船舶在规则波中阻力增加的理论预报与验证

本文介绍船舶波频运动计算程序ＳＶＭＰ－Ｒ中采用的波浪中阻力增加的计算方法：Ｃｅｒｒｉｔｓｍａ＆Ｂｅｕｋｅｌｍａｎ（１９７２） Ｊｏｏｓｅｎ（１９６６），并给出了采用前一方法对一集装箱船四种航速下规则顶浪的阻力增加的理论预报，结果显示与该船的模型试验在整个波频范围内吻合良好，从而验证了该程序的波阻预报功能对一般船舶预报的实用性。     

基于三维辐射能量法的船舶波浪增阻计算分析

船体辐射运动是航行船舶波浪增阻的主要原因。文章基于频域势流理论推导出三维有航速船体辐射能量的具体表达式,其中流体运动速度势的计算采用了移动脉动源格林函数法,进一步根据获得的船体水动力系数和运动计算出航行船舶辐射运动引起的波阻增加,并与基于切片理论的现有方法进行了比较。对Wigley III、S175集装箱船及某型油船三类不同船型在不同航行工况下的波阻增加进行了详细的计算分析。研究表明三维辐射能量法相较于基于切片理论的方法具有更好的准确性和适用性,为船舶波阻增加的预报提供了快速有效的手段。     

节能前置导管对波浪增阻和失速的影响

以8万t巴拿马型级散货船为例,分别进行了光体和带前置导管的快速性节能试验和耐波性波模型试验.试验结果表明,肥大型的散货船安装前置导管可以有效提高船舶推进效率约2％,从而达到节能的目的.前置导管在波浪中有一定的减摇作用,减小船舶在波浪中的阻力增加,减小船舶对船舶的失速差值百分比影响较大,失速差值百分比在10％以上.因此,在波浪中安装节能的前置导管对船舶的失速系数有一定的影响.     

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.     

船舶在波浪中阻力增加预报研究进展

从数值计算和模型试验两个方面,介绍船舶在波浪中阻力增加预报的研究进展,分析各种方法的基本原理,提出阻力增加预报的发展方向.     

波浪增阻预报的研究现状与未来展望

随着国际海事组织减少温室气体排放战略的稳步推进,波浪增阻预报成为近十多年来的热点研究课题之一。作为二阶波浪力,其成因既与船舶本身特征相关,又与其营运状态和海洋环境相关。由于存在各种限制,对其进行精确测定和数值预报均十分困难。该文阐述了各种波浪增阻预报方法的研究现状,包括实验方法、基于势流理论的方法、基于求解黏性方程的方法、半经验方法和数据驱动方法等,回顾和评述了各种方法的发展历程并展望了未来发展趋势;此外,基于半经验公式,文中展示了新型船舶各航速与各海况下的平均波浪增阻等值线图,该图表便于工程实践应用;最后,在充分讨论的基础上,提出了未来研究工作需重点关注的方向。     

阻流板对规则波中船舶阻力及运动特性影响研究

[目的]旨在分析阻流板对规则波中船舶阻力及运动特性的影响。[方法]以一条半排水型方尾船为研究对象,基于RANS方法并结合重叠网格技术进行阻流板安装前后船舶在规则波中的阻力与运动特性数值仿真,总结船舶阻力、姿态与运动响应随波长与航速的变化规律。[结果]结果表明：阻流板在规则波中的减阻率比静水减阻率大1.03%～2.43%;阻流板对垂荡和纵摇传递函数的影响随着波长的增大而变大,λ=2LPP工况下的垂荡传递函数TF3和纵摇传递函数TF5平均降低了3.5%和1.4%;当船舶出现甲板上浪时,阻流板可使TF3和TF5的降低率分别达到9%和3%。[结论]研究方法与研究成果可为船舶节能装置设计与性能预报提供技术参考。     

水翼辅助推进船舶波浪中运动和增阻特性研究

基于在船首两侧增添（固定）水翼的水翼辅助推进船舶的设想,选取集装箱船型作为研究对象,采用三维面元法对原型和水翼船在规则波中的运动和增阻响应进行了预报,并与试验结果进行比较,验证了计算结果的准确性。研究结果表明水翼能够有效地减小船舶在波浪中的纵摇、垂荡和增阻响应,其中添加水翼船在波浪中的纵摇和垂荡响应峰值分别减少了21%和24%,而增阻响应则减小了80%。此外还对水翼展弦比和安装位置对船舶在波浪中的运动和增阻响应的影响进行了研究。     

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.     

高速船波浪增阻数值预报方法研究

海洋气象因子fw是国际海事组织（IMO）提出的EEDI计算公式中的重要成分,而船舶波浪增阻是决定fw的关键,由于国际上关于高速船波浪增阻预报方面的研究很不完善,为此文章基于二维半理论求解水动力和运动响应,利用几种不同方法对波浪增阻进行计算,并与模型试验结果相比较,在此基础上,推荐了一种适合计算高速船波浪增阻的方法。     

海上长球首球尾双体风电维护船波浪增阻研究

为研究不同球首球尾长度双体风电维护船在波浪中的阻力性能,基于CFD技术,探究适用于双体船运动响应和波浪增阻的数值计算方法.通过与试验结果的对比分析,在计算域设定和网格尺寸方面提出适用于双体船的计算方案.利用此方法计算不同球首球尾长度双体风电维护船的升沉与纵摇以及波浪增阻,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.     

