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通过对江海货船的统计和分析,提出了提高货船营运经济性的一些观念和措施:船、机、桨的良好匹配是货船节能降耗的关键,正确掌控货船的经济航速,螺旋桨要素的优选和经济合理地处理江海货船多用途、跨航区的需要。 相似文献
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This paper presents the results of an experimental investigation dealing with the effect of bow overhang extensions on the quantity of shipping water over the foredeck in case of ships advancing in regular head waves. To perform this investigation, a series of free-running tests was conducted in regular waves using an experimental model of a multipurpose cargo ship to quantify the amount of shipping water. The tests were performed on five bow overhang variants with several combinations of wavelength and ship speed conditions. It was observed that the quantity of shipping water was affected by some parameters such as wavelength, ship speed, and bow shape in terms of an overhang extension. The results show the significant influence of an overhang extension, which is associated with the bow flare shape, on the occurrence of water shipping. These results involve the combined incoming regular waves and model speed. 相似文献
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《船舶与海洋工程学报》2016,(1)
This paper presents the results of an experimental investigation dealing with the effect of bow overhang extensions on the quantity of shipping water over the foredeck in case of ships advancing in regular head waves. To perform this investigation, a series of free-running tests was conducted in regular waves using an experimental model of a multipurpose cargo ship to quantify the amount of shipping water. The tests were performed on five bow overhang variants with several combinations of wavelength and ship speed conditions. It was observed that the quantity of shipping water was affected by some parameters such as wavelength, ship speed, and bow shape in terms of an overhang extension. The results show the significant influence of an overhang extension, which is associated with the bow flare shape, on the occurrence of water shipping. These results involve the combined incoming regular waves and model speed. 相似文献
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In order to understand characteristics of low-frequency motions of ships moored inside ports and harbors, analysis on actual cargo handling logbook of stevedoring services company, including events of interruption of cargo handling, and countermeasure for ship mooring problems are investigated by field observations at two ports and numerical simulation on moored ship motions. First model port concerns with interruption of cargo handling due to the low-frequency motions. Second model port relates to a resonant effect of long-period waves or harbor oscillations, and its countermeasure by mooring system. From the investigation, it is confirmed that the low-frequency motions of ships are induced by a resonance between surge motions and long-period waves or harbor oscillations and an asymmetry in the mooring system, and affect safe ship mooring and operation efficiency of cargo handling in ports and harbors significantly. 相似文献
