Wash Waves Generated by High Speed Displacement Ships

It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible.

Numerical Prediction of Added Resistance and Vertical Ship Motions in Regular Head Waves

增加的抵抗和垂直轮船的数字预言一 ITTC (国际拖引坦克会议) 打手势在由我们的自己的内部地不稳定的 RANS 解答者 naoe-FOAM-SJTU 的常规头波浪的 S-175 货柜船在这篇论文被介绍。解答者 naoe-FOAM-SJTU 的发展基于开放源代码 CFD 工具， OpenFOAM。数字分析在常规头波浪与四很不同的波长(0.8L pp 1.5L pp ) 集中于增加的抵抗和垂直轮船运动(举和沥青运动) 。一旦波长在轮船模型的长度附近，抵抗和轮船运动的回答变得强烈由非线性的因素影响了，作为结果在模拟以内的困难发生。在纸，试验性的结果和非线性的长带理论的比较被考察并且基于调查结果，由解答者 naoe-FOAM-SJTU 的 RANS 模拟在大量波长与增加的抵抗和垂直轮船运动的预言被认为能干。

Numerical study on wave loads and motions of two ships advancing in waves by using three-dimensional translating-pulsating source

A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.

Effect of Ship Bow Overhang on Water Shipping for Ship Advancing in Regular Head Waves

这份报纸论述处理鞠躬的效果的试验性的调查的结果悬于发货的数量上的延期在在常规头波浪进展的轮船的情况下在前甲板上流水。执行这调查，一系列免费跑的测试在使用一艘多种用途的货物轮船的一个试验性的模型确定的常规波浪被进行装运水的数量。测试在五个弓上被执行悬于有波长和轮船的几联合的变体加速条件。装运水的数量被象波长，轮船速度，和鞠躬形状那样的一些参数以 overhang 扩展影响，这被观察。结果显示出 overhang 延期的重要影响，它与鞠躬闪光形状被联系，在水发货的出现上。这些结果包含联合到来的常规波浪和模型速度。

Basic models of farfield ship waves in shallow water

Basic models of the farfield waves created by a monohull ship or a catamaran that travels at a constant speed in calm water of uniform finite depth are considered.A classical basic model is the 1-point ship model introduced by Kelvin in 1887 for deep water and extended to uniform finite water depth by Havelock in 1908.Another basic model is the 2-point ship model,which considers the two dominant waves created by the bow and the stern of a monohull ship or by the twin bows of a catamaran,and therefore accounts for main wave interference effects.These 2-point ship models contain information that cannot be found in the classical patterns for the 1-point ship model commonly used since Kelvin.In particular,whereas Havelock’s classical wave patterns for the 1-point model only depend on the Froude number based on the water depth,the farfield waves for the 2-point models of a monohull ship or a catamaran also depend on the Froude number associated with the length of the monohull ship or the spacing between the twin hulls of the catamaran.Moreover,the‘apparent wake angles’associated with the highest waves that result from constructive wave interferences can greatly differ from the cusp or asymptote angles of Havelock’s wave patterns.

Model Test and Design of the Wave Energy System on "Central Fairway No. 1" Light Ship

This paper presents the test of a ship model for the design of a backward-bent duct oscillating water column type wave energy conversion system, to supply electric power for a light ship. This system suggests a new way to produce electric power automatically for large light ships.

Simulation Analysis on Navigation Indexes of Wanzhou Yangtze River Highway Bridge after the Anti-Collision Device Construction by Ship Model Test

After the anti-collision facility construction of Wanzhou Yangtze River Highway Bridge, the conditions of navigation in bridge area are complex. In order to study the navigation conditions of the reach and layout optimization measures, ensuring the safety of the ship navigation test has been carried out on the ship model navigation in the bridge area. According to the requirements of the maximum safety limit of the ship model test, the paper puts forward the best route, the control method and the difficulty of navigation through the analysis of the test results, and finally gives the recommendations and suggestions.

Valid hydrodynamic interaction regions of multiple ships advancing in waves

Based on the 3-D surface panel method combined with the translating-pulsating source Green function, an approximate approach is developed to solve the hydrodynamic interacting problem of multiple ships advancing parallel in waves. Focus is on improving the calculating efficiency. In this approach, each ship is assumed to be in each other＇s far-field, and the near-field term in this Green function is neglected if the source point falls on one ship and the field point on others. Further, a matching relationship between the far-field waves and the interfered regions, which are defined as the overlapping areas between the mean wetted body surface of one ship and the propagating regions of the waves generated by another ship, is introduced to avoid the unnecessary computation of the relative terms of the Green function, if the field point is not in the overlapping areas. The approach is validated through studying the hydrodynamic terms and the free motions of two or three ships in side-by-side arrangement by comparing the obtained results with the model tests and the predictions of the exact method. The average calculating speed for the present approximate method is about 1.65-1.8 times of that for the exact method for solving the hydrodynamic interaction problem of two ships, and 2.56-2.73 times for that of three ships.

