| A Fluidic Dump Combustor for Ramjet Engines |
Dec-2009 |
|
| Authors:
David J Forliti; STATE UNIV OF NEW YORK AT BUFFALO AMHERST RESEARCH FOUNDATION
|
 | Flame stabilization is the act of maintaining combustion in the presence of a high-speed premixed flow, and continues to be an important process that influences the performance and limitations for propulsion applications. A common approach for current generation flame holders involves the employment of a low-speed recirculation zone where hot combustion products are maintained and act as a continuous ignition source. The recirculation zone is often induced using a wake-generating ... |
|
| Towards High-Reynolds-Number Quiet Flow in Hypersonic Wind Tunnels |
13-Apr-2009 |
32 pages |
| Authors:
Steven P Schneider; PURDUE UNIV LAFAYETTE IN AEROSPACES SCIENCES LAB
|
 | This grant was initially focused on developing high-Reynolds-number quiet 0-ow in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue. Reliable quiet 0-ow was achieved at freestream unit Reynolds numbers of more than 3 million per foot, beginning in Sept. 2006. The facility became the only operational hypersonic quiet tunnel, anywhere in the world. Tunnel noise was then shown to have a substantial effect on: (a) roughness-induced transition for the X-51A forebody ... |
|
| Origin and Control of the Flow Structure on Unmanned Combat Air Vehicle |
DEC 2007 |
136 pages |
| Authors:
Donald Rockwell; B. Yaniktepe; M. M. Yavuz; T. Goruney; M. A. Kosoglu; Y. Kim; A. Liakopoulos; LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS
|
| Flow structure on delta wings having low sweep angle, representative of those used in UCAVs and MAVs, is characterized in detail using; technique of quantitative imaging, high-image-density particle image velocimetry. Cases of stationary wings, wings subjected to control at their trailing-edges, and wings undergoing prescribed pitching maneuvers have been addressed as part of this investigation. The sweep `angle of each wing is sufficiently small, such that the patterns of the ... |
|
| Vortex-Induced Vibration: Universal Phenomena in Diverse Systems |
OCT 2007 |
14 pages |
| Authors:
Charles H. Williamson; CORNELL UNIV ITHACA NY OFFICE OF SPONSORED PROGRAMS
|
| The long-term goals of the research under this award have been to discover and understand generic phenomena in a whole class of vortex-induced vibration systems. We discover, using novel controlled damping, that the immense scatter in the classical Griffin plot (peak amplitude versus mass-damping) over 3 decades, can now be collapsed beautifully if one renormalises the axes, taking into account the effect of Reynolds number, which was previously not considered. ... |
|
| Non-Reacting and Combusting Flow Investigation of Bluff Bodies in Cross Flow (Postprint) |
AUG 2007 |
13 pages |
| Authors:
Barry Kiel; Kyle Garwick; Amy Lynch; James R. Gord; Terrence Meyer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This paper is the first in a series of papers studying the behavior of bluff body stabilized flames. In this research a combination of Laser Doppler Velocimetry (LDV), and High Speed Imaging are used to investigate these flames. LDV data taken over several non-combusting operating conditions detail the recirculation zone behind the bluff body as well as the effect of inlet conditions on the Karman Street vortex shedding that occurs. ... |
|
| Cavity-Based Injector Mixing Experiments for Supersonic Combustors With Implications on Igniter Placement (Postprint) |
OCT 2006 |
15 pages |
| Authors:
Lance S. Jacobsen; Campbell D. Carter; Andrew C. Dwenger; GOHYPERSONIC INC (GHI) DAYTON OH
|
| Mixing experiments using simultaneous acetone and NO PLIF were performed in the AFRL/PRA Test-cell 19 supersonic wind tunnel. These experiments investigated the influence of simulated plasma-torch placement in an injector-cavity configuration exposed to a supersonic crossflow. Both the simulated plasma torch and fuel injector holes injected room temperature air, respectively seeded with acetone and nitric oxide (NO). Experiments at the streamwise centerline of the rectangular wind tunnel investigated the differences ... |
