| An Overview of Advanced Concepts for Near-Space Systems |
30-Jun-2009 |
19 pages |
| Authors:
Marcus Young; Stephanie Keith; Anthony Pancotti; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
 | A brief review of both near-term and far-term platforms proposed for near-space operations is given. The primary focus of the paper is, however, a review of potential advanced propulsion systems for such long-duration near-space platforms. The basic requirements for near-space propulsion systems are defined. Low Reynolds number propellers, the current workhorse, are used as a baseline for comparison. Two broad classifications are identified as potential sources of force in near ... |
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| Automated Detection of a Crossing Contact Based on Its Doppler Shift |
Mar-2009 |
117 pages |
| Authors:
Whye Kaong How; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The trade-off between false alarm and detection probability is a fundamental challenge in the automated detection of contacts in passive sonar systems. A common approach is the application of high gain processing followed by successive classification criteria. Most classification schemes (e.g., matching of signature) are complex and tailored to specific target types. By contrast, the Doppler effect is readily observed in all contacts with discrete tonals and relative velocity to ... |
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| Nonequilibrium Hypersonic Aerothermodynamics Using the Direct Simulation Monte Carlo And Navier-Stokes Models |
17-Jan-2008 |
262 pages |
| Authors:
Andrew J Lofthouse; MICHIGAN UNIV ANN ARBOR
|
| Hypersonic flight vehicles are a current topic of interest in both civilian and military research. NASA is currently designing a Crew Transport Vehicle (CTV) [44, 69] and Crew Exploration Vehicle (CEV) [32] to replace the space shuttle; reentry vehicles are, by definition, hypersonic vehicles. Military requirements for reconnaissance and surveillance, as well as the mission of the United States Air Force to rapidly project power globally makes the design of ... |
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| Numerically-Based Ducted Propeller Design Using Vortex Lattice Lifting Line Theory |
01-Jan-2008 |
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| Authors:
John M Stubblefield; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | This thesis used vortex lattice lifting line theory to model an axisymmetrical-ducted propeller with no gap between the duct and the propeller. The theory required to model the duct and its interaction with the propeller were discussed and implemented in Open-source Propeller Design and Analysis Program (OpenProp). Two routines for determining the optimum circulation distribution were considered, and a method based on calculus of variations was selected. The results of ... |
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| A Quantitative Analysis of Starting Jet Vortex Ring Entrainment at Low Reynolds Number |
07 MAY 2007 |
110 pages |
| Authors:
Alex G. Dulude; NAVAL ACADEMY ANNAPOLIS MD
|
| The future propulsion of very small unmanned air and underwater vehicles operating at Reynolds numbers in the hundreds or less may be accomplished by pulsing a jet of fluid rather than more conventional methods of propulsion such as propellers and turbo jets as used by large-scale vehicles. Pulse jet propulsion produces trailing vortex rings and recent research concerning the formation and evolution of vortex rings has suggested that these structures ... |
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| Simulation and Evaluation of Marine Propeller Crashback Through Computational Fluid Dynamics |
04 MAY 2007 |
67 pages |
| Authors:
Matthew P. Shearer; NAVAL ACADEMY ANNAPOLIS MD
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| Crashback is a maneuver which occurs when a ship or submarine reverses its propeller while traveling forward, slowing or stopping the vessel. This results in unpredictable forces and moments that decrease control and maneuverability. This project utilized computational fluid dynamics (CFD) to model the fluid flow during crashback in hopes of determining the physical causes of the unsteady forces and moments that occur. At the Naval Surface Warfare Center in ... |
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| Numerical Simulation of Galvanic Corrosion Caused by Shaft Grounding Systems in Steel Ship Hulls |
07 SEP 2005 |
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| Authors:
Y. Wang; DEFENCE RESEARCH AND DEVELOPMENT ATLANTIC DARTMOUTH (CANADA)
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| The shaft grounding systems used on board HMC ships have substantially reduced the shaft-to-hull resistance and, thus, improved the performance of the shipboard impressed current cathodic protection (ICCP) system. Under some circumstances, however, the shaft grounding systems have been left on while the ICCP system was turned off. This led to the accelerated corrosion of the exposed steel ship hull on paint holidays because of the substantial difference of the ... |
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| Experimental Investigation of a Lift Augmented Ground Effect Platform |
SEP 2005 |
108 pages |
| Authors:
Roberto T. Igue; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
