基于遗传算法的五体船片体布局多目标优化研究

尝试并实现了iSIGHT优化软件与水动力计算软件HydroSTAR的集成优化,以五体船在波浪中的运动响应及增阻为目标函数,对片体布局作了多目标优化研究.运动计算采用三维频域面元法,增阻计算应用了近场压力积分方程,优化算法采用NSGA-II遗传算法,结果给出了Pareto解,还进行了DOE试验设计分析,为五体船片体布局设计提供参考.     

高速三体船波浪中运动与增阻CFD计算研究

基于数值波浪水池技术,对波浪中高速三体船运动及增阻进行CFD计算研究。控制方程—RANS方程和连续性方程使用有限体积法离散,非线性自由面采用VOF方法处理;在入口边界模拟柔性造波板运动产生入射波,使用位于波浪水池尾部的人工阻尼区消波。首先对规则波顶浪中单个主船体的运动和增阻进行了计算,并与高速细长体理论计算结果进行了比较;随后进行了三体船运动和增阻计算,分析了侧片体对主船体阻力增加的影响。为高速三体船耐波性研究提供了数值工具。     

基于ISIGHT的三体维护船侧体布局多目标优化研究

运用多学科设计优化平台ISIGHT针对三体维护船阻力性能和耐波性能进行侧体布局多目标优化。首先,将各侧体布局方案的CFD计算结果作为样本点,结合三体维护船的特定工作海况,运用谱分析方法预报不规则波中增阻平均值、总阻力值及纵摇、垂荡运动有义值,建立上述参数随侧体布局变化的近似模型,代替数值计算。然后,以最小化不规则波中总阻力值和纵摇、垂荡运动有义值为优化目标,以侧体纵向位置和横向位置为设计变量,采用设置权重和比例因子的方法确定目标函数,将所建近似模型作为数据库,选用多目标遗传算法NSGA-II,进行侧体布局多目标优化。最终,获得阻力性能和耐波性能综合最优的侧体布局方案。从而为海上三体风电维护船的设计和相关船型的性能预报提供参考。     

五体船兴波阻力线性理论计算与CFD数值模拟

五体船是继当代三体船之后提出的又一种多体新船型,该新船型付诸实用前必须对其兴波特性和侧体布局减阻设计进行研究。根据五体船各片体的科钦函数线性叠加和坐标变换原理,提出了基于片体科钦函数展开的分项算法和基于片体科钦函数叠加的整体算法求解多体船兴波阻力,得出了单体船、三体船、五体船通用的线性兴波阻力公式。应用CFD通用软件进一步分析五体船阻力及片体兴波干扰特性,提出了基于CFD模拟的自由面波形观测的五体船片体布局优化,对各种侧体布局下的五体船兴波特性直观地定性判定。根据综合兴波阻力线性理论计算和粘性流体动力CFD求解所得五体船阻力结果及其特性,提出具有工程实用意义的五体船优化构型方案。研究表明,势流线性理论计算和CFD求解五体船阻力的方法和所得五体船优化构型方案具有广阔的应用前景。     

海上三体风电运维船阻力和运动性能综合研究

结合海上风电运维船的使用要求和三体船型特点,确定小型高速三体风电运维船船型,并寻求特定海况下阻力性能和运动性能优异的侧体布局方案。基于CFD计算静水阻力和规则波中迎浪增阻与运动响应,并预报不规则波中运动有义值和阻力值。通过比较表明,主、侧体艉部对齐时三体运维船的综合性能最优。从而为海上三体风电运维船的设计和性能预报提供参考。     

基于CFD数值模拟和模型试验的三体船片体位置优化

论文采用低精度CFD数值计算和高精度模型试验相结合的方法，以总阻力为目标，对Fr=0.27速度工况下的某型三体船的片体位置进行优化。利用拖曳水池对不同片体位置的三体船进行模型试验，获得三体船在不同片体位置下的总阻力性能。使用自主开发的CFD黏流数值求解器naoe-FOAM-SJTU对一定范围内的其他片体位置进行水动力数值计算。根据模型试验和数值计算结果，使用自主开发的船型优化软件OPTShip-SJTU对三体船的片体位置进行优化。通过模型试验与数值方法相结合的方式构建Co-Kriging近似模型，并使所构建的模型融合模型试验的信息，以保证优化结果的可靠性。结果显示，沿船长方向不同的片体位置对三体船总阻力的影响有着明显的变化规律。     

基于兴波阻力的三体船片体位置快速优化方法

三体船片体位置优化的工作量很大,不仅要考虑片体间的横向距离,也要考虑片体间纵向距离.为快速优化三体船的片体位置,基于Noblesse细长体理论,按照一阶Kochin函数的表达式,在指数函数展开分离变量方法的基础上,本文推导了三体船兴波阻力的计算公式,并根据这些公式实现了三体船兴波阻力的快速计算.数值计算与模型试验相吻合.数值计算结果和模型试验结果均显示,三体船的片体位置对兴波阻力有很大影响.     