|
| Independent Stage Control of a Cascade Injector (Postprint) |
OCT 2006 |
17 pages |
| Authors:
H. L. Meicenheimer; E. J. Gutmark; M. R. Gruber; D. R. Eklund; C. D. Carter; K.-Y. Hsu; CINCINNATI UNIV OH DEPT OF AEROSPACE ENGINEERING
|
| An experimental investigation of a cascade injector was completed. The objective of this investigation was to determine whether the number of active stages in the cascade injector could be used to control penetration and mixing characteristics. The injector was tested at two overexpanded injection conditions in a Mach 3 crossflow. Shadowgraph and schlieren imaging, Mie scattering, Planar Laser Induced Fluorescence, and pressure profiling were the diagnostic techniques used to reveal ... |
|
| Evolution of the Ion Velocity Distribution in the Near Field of a 200 W Hall Thruster (Preprint) |
JUL 2006 |
12 pages |
| Authors:
Jr. Hargus William A.; Michael R. Nakles; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| This work presents an analysis of near plume velocity distributions of the Busek BHT-200-X3 200 W laboratory Hall thruster derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. The evolution of the axial and radial velocity distributions is presented from the exit plane to approximately 0.7 exit diameters downstream. It is shown that the distributions evolve significantly between the exit channel center and the inner portion ... |
|
| Evolution of the Ion Velocity Distribution in the Near Field of the BHT-200-X3 Hall Thruster |
15 MAY 2006 |
12 pages |
| Authors:
Jr. Hargus William A.; Michael R. Nakles; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| This work presents an analysis of near plume velocity distributions of the Busek BHT-200-X3 200 W laboratory Hall thruster derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. The evolution of the axial and radial velocity distributions is presented from the exit plane to approximately 0.7 exit diameters downstream. It is shown that the distributions evolve significantly between the exit channel center and the inner portion ... |
|
| Mechanism of Suppression and Extinguishment of Communication Cable Fire by Ultra Fine Water Mist in Cross-Flow |
14 APR 2006 |
36 pages |
| Authors:
Chuka C. Ndubizu; Ramagopal Ananth; Damian Rouson; Frederick W. Williams; NAVAL RESEARCH LAB WASHINGTON DC CHEMISTRY DIV
|
| Water mist fire suppression experiments were performed in cross-flow on bare (without outer jacket) communication cables to simulate a worst-case scenario. As fine water droplets are injected at low inlet velocities, an initial envelope flame that engulfed the circumference of the cable recedes and forms a wake flame stabilized behind the cable. At high mist concentration and/or high air velocity, the flame is extinguished by flame shrinking rather than by ... |
|
| Liquid Breakup in Dense Sprays |
21 FEB 2006 |
17 pages |
| Authors:
MICHIGAN UNIV ANN ARBOR DIV OF RESEARCH
|
|
| Stability and Transition Analysis for Reentry Tool, STAR |
2006 |
28 pages |
| Authors:
Helen L. Reed; TEXAS A AND M UNIV COLLEGE STATION DEPT OF AEROSPACE ENGINEERING
|
| The effort is primarily to accelerate delivery of an improved stability and transition analysis tool. The initial goal is to aid contractors supported under the DARPA FALCON program in the development and test of Common Aero Vehicle (CAV) maneuvering reentry configurations. Under this effort, state-of-the-art computational tools developed for hypersonic boundary layer stability research will be integrated into a user-friendly package (the Stability and Transition Analysis for Reentry tool, STAR). ... |
|
| Active Control Strategies to Optimize Supersonic Fuel-Air Mixing for Combustion Associated with Fully Modulated Transverse Jet in Cross Flow |
27 DEC 2005 |
63 pages |
| Authors:
C. Ghenai; G. P. Philippidis; C. X. Lin; FLORIDA INTERNATIONAL UNIV MIAMI APPLIED RESEARCH CENTER
|
| A 76 mm x 76 mm supersonic wind tunnel with variable Mach Numbers (M = 1.5 - 4) was designed and set up. The wind tunnel could support both non-reacting fuel-air mixing and combustion. A back pressure flap was added at the downstream end of the diffuser for dual mode (subsonic- supersonic) combustion studies. A high-speed imaging system was used for the visualization of pure liquid jet, aerated liquid jet ... |