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| This experimental study investigated the feasibility of applying the concept of a skirtless hovercraft into the production of an operational vehicle. A 0.255 m diameter prototype was designed, built and tested. An air bearing table was used as a testing platform, virtually eliminating the influence of friction and providing one degree of freedom for the experiments. Static tests were performed at various heights and craft configurations, providing a wide range ... |
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| Propeller Flow Field Mapping of Model 5415 Using 3-Component Laser Doppler Velocimetry |
17 AUG 2005 |
31 pages |
| Authors:
Christopher Chesnakas; Toby Ratcliffe; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| Subsurface velocities were obtained on Model 5415 using a three-component Laser Doppler Velocimetry System. Data were obtained for the model running at a Froude number of 0.28, which corresponds to a full scale ship speed of 20 knots. Measurements were performed in three planes, x/L = 0.9367 (propelled), x/L = 0.9453 (unpropelled), and x/L = 0.9603 (propelled and unpropelled). A detailed uncertainty analysis was performed. The dominant source of uncertainty ... |
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| Unmanned Underwater Vehicle Tailcone Assembly |
04 APR 2005 |
12 pages |
| Authors:
Robert F. Doleski; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A tailcone assembly for an undersea vehicle includes a first tailcone portion having a cavity and a second tailcone portion positionable in and axially extensible from the cavity. An extensible drive shaft is provided for joining the vehicle's engine to a propeller. The extensible drive shaft includes a first drive shaft joined to the engine, and a second drive shaft rotating with the first drive shaft. The second drive shaft ... |
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| Characterization of Microstructure and Microtexture in Longitudinal Sections from Friction Stir Processed Nickel-Aluminum Bronze |
JUN 2003 |
77 pages |
| Authors:
Kenneth B. Faires; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING
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| Cast nickel-aluminum bronze (NAB) is the material of choice for propellers in both surface ships and submarines. New designs require a material with improved strength and hardness while retaining NAB's corrosion resistance. Friction stir processing (FSP) represents a new technology for surface hardening of as-cast NAB by means of severe plastic deformation induced by a rotating tool that is traversed across the surface of a material. FSP can convert a ... |
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| The Effects of Isothermal Deformation and Annealing on the Microstructure of Nickel-Aluminum-Bronze Propeller Material |
JUN 2003 |
63 pages |
| Authors:
William A. Nabach; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This thesis is a study of annealing and deformation characteristics of cast Nickel-Aluminum Bronze (NAB) in relation to Friction Stir Processing (FSP) of this material. Cast NAB is widely utilized by the U.S. Navy as material used in the production of propellers for surface vessel and submarines. FSP is a novel method of deformation processing that is conducted by use of a rotating tool that is forced onto the surface ... |
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| Aging Mechanisms and Control. Symposium Part A - Developments in Computational Aero- and Hydro-Acoustics. Symposium Part B - Monitoring and Management of Gas Turbine Fleets for Extended Life and Reduced Costs (Les mecanismes vieillissants et le controle) |
FEB 2003 |
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| Authors:
NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
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| Part A: The acoustic characteristics of air and sea vehicles are of increasing importance for war-time as well as peace-time operations. The meeting treated (the potential)of and results obtained with computational aero- and hydro-acoustics. It is a relatively new and rapidly expanding technical discipline with a large potential for (more) accurate prediction of the acoustic characteristics of air and sea vehicles. Examples are: Acoustic signatures. Acoustic fatigue loads and their ... |
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| V-22 Osprey Tilt-Rotor Aircraft |
14 JAN 2002 |
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| Authors:
Christopher Bolkcom; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
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| The V-22 Osprey is a tilt-rotor aircraft that takes off and lands vertically like a helicopter and flies like a plane by tilting its wing-mounted rotors to function as propellers. Combining a helicopter's operational flexibility with the greater speed, range, and efficiency of fixed-wing aircraft, the V-22 can perform such missions as troop/cargo transport, amphibious assault, special operations, and search and rescue operations. Begun in FYl982 by the Army and ... |
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| AHFID Propulsor Performance Prediction |
JAN 2002 |
30 pages |
| Authors:
Thad J. Michael; Stuart D. Jessup; Otto Scherer; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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| The thrust and torque of the propulsor tor the Advanced Hull Form Inshore Demonstrator were predicted using a vortex lattice propeller code coupled with an Euler solver. The propulsor is a post-swirl ducted unit with the rotor band recessed into the duct inner surface. To predict the additional torque due to the recessed band, empirical methods were used. The demonstration- scale propulsor is predicted to absorb 2360 hp (1760 kW) ... |
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| Model and Full Scale Predictions of a Carrier Flow Field |
JAN 2002 |
33 pages |
| Authors:
Joseph Gorski; Henry Hausling; Roderick Coleman; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD HYDROMECHANICS DIRECTORATE
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| Viscous flow calculations using the Reynolds Averaged Navier-Stokes (RANS) equations are performed for a carrier configuration at both model and full scale Reynolds numbers. These calculations are for a bare hull with skeg, bilge keels and outboard propeller shaft. The calculations indicate there are extensive differences between the model and full scale wakes entering the propeller disks. Without the propeller shaft the dominant effect is the bilge vortex particularly at ... |
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| V-22 Osprey Tilt-Rotor Aircraft |
05 NOV 2001 |
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| Authors:
Christopher Bolkcom; LIBRARY OF CONGRESS WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE
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| The V-22 Osprey is a tilt-rotor aircraft that takes off and lands vertically like a helicopter and flies like a plane by tilting its wing-mounted rotors to function as propellers. Combining a helicopter s operational flexibility with the greater speed, range, and efficiency of fixed-wing aircraft, the V-22 can perform such missions as troop/cargo transport, amphibious assault, special operations, and search and rescue operations. Begun in FY1982 by the Army ... |
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| An Expectation-Maximization Approach to Spectral Structure Identification and Estimation |
OCT 2001 |
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| Authors:
Marian Viola; Alan Bolton; Bill Moran; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION SALISBURY (AUSTRALIA) ELECTRONICS AND SURVEILLANCE RESEARCH
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| The method of Expectation-Maximization is applied to find an approximate maximum-likelihood estimate of the amplitudes, phases and frequency shift of a known collection of spectral lines in a signal with Gaussian noise. The technique works well for many frequency components provided that these frequencies are well separated. It is applied to the identification of the frequencies present in a radar return from a propeller driven aircraft, arising from modulation by ... |
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| Monitoring of Boston Harbor Confined Aquatic Disposal Cells |
SEP 2001 |
114 pages |
| Authors:
Lyndell Z. Hales; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICSLAB
|
| The Boston Harbor Navigation Improvement Project (BHNIP) involves deepening of the main ship channel and three tributary channels to the Inner Harbor, and associated berthing areas. Lack of an upland disposal site and resource agency denial of permission to place and cap the contaminated sediments at an open water site resulted in the decision to use in-channel CAD cells for placement of contaminated material that would be dredged with an ... |
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| Performance Evaluation of an OH-58A+ With Dimpletape Installed |
AUG 2001 |
136 pages |
| Authors:
Gregg A. Deetman; TENNESSEE UNIV KNOXVILLE
|
| This flight test investigates the performance benefits of a recently developed vortex generator, called Dimpletape(registered), on an OH-58A+ helicopter rotor blade. This product employs the aerodynamic concepts that are used to reduce the drag on a golf ball. The manufacturer claims significant performance benefits with the product applied to airplane wings and propellers; however, no flight-testing has been conducted on commercial helicopter rotor blades. Four different Dimpletape(registered) lengths where flight-tested ... |
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| Characterization of Underwater Sounds Produced by Bucket Dredging Operations |
AUG 2001 |
18 pages |
| Authors:
Charles Dickerson; Kevin J. Reine; Douglas G. Clarke; Robert M. Engler; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
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| This technical note presents a characterization of underwater sounds produced by bucket dredging operations in Cook Inlet, Alaska. Both continuous sounds, such as those produced by propellers, pumps, and generators, and repetitive sounds produced by particular dredging events (e.g., dredge bucket striking the channel bottom,jaws of bucket clamping shut) are potential sources of underwater noise. This note examines the intensity, periodicity, and attenuation of emitted sounds from bucket dredging operations ... |
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| (ALPHA) 2 (BETA) 1 Integrin-Induced Breast Cancer Differentiation |
