Modelling propeller and rudder induced forces acting on deep drafted vessels in muddy navigation areas

To assess the navigability of deep drafted vessels in muddy navigation areas a mathematical model has been built that takes into account the characteristics of the mud layer. This was achieved with the introduction of a fluidization parameter which determines the corresponding hydrodynamically equivalent depth above a solid bottom. As a result, the under keel clearance dependency of a given mathematical manoeuvring model can be reformulated in such way that the effect of any realistic muddy condition is included. In this article the modelling of the propeller and rudder induced forces and the implementation possibilities of the model will be discussed. It is concluded that the mathematical model, initially formulated for a 6,000 TEU container carrier, provides reliable predictions of the behaviour of larger container carriers and even fuller deep drafted ships.     

基于电子海图的船舶操纵仿真器

本文主要介绍最近研制的由微机、高分辨率显示器、图形卡、操纵控制箱等组成的基于电子海图船舶操纵仿真器的两个主要技术──船舶操纵数学模型和电子海图技术，最后还介绍了该仿真器在航海实际中的一个应用．在数学模型中，考虑到航海实际的需要，提出了一个适合常速、低速和大漂角等各种情况的水动力计算模型以及四象限舵力和浆力的算法．另外，考虑了浅水、岸壁、风、流、浪的影响及附属操纵设备──拖轮、缆绳、锚链等对船舶的作用．本仿真器的电子海图装置，不仅能实时显示船舶所在海域的海图，动态显示船舶的二维俯视图象及运动姿态、航行轨迹，还可根据需要选择性地放大、缩小海图、显示各种岸基设施，并且可以记录模拟过程中的各种数据，制作航迹图的硬拷贝以及在显示器上再现，以供分析研究．     

上海港外高桥挖入式港池进口航道航行条件研究

外高桥挖入式港池规划前期论证的关键内容之一是其进口航道航行条件的评估。交通部上海船舶运输科学研究所接受委托,对规划船型的操纵运动方程进行了仔细研究。对规划船型的典型——“冰河”轮作了水动力测定;利用实船试验资料对操纵运动的数学模型进行科学率定;使用本所研制的船舶操纵模拟器对规划拟定的两个港池——外高桥嘴挖入式港池和五号沟挖入式港池的进口航道航行条件进行了比较深入的试验研究。最后,给出了两个港池安全进口的必要条件,为规划部门选定提供了科学依据。     

基于CFD的内河船深浅水中操纵性预报

由于岸壁效应和浅水效应,内河船舶在限制水域作操纵运动时通常受到比在开阔水域中更大的水动力.这些水动力对船舶操纵性具有不利影响,有可能导致船舶碰撞或触底等海上事故.因此,为了在船舶设计阶段预报其操纵性能,考虑浅水效应和岸壁效应以准确计算内河船舶操纵运动水动力非常重要.本文基于CFD方法,通过对粘性绕流进行数值模拟,对长江中营运的三艘内河船舶的操纵运动水动力进行计算.首先,为了验证数值方法的可靠性,对标模KVLCC2纯横荡和纯首摇试验的水动力进行计算,并将计算结果与现有的试验数据进行对比.然后,对三艘内河船舶在不同水深下的静舵试验、纯横荡和纯首摇试验进行数值模拟,计算得到水动力及相应的线性水动力导数.最后,基于计算得到的水动力导数,获得Nomoto模型中的操纵性参数,对比分析三艘内河船舶在深浅水中的操纵性能.结果表明,本文方法可以揭示不同水深下三艘内河船舶的操纵性变化趋势.该方法可为船舶设计阶段内河船舶深浅水中的操纵性预报提供一种实用的工具.     

Broaching prediction of a wave-piercing tumblehome vessel with twin screws and twin rudders

The new intact stability criteria which are under development at the International Maritime Organization (IMO) are required to cover a broaching phenomenon, well known as a great threat to high-speed vessels which can lead to capsizing. Some reports exist which demonstrate that their numerical models can predict a highly nonlinear phenomenon of broaching. However, additional validation studies are needed for unconventional vessels, in addition to conventional ones, to develop direct stability assessment methods for the new intact stability criteria. In this research, we selected as the subject ship a wave-piercing tumblehome vessel with twin screws and twin rudders, a design expected to be one of a new generation of high-speed monohull ships. Firstly, a series of captive model tests were conducted to measure the resistance, the manoeuvring forces, the wave-exciting forces, the heel-induced hydrodynamic forces, and the roll restoring variation for the unconventional tumblehome vessel. Secondly, the existing mathematical model which had been developed for broaching prediction of conventional vessels with a single propeller and a single rudder was extended to unconventional vessels with twin propellers and twin rudders. Finally, comparisons between numerical simulations and the existing free running model experiments were conducted. As a result, it was demonstrated that fair quantitative prediction of broaching is realised when the rudder force variation, the roll restoring variation and the heel-induced hydrodynamic force for large heel angles are taken into account.     