|
| Numerical Computations of Supersonic Flow Over a Square Cross-Section Missile |
AUG 2005 |
52 pages |
| Authors:
Sidra I. Silton; Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report describes a computational study undertaken to determine the aerodynamics of a nonaxisymmetric missile with a square cross section. Numerical solutions have been obtained at supersonic speeds for various roll orientations and angles of attack using a two-equation Reynolds-averaged Navier-Stokes turbulence model. Numerical results show the qualitative features (vortices and cross-flow separation regions) of the flow field at various stream wise positions along the missile configurations. Aerodynamic coefficients have ... |
|
| Simulation of Flow Unsteadiness in Chemical Oxygen-Iodine Laser Devices |
08 JUL 2005 |
32 pages |
| Authors:
Timothy J. Madden; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
|
| 3-DIMENSIONAL Navier-Stokes simulations of chemical oxygen-iodine laser (COIL) hardware are performed to elucidate the unsteady fluid dynamic aspects of these flowfields. Reacting (COIL) and non-reacting flow simulations are performed on varying resolution grids to explore the unsteadiness, and comparisons to experimental data are made. |
|
| Independent Stage Control of a Cascade Injector (Postprint) |
JUL 2005 |
17 pages |
| Authors:
Heidi L. Meicenheimer; Ephraim J. Gutmark; Campbell D. Carter; Dean R. Eklund; Mark R. Gruber; Kuang-Yu Hsu; CINCINNATI UNIV OH DEPT OF AEROSPACE ENGINEERING
|
| An experimental investigation of a cascade injector was completed. The objective of this investigation was to determine whether the number of active stages in the cascade injector could be used to control penetration and mixing characteristics. The injector was tested at two overexpanded injection conditions in a Mach 3 crossflow. Shadowgraph and schlieren imaging, Mie scattering, Planar Laser Induced Fluorescence, and pressure profiling were the diagnostic techniques used to reveal ... |
|
| Boundary Layer Control of a Circular Cylinder Using a Synthetic Jet |
JUN 2005 |
97 pages |
| Authors:
Christopher K. Smith; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Active control of flow around a circular cylinder at a sub-critical Reynolds number was studied experimentally. The flow was controlled by using a synthetic jet which ran span wise along the cylinder and emanated radially from the cylinder. The experiments were conducted over a two dimensional cylinder in a water tunnel at a Reynolds number of approximately 5800. Seven different jet locations and seven different jet oscillation frequencies were examined. ... |
|
| Design Tools for Zero Net Mass flux Devices: CFD Effort |
MAY 2005 |
33 pages |
| Authors:
Rajat Mittal; GEORGE WASHINGTON UNIV WASHINGTON DC
|
| Numerical simulations have been used to examine the fluid dynamics of zero-net mass flux devices. The emphasis is on extracting insights that can be used in developing simple models of these actuators for use in separation control. The unsteady evolution of a transitional synthetic jet in the absence of cross-flow is investigated by time-accurate three- dimensional direct numerical simulations of incompressible Navier-Stokes equations and the results compared with one of ... |
|
| Structures of Angled Aerated-Liquid Jets in March 1.94 Supersonic Crossflow |
MAR 2005 |
82 pages |
| Authors:
Dion R. Dixon; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| The structures of aerated-liquid jets injected into a supersonic crossflow have been studied experimentally. Aerated-liquid injectors with diameters of 0.020", 0.040" and 0.060" were flush mounted on the bottom plate of a supersonic wind tunnel to provide normal and angled injection. Free stream Mach number and temperature were held constant at 1.94 and 500 degrees F, respectively. Water at room temperature was used as the liquid injectant and nitrogen gas ... |
|
| Fluidic-Based Virtual Aerosurface Shaping |
01 OCT 2004 |
