Day 1 Sat, October 24, 1998最新文献

{"title":"Investigation of the Dynamics of Attached Cavitation on Hydrofoils","authors":"S. Ceccio, D. George, C. Iyer","doi":"10.5957/attc-1998-017","DOIUrl":"https://doi.org/10.5957/attc-1998-017","url":null,"abstract":"An electrical impedance probe is used to study the properties of partial attached cavitation. The method uses a series of electrodes mounted flush to the surface of a cavitating hydrofoil to obtain ti.me-dependent information about the presence of liquid or vapor in the region of interest. The impedance technique is used to measure the near-surface vapor-phase velocity and the shedding frequency of the cavity. The dependence of velocities upon cavity dimensions is discussed, and the measured frequencies are compared to current cavitation theory.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125709045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of Near-Surface Bow Bulbs in Irregular Waves","authors":"D. S. Cusanelli","doi":"10.5957/attc-1998-013","DOIUrl":"https://doi.org/10.5957/attc-1998-013","url":null,"abstract":"The U.S. Navy has been investigating the viability of a combined bow bulb and sonar dome concept on a combatant hull. A new type of near-surface, small volume, hydrodynamic bow bulb was developed, and integrated into the existing combatant bow which houses a sonar dome. Substantial resistance reduction was demonstrated through initial calm water model tests, which defined parameters for bow bulb volume and longitudinal position. An investigation was then undertaken to quantify the effectiveness of the near-surface bow bulb concept in irregular waves. The goal was to improve the bulb design so that the calm water resistance reduction was retained through rough water of sea states 2 and 4. The bow bulb was evaluated with variations in bulb height, breadth, cross-sectional shape, and depth of submergence, while retaining equivalent bulb volume and longitudinal position.\u0000 Through several design refinements, a small volume, near-surface bow bulb was developed that significantly reduced resistance in calm water, and retained an equivalent resistance reduction in sea states 2 through 4, Figure 1. The selected bulb had a substantial performance improvement compared to the baseline (no bulb) configuration, in calm water and rough water, throughout most of the speed range. One of the energy enhancing characteristics of this bulb design was its effectiveness at reducing resistance at all ship speeds, even as low as 5 knots, in both calm and rough seas.\u0000 Some guidance is also offered as to bow bulb design compromises necessitated in order to balance both calm water and rough water bulb effectiveness. Bulb cross­sectional shape appeared to have less of an influence on bulb performance than the vertical positioning.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130500462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resistance, Sinkage and Trim, Wave Profile, and Nominal Wake Tests and Uncertainty Assessment for DTMB Model 5512","authors":"J. Longo, F. Stern","doi":"10.5957/attc-1998-004","DOIUrl":"https://doi.org/10.5957/attc-1998-004","url":null,"abstract":"Results from towing-tank experiments for David Taylor Model Basin model 5512 are presented for resistance, sinkage and trim, wave profile, and nominal wake tests and uncertainty assessment. The resistance and sinkage and trim data are for Froude numbers 0.05-0.45 and free-model condition. The wave profiles and nominal wake data are for Froude numbers 0.28 and 0.41 and fixed-model condition (at the dynamic sinkage and trim for each Fr). The test design, measurement systems, and uncertainty assessment are described. The uncertainty assessment methodology rigorously follows the AlAA Standard S-071-1995. The results are discussed with regard to the data ends and uncertainties, including Fr effects. Future work is mentioned. The data contributes to the surface-ship resistance and propulsion model-scale database for computational fluid dynamics validation, as part of an international collaborative project between Iowa Institute of Hydraulic Research, lstituto Nazionale per Studi ed Esperienze di Architettura Navale, and David Taylor Model Basin on experimental and computational fluid dynamics and uncertainty assessment for a combatant geometry.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123512638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Horizontal Plane Characteristics of Two Full Size Personal Watercraft","authors":"S. Cohen","doi":"10.5957/attc-1998-003","DOIUrl":"https://doi.org/10.5957/attc-1998-003","url":null,"abstract":"Efforts to design water jet craft with safe stopping characteristics have been hampered by lack of straight ahead and yawed resistance data. The characteristics of a Kawasaki model 300 stand-up Jet Ski are contrasted with a Polaris model 750 SLT multi-chine three-person watercraft. Drag and lift were measured in the towing tank with no jet thrust enabling directional control. To identify other variables that could be useful in design, turning circle and stopping field tests of the Polaris craft were made. It was found that most of these quantities follow linear theory, or are approximately constant as non-dimensional variables. Measurements of the hydrodynamic forces at midships acting on an unpowered jet ski are the first step to understand vessel control in situations when the engine has been stopped or at very low RPM These results can be used to quantify personal watercraft characteristics, and predict stopping distances and turning circle diameters for constant power.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124905914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design Method for Foil Assisted 26 ft. Catamaran","authors":"R. Latorre, A. S. Onas","doi":"10.5957/attc-1998-009","DOIUrl":"https://doi.org/10.5957/attc-1998-009","url":null,"abstract":"One method to improve high-speed catamaran performance is to fit transverse hydrofoils between catamaran hulls. These foil result in decreased catamaran resistance from reduced hull draft and reduced wetted surface. To develop workable designs it is necessary to size the hydrofoils to support the hull. This paper presents a design method developed for sizing the hydrofoils and two examples.