The overall motion induced interruptions as operability criterion for fishing vessels

A new index, namely the overall motion induced interruptions (OMII), is proposed as a seakeeping criterion for fishing vessels, to compare ships having different hull forms and dimensions by means of an only parameter, in a human centred approach, mainly related to the onboard risk level. Therefore, the first aim of the paper is to investigate the factors affecting fishing vessels’ seakeeping performances to improve them to reduce the high number of injuries occurring during fishing operations, mainly related to both risk perception and harsh weather conditions. Despite the classical approach, where motion induced interruption is determined for a certain sea state with regard to several location points, the new index accounts for all crew members’ positions on the working deck, all heading angles the vessel may experience during fishing operations, based on relevant operating scenario, and all sea states the ship may encounter in the fishing area. The influence of position, heading angles and sea states on the attained risk level is fully investigated, analysing seakeeping performances of four fishing vessels with different hull forms and dimensions. Finally, a new operability criterion is proposed, based on OMII, to investigate the influence of ship size and operating scenario on the risk of injuries during fishing operations. Main factors affecting fishing vessels’ seakeeping performances are fully discussed, paying attention to relevant correlation with ship roll natural period.     

波浪引起破损船的垂向运动和弯矩（英文）

The wave-induced vertical ship motions and bending moments of a double hull-oil tanker in realistic flooding conditions are studied. The scenarios investigated are represented by water ingress into the starboard ballast tanks for collision damage cases and both starboard and portside ballast tanks for grounding situations. Seakeeping computations are performed for eight damage scenarios and for the intact condition, each corresponding to different changes in displacement, trim, and heel. For each of the damage conditions, transfer functions of vertical motions and loads are calculated using a potential linear 3 D panel hydrodynamic code in the frequency domain that includes effect of the motion of the water in flooded tanks. A MATLAB code is developed to facilitate automated hydrodynamic simulation of many damage scenarios. Verification of seakeeping results is performed by comparing transfer functions with results of the previous study. Wave-induced vertical responses of damaged ship are then compared to those of intact ship using two spectral-based methods originating from uncertainty analysis of wave loads, which are convenient tools to assess consequences of damage on short-term ship responses. Generally, observed trend is that vertical wave-induced responses of damaged ship converge toward those of intact ship with increasing wave period. Fairly small differences between responses of asymmetrically damaged ship with respect to the symmetrical incoming wave directions are found. The results of the study are an efficient method for seakeeping assessment of damaged oil tankers and the framework for evaluating consequences of damage scenarios, heading angles, and sea conditions on seakeeping responses of damaged ships.The results can be used to decide if the intact ship model can be used instead of the damaged one for the emergency response procedure or for the risk assessment studies when modeling and computational time represent important limitations.     

沿海高速双体搜救艇水动力性能试验

为了满足沿海船只发生海损时,搜救船舶应能第一时间到达事故发生位置,并且完成勘察现场、事故人员救助的任务,设计了2种线型的双体搜救艇.通过船模阻力试验选出阻力性能较优的一种,对其进行耐波性分析,与某双体船试验数据进行对比,并用ITTC双参数谱预报了实船耐波性,验证了该船型能满足沿海海况和日常任务的需求.     

小水线面双体船在波浪中的运动响应预报

用切片理论方法发展了SWATH船耐波性预报程序，提供了390t方案的油田小水线面交通船计算分析结果，包括规则波中纵向运动频率响应函数的计算及不规则波中各种海况下的运动有义值预报。     

提高直升机起降海情的频域时域综合预报模式

突破舰船耐波性预报领域里极短期预报用时域分析法、短期预报用频域分析法的框架，从舰船实际运行需求出发，以风浪中预报舰载直升机安全起降时机为例，提出了先用频域分析法优选舰船在风浪中航向航速，再用时域预报方法，准确求出该航向航速上适于直升机起降的时刻，从而使舰—机组合能在较高海情下作业，井为舰船耐波性研究拓宽了领域。     

基于CFD的舰船遭遇畸形波数值模拟的验证研究

畸形波对船舶航运极具威胁,已引发多起海上事故,因此有必要对舰船遭遇畸形波进行数值模拟研究。该文基于随机波浪的Longuet-Higgins模型,在相位调制方法的基础上考虑了航速航向的影响,调制部分组成波的初相位,可以实现舰船定时定点遭遇畸形波。在此基础上,利用CFD方法对舰船顶浪态势下遭遇畸形波进行数值模拟,并将结果与水池实验值进行比对,验证了文中所建模型的有效性,对于研究舰船在极恶劣海况下的耐波性及完善船舶设计规范等具有不可忽视的意义。     

海上长球首尾双体风电维护船阻力和耐波性能研究

近年来,海上风电场迅猛发展,风电维护船成为迫切需求。借鉴小水线面双体船优良的阻力性能和穿浪双体船优秀的耐波性能,根据中国海上风电场维护船航行的环境和使用特点,选用阻力和耐波性能优良的长球首尾双体船型作为风电场维护船型。在此基础上采用CFD数值仿真计算阻力性能,运用NAPA软件计算耐波性能。从而得到不同条件下较优良的船型,为海上风电维护船的设计提供一定的参考和借鉴。     

