模似器在港口航道设计中的应用

阐述船舶操纵模拟器在港口航道设计中的应用情况。通过上海港外高桥挖入式港池设计研究的实例说明模拟器的成功运用。这些模拟技术和方法对于降低航道费用、增强船舶营运安全和提高港口生产效率都有较大作用。     

模拟器在港口航道设计中的应用

阐述船舶操纵模拟器在港口航道中的应用情况。通过上海港外高桥挖入式港池设计研究的实例说明模拟器的成功运用。这些模拟技术和方法对于降低航道费用、增强船舶营运安全和提高港口生产效率都有较大作用。     

应用船舶模拟技术进行通航安全论证

介绍了船舶操纵模拟器的特点和优势。运用船舶操纵模拟技术对新建港口和航道的通航安全评估论证有强有力的技术支持和检验作用。     

再论引航员引航时船长的责任

引航员是具有驾驶和操纵船舶能力、熟悉航道和港口情况,为船舶在港口以外的航道的安全航行和港内靠离泊操纵提供引航技术咨询服务的专业人员。保证被引船航行和港内操纵的安全是引航员应尽的职     

大连港某公共航道平面布置

航道平面布置受地形、地质、潮流以及周边环境条件等因素影响较大。以某公共航道工程为实例，采用潮流泥沙数学模型试验和船舶操纵试验等方法，从工程区域自然条件、工程与环境保护区的关系以及港口中远期发展规划等方面对航道平面布置进行分析论证，确定最优轴线方案。并论述航道尺度确定时的设计创新内容，为综合制约因素较多的类似长里程航道项目平面布置提供技术参考。     

MRNS—9000型航海雷达模拟器船型编辑功能的开发

船舶操纵模拟器用于航道、港口开发已是当前先进而有效的手段。本文对“海河通航标准研究”课题在MRNS-9000型航海雷达模拟器上所进行的船型拟合工作作了概述，并提出了在航海雷达模拟器上拟合船舶数学模型时所采用的主要依据，即利用船舶操纵性标准、与在航船舶操纵行为密切相关的标准同船舶数学模型进行拟合。目前，此法已成功地用于“海河通航标准研究”这一课题中。同时，作者对船舶航行时受风力影响的问题也提出了看法。     

不均匀流中船舶操纵运动仿真模型及应用

本文给出不均匀流中船舶操纵运动数学模型，研究了在不均匀流中作用于船体上流体动力的估算及不均匀流场的生成，提出了不均匀流中船舶操纵运动的仿真方法。最后介绍了在港口引航实践中的两个仿真应用。     

内河航道船舶航行操纵平面二维数值模拟在复杂流态下的应用

基于平面二维水流数学模型和船舶航行操纵数学模型的基本原理,开发了适合内河航道的曲线拟合坐标系下的船舶航行操纵平面二维数学模型,其中水流数学模型采用贴体坐标系下的平面二维水流数学模型,船舶航行操纵数学模型采用比较流行的"组合型"水动力模型。在实船和船模在静水条件及均匀流条件下的航行试验验证的基础上,通过复杂流态河段船舶航行操纵数值模拟的研究,表明该船舶数模基本能够模拟船舶在复杂流态下的航行操纵情况。     

港内拖轮协助操船仿真数学模型的研究

本文为研制高精度、多功能的船舶操纵模拟器和进行船舶操纵安全评价的需要，首次提出了拖轮流体动力和拖轮Ｚ型导管螺旋桨四象限推力系数的实用估算方程。在此基础上，建立了港内拖轮协助操船仿真的数学模型。最后介绍了在港口引航实践中的两个仿真应用例。     

船舶操纵模拟器在船舶通航安全评估中的应用

船舶日趋大型化，导致原有航道和港口不能满足大型船舶的安全通航或靠泊要求。针对转向频繁、转角大、掉头区域不足、水深较浅的高难度航道，在船舶操纵模拟器上实施大型船舶通航安全的模拟试验，并对结果进行评估，进而对狭航道的设计或改造工程进行验证，并提出通航安全方面的合理化建议。     

将断裂理论引进基坑开挖的有限元分析中

断裂力学是近年来新兴的一门综合学科,本文将断裂力学的基本原理与土的强度理论相结合,采用适用于土体的抗裂强度理论,建立开裂后土体的本构关系,分析土体开裂对基坑支护结构的影响。开发了弹塑性有限元程序。并将程序的计算结果与模型实验的结果进行了对比。     

PIV velocity field measurements of flow around a KRISO 3600TEU container ship model

