Day 3 Thu, August 10, 1989最新文献

Self-Propulsion Experiment for Icebreakers in Ice and Open Water 破冰船在冰面和开阔水域的自推进试验

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-038

W. Molyneux

引用次数: 2

On the Nonlinear Calculation of the Steady Bow Wave of a Ship 船舶船首定常波的非线性计算

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-044

F. Noblesse

{"title":"On the Nonlinear Calculation of the Steady Bow Wave of a Ship","authors":"F. Noblesse","doi":"10.5957/attc-1989-044","DOIUrl":"https://doi.org/10.5957/attc-1989-044","url":null,"abstract":"A nonlinear local analysis of the steady potential flow at a ship bow and stern, and more generally at any point along a ship waterline, is presented. The hull boundary condition and the nonlinear kinematic and dynamic free-surface boundary conditions are satisfied exactly, at the actual position of the free surface, in this analysis. The bow-flow analysis shows that the free surface at a ship bow is tangent to the stem.This theoretical result appears to agree with existing experimental measurements of the steady bow waves of the Wigley hull and the Series 60 CB=0.60 model. Furthermore, simple analytical expressions defining the fluid velocity at the bow and the stern, and at any other point along the ship waterline, in terms of the elevation of the free surface at the corresponding point are also obtained. These analytical expressions and the available experimental measurements of the wave profiles along the Wigley hull show that the velocity of the flow disturbance due to this hull is fairly small compared to the hull speed everywhere along the waterline except in very small regions around the bow and the stern, where the total fluid velocity is nearly equal to the hull speed in magnitude but directed vertically. Nonlinearities therefore appear to be quite important, although only in extremely small regions surrounding a ship bow and stern. A successful nonlinear method of calculation must then be able to represent the very rapid variation in the direction of the fluid velocity occurring within small regions around a ship bow and stern. In particular, a sufficiently fine discretization is required in these regions.","PeriodicalId":421711,"journal":{"name":"Day 3 Thu, August 10, 1989","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131172207","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}

引用次数: 0

Mean-Flow Measurements in the Boundary Layer and Wake of a Series 60 CB = .6 Model Ship With and Without Propeller 60系列CB = .6模型船带和不带螺旋桨的边界层和尾迹平均流量测量

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-039

Y. Toda, F. Stern, I. Tanaka, V. C. Patel

引用次数: 20

Four Screw Powering Experiments: Data Reduction, Extrapolation and Correlations 四螺杆动力实验:数据简化、外推和相关性

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-036

P. Chang, W. Beaver

引用次数: 0

The effects of Reynolds Number, Section Shape, and Turbulence Stimulation on the Lift of a Series of Model Control Surfaces 雷诺数、截面形状和湍流刺激对一系列模型控制面升力的影响

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-046

Edward J. Lewandowski

{"title":"The effects of Reynolds Number, Section Shape, and Turbulence Stimulation on the Lift of a Series of Model Control Surfaces","authors":"Edward J. Lewandowski","doi":"10.5957/attc-1989-046","DOIUrl":"https://doi.org/10.5957/attc-1989-046","url":null,"abstract":"A series of model control surfaces with equal areas but varying aspect ratio, was lasted in a towing tank on a ground board. The size of the fins, approximately 3 inches span and two inches chord, is typical of control surfaces used on models which are about five feel long. Lift and drag on the fins were measured over a range of angles of attack of 0 to 35 degrees. The tests covered a range of chord-based Reynolds numbers between 42,000 and 150,000.\u0000 Two sets of fins were tested, one having flat-plate sections and the other having NACA 0015 sections. The fins were each tested with and without turbulence stimulation In the form of tape with a serrated leading edge placed at 5% of the local chord aft of the leading edge of the foil.\u0000 The study has shown that the lift of the NACA 0015 fins was insensitive to Reynolds number in the range of the tests, and that the lift rates compare well with the results of previous tests carried out at high Reynolds numbers. Differences were noted in the characteristics of flat-plate and NACA 0015 fins which would indicate that the use of flat plates in the place of foil-shaped fins to save model construction cost is not good practice. Turbulence trips increase the measured drag, as expected, but also reduce the lift rate, most noticeable on the flat-plate fins.","PeriodicalId":421711,"journal":{"name":"Day 3 Thu, August 10, 1989","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122720827","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}

引用次数: 3

An Investigation into Effect of Hull Form on the Wake Wave Generated by Low Speed Vessels 船体形状对低速船舶尾流影响的研究