基于SHIPFLOW的某大型集装箱船阻力预报与试验验证

以势流兴波阻力理论中的Rankine源方法为计算基础,利用SHIPFLOW软件模拟了某大型集装箱船的周围流场,考虑流体粘性及自由表面影响,预报了集装箱船的船模阻力。选择三种船体网格(FM,MM,CM)进行船体表面网格划分,采用势流理论与粘流理论的分区分步计算方式(ZONAL法),将数值计算的船舶总阻力值与船模试验值进行对比。计算结果表明网格划分形式MM的计算结果最为准确,同时也验证了SHIPFLOW软件求解技术的可靠性并提高了计算效率。最后选择MM网格划分形式,基于改造母型船法,对原球艏形式进行了改型,计算结果表明:改型球艏船型较原始船型具有更好的阻力性能,达到了船型优化的目的。

CFD-Based Method of Determining Form Factor k for Different Ship Types and Different Drafts

The value of form factor k at different drafts is important in predicting full-scale total resistance and speed for different types of ships. In the ITTC community, most organizations predict form factor k using a low-speed model test. However, this method is problematic for ships with bulbous bows and transom. In this article, a Computational Fluid Dynamics(CFD)-based method is introduced to obtain k for different type of ships at different drafts, and a comparison is made between the CFD method and the model test. The results show that the CFD method produces reasonable k values. A grid generating method and turbulence model are briefly discussed in the context of obtaining a consistent k using CFD.

Numerical Simulation on the Resistance Performance of Ice-Going Container Ship Under Brash Ice Conditions

Ice resistance prediction is a critical issue in the preliminary design of ships navigating brash ice conditions, which is closely related to the safety of a ship to navigate encounter brash ice, and has significant effects on the kinds of propellers and motor power needed. In research on this topic, model tests and full-scale tests on ships have thus far been the primary approaches. In recent years, the application of the finite element method(FEM) has also attracted interest. Some researchers have conducted numerical simulations on ship–ice interactions using the fluid–structure interaction(FSI) method. This study used this method to predict and analyze the resistance of an ice-going ship, and compared the results with those of model ship tests conducted in a towing tank with synthetic ice to discuss the feasibility of the FEM. A numerical simulation and experimental methods were used to predict the brash ice resistance of an ice-going container ship model in a condition with three concentrations of brash ice(60%, 80%, and 90%). A comparison of the results yielded satisfactory agreement between the numerical simulation and the experiments in terms of both observed phenomena and resistance values, indicating that the proposed numerical simulation has significant potential for use in related studies in the future.

Experimental Study on the Resistance of a Transport Ship Navigating in Level Ice

这研究调查由在天津大学在一辆冰坦克进行一系列模型测试在北极水里遨游的一艘运输轮船的抵抗。实验室规模模型轮船用一个一个方向性的负担房间在一辆僵硬马车上被装然后以不同速度通过一张冰表拖引。我们在轮船的不同部分和冰大浮冰的运动观察了打破冰的过程并且在不同速度下面测量了电阻决定在打破冰的过程和冰抵抗之间的关系。在肩膀区域的弯曲失败被发现引起最大的抵抗。而且，我们为估计冰抵抗介绍了 Lindqvist (1989 ) 的分析方法然后从我们的模型测试把这些计算结果与那些作比较。结果显示计算全部的电阻比那些高我们在模型测试决定了。

Design and implementation of model test installation of heave compensation system of deepsea mining

In order to validate the simulation model and develop heave compensation control strategy,heave compensation model tests were performed.The model test installation includes themining ship motion simulator,the heave compensation system,the lifting pipe simulator,the buffer simulator and the water pool.The tests ofmining ship motion simulator show that it is able to perform under the predetermined attitude path smoothly and can meet the requirements of themining ship motions.The heave compensation effect is more than 60% under random wave and the goal is set to be 50%.The model test results indicate that this heave compensation system is effective and feasible.

Discussion on the Correlative Problem of Maneuverability Model Test for Vessels with Large Scale

It is well known that model test is one of approaches to investigate the maneuverability of vessels and the correlative method is an important problem of model test for vessels with large scale. Some of correlative problems,which should be solved with care in model test,are presented from analysis of the similarity principle for the ship maneuverability in this paper.A corrective method of appropriate angle of rudder is provided based on the result of maneuverability model test for a tanker with large scale and the corresponding prediction of the maneuverability for full scale tanker is satisfactory in view of engineering practice.