AUG 2001 |
29 pages |
| Authors:
Tetsuji Kamata; SCRIPPS RESEARCH INST LA JOLLA CA
|
| Cell adhesive events play essential roles in the pathophysiology of breast cancer. Two important biological phenomena have been shown to depend upon integrins. The differentiation of breast cancer cells depends upon the expression of alpha2beta1 integrin on the cell surface. The creation of distant metastasis is supported by the association of breast cancer cells with platelets. This association depends on the interaction between the activated alpha2beta3 integrin on the breast ... |
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| Unsteady Propeller Hydrodynamics |
JUN 2001 |
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| Authors:
Dirk H. Renick; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING
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| One of the main problems affecting modern propulsor design engineers is the ability to quantitatively predict unsteady propeller forces for modern, multi-blade row, ducted propulsors operating in highly contracting flowfields. Current algorithms provide valuable insight into qualitative trendlines for these modern designs. This thesis has focused on the more accurate quantitative force prediction by introducing more physical modeling into the numerical computations, using more accurate analytical representation of continuous physical ... |
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| Drag Reduction Technologies |
2001 |
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| Authors:
V. T. Truong; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AERONAUTICAL AND MARITIME RESEARCH LAB
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| Diluted polymer solutions, surfactants, microbubbles and compliant coating as drag reducers have been reviewed in this report. The advantages and disadvantages of each method have been discussed. For the polymer solutions, it is possible to achieve up to 80% drag reduction with only a few parts per million of polymer. Ionic and non-ionic surfactants can also offer similar drag reduction as polymer solutions but at a high concentration of few ... |
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| Weapons of Choice: The "Propeller versus Jet" Controversy and the "Appropriate Technology" Dilemma |
JUN 2000 |
77 pages |
| Authors:
Robert K. Abernathy; AIR UNIV MAXWELL AFB AL SCHOOL OF ADVANCED AIRPOWER STUDIES
|
| This study examines the difficulties involved in fielding technology appropriate to the mission. Using Graham Allison's models of decision-making as analytical lenses, the author shows how the "appropriate technology dilemma" challenged those responsible for interdicting the North Vietnamese Army along the Ho Chi Minh Trail in 1966-67. Known as the "propeller versus jet" controversy, there was a difference of opinion between the "unconventional" Air Commandos and the "conventional" Air Force ... |
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| Computer Simulations of Molecular Propellers |
04 SEP 1999 |
6 pages |
| Authors:
Jaroslav Vacek; CZECHOSLOVAK ACADEMY OF SCIENCES PRAGUE J HEYROVSKY INST OF PHYSICAL CHEMISTRY AND ELECTROCHEMISTRY
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| This report results from a contract tasking J. Heyrovsky Institute of Physical Chemistry & Electrochemistry as follows: The contractor will improve upon an existing computer code modeling the classical dynamics of a molecular structure within a solid (intramolecular bonding and vibrations intermolecular collisions and electrostatic interactions). The new program will be used to explore computationally a variety of possible structures for the synthesis of new materials capable acquiring significant internal ... |
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| Dynamic Effects on Propeller Blade Section Lift, Drag, and Pitching Moment Coefficients |
AUG 1999 |
63 pages |
| Authors:
Young T. Shen; Donald Fuhs; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| The Propeller Force Module (PFM) uses the blade element/momentum theory to predict propeller forces during maneuvers. A typical inflow angle distribution is studied. The blade sections will encounter spatial and temporal variations in angles of attack. Theories to calculate unsteady effects on section lift, drag, and pitching moment coefficients are formulated and presented in this report. Using the classic approach developed in aerodynamics, the section lift and pitching moment are ... |
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| Unmanned Aerial Vehicle/Remotely Piloted Aircraft Design Selection Based on Service-Stated Meteorological/Oceanographic Requirements |
MAR 1999 |
100 pages |
| Authors:
Robert J. Stanton; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A decision tool for choosing most efficient unmanned aerial vehicles (UAV's)/remotely piloted aircraft (RPA) for Meteorological/ Oceanographic (METOC) data collection is presented. A Microsoft Access database query (written in Structured Query Language) links RPA flight performance parameters to individualized METOC Elements of Measurement, a subset of a larger Joint Service METOC Requirements database table, presented elsewhere in the thesis in full. Successful aircraft performance parameters include vast controllability/ programmability ranges, ... |