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131909660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NUWC Supercavitating High Speed Bodies Test Range: Description and Test Results","authors":"J. Hrubes, C. Henoch, I. Kirschner, Clifford M. Curtis, Pierre J. Corriveau","doi":"10.5957/attc-1998-020","DOIUrl":"https://doi.org/10.5957/attc-1998-020","url":null,"abstract":"As submarine operations increasingly move into coastal waters, the risk of submarine close encounters increases, as does the vulnerability of the platform to advanced threat weapons systems. A hard-kill terminal defense system would provide an effective response against these close-in threats. This system must detect. classify and localize a potential threat. aim an underwater gun, and launch a very high-speed projectile towards a target to neutralize it. To deliver enough kinetic energy to the target without enormous parasitic drag requires unconventional methods -- supercavitation technology.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131916560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Future Naval Surface Ship Design and Hydrodynamic Performance Assessment","authors":"J. Webster, Ian Mutnick, Jim Rice","doi":"10.5957/attc-1998-005","DOIUrl":"https://doi.org/10.5957/attc-1998-005","url":null,"abstract":"The role of ship model tank testing in DoD ship construction programs has changed due to DoD policy and the advances made in hydronumeric modeling and simulation (M & S) computer codes. Performance improvements associated with innovative solutions need to be characterized in technical, schedule and cost areas in order to justify consideration. Computer simulations of system solutions performed early in the design cycle enable a wider range design space to be evaluated. Elements of steady flow and ship motions behavior have been successfully characterized with computer models. The validated range over which the performance of design concepts can be evaluated by computer models, however, is limited.\u0000 The hydrodynamic performance risk associated with advanced hull forms developed for two surface ship programs has been handled using state of the art physical and computer modeling techniques. Hydronumeric computer codes using potential flow theory were used to develop the design concepts. The performance of the resulting concepts and the ability of the computer code to predict hydrodynamic behavior has been validated by physical model testing in this project.\u0000 Water surface topological definition for the steady flow condition was obtained for ship models operating over a range of ship speeds. This data was obtained from towing tank experiments of candidate future surface-ship-hull forms conducted at the US Naval Academy and David Taylor Model Basin. These experiments included measurements of hull resistance, sinkage and trim, stern wave topology, and longitudinal and transverse wave cuts. The approach and results of the design process, the hydronumeric predictions used to develop the hydrodynamic designs, and ship model tests used to verify performance and increase the validated range of code predictions are presented. Details of the experimental procedures and data are provided. The test configuration, tank definition, model condition and other test conditions provide the code developers with an understanding of how the data was produced. Wave cut, free surface topology, model geometry, and test condition data will be provided on the DTMB Model 5415 web site when cleared for release.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133761652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrodynamic Performance with Pod Propulsion - US Navy Experience","authors":"G. Karafiath, D. Lyons","doi":"10.5957/attc-1998-012","DOIUrl":"https://doi.org/10.5957/attc-1998-012","url":null,"abstract":"The U.S. Navy has been interested in podded propulsion for over 20 years and has conducted model experiments on several designs in order to define their powering performance and other hydrodynamic characteristics. The model test drag data on several of these designs are analyzed and presented in terms of drag coefficient and pod residuary resistance. The model powering tests form a data base for estimating thrust deduction and wake fraction.\u0000 Podded propulsion frees the designer from the constraints imposed by the traditional propeller support arrangements to offer advantages with regard to better hull design for lower resistance, improved propeller inflow, and more efficient propellers. Compared to the traditional design, some podded designs are predicted to reduce the delivered power at the propeller by as much as 20%. The design objectives, design constraints and reasons for improved performance are discussed for each of the podded designs that are presented.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"164 2-3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115878290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Propulsive Thrust of an Oscillating Foil at Large Angles of Attack: Experimental Study","authors":"L. Luznik, N. Bose, Pengfei Liu","doi":"10.5957/attc-1998-014","DOIUrl":"https://doi.org/10.5957/attc-1998-014","url":null,"abstract":"An experimental study to measure developed thrust from a rigid foil subjected to unsteady oscillatory motion was conducted in the towing tank at Memorial University of Newfoundland. The foil tested had a rectangular planform, NACA0019 section, span of 400 mm, and aspect ratio 6. In the experiment the heave amplitude to chord ratio was large (of order 1) and the pitch amplitudes tested were 6, 13, 17.5, and 21 degrees. The pitching axis position was fixed at the mid-chord, and pitch led heave motion by 90 degrees.\u0000 Results of developed thrust are presented· and examined with respect to three areas of interest: large amplitude motion, foil performance at large angles of attack, and a comparison with an existing 3D large amplitude unsteady panel code to predict developed thrust Agreement between the numerical and experimental results is discussed and remarks concerning the limitations of the computational results are made. Uncertainty analysis on the experimental data was performed.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128517577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Uncertainty Analysis of Full-Scale Submarine Propulsion Predictions Using Two-Tank Model Tests","authors":"F. Noblesse, J. R. Lee, M. Pfeifer, R. B. Hurwitz","doi":"10.21236/ada353450","DOIUrl":"https://doi.org/10.21236/ada353450","url":null,"abstract":"Estimates of the uncertainties attached to full-scale predictions of submarine resistance and propulsion based on standard submarine tow-tank model tests are obtained by means of a global uncertainty analysis. The analysis takes into account all the component uncertainties, including the uncertainties associated with the prediction procedure and the measurements performed both at model scale and at full scale, which influence the overall uncertainty of full-scale predictions.","PeriodicalId":202192,"journal":{"name":"Day 1 Sat, October 24, 1998","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121823731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}