基于混沌分析的船舶参数激励横摇运动及其减摇鳍控制研究

船舶参数激励横摇可能导致船舶的大幅度横摇运动,威胁船舶、货物和海上人命安全。为了减小参数激励带来的不利因素,通过李亚普诺夫指数和功率谱对船舶在规则纵浪中运动的稳定性进行分析。从而分析船舶参数激励横摇运动的产生机理,不仅分析了船舶参数激励横摇产生混沌现象的条件,而且确定出船舶参数激励横摇运动的安全与危险区域。然后基于Backstepping算法和闭环增益成形算法设计出减摇鳍控制器,并且在考虑一定的干扰后进行了仿真试验。仿真结果表明该控制策略对于消除船舶参数激励横摇系统的混沌现象是十分有效的,并且其鲁棒性能令人满意。     

关于滚装客船安全管理浅析

近年来随着我国航运业的发展,滚装客船的数量不断增加,相继也出现了有关管理方面的一些问题,尤其是1999年在我国北部渤海湾海域相继发生的几起重大海难事故,有令人震惊的船舶和生命俱失的血泪教训,也有成功自救转然为安的可贵经验。为有利于滚装客船的安全运输,加强对滚装客船船员特殊培训管理是十分重要的。     

Influence of varying restoring moment curve on parametric roll motion of ships in regular longitudinal waves

This paper examines the influence of stability characteristics on roll motion in the main parametric resonance region. For this purpose, parametrically exited roll motion was modeled as a single degree of freedom system considering heave and pitch effects by means of time varying restoring moment. In addition, restoring moment variations in waves with respect to time and instantaneous roll angle was modeled analytically using the restoring moment curves for the wave crest and wave trough conditions. Roll responses were evaluated in frequency domain by solving the model with an averaging method. Notable correlation between the stability of roll responses and moment curves were observed. The results revealed that, the ratio of metacentric height (GM)between the wave trough and wave crest affects the stability of the trivial solution. Furthermore, the shape of the restoring moment curves in wave trough and wave crest conditions affects the stability of the non-trivial solution or, in other words, the pitchfork bifurcations.     

船模静水横摇试验的不确定度分析

为提高船模横摇阻尼力矩系数测量精度,对船模进行6次静水横摇试验。通过试验获得小角度船模静水横摇消灭曲线,根据最小二乘法计算得到的拟合曲线的斜率,即衰减系数;利用过原点拟合直线斜率的不确定度分析方法,得到衰减系数的不确定度;对横摇周期、横摇转动惯量的不确定度分别进行估算,进而得到阻尼力矩系数的不确定度。结果表明:衰减系数的B类不确定度分量对合成标准不确定度的贡献率达到了74.92%,衰减系数的合成标准不确定度分量在阻尼力矩系数的合成标准不确定度中占79.88%。横摇角的测量精度是横摇阻尼力矩系数不确定度的主要来源,提高横摇角测量仪器的精度,可降低阻尼力矩系数的不确定度。     

基于三维时域混合源法的顶浪 不规则波参数横摇研究

国际海事组织(IMO)船舶设计建造分委会(SDC)第4次会议把参数横摇稳性直接评估提上议程,如何准确预报和评估不规则波中的参数横摇是亟待解决的问题。文章提出采用一种三维时域面元法进行不规则波中参数横摇的预报和评估,该方法首先采用混合源法,即在内域采用Rankine源,在外域采用瞬态的时域Green函数,该混合源法充分考虑了船体的定常和非定常运动,以及定常运动对非定常运动的影响;其次考虑了船体与不规则波浪的瞬时相对位置,沿船体瞬时湿表面进行压力积分求解Froude-Krylov力和静水力;然后通过时域求解垂荡—纵摇—横摇三自由度耦合方程计算参数横摇。文中以国际标模C11集装箱船为研究对象,研究了不同随机波浪谱下参数横摇的发生规律,进行了统计分析,并通过已有的试验结果验证了文中采用方法的有效性。结果表明,该文采用的三维时域面元法可有效用于顶浪不规则波中参数横摇的直接数值预报。     