沅水桃源枢纽左岸船闸桥区船模通航条件试验研究

沅江大桥通航环境十分复杂,原大桥通航孔布置不合理,严重制约了桃源枢纽二线船闸扩建工程建设。针对桥区通航条件差的问题,对其左岸桥梁通航孔布置方案进行船模试验研究,采用定床河工模型和小尺度船模试验相结合,并从船模试验的舵角、漂角和航速等航行参数进行综合分析,结果表明:在相同通航总净宽的情况下,双孔双向要优于双孔单向;桥梁通航孔右移可降低一线船闸船舶下行过桥难度,但会增加二线船闸船舶上行过桥的难度。建议左岸新建桥梁通航孔净宽应不小于220 m,桥位相比于现状桥梁右移约75 m,采用双孔双向,两线船闸分槽航行的方式。

船模静水参激横摇阻尼测量实验研究

针对船舶参数横摇独特的运动特征,设计激励稳性参数的船模静水参激横摇实验,研究与船舶参数横摇特征吻合的横摇阻尼测量方法.基于船舶参数横摇机理,设计了由激励船模重心高度的激振器,控制电机与测量船模运动的测控仪为主要设备组成的实验系统.由阻尼耗散、激励释放和复原力矩三项能量的平衡,推导了横摇阻尼系数的计算公式.露天船模水池的静水参激横摇阻尼测量实验.结果表明:稳态响应的横摇幅值持续稳定,大幅横摇阻尼可测,实验测量的重复性好.

基于虚拟现实技术的船舶航行实景三维模型设计

为提升船舶驾驶人员及船员的船舶整体认知以及海况应对能力,确保船舶航行以及作业安全,设计基于虚拟现实技术的船舶航行实景三维模型。按船舶航行需遵循的物理定律以及原理,建立船舶航行运动姿态数学模型,并通过3Dmax构建船舶航行环境实体以及地形模型,利用PM海浪谱法构建海表面三维模型,而后通过Unity3D虚拟现实仿真软件驱动调整构建的三维模型,并对所构船舶三维模型采用改进混合包围盒法实施碰撞检测,把地形以及海浪等实际数据信息融入到导入的模型之中,仿真模拟船舶航行实景,实现人机交互。实验结果表明,基于虚拟现实技术实现的船舶航行实景三维模型,可较为真实模拟船舶航行实景,为确保船舶航行以及作业安全提供可靠参考与保障。

江海直达集装箱船线型开发研究

以万吨级江海直达集装箱船为研究对象,针对其船型设计需求,结合计算流体动力学(CFD)方法开展了线型优化,优化线型首部采用低阻的隐形球首形式,尾部采用有利于螺旋桨推进效率的双尾鳍形式,经过优化形成了满足要求的优化线型。基于优化线型进行了快速性模型试验验证,模型试验结果表明,优化线型在设计吃水指定功率下航速可达13.55 kn,高于预期航速,进一步验证了该万吨级江海直达集装箱船线型开发满足设计需求。本文开发的万吨级江海直达集装箱船线型以及优化思路可为后续开展江海直达船线型优化设计提供借鉴与参考。

船舶智能航行的物理测试平台设计及应用

受测试成本、安全性、可靠性等因素的制约,需要依托以模型船为载体的物理实验平台实现从虚拟仿真测试到全尺寸实船测试之间的过渡。本文基于“航行脑”系统体系架构设计思想,采用船-岸-云分布式监控与数据采集架构,研发由能源管理、感知、决策、执行、通信等模块组成的船舶智能航行功能物理试验平台,打造“求新”系列缩尺比自航船模。开展回转试验、Z形试验、单船自主循迹、船舶编队等测试,验证了系统的有效性,并提出未来改进方向。

船舶操纵性约束模测量系统设计与分析

为解决实验室船舶操纵性约束模实验中的测量及数据分析处理技术问题,开发组建实验测量系统,推导数据分析处理方法,以期实现约束模实验的测量与数据在线分析处理;根据前期研究经验,设计了较为完善的测量硬件系统方案;为实现约束模中精确的零相位整周期测量要求,采用光电开关利用数据采集卡的硬件触发启动功能,并给出了整数周期测量的方案;利用最小二乘拟合及傅里叶分析等方法推导给出各船舶水动力导数数据处理方法;在此基础上,作为重点编写了完整的在线测量与数据在线分析程序,主要功能内部独立实现;该系统手工介入频度低,基本实现了测量的自动化,效率得到大幅提高;最后进行实际测量验证,数据的拟合结果与测量结果符合良好,验证了该系统的可靠性;同时处理结果显示船舶附加质量导数Y同船舶惯性质量很接近,而导数Y′r,N′数值很小,近于零。