20 pages |
| Authors:
Ari Glezer; GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
|
| Recent work on a novel approach to the control of the aerodynamic performance of lifting surfaces by fluidic modification of their apparent aerodynamic shape, or virtual aerosurface shaping is reviewed. This flow control approach emphasizes fluidic modification of the "apparent" aerodynamic shape of the surface with the objective of altering or prescribing the streamwise pressure gradient. Control is effected by the interactions of arrays of synthetic jet actuators with the ... |
|
| 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
|
| 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 ... |
|
| Flight Testing of Laminar Flow Control in High-Speed Boundary Layers |
01 OCT 2004 |
9 pages |
| Authors:
William S. Saric; Helen L. Reed; Daniel W. Banks; ARIZONA STATE UNIV TEMPE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This paper presents data from a series of laminar-flow flight tests at NASA Dryden flight Research Center on the F-15B. It is shown that periodic discrete roughness elements near the leading can increase the laminar flow region at both supersonic and subsonic flight Mach numbers. Infra-red thermography was used to visualize laminar-turbulent transition. Although the experiment was designed for Mach 1.85, it was possible to obtain data at other Mach ... |
|
| A Review of Submarine Out-of-Plane Normal Force and Pitching Moment |
AUG 2004 |
|
| Authors:
M. Mackay; DEFENCE RESEARCH AND DEVELOPMENT ATLANTIC DARTMOUTH (CANADA)
|
| The normal force and pitching moment experienced by a submarine in a turn, or at an angle of drift, are called out-of-plane because they are loads induced in the vertical plane by a maneuver in the horizontal plane. They arise from the interaction of flow circulation generated by the sail with cross flow on the hull aft of the sail, i.e., the Magnus Effect. Smaller than the corresponding in-plane loads, ... |
|
| Near-Shore Hydrodynamic Conditions and Chemical Plume Tracking |
22 JUL 2004 |
5 pages |
| Authors:
Derek Fong; Stephen Monismith; STANFORD UNIV CA DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING
|
| We characterize the hydrodynamic conditions relevant to a bottom source plume in a nearshore environment. Analyzing a dye concentration data set collected by a state of the art autonomous underwater vehicle and fixed hydrodynamic measurements, we quantify the meandering and lateral dispersion of a plume. We find that both processes are important to ultimate plume fate and transport. The lateral dispersion is governed by a scale-dependent processes that is driven ... |
|
| Drag Measurements on Long Thin Cylinders at Small Angles and High Reynolds Numbers |
15 JUL 2004 |
29 pages |
| Authors:
William L. Keith; Kimberly M. Cipolla; David R. Hart; Deborah A. Furey; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| Measurements of the drag caused by turbulent boundary layer mean wall shear stress on cylinders of aspect ratio Lla = 480 and 960 at varying small angles of attack to the tow direction and at length Reynolds numbers of 8 x 106 < ReL < 6 x 10% are presented. The use of a full-scale, high-speed towing tank allowed turbulent boundary layers to be developed on cylinders made of either ... |
|
| Measurements of the Tip-Gap Turbulent Flow Structure in a Low-speed Compressor Cascade |
15 MAY 2004 |
384 pages |
| Authors:
Genglin Tang; Roger L. Simpson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCEAN ENGINEERING
|
| Experimental results are presented from a study of the tip-gap turbulent flow structure in a low-speed linear compressor cascade wind tunnel at Virginia Tech that includes a moving belt system to simulate the relative motion between the tip and the casing. Endwall pressure measurements and surface oil flow visualizations were made on a stationary endwall to obtain some global flow features. A custom-made miniature 3-orthogonal-velocity-component fiber-optic laser-Doppler velocimeter (LDV) with ... |
|
| Investigation of Combined Low-Angled Jets and Variable Wall Geometry for Hypersonic Aerodynamic Control |