三体船侧体布局及型线优化设计研究

采用分层次优化,首先以总阻力最小为优化目标对某三体船侧体横向和纵向的相对位置进行了优化研究,得到阻力性能最优的三体船侧体布局方案;然后基于侧体最优布局,进行型线优化,最终完成三体船的侧体布局和型线的序列优化。结果表明,所采用的三体船侧体布局及型线优化方法具有可行性,可为三体船船型设计提供参考依据。     

五体船侧体布局及兴波阻力优化

采用线性兴波阻力计算方法,结合CFD通用软件模拟,对比分析前后片体横向间距不等五体船、五片体简单叠加及前后片体横向等间距五体船阻力特性,研究侧体布局对兴波阻力影响的规律及其减阻优化效果。研究结果表明,五体船前后片体分别纵向靠近首尾布置,可以扩大有利兴波干扰速度范围,高速段侧体横向偏内可以获得较佳阻力值,并且片体纵向位置的改变相比横向位置的变化,对阻力值影响更大。     

基于EEDI的小水线面双体船片体尺度要素多目标优化

为寻求节能高效的小水线面双体船片体尺度要素，以一艘典型小水线面双体渡船为研究对象，从多目标优化的角度出发，做出合理假设根据海军部系数法和国际吨位丈量公约分别将子目标设计航速和总吨参数化，进而使主目标能效设计指数（energy efficiency design index, EEDI）成为片体尺度要素函数。基于MATLAB优化工具箱应用多目标遗传算法（Multi-Objective Genetic Algorithm, MOGA）,以阻力、强度、结构和能效要求等因素为依据定义约束条件，设置优化参数并考虑混合函数的影响，得到优化船型Pareto解集。最后讨论多目标优化的计算结果，并且与单目标优化的结果进行了比较，还分析了多目标优化优化船型方案中片体尺度要素的分布情况。     

基于波浪增阻的长球首球尾双体风电维护船仿真研究

根据中国海上风电场维护船的使用要求和航行的环境特点,本文选取快速性和耐波性良好的长球首球尾双体船作为风电维护船船型。利用基于CFD的数值仿真方法模拟长球首球尾双体风电维护船在波浪中的纵摇和升沉运动,计算其波浪增阻。研究球首球尾长度和片体干扰对长球首球尾双体船在波浪中阻力性能的影响,为球首球尾双体船以及风电维护船的船型设计与优化提供参考。     

对称、非对称不同船体构型下高速非交错五体船模阻力特性（英文）

Pentamaran, a vessel with five hulls, can be an alternative for high-speed vessels due to its advantages, for instance, its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement. The destructive interference between the system of waves produced by the vessel's hulls might benefit the reduction of power consumption. This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull configurations and three variations of hull separation. The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr) ranging from 0.55 to 1.00. A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations. Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries, that is, symmetries produced steadier trends than asymmetries. The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude) under the same configuration. Although not a single configuration outperformed the others in the entire range of Fr, three configurations were noteworthy as optimum models based on their Fr range. Moreover, a configuration of asymmetric hull with S/L = 0.22 could generate a constant destructive interference throughout the investigated Fr range.     

船舶航线优化中任意浪向的航速损失预测模型（英文）

This paper proposes a semi-empirical model to predict a ship's speed loss at arbitrary wave heading.In the model,the formulas that estimate a ship's added resistance due to waves attacking from different heading angles have been further developed.A correction factor is proposed to consider the nonlinear effect due to large waves in power estimation.The formulas are developed and verified by model tests of 5 ships in regular waves with various heading angles.The full-scale measurements from three different types of ships,i.e.,a PCTC,a container ship,and a chemical tanker,are used to validate the proposed model for speed loss prediction in irregular waves.The effect of the improved model for speed loss prediction on a ship's voyage optimization is also investigated.The results indicate that a ship's voyage optimization solutions can be significantly affected by the prediction accuracy of speed loss caused by waves.     

