often used to suppress such noise. This research compares the effectiveness of various windscreens to suppress wind noise while tested in a controlled environment. |
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| A CFD Analysis of The Performance of Pin-Fin Laminar Flow Micro/Meso Scale Heat Exchangers |
SEP 2005 |
107 pages |
| Authors:
Sotirios Dimas; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A full three dimensional computational study was carried out using a finite-volume based solver for analyzing the performance of pin-fin based micro/meso scale heat exchangers with air as the working fluid. A staggered arrangement of cylindrical pin fins in rectangular channel geometry was used. Various configurations were considered consistent with a parallel experimental study being conducted based on a micro-wind tunnel setup. The pin/channel height used was 0.4 mm, and ... |
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| Laminar Boundary-Layer Instabilities on Hypersonic Cones: Computations for Benchmark Experiments |
AUG 2005 |
147 pages |
| Authors:
Tyler W. Robarge; PURDUE UNIV LAFAYETTE IN
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| Although significant advances have been made in hypersonic boundary-layer transition prediction in the last several decades, most design work still relies on unreliable empirical correlations or wind-tunnel tests. Codes using the semi-empirical eN method will need to be well verified and validated before being used for expensive flight vehicles. The code package STABL and its PSE-Chem stability solver are used to compute first and second-mode instabilities for both sharp and ... |
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| Control of Aerodynamic Flows. Delivery Order 0051: Transition Prediction Method Review Summary for the Rapid Assessment Tool for Transition Prediction (RATTraP) |
15 JUN 2005 |
95 pages |
| Authors:
Myron B. Davis; Helen Reed; Harold Youngren; Brian Smith; Erich Bender; LOCKHEED MARTIN AERONAUTICS CO FORT WORTH TX
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| The purpose of this report is to review available methods for predicting the transition of boundary layers. The emphasis will be on methods for transition mechanisms which are relevant to the flight conditions and geometric configurations of high altitude, long endurance aircraft, although the methods themselves may be much more general than this specific case. Each method will be evaluated according to certain criteria which are appropriate to the development ... |
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| Air Vehicles Technology Integration Program (AVTIP). Delivery Order 0020: Prediction of Manufacturing Tolerances for Laminar Flow |
JUN 2005 |
290 pages |
| Authors:
Aaron Drake; Anne M. Bender; William D. Solomon Jr.; Andrea J. Vavra; NORTHROP GRUMMAN CORP EL SEGUNDO CA AIR COMBAT SYSTEMS
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| An examination of the effects of surface excrescences on boundary layer transition has been performed, including both experimental and computational components. The experimental study focused on stagnation-line starting condition boundary layers in incompressible flow without sweep effects. The study was performed at low-Reynolds number-less than 106-and included the effects of both adverse and favorable pressure gradients. The results for both forward and aft-facing steps indicate a substantial stabilizing effect of ... |
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| Laminar Boundary-Layer Instabilities on Hypersonic Cones: Computations for Benchmark Experiments |
JUN 2005 |
19 pages |
| Authors:
Tyler W. Robarge; Steven P. Schneider; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
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| Although significant advances have been made in hypersonic boundary- layer transition prediction in the last several decades, most design work still relies on empirical correlations or wind tunnel tests. Codes using the semi- empirical eN method will need to be verified and validated before being used for expensive flight vehicles. The STABL code package and its PSE-Chem stability solver are used to compute first and second mode instabilities for both ... |
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| Molecular Dynamics Simulations of Supercritical Jets |
30 APR 2005 |
21 pages |
| Authors:
Michael Oschwald; Mike M. Micci; H. Shin; N. Hammou; G. Schneider; DEUTSCHES ZENTRUM FUR LUFT-UND RAUMFAHRT E V LAMPOLDSHAUSEN (DLR) HARDTHAUSEN (GERMANY)
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| In a previous report, we have presented the argon nanojet injection simulation results under vacuum condition. This study also focused on the effect of injector shape on jet breakup behavior. However, geometrical effects were not so prominent. After a thorough analysis, we concluded that the temperature of the liquid in the solid injector is the governing factor for subsequent nanojet breakup characteristics. We will introduce this conclusion with detailed description ... |
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| Array System for Supercavitating Hydrofoils |
19 JAN 2005 |
13 pages |
| Authors:
Thomas J. Gieseke; DEPARTMENT OF THE NAVY WASHINGTON DC
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| This patent application discloses a sonar system that includes a forward-looking array that is embedded in a cavitator for generating a gaseous cavity that minimizes hydrodynamic noise resulting from turbulent pressure fluctuations. A marine vessel incorporating the sonar system includes a hull, a hydrofoil suspended beneath the hull by a strut, and a cavitator for generating a laminar flow over the hydrofoil and for creating a cavity for eliminating turbulent ... |
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| Apparatus for Producing Gaseous Vapor Baffle |
19 JAN 2005 |
16 pages |
| Authors:
Thomas J. Gieseke; DEPARTMENT OF THE NAVY WASHINGTON DC
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| This patent application discloses an apparatus that produces a gaseous vapor baffle that isolates an undersea sonar system from acoustic noise. The apparatus allows for craft carrying undersea sonar systems to travel at relatively high speeds while substantially isolating the undersea sonar systems from acoustic noise interference produced by propulsion systems, hull appendages, waves, and bubbles. The apparatus has a support strut that has one end that is joined or ... |
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| Chemical Kinetics and Aerodynamics of Ignition |
07 DEC 2004 |
18 pages |
| Authors:
Chung K. Law; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| The present program aimed to study ignition in nonhomogeneous systems that are of relevance to practical combustion devices. The investigation was conducted in both laminar and turbulent environments, and involved experimental, computational, and analytical components. For turbulent ignition, four specific projects were undertaking, namely: (1)Characterization of non-reacting turbulent flow fields in counterflow; (2)turbulent non-premixed ignition experiments; (3) modeling study of turbulent nonpremixed ignition; (4)computational simulation of the ignition of an ... |
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| Turbulent Spot/Separation Bubble Interactions in a Spatially Evolving Supersonic Boundary-Layer Flow |
01 OCT 2004 |
16 pages |
| Authors:
L. Krishnan; N. D. Sandham; SOUTHAMPTON UNIV (UNITED KINGDOM) DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The growth and breakdown of localized disturbances into a turbulent spot in a Mach 2 boundary-layer flow were investigated using direct numerical simulation. In particular, the interaction of a turbulent spot with a shock-induced separation bubble was studied. The primary vortex structures triggered by the injected low momentum fluid and the metamorphosis of the hairpin structures into a turbulent spot were clearly identified in the study. The spot-separation bubble interaction ... |
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| Stability of Shear Layers over Rough Surfaces |
01 OCT 2004 |
11 pages |
| Authors:
J. M. Floryan; UNIVERSITY OF WESTERN ONTARIO LONDON DEPT OF MECHANICAL AND MATERIALS ENGINEERING
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| Presence of surface imperfections may have significant impact on the stability of the adjacent shear layer and on the laminar-turbulent transition process in this layer. The main objective of the present study is the quantitative assessment of such effects in the case of distributed surface roughness. The analysis is focused on the linear stability theory and considers asymptotic as well as transient growth of flow perturbations. The explicit calculations are ... |
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| A Rapid Method of Calculating N-Factors for Estimating Transition Position |
01 OCT 2004 |
13 pages |
| Authors:
M. Gaster; LONDON UNIV (UNITED KINGDOM) DEPT OF ENGINEERING
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| Transition estimation using the E-to-N approach involves evaluating large numbers of eigenvalues of the linear perturbation equations. These eigenvalues provide the amplification rates of the modes of various frequencies and angles of orientation. The number of evaluations required to determine the N-factors can be large, especially when cross-flow modes over a leading edge are important. But since the variation in the values of the amplification rates varies relatively slowly and ... |
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| Reactive and Nonreactive Binders in Glass/Vinyl Ester Composites |
SEP 2004 |
44 pages |
| Authors:
John C. Brody; John W. Gillespie Jr; DELAWARE UNIV NEWARK CENTER FOR COMPOSITE MATERIALS
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| This study characterizes and evaluates two types of preform binders reactive thermosets and nonreactive thermoplastics. The interply adhesion between woven glass plies was measured as a function of binder type, concentration, and preforming conditions. It was found that reactive binders offer the potential to provide much larger interply adhesions between glass plies in a preform than thermoplastics and are thus superior choices for the fabrication of complex-shaped preforms requiring little ... |