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| Evaluation/Validation of an Electronic Engine Speed Pilot on the USCGC TAMPA (WMEC 902) |
OCT 1998 |
62 pages |
| Authors:
Bert Macesker; Robert Desruisseau; Hank Kocevor; Charlie Marino; COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CT
|
| The need to reduce and manage energy and fuel in the Coast Guard was promulgated in Commandant Instruction 4100.2D, dated 6 March 1997. The Coast Guard is required by law to reduce its overall energy consumption and to minimize the use of petroleum fuel in all its facilities and platforms. The Coast Guard Energy Program Director recognizes the need to introduce future low- cost and proven engineering retrofit changes to ... |
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| Rotating Arm Captive Model Tests of the U.S. Coast Guard Prototype 47-FT Motor Lifeboat |
OCT 1998 |
120 pages |
| Authors:
Edward M. Lewandowski; Walter E. Klosinski; COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CT
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| The USCG prototype 47-Fr Motor Lifeboat (MLB) experienced transient roll angles of as much as 40 degrees in a turn at 27 knots with 30 degrees of rudder. The prototype was modified to correct this problem, by moving the rudders to a vertical position, vice 15 degrees outboard angle. The tests reported on here were part of an effort to develop a computer simulation of this snap roll phenomenon. Captive ... |
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| MIT/Draper Technology Development Partnership Project: Systems Analysis and On-Station Propulsion Subsystem Design |
04 AUG 1998 |
127 pages |
| Authors:
Theodore E. Conklin; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| The objective of this thesis is to describe the process for, and the overall design that resulted from the MIT/Draper Project from August, 1996 to May, 1997, including the specific design of the on-station propulsion subsystem for the Wide Area Surveillance Projectile, WASP. A summary of the technological needs of this nation, as determined by the MIT/Draper Project team begins the thesis. Possible opportunity areas ... |
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| Submarine Launched Unmanned Aerial Vehicle |
01 APR 1997 |
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| Authors:
Steven P. Bourlett; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A submarine launched unmanned aerial vehicle comprises an elongated generally cylindrically-shaped body. Tail fins are stored in the body and are self deployable to extend outwardly from the body. A booster motor is fixed to an aft end of the body and is self releasable from the body. A propeller is disposed at the aft end of the body and is self deployable to an exposed position at the aft ... |
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| Physical Model Studies for Riprap Design of Tow-Induced Forces |
APR 97 |
261 pages |
| Authors:
Sandra K. Martin; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS COASTAL HYDRAULICS LA B
|
| As commercial towboats navigate inland waterways, physical forces in the form of waves and currents are generated. In confined or restricted waterways, these vessel induced forces can have a significant effect on the surrounding environment. Evaluating the impacts of navigation induced forces on the riverine environment has become a topic of serious discussion and intense debate in recent years. Technical studies related to navigation effects investigate the characteristics of the ... |
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| T56 Propulsion System Cost Study |
NOV 96 |
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| Authors:
Kevin M. Jaansalu; Robert R. Hastings; Greg N. Nelson; DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
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| This study analyzes operating costs and flight safety data of the propulsion systems on the CC-130 Hercules and CP-140 Aurora/Arcturus aircraft to identify where R&D investment could provide airworthiness or program cost benefits. Operational impact and R&O cost data are provided on the gas turbine engine, the reduction gearbox, and the propeller systems. The propeller system has a greater impact for both aircraft types on flight safety occurrences than the ... |
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| Delayed Recovery of Seagrass Beds Along Navigable Waterways: Interaction Between Disturbance and Nuisance Algae |
02 MAY 96 |
47 pages |
| Authors:
Jeff G. Holmquist; PUERTO RICO UNIV MAYAGUEZ DEPT OF MARINE SCIENCES
|
| In coastal systems, patches of seagrass are frequently destroyed by propeller scarring and anchor damage near waterways, resulting in denuded 'blowouts'. Persistence of blowouts is a poorly understood phenomenon, and I proposed that (1) benthic 'drift' algae (marine analogs of terrestrial tumbleweeds) settle in blowouts and protract recovery of seagrass by shading the affected patches, and (2) that algal masses may be more easily trapped in small blowouts than in ... |
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| Development of a Forecasting Model of Naval Aviator Retention Rates |
MAR 96 |
71 pages |
| Authors:
Matthew F. Coughlin; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this thesis is to develop an estimating model to predict the effects of various internal and external variables on Naval aviator retention rates. The estimating model will be useful to aviation program managers to develop a spreadsheet tool for predicting retention rates for Naval aviators. Past analyses have focused mainly on analyzing micro-level data. This thesis uses grouped retention rates for all Naval aviators for fiscal years ... |
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| Marine Propeller. |
07 NOV 1995 |
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| Authors:
Robert M. Williams; Ernest O. Rogers; Maurice M. Sevik; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A marine propeller using the circulation control principle of blowing tangentially over a Coanda surface at the trailing edge of each blade to develop high blade lift (thrust). Each blade has internal chambers and two blowing slots so that blowing is controllable for forward and for reverse thrust without reversing rotational direction of the propeller. This propeller is capable of generating much greater thrust and ship speed at lower RPM ... |
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| A Contrarotating Propeller Design for a High Speed Patrol Boat with Pod Propulsion |
NOV 95 |
32 pages |
| Authors:
Benjamin Y-H. Chen; Carol L. Tseng; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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| A contrarotating (CR) propeller design with a tractor pod for a high speed patrol boat is addressed. In the current arrangement, a CR propeller is placed at the forward end of a pod which is aligned with the local inflow. The powering and cavitation experiments show the performance prediction agree well with measurements. Compared to the existing controllable pitch propeller with shaft and strut configuration, the pod-mounted CR propeller show ... |
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| Numerical Modeling of Propeller Tip Flows with Wake Sheet Roll-up in Three Dimensions |
JUL 95 |
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| Authors:
Sangwoo Pyo; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING
|
| A boundary element method is applied to the prediction of the flow around propeller blades, with emphasis at the tip region. The presented work is divided into three major parts. In the first part, a new panel arrangement, namely the FLow Adapted Grid (FLAG), is proposed. This grid is normal to the blade leading edge outline and adjusted to the force free wake geometry at the trailing edge. The location ... |
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| Numerical Studies of Turbulent Free Surface Flows and Unsteady Propeller Flows |
31 MAR 95 |
62 pages |
| Authors:
Steven A. Orszag; Vadim Borue; Ilya Staroselsky; Yansi Zhang; CAMBRIDGE HYDRODYNAMICS INC PRINCETON NJ
|
| Two main problems have been studied, viz. the structure of turbulence near a free surface and the Reynolds-averaged solution of unsteady propeller/ hydrofoil flows by the renormalization group (RNG) two-equation turbulence transport model. A variety of free-surface turbulence simulations demonstrate the key modifications in turbulence structure due to the free surface. In addition, we determine the modifications in surface wave spectra due to the turbulence beneath the free surface as ... |
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| Computational Modeling of Coating Integrity Effects on Impressed Current Cathodic Protection System |
28 MAR 95 |
16 pages |
| Authors:
Virginia G. DeGiorgi; C. P. Hamilton; NAVAL RESEARCH LAB WASHINGTON DC
|
| Coatings are often used in conjunction with impressed current cathodic protection (ICCP) systems to minimize the effect of corrosion on marine structures. The presence of a coating reduces the current required by an ICCP system. The integrity and efficiency of the coating determines the level of current reduction achieved over the bare metal condition. One of the difficulties is designing a combined coating and ICCP system is that coatings deteriorate ... |
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| A Mine Search Algorithm for the Naval Postgraduate School Autonomous Underwater Vehicle |
DEC 94 |
102 pages |
| Authors:
Rodrigues Neto; Jose Augusto; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis develops, implements and tests a mine search algorithm for the Naval Postgraduate School Autonomous Underwater Vehicle (Phoenix). The vehicle is 72 inches long and displaces 400 pounds. Its maneuvers are performed using two propellers and four thrustem. It contains two embedded computer systems. The algorithm directs the autonomous search of a specified area mapping all obstacles and computing an estimate of the cumulative probability of detection. The algorithm ... |
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| A Review of Selected Modular Maneuvering Models |
NOV 94 |
128 pages |
| Authors:
Robert D. Sedal; Nathan R. Fuller; COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CT
|
| This report summarizes rotating arm model tests performed on a small and large-scale MARINER model, and on a systematic series of 14 small models based on variations of the MARINER hull form. Forces and moments on all the fully fixed models were recorded. In the large-scale MARINER tests, data on rudder inflow velocities, and the effect of the rudder and propeller on hull forces and moment were also obtained. The ... |