05 MAY 2004 |
84 pages |
| Authors:
Rodney D. Bowersox; Charles L. Karr; Muhammad Sharif; ALABAMA UNIV TUSCALOOSA DEPT OF AEROSPACE ENGINEERING AND MECHANICS
|
| The principal objective of the present research proposal was to investigate, experimentally and numerically, the use of jets to actively control the aerodynamic forces for high-speed flight vehicles. As a test bed, single port injection into a Mach 5.0 crossflow through diamond and circular orifices, at various incidence angles and momentum ratios were examined. To meet the objective, a research program was performed to characterize and control the secondary flow ... |
|
| Fluidic Virtual Aerosurfaces for Flow Control Applications |
MAR 2004 |
74 pages |
| Authors:
Ari Glezer; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
|
| This research program has focused on a novel approach to the control of the aerodynamic performance of lifting surfaces by fluidic modification of their apparent aerodynamic shape, or virtual aerosurface shaping, This flow control approach emphasizes fluidic modification of the "apparent" aerodynamic shape of the surface with the objective of altering or prescribing the streamwise pressure gradient. Control is typically effected by the interactions of arrays of synthetic jet actuators ... |
|
| NAVO MSRC Navigator. Spring 2004 |
Jan-2004 |
29 pages |
| Authors:
NAVAL OCEANOGRAPHIC OFFICE STENNIS SPACE CENTER MS MAJOR SHARED RESOURCE CENTER
|
| The NAVO MSRC provides Department of Defense (DoD) scientists and engineers with high performance computing (HPC) resources, including leading edge computational systems, largescale data storage and archiving, scientific visualization resources and training, and expertise in specific computational technology areas (CTAs). These CTAs include Computational Fluid Dynamics (CFD), Climate/Weather/Ocean Modeling and Simulation (CWO), Environmental Quality Modeling and Simulation (EQM), Computational Electromagnetics and Acoustics (CEA), and Signal/Image Processing (SIP). Articles in this ... |
|
| Stationary Electric Arc Plasma Generator for Influencing on Supersonic Gas Flow |
OCT 2003 |
9 pages |
| Authors:
N. Ardelyan; V. Bychkov; K. Kosmachevskii; I. Timofeev; MOSCOW STATE UNIV (RUSSIA)
|
| Studies of plasma jet interaction with cross flows has been made for development of the concept of enhancing of combustion and ignition at application of plasma jets. A computer simulation of a cross flow nitrogen plasma nitrogen jet from the divergent plasma generator in nitrogen has been carried out. This model involves a realistic equation of state, plasma radiation associated with plasma formation inside the plasma jet as well as ... |
|
| PC Desktop Aerodynamic Models for Store Separation from Weapons Bay Cavities and Related Vortical Processes |
MAR 2003 |
21 pages |
| Authors:
Norman Malmuth; J. Cole; A. Fedorov; V. Shalaev; M. Hites; D. Williams; ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER
|
| Many of the previous investigations of store separation have been confined to external store carriage. Comparatively less attention is being given to separation from cavities and bays. This is probably due to the additional complications related to the interaction of the store with the shear layer as well as the store's coupling with the walls of the cavity. Many large-scale computational simulations have focused on acoustic interactions with the cavity ... |
|
| Physics Based Simulation of Reynolds Number Effects in Vortex Intensive Incompressible Flows |
MAR 2003 |
15 pages |
| Authors:
K. Sreenivas; D. Hyams; B. Mitchell; L. Taylor; W. R. Briley; COMPUTATIONAL SIMULATION AND DESIGN CENTER MISSISSIPPI STATE MS
|
| An understanding of Reynolds number effects is essential for extrapolating model- or quarter-scale results to full-scale. The state-of-the- art in the prediction of full-scale maneuvering performance utilizes a combination of experience, heuristics, and empiricism. To better understand these scale effects, it would be ideal to validate the flow solver at full-scale Reynolds numbers. However, the preponderance of experimental data available for undersea vehicles is limited to model-scale. The unavailability of ... |