新型零航速矢量减摇系统研究

针对海洋科研平台、科考船等减摇系统的快速响应性工作需求,在螺旋桨推进器基础上开发了一种零航速矢量减摇系统。本文介绍系统机构设计及其工作原理,结合耐波性计算分析获取船舶横摇规律,采用滑台搭载重物往复移动方式,模拟船舶规则横摇以获得规则波实验条件,并通过船模实验验证该减摇装置作用下的船舶横摇减摇效果。零航速规则波模拟实验研究表明,该减摇装置具有可控性强、易改装的特点,能够大幅提高船舶的耐波性,为后续工程试验船舶上安装该减摇系统奠定理论与实验基础。     

船舶耐波性与船舶航速

通过对耐波性的分析,总结了船舶在波浪中航行时的耐波性标准,并提出了船舶在考虑了耐波性标准后应采取的经济航速,为船舶在大风浪中的开航安全评估提供了依据。     

Dynamic interaction of parallel moving ships in close proximity

Nowadays,there are many studies conducted in the field of marine hydrodynamics which focus on two vessels traveling and floating in sufficiently close proximity to experience significant interactions.The hydrodynamic behavior of parallel moving ships in waves is an interesting and important topic of late.A numerical investigation has been carried out for the prediction of wave exciting forces and motion responses of parallel moving ships in regular waves.The numerical solution was based on 3D distribution technique and using the linear wave theory to determine the exciting forces and ship＇s motion.The speed effects have been considered in the Green function for more realistic results.The numerical computations of wave exciting forces and motion responses were carried out for a Mariner and Series 60 for the purpose of discovering different Froude numbers and different separation distances in head sea conditions.Based on the numerical computations,it was revealed that the sway,roll and yaw have a significant effect due to hydrodynamic interaction.     

海上风电场维护船船型总阻力和纵摇升沉运动研究

根据海上风电场维护船的使用和性能要求,分析小型单体船、双体船、多体船对于海上风电场的实用性,最终确定采用双体船型为风电维护船船型。结合小水线面双体船和穿浪双体船的船型优点,对风电维护船片体进行改进,得到常规型和改进型双体风电维护船型方案。采用CFD仿真技术,利用常规双体船型探索双体船阻力CFD仿真方法,对改进船型进行阻力仿真计算。采用船舶设计软件NAPA的耐波性模块计算分析两种船型的纵摇和升沉性能,得到了维护船不同速度和浪向角时两船型的纵摇和升沉响应曲线。     

A unified seakeeping and maneuvering analysis of ships in regular waves

The behavior of a ship in regular waves during maneuvering was studied by using a two-time scale model. The maneuvering analysis was based on Söding’s (Schiffstechnik 1982; 29:3–29) nonlinear slender-body theory generalized to account for heel. Forces and moments due to rudder, propeller, and viscous cross-flow follow from the state-of-the-art procedures. The developed unified theory of seakeeping and maneuvering was verified and validated for calm water by comparing it with experimental and calculated zigzag and circle maneuvers. Linear wave-induced motions and loads were determined by generalizing the Salvesen-Tuck-Faltinsen (Trans SNAME 1970; 78:250–287) strip theory. The mean second-order wave loads in incident regular deep water waves in oblique sea conditions were estimated by the potential flow theories of Faltinsen et al. (Proc 13th Symp Naval Hydrody 1980), Salvesen (Proc Intl Symp Dynam Mar Vehicl Struct Wave 1974), and Loukakis and Sclavounos (J Ship Res 1978; 22:1–19). The considered theories cover the whole range of important wavelengths. Comparisons between the different mean second-order wave load theories and available experimental data were carried out for different ship hull forms when the ship was advancing forward on a straight course. The mentioned methods have been incorporated into the maneuvering model. Their applicability from the perspective of the maneuvering ability of the selected types of ships was investigated in given wave environments. The wave conditions are valid for realistic maneuvering cases in open coastal areas. It was demonstrated that the incident waves may have an important influence on the maneuvering behavior of a ship. The added resistance, mean second-order transverse force, and yaw moment also play important roles.     