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| Effects of Various Shaped Roughness Elements in Two-Dimensional High Reynolds Number Turbulent Boundary Layers |
28 AUG 2004 |
305 pages |
| Authors:
Jeremy L. Bennington; Roger L. Simpson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCEAN ENGINEERING
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| The present research is centered around the experimental investigation of seven various shaped single roughness elements and their effects on turbulence quantities in a two-dimensional turbulent boundary layer. The elements under scrutiny are as follows: cone, cone with spatial variations equal to the smallest sublayer structure length scale, cone with spatial variations equal to 2.5 times the smallest sublayer structure length scale, Gaussian-shaped element, hemisphere, cube aligned perpendicular to the ... |
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| Introduction to CFD++, its Transient and Moving Body Capabilities |
JUL 2004 |
5 pages |
| Authors:
Sukumar Chakravarthy; METACOMP TECHNOLOGIES INC AGOURA CA
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| CFD++ is a Computational Fluid Dynamics software suite built to tackle engineering and scientific applications in aerospace, automotive, marine, biomedical, manufacturing, electronics, chemical, power, construction, cooling systems, and household products. Some of the features of CFD++ are unified physics, unified grid and unified computing; Reynolds-averaged Navier-Stokes (RANS) with state-of-the-art, realizable turbulence closures; large eddy simulation (LES) and hybrid RANS/LES; advanced wall-function treatments; coarse- grid turbulent flow-field prediction capability; compressible fluid ... |
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| U.S. Air Force Basic Research in Weakly Ionized Gasdynamics |
25 JUN 2004 |
24 pages |
| Authors:
Julian Tishkoff; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| RESEARCH OBJECTIVE: Understand, predict, and control weakly ionized flows to revolutionize the performance of aerospace vehicles. |
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| Spray Combustion Modeling Including Detailed Chemistry |
22 JUN 2004 |
34 pages |
| Authors:
Eva Gutheil; HEIDELBERG UNIV (GERMANY F R)
|
| SUMMARY AND CONCLUSIONS: LOX/H2 spray flames in the counter-flow configuration have been studied, and the gaseous oxygen profile shows a non-monotonic behavior because of the high reactivity of the system. The flames persist to strain rates up to 25,000/s, and extinction has not yet been found. Multiple structures of laminar methanol/air counter-flowing spray flames have been identified at low strain rates up to 400/s on the spray side of the ... |
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| Experimental Investigation into the Aerodynamic Performance of Both Rigid and Flexible Wing Structured Micro-Air-Vehicles |
MAR 2004 |
174 pages |
| Authors:
Anthony M. DeLuca; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The Air Force Research Lab, Munitions Directorate, Eglin Air Force Base, Florida has designed a man-portable carbon-fiber Micro-Air-Vehicle (MA V) used for on-the-spot surveillance by Special Operations Forces (SOF) for enemy reconnaissance as well as post-strike Battle Damage Assessment (BDA).The main goals of this experiment are: 1) characterize the flow quality of the new AFIT 3' x 3' wind tunnel and 2) determine the aerodynamic performance characteristics of the 24" ... |
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| Physical and Chemical Processes in Flames |
29 FEB 2004 |
16 pages |
| Authors:
Chung K. Law; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The objective of the present program was to study the structure and response of laminar premixed and nonpremixed flames with emphases on effects of high pressure, flame/flow unsteadiness, and chemistry. The investigations were conducted through laser-based experimentation, computational simulation with detailed chemistry and transport descriptions, and advanced mathematical analysis. Specific phenomena studied during the reporting period include the intrinsic pulsating instabilities of premixed and diffusion flames and the effects of ... |
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| Design Considerations of a Differentially Pumped Cathode System for LAPPS |
27 FEB 2004 |
20 pages |
| Authors:
David Blackwell; Scott G. Walton; Darrin Leonhardt; Richard Fernsler; Robert A. Meger; NAVAL RESEARCH LAB CHESAPEAKE BEACH MDCHESAPEAKE BAY DIV
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| The results of tests of a differential pumping system separating a plasma production cathode chamber and a processing chamber are presented. The tests are a series of measurements taken to evaluate two aspects of system performance. These are the effectiveness of the system to maintain large differential pressures, and, the degree to which different gases in the two chambers can be isolated from one another. It is found that the ... |
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| Optimal Aeroacoustic Shape Design Using the Surrogate Management Framework |
09 FEB 2004 |
25 pages |
| Authors:
Alison L. Marsden; Meng Wang; John E. Dennis Jr; Parviz Moin; RICE UNIV HOUSTON TX DEPT OF COMPUTATIONAL AND APPLIED MATHEMATICS