Evaluation of added resistance in regular incident waves by computational fluid dynamics motion simulation using an overlapping grid system

A computational fluid dynamics simulation method called WISDAM-X was developed to evaluate the added resistance of ships in waves. The Reynolds-averaged Navier–Stokes (RANS) equation was solved by the finite-volume method and a MAC-type solution algorithm. An overlapping grid system was employed to implement rigorous wave generation, the interactions of ships with incident waves, and the resultant ship motions. The motion of the ship is simultaneously solved by combining the solution of the motion of the ship with the solution of the flow about the ship. The free surface is captured by treatment by the density-function method. The accuracy of WISDAM-X is examined by a comparison with experimental data from a container carrier hull form, and shows a fairly good agreement with respect to ship motion and added resistance. Simulations were also conducted for a bow-form series of a medium-speed tanker to examine the effectiveness of the WISDAM-X method as a design tool for a hull form with a smaller resistance in waves. It was confirmed that the WISDAM-X method can evaluate the added resistance with sufficient relative accuracy and can be used as a design tool for ships.     

短波顶浪中KVLCC2船模阻力增加CFD计算研究

波浪中航行船舶阻力增加,特别是短波中的阻力增加,是船舶界关注的焦点之一,也是船舶水动力学界研究的热点之一。论文采用基于RANSE的数值波浪水池技术,针对KVLCC2船型,开展了短波顶浪中船舶阻力增加的数值计算研究。与模型试验结果的比较表明,文中的CFD方法能够相当准确地计算短波顶浪中航行船舶的阻力增加;对船体各部分波浪增阻的分析表明,船体艏段产生的波浪增阻占主导地位,艉段的波浪增阻很小,而平行中体段对波浪增阻几乎无贡献。     

基于纵倾调整的集装箱船实海域航行阻力减少的研究

为应对"能效运营指标(EEOI)自愿应用导则",提出了在航行中采用调节纵倾的方法,降低营运能耗。选取了3100TEU集装箱船作为研究对象,应用Rankine源自由面势流理论计算不同纵倾下船舶兴波阻力系数以及总阻力系数,应用三维面元法计算了规则波中的波浪增阻,并针对实海域进行了増阻预报。研究表明,一定的艉倾能减小兴波阻力和总阻力。通过实海域増阻预报,服务航速下采用艉倾0.4°的纵倾航行会使波浪増阻增加4.21%,但总阻力仍能减少3.38%,较有效地降低了EEOI值。     

应用五体船型降低集装箱船EEDI

在当今船舶行业绿色环保、节能高效的前提下,提出了应用五体船型来达到降低EEDI的相应要求,介绍了五体船的主尺度选取办法,最后估算出其EEDI值,与常规集装箱船型作比较后发现五体船型可以有效地降低EEDI值,更加满足环保要求。     

短波增阻对船舶失速系数的影响分析

船舶失速系数fw的理论预报较为复杂,仅就波浪增阻这一影响fw的重要因素,选择一条8万t级散货船开展了模型试验研究.试验结果表明,在BF6级典型海况中短波增阻占到船舶波浪增阻的50%左右,由此试验结果分析失速系数fw表明短波增阻对fw的影响可达3%.这一研究表明对于大中型船舶,短波成份是影响波浪增阻的重要因素,需要在模型试验和数值计算中重点关注.     

采用遗传算法进行球鼻艏优化的流体动力计算(英文)

Computational fluid dynamics(CFD) plays a major role in predicting the flow behavior of a ship.With the development of fast computers and robust CFD software,CFD has become an important tool for designers and engineers in the ship industry.In this paper,the hull form of a ship was optimized for total resistance using CFD as a calculation tool and a genetic algorithm as an optimization tool.CFD based optimization consists of major steps involving automatic generation of geometry based on design parameters,automatic generation of mesh,automatic analysis of fluid flow to calculate the required objective/cost function,and finally an optimization tool to evaluate the cost for optimization.In this paper,integration of a genetic algorithm program,written in MATLAB,was carried out with the geometry and meshing software GAMBIT and CFD analysis software FLUENT.Different geometries of additive bulbous bow were incorporated in the original hull based on design parameters.These design variables were optimized to achieve a minimum cost function of "total resistance".Integration of a genetic algorithm with CFD tools proves to be effective for hull form optimization.