The main purpose of this investigation was to demonstrate a useful application of the particle image velocimetry (PIV) method to analyze the complex flow characteristics around a ship. For a sample illustration, the KRISO 3600TEU container ship model was chosen. The flow structure in the stern and near-wake region of the model has been investigated experimentally in a circulating water channel. Instantaneous velocity fields measured by the PIV velocity field measurement technique have been ensemble-averaged to give details of flow structures such as the spatial distributions of the local mean velocity, vorticity, and turbulent kinetic energy. The free-stream velocity was fixed at U _o = 0.6m/s, and the corresponding Reynolds number based on the length between perpendiculars was about 9.0 × 10⁵. The container ship model shows a complicated three-dimensional flow structure in the stern and near-wake regions. The PIV results clearly revealed the formation of large-scale bilge vortices in the stern region and their effect on the flow in the near-wake. The results shown here provide valuable information for hull form design and the validation of viscous ship flow codes and of turbulence models.     

Acoustic excitation of hull surfaces by propeller sources

We present preliminary results from our new ship motion model that includes both strong and weak three-dimensional interactions between environmental surface waves and ship bodies in arbitrary water depth. The linear solutions of steady flow using the new model agree well with those obtained using the Green function methods. When the Froude number Fn is large, the fully nonlinear solutions of our model are significantly different from linear solutions, even in calm water. The interactions between the ship and incident gravity waves are completely different from those in linear solutions even with small Fn and moderate-amplitude surface waves (e.g., Fn = 0.25 and a significant wave height of about 1–3m).     

Non-intrusive polynomial chaos for efficient uncertainty analysis in parametric roll simulations

Monte Carlo analyses are generally considered the standard for uncertainty analysis. While accurate, these analyses can be expensive computationally. Recently, polynomial chaos has been proposed as an alternative approach to the estimation of uncertainty distributions (Hosder et al. A non-intrusive polynomial chaos method for uncertainty propagation in CFD simulations. In: 44th AIAA aerospace sciences meeting and exhibit, Reno, Nevada, 2006; Wu et al. Uncertainty analysis for parametric roll using non-intrusive polynomial chaos. In: Proceedings of the 12th international ship stability workshop, Washington, DC, USA, 2011). This approach works by representing the function as a series of orthogonal polynomials; the weights for which can be calculated via several methods. Previous studies have demonstrated the usefulness of this technique for comparatively simple systems such as parametric roll modeled by the Mathieu equation with normally distributed parameter values (Wu et al. Uncertainty analysis for parametric roll using non-intrusive polynomial chaos. In: Proceedings of the 12th international ship stability workshop, Washington, DC, USA, 2011). In the present work, a polynomial chaos method is applied to a nonlinear computational ship dynamics model with normally distributed input parameters. Test cases were selected where parametric roll was expected to potentially occur. The resulting probability distributions are compared to the results of a Monte Carlo analysis. In general, these results demonstrate good agreement between Monte Carlo simulation and polynomial chaos in the absence of capsize with significant computation gains found with polynomial chaos. Overall, we conclude that polynomial chaos is an effective tool for reducing simulation time costs when studying parametric roll, and potentially other ship dynamics phenomena, particularly in the absence of capsize-like bifurcations.     

基于AHP分析法的船舶碰撞事故法律责任划分

船舶碰撞事故法律责任划分是一项复杂的技术分析工作,运用各种先进的分析手段可以改善人脑分析中的不稳定性。在对海事法规归纳整理的基础上,结合多属性决策中的层次分析法,为解决船舶碰撞的责任分析及责任划定提供了一个行之有效的数学模型。考虑到碰撞事故责任划分的复杂性、综合性,针对不同的因素采用不同数学手段确定权重值,得出责任划分的具体结果。     

Added resistance acting on hull of a non ballast water ship

In this paper, added resistances acting on a hull of non ballast water ship(NBS) in high waves is discussed. The non ballast water ships were developed at the laboratory of the authors at Osaka Prefecture University, Japan. In the present paper, the performances of three kinds of bow shapes developed for the NBS were theoretically and experimentally investigated to find the best one in high waves. In previous papers, an optimum bow shape for the NBS was developed in calm water and in moderated waves. For a 2 m model for experiments and computations, the wave height is 0.02 m. This means that the wave height is 15% of the draft of the ship in full load conditions. In this paper, added resistances in high waves up to 0.07 m for a 2 m model or 53% of the full load draft are investigated. In such high waves linear wave theories which have been used in the design stage of a ship for a long time may not work well anymore, and experiments are the only effective tool to predict the added resistance in high waves. With the computations for waves, the ship is in a fully captured condition because shorter waves, λ/Lpp0.6, are assumed.     