Black-box modeling of ship manoeuvring motion based on feed-forward neural network with Chebyshev orthogonal basis function

Based on polynomial interpolation and approximation theory, a novel feed-forward neural network, the feed-forward neural network with Chebyshev orthogonal basis function, is proposed for black-box modeling of ship manoeuvring motion. The neural model adopts a three-layer structure, in which the hidden layer neurons are activated by a group of Chebyshev orthogonal polynomial activation functions and the other two layers’ neurons use identity mapping as activation functions. Weight update formulas are derived by employing the standard back-propagation (BP) training method. With the simulated 15º/15º zigzag test data as input and calculated values of the hydrodynamic forces and moment as output, the feed-forward neural network with Chebyshev orthogonal basis function and the BP neural network are applied to identify the nonlinear functions in the nonlinear hydrodynamic model of ship manoeuvring motion. With the simulated 20º/20º zigzag test data and 35º turning test data as input, the hydrodynamic forces and moment are predicted by using the identified nonlinear functions. Comparison between the calculated and predicted hydrodynamic forces and moment shows that the feed-forward neural network with Chebyshev orthogonal basis function is superior to the BP neural network in identifying the nonlinear functions of the nonlinear hydrodynamic model of ship manoeuvring motion and is an effective method to conduct the black-box modeling of ship manoeuvring motion.     

舵减摇仿真研究

本文通过建立船舶操纵运动和周期性摇荡运动的耦合数学模型，进行了舵减摇仿真研究。计算表明，只要适当选择舵角控制函数中的反馈系数，可以在合理的转舵速率和允许的航向变化幅度下取得满意的减摇效果。     

船舶操舵仪仿真系统数学建模

考虑到船舶操舵仪是船舶操纵人员培训的重要工具,准确的数学模型是实现设计目标的关键,建立三自由度船舶运动模型和液压舵机模型,并进行仿真计算,验证模型的准确性,说明该模型可以提高培训效果.     

高速单体船推进和操纵智能控制联合仿真

文章建立了高速单体船推进和操纵系统的数学模型,并在MATLAB/Simulink平台上建立了相应的仿真模型,实现了高速单体船推进和操纵的联合运动仿真;在仿真过程中,文中使用了模糊控制器和粒子群优化的PID控制器分别对推进和操纵系统进行了控制;仿真结果表明:高速单体船的平面运动过程被比较客观地反映出来,同时两种智能控制方法的控制效果很好,使得在航向控制时,不仅超调量小,而且稳定性好.文中的研究为船舶推进和操纵同时考虑的动态综合分析提供了一种评判优劣的平台;同时这种联合的带智能控制的方法也为船舶初步设计时的综合分析提供了一种参考.     

对某一水下航行器集成式周期变距螺旋桨的试验研究（英文）

A series of experimental studies of the innovative propulsor named Collective and Cyclic Pitch Propeller(CCPP) applied to an underwater vehicle were designed and performed at the Australian Maritime College, University of Tasmania. The bollard pull and captive model tests were conducted to investigate the characteristics of CCPP and to examine the effect of different parameter settings to its performance. The results show that the CCPP is able to generate effective manoeuvring forces in various operational condition. In addition, the obtained results in the form of force coefficients provide a useful empirical model for the simulation and control of an underwater vehicle equipped with this propulsor.     

南通航段超大型船舶航行富余水深计算方法

针对南通航段的实际情况,通过比较3种富余水深的计算方法,找出适于南通航段超大型船舶航行富余水深的计算方法;并对南通港超大型船舶航行富余水深标准提出建议。     

粘性对船舶操纵运动水动力影响的探讨

船舶操纵运动水动力学理论计算研究，一直受到广泛重视，但现有的方法都示达到的实用阶段，本文提出了考虑边界层排挤厚度影响的等价船体法和计及分离涡影响的粘性损失法，旨在分析结果对船舶操纵运动水动力的影响，对充实和完善船舶操纵运动水动力的理论计算方法作了一些探讨。     

Manoeuvring characteristics of twin-rudder systems: rudder-hull interaction effect on the manoeuvrability of twin-rudder ships

With a recent increase in ship capacity and propulsion performance, a wide-beam ship fitted with a twin-rudder system has been adopted in many cases. However, to improve ship manoeuvring, it is still necessary to have a better understanding of rudder-hull interactions in twin-rudder ships. Captive model tests (oblique towing and circular motion test) as well as free-running tests with a single-propeller twin-rudder ship and a twin-propeller twin-rudder ship are carried out. The effect of drift angle on the rudder forces and some peculiar phenomena concerning rudder normal force for twin-rudder ships are evaluated. A method for estimating the hull-rudder interaction coefficients based on free-running experimental results is proposed.     