滚装重荷载应急卸载过程的浮基多体系统动力学分析

在救灾和战争等非常情况下，利用中小型近海滚装渡轮或改装后的渔轮渡海输送重荷载，具有可征用船只数量多和装卸载不依赖吊装设备等优点。缺乏港口屏蔽的海浪环境中重荷载进行滚动卸载时，必须考虑波浪对船的作用和重荷载与船的相互作用。本文通过对船在波浪中所受表观重力和表观浮力的分析，导出波浪作用力矩的计算公式。运用浮基多体系统动力学方法，建立波浪-浮基-重荷载系统的动力学方程。使用标准的龙格-库塔四阶方法进行数值积分求解。考虑海况、船型和重荷载在船上运动参数等因素，计算了各工况下的横摇运动响应。进而给出了重荷载安全快速卸载的驾驶操作要求及相关运动规律。     

舰船大风浪中航行最大允许航速计算模式研究

舰艇在大风浪中航行,当航向已定时如何确定最大允许航速是航海界关注的课题。本文采用CFD(计算流体力学)方法和耐波性理论相结合的新模式,分别研究了浪增阻、风增阻及螺旋桨推力损失的计算方法,给出了比较精确的舰艇大风浪航行时的船体负载。在此基础上,运用船—机—桨理论,解决了最大允许航速(轮转速)的求解问题。     

舰船风浪中航行及操纵系统

基于风浪中经验航法和理论航法相结合的观点；汲取耐波性等领域的研究成果，提出了一种实用的风浪航行操纵系统，集合3个子系统（海浪计算子系统，航向航速优选子系统，摇荡短期时历预子系统）的计算结果，合理组合，可满足风浪航行及转向时机，舰载直升机起降时同，海上补给及拖带航向航速选择等决策的需求。     

几种千吨级高性能船耐波性对比分析

为了对比分析千吨级单体圆舭船型、深V船型、穿浪双体船型、三体船的耐波性能,采用二维半理论方法计算各船型在迎浪规则波中的摇荡及首中尾部垂向加速度的频率响应函数,其中应用时域格林函数求解水动力系数,应用谱分析计算各船型在不规则波中的运动有义值.结果表明,几种千吨级高性能船在波浪中的纵向运动性能均比常规圆舭船型优,其中三体船纵向运动性能最佳.计算结果可为该吨级舰船平台选型提供技术支持.     

一种有效近似建模方法及船舶耐波性代理模型构建

船舶耐波性能预报计算过程复杂,会受到诸多设计变量的影响;且采用高精度商业软件如CFD预报船舶性能的计算代价非常高。文章采用拉丁超立方方法进行了设计空间抽样。定义了一个新的综合衡准指标来表达船舶耐波性能,即短期和长期作用下船舶非工作时间百分数。考虑了船舶耐波性能中的五个运动方向：横摇、纵摇、转艏、横荡和升沉。为提高船舶耐波性能计算效率,一种有效的近似建模方法—单参数Lagrangian 支持向量回归算法被用于训练并构建代理模型以预报船舶耐波性能,且该算法是由作者在过去的研究工作中首次提出。以海洋平台支援船（OSV）为例,采用SPL-SVR算法预报船舶耐波性能,并与基于NAPA计算仿真结果、人工神经网络和经典支持向量回归算法进行对比。该文考虑OSV的两种速度,建立了海洋平台支援船短期作用下非工作时间百分数的耐波性能响应面模型,结果显示采用SPL-SVR算法建立的船舶耐波性能响应面模型比较适合船型初步设计的工程实际应用,并具有较高的计算效率。     

国外核动力潜艇耐波性理论预报

采用STF理论和Frank源分布-紧密拟合法对国外核潜艇潜望状态进行了纵荡、垂荡、纵摇、横荡、横摇、艏摇和垂向加速度等波频运动耐波性理论预报.给出了不同航速、航向时的规则波运动响应和不同航速、航向、波高、波浪平均周期时的不规则波运动统计值.对典型艇型进行变化稳心高、纵向和横向惯性系数计算.最后对各艇进行了耐波性能比较.     

科学利用气象传真图分析判断台风路径

热带风暴、台风是影响船舶航行与海上没施作业安全的重大灾害性天气。在现场利用气象传真图分析判断热带风暴、台风的移动路径，将预报图和高空实况图结合起来进行连续科学分析，相互印证，对采取正确的避台风措施，保证人员、船舶安全和海洋防灾减灾具有非常重要的意义。     

Analysis of hydrodynamic characteristics for arbitrary multihull ships advancing in waves

Multihull vessels have emerged as popular alternatives to conventional monohull ships for high-speed crafts. However, the bridging structures connecting the hulls are vulnerable to various wave actions and the wave impact on the bottom of them is the most serious problems associated with multihulled vessels. In this study, prediction of relative wave elevations under the bridging structures is investigated for multihull ships traveling with forward speed in waves. A computer code YNU-SEA using the three-dimensional (3D) Green function method with forward speed has been developed and used to analyze the hydrodynamic radiation and diffraction forces and motion responses for high-speed catamarans in waves. The results of the present calculations are compared with those of previous calculations as well as with experimental results. The numerical results reveal that the present computer code can be used as a powerful tool for the accurate numerical computation of seakeeping problems for multihull ships advancing in waves. Numerical calculations of wave pattern are also carried out including wave interactions between the hulls to analyze the effects of hull form on the free surface flow around catamarans advancing in waves. The analysis of the wave pattern allows the determination of relative wave height including radiation and diffraction waves. Finally, some discussions are included based on these numerical results which may be helpful for the accurate prediction of relative wave height and wave breaking load on the deck associated with multihull ships.