|
| A Quasi-Steady Evaluation of Submarine Rising Stability: The Stability Limit |
MAR 2003 |
|
| Authors:
George D. Watt; Jan Hooft; DEFENCE RESEARCH ESTABLISHMENT ATLANTICDARTMOUTH (NOVA SCOTIA)
|
| When submarines blow ballast to the surface from deep depths in an emergency, they can experience roll instability if they ascend with a large flow incidence angle. It is shown that an instability is caused by the destabilizing hydrodynamic rolling moment on the sail (which points upwards into the onset crossflow) overcoming the static righting moment (the center of gravity is below the center of buoyancy) as the boat is ... |
|
| Experimental Study of Controlled Disturbances Development In A supersonic Boundary Layer on A Swept Wing |
JUL 2002 |
|
| Authors:
V. Ya. Levchenko; A. D. Kosinov; N. V. Semionov; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSK INST OF THEORETICAL AND APPLIED MECHANICS
|
| The experimental results on the laminar-turbulent transition in three-dimensional boundary layers for M > 1 are described. Stationary structures were registered using different methods of flow visualization. The first experimental studies of instability of a three-dimensional boundary layer at supersonic velocities were conducted. Evolution of natural fluctuations in the boundary layer on a swept wing was studied. It was shown that the character of distribution of the mean and fluctuating ... |
|
| Controlled Experiments on Instabilities and Transition to Turbulence on Elliptic Cones at Hypersonic Mach Numbers |
24 JUN 2002 |
19 pages |
| Authors:
Thomas C. Corke; NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| This work involved the study of instabilities and transition to turbulence in boundary layers on cones at different angles of attacks at high supersonic and hypersonic Mach numbers. It utilized facilities at NASA Langley Research Center, which makes use of 'quiet' design nozzles to minimize the level of acoustic disturbances. The experiments involved two models. The first was a 7 half-angle circular cross-section cone designed by Cavalier. It was used ... |
|
| Demonstration of Temperature Measurement on a Curved Surface Using Thermographic Phosphors |
MAY 2002 |
26 pages |
| Authors:
Jamie Ervin; Christopher Murawski; Charles MacArthur; Minking Chyu; David Bizzak; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| An optical technique for surface temperature measurement based on the fluorescent emission of rare-earth ion-doped phosphors was demonstrated in an experiment with a heated cylinder in cross flow. In this experiment, a uniform heat flux is imposed by applying a constant voltage across the thin stainless- steel cylinder surface to produce surface temperatures between 24 deg. C and 55 deg. C. The fluorescent emission of a thermographic phosphor, lanthanum oxysulfide ... |
|
| Combined Asymptotics and Numerical Methods in Transonic Store Interactions |
FEB 2002 |
206 pages |
| Authors:
N. Malmuth; V. Shalaev; A. Fedorov; ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA
|
| Combined asymptotic and numerics procedures were coupled with dynamics equations to simulate two and three-degree of freedom store separation from cavities. New solutions were obtained that provide insight into how the shear layer can interact with the body motion and cause re-contact and ricochet with the parent body. The theoretical models simulated these phenomena by adjustment of initial launch conditions such as initial plunge and pitch velocities among other lumped ... |
|
| Novel Nonporous Fouling-Resistant Composite Nanofiltration Membrane and Membrane Separation systems for Wastewater Treatment Important for CPSON5/ PPSON1: Minimization of Oily and Non-Oily Wastewater |
SEP 2001 |
35 pages |
| Authors:
Benny D. Freeman; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF CHEMICAL ENGINEERING
|