Hydrodynamic performance of multiple-row slotted breakwaters

This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes second-order waves. The numerical results obtained for limiting cases of double-row and triple-row walls are in good agreement with results of previous studies and experimental results. Comparisons with experimental measurements of the reflection, transmission, and dissipation coefficients (C _R , C _T , and C _E ) for double-row walls show that the proposed mathematical model adequately reproduces most of the important features. We found that for double-row walls, the C _R increases with increasing wave number, kd, and with a decreasing permeable wall part, dm. The C _T follows the opposite trend. The C _E slowly increases with an increasing kd for lower kd values, reaches a maximum, and then decreases again. In addition, an increasing porosity of dm would significantly decrease the C _R , while increasing the C _T . At lower values of kd, a decreasing porosity increases the C _E , but for high values of kd, a decreasing porosity reduces the C _E . The numerical results indicate that, for triple-row walls, the effect of the arrangement of the chamber widths on hydrodynamic characteristics is not significant, except when kd<0.5. Double-row slotted breakwaters may exhibit a good wave-absorbing performance at kd>0.5, where by the horizontal wave force may be smaller than that of a single wall. On the other hand, the difference between double-row and triple-row vertical slotted breakwaters is marginal.     

Investigation of springing in ship structures using experimental methods and 3-D hydroelastic theory

Large and long ships experience springing behavior. Depending on the trade routes and design of such ocean-going ships, wave-induced vibrations may be due to springing and whipping effects. In this paper, we address the wave-induced vibrations in an ultra-large ore carrier under fully loaded and ballast conditions. The experimental measurements from tests performed using a flexible model of the ship were compared with the numerical predictions from 3-D hydro-elastic theory (THAFTS) (Wu, Hydroelasticity of floating bodies. PH.D thesis, Brunel University, 1984). The measurements showed multiple frequencies between the encountered wave frequency and the 2-node bending frequency that occurred only in ballast conditions, whereas the springing vibrations were more apparent with forward speed under ballast conditions in both regular and irregular waves. The numerical method predicted the vertical bending moment quite well in the fully loaded condition but underestimated it in the ballast condition. This result was primarily due to an inability to capture the prediction of the multiple frequencies between the encountered wave frequency and the 2-node bending frequency. Using THAFTS, a new ship form with a deep draft was introduced, and this vessel was shown to reduce springing vibrations.     

Numerical study on breaking phenomena of ships’ waves in narrow and shallow waterways

The environmental impact of a ships waves, such as the risk of erosion of coasts and riverbanks, and unacceptable ship movements in a restricted waterway, is now a significant ship design criterion. Therefore, it is necessary to predict ship-wave phenomena accurately in a restricted waterway. In this study, a numerical investigation of the breaking phenomena of a ships waves in restricted waterways was carried out. Incompressible Navier–Stokes and continuity equations were employed. The equations are discretized by a finite-difference method in a curvilinear coordinate system. The interface capturing method was applied to simulation of a ships waves, including wave-breaking. A modification of the level-set method is proposed to find the free surface shape clearly and without difficulty of the implemation of the boundary conditions for the distance function. In order to obtain a high resolution of wave height, a constrained interpolated profile (CIP) algorithm is adopted. In order to check the advantage of the CIP method, computations by two numerical methods, the CIP and the 3rd-order up-wind scheme, were compared. The computations for a Wigley hull in restricted waterways were performed and compared with experiments. The phenomena of ships waves in restricted waterways are discussed in order to understand the mechanism of wave-breaking in relation to the change in water depth along a waterway.     

Study on the preciseness of hot spot stress of web-stiffened cruciform welded joints derived from shell finite element analyses

A new simple and accurate shell FE-based structural Hot Spot Stress (HSS) determination method for web-stiffened cruciform joints has been proposed. Local stress of welded joints in full-scale bulk carrier (BC)’s lower stool models subject to bending and pressure loadings are examined. HSSs determined by the proposed method are compared with those derived by Lotsberg’s method and the conventional 0.5t-1.5t extrapolation. As results, following are found:

(1)

The local stress of full-scale BC lower stool models with various stool angle and plate thickness can be calculated accurately solely from shell FE results by means of the proposed method.

(2)

HSSs of welded joints in full-scale BC lower stool models subject to bending and pressure loadings derived by the proposed method show good agreement with the target HSSs determined from fine solid models. This demonstrates the validity of the proposed method for actual ship structures under the real load.

(3)

The excessive safety allowance of HSS determined by the conventional 0.5t-1.5t extrapolation can be reduced substantially by adopting Lotsberg’s method or our proposal. The proposed HSS determination method gives more accurate estimates compared to Lotsberg’s method under the conditions chosen, and the application range of the proposed method is equal to or wider than Lotsberg’s method.