Circular motion tests and uncertainty analysis for ship maneuverability

Circular motion test data and uncertainty analysis results of investigations of the hydrodynamic characteristics of ship maneuvering are presented. The model ships used were a container ship and two tankers, and the measured items were the surge and sway forces, yaw moment, propeller thrust, rudder normal and tangential forces, pitch and roll angles, and heave. The test parameters were the oblique angle and yaw rate for the conditions of a hull with a rudder and propeller in which the rudder angle was set to zero and the propeller speed was set to the model self-propulsion conditions. Carriage data showing the accuracy of the towing conditions in the circular motion test are also presented. It was confirmed that the uncertainties in the hydrodynamic forces such as the surge and sway forces, yaw moment, rudder tangential and normal forces, and propeller thrust were fairly small. The reported uncertainty analysis results of the circular motion test data may be beneficial in validating data quality and in discussing reliability for simulation of ship maneuvering performance.     

舰船编队电磁干扰分析中不定因素的研究

舰船编队的电磁干扰(EM I)分析预测比单舰要复杂得多,这是由于编队中各舰相对运动产生的不定因素对预测结果产生一定的影响。本文具体讨论了编队中舰舰间距离、方位和雷达天线转动等不定因素的扰动对耦合度的影响,提出了在舰船编队电磁兼容性分析预测中应采用统计分析技术。     

二甲基醚发动机热力循环模拟与参数分析

用零维热力学模型模拟计算二甲基醚发动机的燃烧放热率，将模拟计算结果与实验结果进行对比，两者数据吻合；在对三种热力学模型的预测结果进行对比分析的基础上，选取与实验值吻合最好的Watson模型对相同结构和运行参数的DME发动机与柴油机进行计算对比，结果符合理论分析与实验观察；说明零维模型不仅适用于柴油机的性能预测分析，亦适用于DME发动机运行参数的预测。     

复杂预应力对立管参激振动特性的影响分析

针对立管结构中存在着复杂预应力分布的现象,提出了立管在只考虑顶端平台升沉激励引起的纯参激振动问题。基于结构预应力理论,建立了含复杂预应力的立管结构运动控制微分方程,提出了一种可适用于含复杂预应力分布的立管参激振动特性分析方法。以此为基础,应用数值计算对比了复杂预应力对立管结构的自然频率、振型等振动特性的影响。计算结果表明,复杂预应力的存在对立管结构的动力特性有着重要的影响。     

舰船编队EMI分析中不定因素的研究

舰船编队的电磁干扰（EMI）分析预测比单舰情况复杂，这是由于编队中各舰相对运动产生的不定因素对预测结果会产生一定的影响。具体讨论了编队中舰舰间距离、方位和雷达天线转动等不定因素的扰动对耦合度的影响，提出了在舰船编队电磁兼容性分析预测中应采用统计分析技术。     

潜水器载人舱的不确定性测度计算方法研究

本文研究状态函数中存在概率数和证据数的混合状态下的系统不确定性分析方法问题,用于解决在产品实现过程中部分信息的认知不足。传统概率分析方法无法建立认知不确定信息模型,无法反映产品在实现过程中不确定性影响的问题。本文将证据理论不确定度分析方法融入传统JC算法,在计算随机变量迭代时开展认知变量极值计算,进而可以处理随机和认知不确定性变量同时存在时的混合不确定性问题。本文建立了4500 m载人潜水器载人舱不确定度分析模型,基于改进JC算法计算得到载人舱失效似然性测度和失效可信性测度值,同时采用实验设计法对影响载人舱不确定性测度的因素进行分析,分析表明测度影响较大的因素是真球度和极限拉伸强度,测度对真球度和厚度两个因素的单位数量变化比较敏感。     