| Navy ships generate large volumes of wastewater (about 20-70 gal/day of water per crew member) which, to meet new regulations, require treatment prior to overboard discharge. In the past, all wastewater was simply discharged overboard. More recently, regulating bodies such as MARPOL, the EPA, the U.S. Coast Guard, and some states have enacted restrictions on the location and extent of such discharges. Polymeric nanofiltration/ultrafiltration membranes able to produce dischargeable water ... |
|
| Modeling Diesel Engine Injector Flows |
31 AUG 2001 |
99 pages |
| Authors:
S. D. Heister; G. A. Blaisdell; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
|
| Models have been developed to assess flow fields inside diesel injector orifice passages in order to increase our understanding of the spray formation process which governs performance and emissions in these engines. Fully viscous, unsteady, and two phase codes have been developed to analyze 2-D and 3-D flows and the effect of turbulence has also been incorporated in the 2-D models. A series of parametric studies have been conducted to ... |
|
| An Examination of Wake Oscillator Models for Vortex-Induced Vibrations |
01 AUG 2001 |
18 pages |
| Authors:
Leslie Ng; Richard H. Rand; Timothy Wei; William L. Keith; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| Experimental results for vortex-induced vibrations of both pivoted and non-pivoted cylinders in a crossflow are presented in this report. Simplified models involving two ordinary differential equations are reviewed and shown to exhibit many of the features of the experimental results. Results of perturbation analysis of the simplified model are presented and used to explain some qualitative features, such as resonant frequency locking and hysteresis, in terms of bifurcations in the ... |
|
| Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct at Low Reynolds Number |
AUG 2001 |
|
| Authors:
M. Piller; E. Nobile; TRIESTE UNIV (ITALY) DEPT OF NAVAL ENGINEERING
|
| In this paper, we present the results from Direct Numerical Simulations of turbulent, incompressible flow through a square duct, with an imposed temperature difference between two opposite walls, while the other two walls are assumed perfectly insulated. The mean flow is sustained by an imposed, mean pressure gradient. The most interesting feature, characterizing this geometry, consists in the presence of turbulence-sustained mean secondary motions in the cross-flow plane. In this ... |
|
| Instability of the Shear Layer Separating from a Circular Cylinder |
AUG 2001 |
|
| Authors:
Jinsung Kim; Haecheon Choi; SEOUL NATIONAL UNIV (KOREA) SCHOOL OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The instability of the shear layer separating from a circular cylinder has been investigated using large eddy simulation at two different Reynolds numbers of 1600 and 3900 based on the free-stream velocity and cylinder diameter. Two distinct types of the shear layer instability are found in this study: one is a completely three-dimensional type and the other is a quasi-two-dimensional type. The instability of three-dimensional type is generated by a ... |
|
| Unsteady Skin-Friction Measurements on a Maneuvering DARPA2 Suboff Model |
15 JUN 2001 |
226 pages |
| Authors:
Serhat Hosder; Roger L. Simpson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCEAN ENGINEERING
|
| The skin-friction magnitude was measured for steady and unsteady flow over a Suboff submarine model by surface hot-film constant temperature sensors. The locations of the local spatial minima in the skin-friction magnitudes are used to obtain the separation locations. Steady surface static pressures were measured at 100 and 200 angles of attack. The dynamic plunge-pitch-roll model mount (DyPPiR) in the Stability Wind Tunnel was used to simulate rapid pitch-up maneuvers, ... |
|
| Analysis of Jet Interaction for Supersonic Flow Control |
JUN 2001 |
6 pages |
| Authors:
E. Collin; S. Barre; J. P. Bonnet; POITIERS UNIV (FRANCE) LAB DE MECANIQUE DES FLUIDES
|
| In a lot of industrial applications, especially in ejectors and propulsive jets, most of the dynamical behaviour of the system is strongly influenced by the mixing efficiency in a supersonic jet. This is particularly the case when dilution of hot propulsive jets is required for example to reduce infrared signature of a military aircraft. Many mechanical devices have been used to increase mixing in free shear flows. Most of these ... |