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-049

M. Renilson, S. Lenz

引用次数: 0

Computation of Total Forces and Moments of Bodies of Revolution Moving Beneath the free Surface 在自由表面下运动的旋转体的总力和力矩的计算

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-045

Y. Hong

{"title":"Computation of Total Forces and Moments of Bodies of Revolution Moving Beneath the free Surface","authors":"Y. Hong","doi":"10.5957/attc-1989-045","DOIUrl":"https://doi.org/10.5957/attc-1989-045","url":null,"abstract":"The accurate prediction of the total forces and moments of a body of revolution which is moving beneath the free surface with and without an angle of attack is one of the important areas in ship hydrodynamics. The experiments to measure these forces and moments were undertaken in the past by several researchers. The experimental results of forces and moments for a body of revolution near the free surface were reported in Reference 1 for various angles of attack and depths. Those of deep submergence were given in References 2, 3, and 4 for different angles of attack. Although there are many other published papers on the measurement of forces and moments, only the results of References 1-4 are used in this paper to compare with the predicted results. The total forces and moments consist of two parts in the present method; namely the inviscid part and the viscous part. The inviscid part of the forces and moments is computed using three-dimensional potential theory. The body boundary condition is exact and the free-surface condition is linearized. The body surface is discretized with many surface elements and the unknown strengths of the source and sink at each surface element are assumed to be constant. The velocities at surface elements are computed and saved for later computation of the viscous forces and moments. The viscous part of the forces and moments is computed with the application of the boundary layer theory for laminar and turbulent flows. The method developed by Young (Reference 5) is used to compute the total drag of bodies of revolution. It is assumed in this method that there is no flow separation. The axial force is computed with this method. The lateral force and pitching moment are computed under the assumption that there is separation in the two-dimensional cross flow. The boundary layer equation is solved to the separation point and the friction force is integrated to compute frictional drag. Furthermore, it is assumed that a constant pressure is acting on the two-dimensional section beyond the separation point.","PeriodicalId":421711,"journal":{"name":"Day 3 Thu, August 10, 1989","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126185532","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}

引用次数: 0

Drag Reduction with Riblets on Rowing Shells 减少阻力与波纹在划船壳

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-048

D. Coder, D. Walker

{"title":"Drag Reduction with Riblets on Rowing Shells","authors":"D. Coder, D. Walker","doi":"10.5957/attc-1989-048","DOIUrl":"https://doi.org/10.5957/attc-1989-048","url":null,"abstract":"An experiment is described in which riblets, which are longitudinal surface groves that have been shown by NASA to reduce turbulent flow skin friction on flat plates by much as 8 percent, are used to attempt to reduce the overall vehicle drag of rowing shells. Two single rowing shells, borrowed from the USNA rowing team and ballasted (with the outriggers removed) to represent a 200 lbf rower, were attached to the drag balance of the carriage of the USNA tow tank and towed at steady velocities from 4 to 20 ft/sec in 2 ft/sec increments. The attachment mechanism allowed the shells to move freely in heave and pitch (sinkage and trim) which were measured with a sonic height probe and angleometer, respectively. Various surface conditions tested include bare hull, flat (non-ribleted) tape, and riblet tape (cleaned and uncleaned) in combination with two sizes of trip wire and three trip locations. The particular riblet tape used provided a surface geometry of saw-tooth pattern transverse to the flow with a height and spacing of 0.003 in.\u0000 This provided an optimum non-dimensional height (s+) recommended by Walsh and Lindemann (1984) of NASA of 12 to 15 over most of the shell length for the higher velocities. The overall vehicle drag results are compared with and without riblets and with and without trip wire. Riblet drag reductions of between 3 and 5 percent are observed. The trip wire results showed an increase in drag due to their parasite drag at. the lower velocities but a drag reduction at the higher velocities. Predictions of the viscous component of the drag difference between configurations are developed including the effects of sinkage and trim. The predictions compare qualitatively with the experimental results except for the apparent drag reduction with a trip wire at the higher velocities.","PeriodicalId":421711,"journal":{"name":"Day 3 Thu, August 10, 1989","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129616928","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}

引用次数: 0

Uncertainty in Measurement of Ship Model Wave Profiles and Wave Pattern Resistance 船舶模型波浪剖面和波浪阻力测量中的不确定性

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-047

T. Ratcliffe, M. B. Wilson

引用次数: 0

A Design Method and an Application for Contrarotating Propellers 一种旋转螺旋桨的设计方法及应用

Day 3 Thu, August 10, 1989 Pub Date : 1989-08-08 DOI: 10.5957/attc-1989-042

B. Y. Chen, A. Reed

引用次数: 7