船舶CFD模拟不确定度分析与评估新方法研究

比拟测量不确定度,视CFD模拟结果为随机变量,阐述了CFD模拟不确定度的定义、来源、分类和表示形式.基于正交试验设计和方差分析方法,提出了CFD不确定度分析中验证的内涵及实施流程;基于统计推断理论,提出了CFD不确定度评估中确认的标准及判断程序.应用Fluent软件及文中所建方法,针对阻力系数和伴流分数进行CFD模拟不确定度分析评估的实例计算,给出了对模拟结果有重要影响的计算因子和交互作用以及各类不确定度分量的大小,并指出就目前采用的CFD模拟技术而言,尽管其结果的分散性或不确定度数倍于物理试验,但其近似性或可信度已可接受.     

参数化有限元分析在集装箱船CAE的应用

近年来,基于有限元的机械结构强度分析、应力应变分析、振动分析等技术在机械制造、航空宇航、船舶、汽车等各个领域取得了广泛的应用,逐渐成为一种必须的工程分析手段。为了提高我国船舶工业的制造水平,必须要大力发展有限元分析技术和计算机辅助工程软件(CAE)方法。随着远洋物流运输业的发展,集装箱船因其运输量大、航速快等优点,在世界范围内获得了广泛重视。本文针对大型集装箱运输船舶,对其舱段结构进行了参数化有限元分析,并建立了集装箱船结构的CAE分析模型。     

波浪中三体船非线性横摇运动近似解析解及特性分析

为了深入研究三体船横摇运动特性,本文应用多尺度法计算了波浪中非线性横摇运动的近似解析解,并通过数值方法及模型试验进行了三体船适用性验证.研究结果表明:三体船型的特殊性引起的非线性横摇阻尼和非线性恢复力使其具有特殊的横摇运动特性.其中,非线性阻尼主要影响横摇幅值变化,特殊的高阶非线性恢复力导致幅频曲线刚度渐硬,小阻尼共振状态下可能会发生不稳定大幅横摇运动.该研究从理论角度解释了三体船在波浪中可能表现出的与常规单体船不同的大幅横摇、跳跃、多值等非线性现象.     

船舶避撞过程中掌舵者的不定性分析

随着我国内河航运和海上航运业的迅速发展,水上交通变得愈加拥挤,船舶碰撞事故也频繁发生。船舶碰撞带来的后果是灾难性的,统计表明,每年因船舶碰撞造成的人员伤亡和海上环境污染问题日益严重。掌舵者是船舶的操作人员,研究掌舵者行为的不确定性,并减少掌舵者误操作几率,对船舶安全、稳定、高效的航行有重要意义。本研究建立了船舶掌舵者的不定性模型,利用GO法对掌舵者的行为进行分析,并对掌舵者反应时间与船舶碰撞概率的关系进行仿真研究。     

Nonlinear analysis of parametric rolling in longitudinal and quartering seas with realistic modeling of roll-restoring moment

Parametric rolling of a containership in longitudinal and quartering seas is examined by applying nonlinear dynamics to a 1DOF mathematical model with realistic modeling of the wave effect on roll-restoring moment. In our previous work, we confirmed that a mathematical model with a roll-restoring moment in waves calculated with the Froude–Krylov assumption could considerably overestimate the danger of capsizing associated with parametric rolling. Therefore, in the present work, all numerical calculations based on nonlinear analysis were carried out with the direct aid of a measured roll-restoring moment in waves. For this purpose, captive model experiments were conducted for various sets of wavelengths in longitudinal seas. This experiment demonstrates that the Froude–Krylov prediction could not explain the wavelength effect on restoring moment as the wave-steepness effect. Using the numerical model with the aid of this measured roll-restoring moment, the Poincaré mapping technique was applied to identify bifurcation structures of roll motions not only in longitudinal seas, but also in quartering seas. As a result, it was confirmed that capsizing associated with parametric rolling is more likely to occur in following seas than in quartering seas. However, period-doubling and chaos appeared in quartering seas. Finally, an averaging method assuming a period-2 orbit was applied to the same model with the same conditions as the Poincaré map. Reasonably good agreement was obtained between the numerical results with a Poincaré map and those with the averaging method in longitudinal seas, but the averaging method has limited capability in quartering seas.     