|
| Turbulent Spot Characterization and the Modeling of Transitional Heat Transfer in Turbines |
02 APR 2001 |
21 pages |
| Authors:
John E. LaGraff; SYRACUSE UNIV NY OFFICE OF SPONSORED PROGRAMS
|
| Optimum design of gas turbine blades depends on accurate prediction of boundary layer transition. The purpose of this research is to obtain more information on the generation. propagation and coalescence of turbulent spots in a transitional boundary layer and examine the effects of free stream turbulence pressure gradient and cross flow. Experimental data from this study may be used to improve existing CFD models, allowing designers to make more accurate ... |
|
| Pulsed Injection for Nozzle Throat Area Control |
05 FEB 2001 |
|
| Authors:
Daniel N. Miller; Patrick J. Yagle; Erich E. Bender; K. B. Ginn; Brian R. Smith; LOCKHEED MARTIN TACTICAL AIRCRAFT SYSTEMS FORT WORTH TX
|
| Computational fluid dynamics (CFD) and experimental methods were used to investigate two unsteady injection techniques for increasing the penetration and blockage of an injected stream in a confined, expanding crossflow. The obstruction produced by an injected stream is a basic mechanism related to the efficacy of fluidic nozzle control techniques. A CFD simulation methodology was developed for unsteady injection, which showed the effects of grid resolution, turbulence model, and numerical ... |
|
| IUTAM Symposium: Laminar-Turbulent Transition |
20 DEC 2000 |
6 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| The origins of turbulent flow and the transition from laminar to turbulent flow are among the most important unsolved problems of fluid mechanics and aerodynamics. Besides being a fundamental question of fluid mechanics, there are any number of applications for information regarding transition location and the details of the subsequent turbulent flow. The IUTAM Symposium on Laminar- Turbulent Transition, Co-hosted by Arizona State University and the University of Arizona, was ... |
|
| Investigation of Cross Flow Fan Propulsion for Lightweight VTOL aircraft |
DEC 2000 |
88 pages |
| Authors:
Dean H. Gossett; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| As world population increases, road and airport congestion will become increasingly prevalent. A small, cheap vTOL aircraft which can be flown from a driveway to the workplace parking lot would reduce traffic congestion and travel time. A lightweight, single seat commuter type VTOL aircraft is envisioned as the solution to this problem. To achieve a goal of minimum weight, the aircraft aerodynamic design should be optimized for forward flight. Vertical ... |
|
| A High Capacity Advanced Fuel Filtration System |
15 NOV 2000 |
46 pages |
| Authors:
Chang-Wei Jen; MECHANICAL SOLUTIONS IN PARSIPPANY NJ
|
| This project demonstrated the feasibility of an innovative design that combines a water-selective, cross-flow filtration (CFF), and a high capacity spiral-wound membrane element design into an integrated and individually contained filter cartridge. The filtration unit is composed of the individually contained cartridges (module). The modular design makes the upgrade and down-grade of the system capacity very flexible. Several potential hydrophobic membranes were tested, and the ... |
|
| An Analytical Vacuum-Assisted Resin Transfer Molding (VARTM) Flow Model |
OCT 2000 |
65 pages |
| Authors:
Bruce K. Fink; Kuang-Ting Hsiao; Roopesh Mathur; John W. Gillespie Jr.; Suresh G. Advani; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A closed form solution for the flow of resin in the vacuum-assisted resin transfer molding (VARTM) process is used extensively for affordable manufacturing of large composite structures. During VARTM processing, a highly permeable distribution medium is incorporated into the preform as a surface layer. During infusion, the resin flows preferentially across the surface, simultaneously through the preform, to a complex flow front. The analytical solution presented here provides insight into ... |
|
Reports by Keyword(s)
CROSS FLOW