New generic mathematical model to predict hydrodynamic interaction effects for overtaking maneuvers in simulators

To improve the formulation of ship–ship interaction forces and moments in a mathematical model of a ship maneuvring simulator, we developed a new generic mathematical model for the overtaking maneuver. This process involves using the numerical results, which provide a potentially complete set of data from which (within the constraints of the numerical modelling) everything necessary can be acquired. We found that the new generic mathematical model is as accurate as the numerical model. It is also more accessible to a navigator, master, or pilot, who could use it on a palmtop computer by keying in a few numberical estimates of the size, position, and speed of the neighboring ship and receive almost instant aneous results, giving time for a refined strategy to be validated if necessary. These results can also readily be used by simulation program developers to simulate the worst possible scenarios.     

激光船模轨迹仪研制

激光船模轨迹仪采用激光扫描三角法和微机处理,能自动测量船模的轨迹和二维姿态,为船舶和海洋工程研究提供了新颖的、自动化的测量手段。本文着重阐述该仪器的工作原理和性能分析,并介绍该仪器的技术指标及在船舶操纵性和耐波性研究中应用的情况。     

基于MOGA的潜器快速性和操纵性综合优化研究

基于Pareto解的多目标优化方法NSGA-II应用至潜器的快速性与操纵性综合优化设计之中。通过回转体潜器阻力性能的数值计算结果建立了阻力的近似计算模型,并与系列模型试验结果进行了比较;通过估算潜器的水动力系数,根据水平面线性运动方程得出水平面操纵运动稳定性和机动性的衡准指标。优化后,得到了阻力与回转直径的Pareto最优解的散点图,设计者可针对不同需求的潜器,从中进行选择,保证了Pareto最优解对应的每一艇型设计方案在满足操纵性要求下阻力最小,或在该阻力值的条件下操纵性最优。     

水下推进器热动力系统启动过程仿真数学模型

以某型鱼雷动力推进系统为对象,在进行了必要的假设前提下,通过分析其工程过程,根据能量守恒、质量守恒以及工程热力学原理,建立了动力系统启动过程数学模型,并采用ＦＯＲＴＲＡＮ语言进行程序设计。通过数学仿真研究了固体药柱燃烧、固液混合燃烧以及液体过程、燃烧室内压力和温度的瞬时变化及雷机桨匹配关系,同时也分析研究了进主燃料时间以及速制转换、鱼雷初始速度、航行深度等对启动过程的影响。此外,通过与国外资料提供     

不对称流动对航道中航行船舶的影响

本文利用能够处理不对称自由面流动的改进的Dawson's方法来研究当船偏离航道航行时航道岸壁及水深对船舶所受的水动力的影响.计算结果与模型试验进行了比较,结果表明当航道水深不是很浅时,本文提出的方法和计算程序可以给出比较满意的结果,同时还可以发现当船舶偏离中心航道航行时,船两侧湿表面压力以及水面变化也是不对称的,水深以及岸边距离都能影响船体所受水动力及船波.     

Artificial forces for virtual autonomous ships with encountering situations in restricted waters

ABSTRACT

Even if the same two ships operate in the same encountering situation, the actual strategies and timing of operations may be different. Therefore, the fixed collision avoidance trajectory and ship movements are no longer suitable for simulating the real ship behaviour. This paper tries to develop an artificial intelligent system that fully sensitive to the local circumstances and command a ship in virtual environment. Based on AIS (Automatic Identification System) data, this study has developed artificial forces which help decision makings on-board independently under different situations and catching the stochastic nature of ship behaviours during collision avoidances manoeuvring. Actual ship tracks are helpful for ascertaining the parameters that contribute to artificial forces in collision avoidances, while the correlation coefficient analysis is helpful to distinguish the parameters. This study will help to develop a navigation traffic simulation to reflect the realistic ship behaviour and provide reliable information for port and waterway planning, risk analysis, and mitigation measures. The method can be used in developing algorithms for autonomous ships. The method introduced in this study lays a foundation for developing artificial forces at intersections or bends, although the model is only applicable in straight channels at the moment.