Measurements of hydrodynamic forces, surface pressure, and wake for obliquely towed tanker model and uncertainty analysis for CFD validation

This article presents hydrodynamic forces and moments, surface pressures, estimated side force distributions, and wakes under oblique towing conditions for a practical tanker model (model KVLCC2M), which was designed by the Korea Research Institute of Ships and Ocean Engineering (KRISO). Ship offset data is readily available and can be obtained from the Internet. The model ship has no appendages and no rudder. Trim and sinkage were adjusted to zero in the static condition and the model ship was constrained against any motion. Although the drift angle β was primarily set to 0°, 6°, and 12°, other settings were used in some experiments. All experimental results were processed using uncertainty analysis. The uncertainty analyzing method follows the ANSI/ASME Performance Test Code (PTC19.1-1985) and the AIAA Standard S-071-1995. Only a few error components were considered here and they were empirically chosen because they had a heavy weighting when used in the uncertainty calculation. The results of these towing tank experiments will contribute to the development of computational fluid dynamics (CFD) research in ship hydrodynamics.     

Validation of 6-DOF motion simulations for ship turning in regular waves

In this study, a six degrees of freedom (6-DOF) motion simulation method of a ship steering in regular waves is validated. The proposed simulation model is based on the two-time scale concept where the 6-DOF motions are expressed as the sum of the low-frequency maneuvering motions and high-frequency wave-induced motions. Turning simulations of a KCS container ship model with a rudder angle of \(\pm 35^\circ\) in calm water and regular waves are performed and the obtained results are compared with the results of a free-running model test. The model tests were conducted using a ship model of length 3.057 m in a square tank at the National Research Institute of Fisheries Engineering, Japan. The wave conditions were as follows: the wave height was 3.6 m at full-scale, ratio of wavelength to ship length was 1.0, and the ship approached in the head wave direction before it was steered. The present method can simulate both the turning motion and wave-induced motions in regular waves with practical accuracy.

     

波浪中多船多墩柱受力和运动的快速计算方法

文章对多船多墩柱相互作用问题提出了一个快速计算方法.该方法是将船体剖面用具有相等面积的等效矩形代替,并将流场划分为船底与水底之间的内场和船侧面之外的外场.对内场,采用简单的解析解;对外场,由于剖面是矩形的,所以可采用在船体水面周线上分布源汇的简单的源汇分布法.对内外场进行耦合匹配进行求解.直立柱体则相当于船底和水底之间间隙为零的情况,所以上面也可包括直立柱体的情况,这样该方法对多船多墩柱的问题可以给出简便快速的算法.通过与试验结果和数值结果的比较,验证了文中计算的有效性.     

Mathematical modelling of response amplitude operator for roll motion of a floating body: Analysis in frequency domain with numerical validation

This paper investigates mathematical modelling of response amplitude operator （RAO） or transfer function using the frequency-based analysis for uncoupled roll motion of a floating body under the influence of small amplitude regular waves. The hydrodynamic coefficients are computed using strip theory formulation by integrating over the length of the floating body. Considering sinusoidal wave with frequency （ω ） varying between 0.3 rad/s and 1.2 rad/s acts on beam to the floating body for zero forward speed, analytical expressions of RAO in frequency domain is obtained. Using the normalization procedure and frequency based analysis, group based classifications are obtained and accordingly governing equations are formulated for each case. After applying the fourth order Runge-Kutta method numerical solutions are obtained and relative importance of the hydrodynamic coefficients is analyzed. To illustrate the roll amplitude effects numerical experiments have been carried out for a Panamax container ship under the action of sinusoidal wave with a fixed wave height. The effect of viscous damping on RAO is evaluated and the model is validated using convergence, consistency and stability analysis. This modelling approach could be useful to model floating body dynamics for higher degrees of freedom and to validate the result.