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| Shape optimization is applied to time-dependent trailing-edge flow in order to minimize aerodynamic noise. Optimization is performed using the surrogate management framework (SMF), a non-gradient based pattern search method chosen for its efficiency and rigorous convergence properties. Using SMF, design space exploration is performed not with the expensive actual function but with an inexpensive surrogate function. The use of a polling step in the SMF guarantees that the algorithm generates ... |
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| An Empirical Study of a Pin Fin Heat Exchanger in Laminar and Turbulent Flow |
DEC 2003 |
121 pages |
| Authors:
Jeffrey W. Summers; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This study concentrates on the empirical characterization of a staggered array pin fin compact heat exchanger placed in a modular, rectangular wind tunnel. A full analysis of the heat transfer and pressure drop behavior was conducted on various pin-fin shapes, sizes, and configurations. The study was based on airflow over a range of low Reynolds numbers in the laminar and low turbulent flow, as well as higher turbulent flow regimes. ... |
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| Experimental and Detailed Numerical Studies of Fundamental Flame Properties of Gaseous and Liquid Fuels |
NOV 2003 |
14 pages |
| Authors:
Fokion N. Egolfopoulos; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| The dynamic behavior of laminar flames was studied for a wide range of conditions. The parameters considered included the fuel type, reactant composition, flame temperature, and combustion mode. The derived experimental data constitute a basis for partially validating the combustion chemistry for fuels ranging from hydrogen to gaseous and liquid hydrocarbons and alcohols. Emphasis was given to kinetics regimes that have not been systematically probed and/or in which current knowledge ... |
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| Performance and Flow Regimes in Plane 2-D Diffusers With Exit Channels at Low Reynolds Numbers |
SEP 2003 |
99 pages |
| Authors:
Epameinondas Trivilos; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A numerical study on laminar incompressible flows in 2-D straight walled diffusers in the low Reynolds number regime (105-1048) is presented to investigate performance and various flow regimes that might exist. Tail channels are situated downstream the diffusers. Geometries with area ratios AR-=1.15 to 5 and non-dimensional lengths of L/W1=1 to 48 are considered. Results are presented in terms of flow regime maps for Reynolds numbers of 105, 210, 314, ... |
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| Study of the Boundary Layer in the Inboard Sections of a Tilt-Rotor Blade by Embedded LDV Measurements |
JUL 2003 |
19 pages |
| Authors:
Christian Maresca; Marcellin Nsi Mba; Eric Berton; Daniel Favier; Charlie Barla; MEDITERRANEE UNIV MARSEILLE (FRANCE) LAB D'AERODYNAMIQUE ET DE BIOMECANIQUE DU MOUVEMENT
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| This report focuses on the boundary layer (BL) velocity distribution in the inboard region of a tiltrotor blade. The instrumentation consists of a Laser Doppler Velocimeter embedded in the inboard region of the blade. This set up allows measuring the chordwise and spanwise component of the boundary layer velocity from a distance of 0.3 mm to 20 mm along a direction normal to the blade surface. The experiments were carried ... |
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| US Navy Evaluation of the High Reynolds' Number Thermal Stability (HiReTS) Test Unit |
23 APR 2003 |
78 pages |
| Authors:
John E. Colbert; Clarence J. Nowack; Richard A. Kamin; Douglas F. Mearns; NAVAL AIR SYSTEMS COMMAND PATUXENT RIVER MD FUELS AND LUBRICANTS DIV
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| The HiReTS was developed by Shell Global Solutions, Fuels Business Group as a small- scale unit for evaluating the thermal stability of jet fuel prior to shipment to the consumer. The HiReTS was designed to operate at high fuel flow rates through a heated, stainless steel tube (capillary) representative of turbulent flow conditions in actual engine fuel injectors. At the standard operating conditions (SOC), the HiReTS has a Reynolds' Number ... |
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| Time Accurate Simulations of High-Alpha Aerodynamics for Pitching Delta Wings |
MAR 2003 |
15 pages |
| Authors:
Y. Le Moigne; A. Rizzi; ROYAL INST OF TECH STOCKHOLM (SWEDEN) DEPT OF AERONAUTICS
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| Fighter airplanes are designed to transiently fly at very high angles of attack. The types of maneuvers they do involve high pitch rates and flight at incidences beyond the static stall angle of attack. The performance of fighters in high angle-of-attack maneuvers is often reached thanks to the use of a delta wing. The aerodynamics of these wings at incidence is characterized by the formation of a pair of strong ... |
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Reports by Keyword(s)
LAMINAR FLOW