基于兴波理论与阻力图谱资料的高速双体船阻力预报方法

在原苏联"方尾图谱"重分析和改进的基础上[1],基于兴波阻力的薄船理论与船模试验数据的结合,提出用兰金(Rankine)体的波幅函数代替实际船型的波幅函数,以确定双体船片体间的阻力干扰因子,从而计算得到双体船的兴波阻力.整个计算过程直接使用Microsoft Excel,对新方尾单体船电子阻力数据执行查值和进行主要影响系数的修正计算,粘性影响修正与总阻力计算;进行不同尺度的快速性方案比较,以及确定高速单体船或高速双体船的总阻力与有效功率曲线.通过WP60穿浪双体船一算例与船模试验结果的比较表明,该方法是一种实用、高效、灵活、便捷和可靠的计算方法.     

Systematic study on the hull form design and resistance prediction of displacement-type super-high-speed ships

Systematic theoretical and experimental studies were carried out to establish methods for hull form design, optimum dimension selection, and resistance estimation for displacement-type super-high-speed ships. In this study, a theoretical hull form design method for displacement-type super-high-speed ships was first developed using the minimum resistance theory and a sectionally varying hull form equation. Using an established hull form design method, a series of 60 hull forms were prepared with systematic variations of the most important design variables, and model tests were conducted for these ship models. Finally, regression analyses were performed for the results of the model tests. The study was very successful, and the prepared computer programs are now being actively used as efficient tools for the design of the displacement-type super-high-speed ships.     

基于CFD的钻井船线型优化及阻力计算

为了对钻井船阻力性能进行优化,以某钻井船为研究对象,通过建立首尾部半参数化船体模型,针对月池关闭状态下的钻井船,对其首尾部的型线进行优化,选出最佳优化方案.钻井船的首尾部型线经过优化后,总阻力降低了2.003％.其中,摩擦阻力降低0.13％,剩余阻力优化效果为8.9％.本文研究可为钻井船的型线设计优化提供一定的参考和建...     

Long-term prediction method for the green water load and volume for an assessment of the load line

 To develop a practical prediction method for the green water load and volume on the bow deck in irregular waves, model tests were conducted using a tanker and a cargo ship on a domestic Japanese voyage. The relation between green water load and relative water height at the stem was considered. Based on the finding that the maximum value of the green water load is proportional to the square of the maximum value of the water elevation over the bow top, the probability density functions of the green water load and volume in short-term predictions were proposed. It was verified that the proposed functions show good agreement with the measured distributions, especially in the tails, and were better than conventional functions. Using these functions, long-term predictions of the green water load were carried out. It was confirmed that the present method is more rational than the conventional one for estimating the long-term probability of the green water load. An assessment of the bow height of a domestic Japanese ship from the viewpoint of deck wetness was carried out using these prediction methods. This research was used as the technical background for the revision of domestic rules on load lines, which was enforced in October 2001. Received: July 19, 2002 / Accepted: October 30, 2002 Acknowledgment. Some of the present study was carried out as part of a cooperation project (RR45) with the Shipbuilding Research Association of Japan, supported by the Nippon Foundation. Address correspondence to: Y. Ogawa (e-mail: ogawa@nmri.go.jp)     

基于船模水池试验的船舶顺浪纯稳性损失计算扩展模式

船舶顺浪航行的纯稳性损失研究,已成为国际航海界和国际海事组织(IMO)关注的课题之一.在Ю.И.涅查耶夫根据28艘渔船和运输船船模水池试验的船舶顺浪纯稳性损失计算方法的基础上,提出了扩展模式,扩大了其适用范围,并给出了大长宽比(船长/船宽)舰艇纯稳性损失的算例,同时实现了该扩展模式的程序化,生成了实用化的软件.最后通过与CFD试验方法和一般理论计算法所得结果的对比,验证了该扩展模式计算结果的可信度.     

海事司法中扣押方便旗船的可行性及途径探析

在国际海事司法实践中,扣押船舶是非常重要的一种担保债务人履行债务的方式,但是在两大法系中,船舶扣押制度的性质不同,实现方式也不同。如果涉及到方便旗船扣押,情况会变得更复杂。因为方便旗船涉及到船舶登记所有人、实际所有人及经营人等几个当事人之间复杂的关系,形成了几种不同的方便旗船运营模式,这给海事请求权人提起扣押方便旗船的申请带来了困难。文中通过分析两大法系针对船舶扣押的不同态度,基于剖析几种不同的方便旗船经营模式,分析海事请求人提出扣押方便旗船申请的可行性及可能的途径,从而保障海事请求权人的合法权益。     

长江中游沙市河段河床演变分析及趋势预测

通过分析认为:太平口心滩存在被解体的可能;腊林洲高边滩滩头将继续冲蚀后退;守护当前的三八滩对改善该河段的航道条件益处不大;目前的河型条件下要保证主、副通航孔都能通航可能是比较困难的;三八滩将继续变形、移位;该河段水流的动力轴线的变化和摆动是常态。