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| Multi-Propeller Drive System. |
05 JUL 1994 |
|
| Authors:
Robert V. Belenger; DEPARTMENT OF THE NAVY WASHINGTON DC
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| This patent application discloses an invention which relates to dual propeller drive systems and more particularly to device for converting a single drive shaft to a multi-propeller system. This multi-propeller drive system has a single input shaft for connect to an engine system, a differential gear assembly. The differential gear assembly operates in a manner wherein one output shaft, if required, is permitted to resolve at a different rate than ... |
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| Scale Effects on Aircraft and Weapon Aerodynamics (Les Effets d'Echelle et l' Aerodynamique des Aeronefs et des Systemes d' Armes) |
JUL 94 |
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| Authors:
A. B. Haines; ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)
|
| The present state of knowledge on scale effects at high lift and low speeds, at transonic speeds, and on aircraft drag are presented. In addition, scale effects in various important specific scale-sensitive areas such as forebody vortex flows, the flow in and near open cavities, the flow into an air intake, the flow over propellers, and on ice accretion simulation testing are discussed. The emphasis is on scale effects that ... |
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| Development of Naval Diesel Engine Duty Cycles for Air Exhaust Emission Environmental Impact Analysis |
MAY 94 |
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| Authors:
Stephen P. Markle; STATE UNIV OF NEW YORK AT STONY BROOK COLL OF ENGINEERING
|
| A strategy for testing naval diesel engines for exhaust emissions was developed. A survey of existing international and national standard diesel engine duty cycles was conducted. All were found to be inadequate for testing and certification of engine exhaust emissions from naval diesel powered ships. Naval ship data covering 11,500 hours of engine operation of four U.S. Navy LSD 41 Class amphibious ships was analyzed to develop a 27 point ... |
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| Combined Bulbous Bow and Sonar Dome for a Vessel. |
25 JAN 1994 |
|
| Authors:
Gabor Karafiath; Dominic S. Cusanelli; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| To reduce the total ship resistance and to improve a Propeller efficiency and cavitation performance due to the reduced thrust loading on the propeller for ships or vessels having a sonar dome or an equivalently shaped designs located below the baseline of the hull, a tear-drop-shaped bulbous bow is attached to the ship stem bow between the forward perpendicular of the bow and 12.7 ft forward of the forward perpendicular ... |
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| DD 21A-A Capable, Affordable, Modular 21st Century Destroyer |
DEC 93 |
275 pages |
| Authors:
William J. Levedahl; Samuel R. Shank; William P. O'Reagan; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| Future Navy ships must be superior but inexpensive. A new philosophy and configuration provide the 21st century destroyer, the DD 21A, with global range; reduced lightship displacement and cost; superior seakeeping; no seawater ballast; sharper turns and stops; and greatly reduced installed power, fuel consumption, and pollution. These benefits result from a new machinery-driven ship design paradigm centered on simplicity and efficiency. All main machinery is modular and outside the ... |
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| Verification of the Boundary Element Modelling Technique for Cathodic Protection of Large Ship Structures |
DEC 93 |
61 pages |
| Authors:
Harvey P. Hack; Robert M. Janeczko; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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| Boundary element computer modeling is gaining acceptance for predicting the distribution of cathodic protection potentials on large immersed structures. Much has been published on this technique, including experimental verification on a laboratory scale. However, there has been little published on experimental verification of the model predictions on large structures, especially ships. Since the accuracy of a computer model depends on the boundary conditions used for the model, experimental verification is ... |
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| Design and Fabrication of an Ultra-Low-Cost Turboprop for RPV/UAV applications |
22 NOV 93 |
50 pages |
| Authors:
Bryan J. Seegers; Jonathan A. Sherbeck; M-DOT INC PHOENIX AZ
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| During the performance period, a heavy-wall ground-test turboprop engine was designed, fabricated and tested. The engine was comprised of turbine stator and rotor, exhaust duct, reduction drive, propeller, lubrication system and electronic control, all mated to the exhaust pipe of a Sundstrand TJ-90 expendable turbojet engine. Maximum horsepower attained was 118 at an inter- turbine temperature of 1536 deg F and output shaft speed of 2963 rpm at ambient conditions ... |
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