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大型公务船泊外形与普通散杂货、集装箱船舶差别较大,靠泊船型外形轮廓对码头护舷选型与布置影响较大。福建沿海某公务船码头原护舷选型及布置未充分考虑公务船外形及大水位差影响,实船试靠时护舷不满足安全靠泊需要。通过广泛调研,并吸收借鉴类似码头护舷布置经验,对该码头护舷进行了适当的改造。主要在码头面上设置靠船立柱,配置转动式橡胶护舷,经过实船涨退潮周期靠泊验证,总体使用效果良好。该码头护舷改造为大水位差地区大型公务船泊位护舷选型及布置提供了一定的借鉴。 相似文献
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散货船装载的镍矿、铁矿在运输过程中会发生流态化,流态化导致货物流动性增强,从而降低船舶稳性。当船舶在波浪中航行时,货物的移动会产生一个额外的力矩,该力矩有可能导致船舶倾覆。基于离散元方法,对不同含水率的货物进行了静倾斜、休止角的数值模拟,在全尺度计算中给定了颗粒尺寸和时间步长的选取标准,并采用全尺度货舱模型分析了影响货物稳定性的关键参数。该数值分析方法可为固体散货海上运输过程中船舶稳性预测和安全隐患评估提供参考。 相似文献
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Kjetil Fagerholt 《Maritime Policy and Management》1999,26(2):105-109
A simulation study on the design of flexible cargo holds in small-sized bulk ships is presented. The ships considered are equipped with moveable bulkheads which can be placed in a given number of positions in the cargo hold. In this way the ships' cargo holds can be partitioned into several smaller holds with flexible sizes, and several cargoes can be lifted simultaneously by the same ship. The simulation study deals with designing an optimal cargo hold 'configuration' which gives the best flexibility when cargo quantities vary. The results show that there are significant potential savings by finding an optimal cargo hold configuration. 相似文献
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为保障非标准货物的运输安全,根据船舶耐波性理论,分析航运过程中作用在货件上的惯性力,推导出惯性力及综合外力的计算公式,结合SOLAS公约中非标准货物系固方案的校核要求,为船舶载运非标准货物时柔性系固方案的校核提供一种系统有效的方法。 相似文献
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潜水员梯是通过销轴连接在母船舷侧为潜水员执行潜水作业时上下船的平台,为保证在波浪中使用时的安全性,对其波浪作用力、运动响应及销轴处的动作用载荷设计有较高要求。为研究母船干扰下潜水员梯的动态响应特性,采用基于深水格林函数为积分内核的边界元方法,先计算母船及潜水梯这一整体的运动响应及其平均湿表面的辐射和绕射压力分布,依据刚体运动合成原理求解得到潜水梯重心处的运动。再以潜水员梯为研究对象,采用压力积分方法获得潜水员梯的波浪力作用,并将其运动、波浪力和销轴处的作用力联立构成动力学平衡方程,逆向求解出销轴处的动作用力。基于上述思路,系统研究了波长、航速及潜水员梯与母船相对位置变化时潜水员梯的运动、波浪作用力及销轴处作用力的变化规律,为潜水员梯的布置、销轴的选型及潜水作业时母船的操纵可提供指导意义。 相似文献
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构皮滩水电站通航建筑物采用带二级中间渠道的三级垂直升船机方案,其中第一级中间渠道由单线通航隧洞、渡槽、明渠及错船段组成。采用水工物理模型和船模试验,对第一级中间渠道的航行水力条件、单线通航隧洞和渡槽的尺度进行了系列研究。结果表明,船舶航行阻力、下沉量和渠道内水位波动随着船舶航速的增大而增大,一定航速条件下,渠道内还将产生横波,对船舶航行安全影响较大,应避免;错船段和单线渠道的连接应平顺,并应注意船舶从单线渠道航行至错船段时,因阻力减小,造成航速突然增大的影响。试验提出了不同航速条件下的单线通航渠道合理尺度,优化了错船段的位置,建议单线渠道宽采用18 m,水深不小于3.0 m,船舶航速小于等于1.2 m/s。 相似文献
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在分析张力作动筒高架索恒张力控制系统性能、货物滑车在高架索上的运动状态和货物滑车全程自动传输控制系统性能的基础上,建立了海上航行横向干货补给系统的数学模型,利用Matlab/simulink软件建立了仿真模型。通过对高架索恒张力系统性能和货物滑车全程自动传输控制性能仿真,表明建立的仿真模型是可行的,货物滑车采用PID控制方式传输是稳定的,在高海况下能按照预设好的传输速度从补给船传输到接收舰,但采用梯形加减速控制方法不利于滑车的平稳传输。 相似文献
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航行船舶的三维非线性水弹性分析 总被引:3,自引:0,他引:3
基于Wu提出的浮体二阶水弹性理论[1],研究大浪中航行船舶的非线性水弹性响应,给出了数值方法和计算结果.在二阶水弹性分析中,主要考虑了大角度刚体转动和瞬时湿表面变化引起的非线性水动力.根据三维线性水弹性理论[2],采用移动脉动源格林函数和Kelvin定常兴波假定,求解了对二阶水动力做主要贡献的一阶速度势及响应.最后以航行于不规则波中的小水线面双体船为例,讨论了航速和定常兴波流场对水弹性响应的影响,并对线性和非线性响应的预报结果进行了比较. 相似文献
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散货船在不同货物舱装货时选择哪个压载舱来配平,在货物舱注入货物时候如何调节流量来保持船舶即时平衡,这些问题涉及到船舶的重心和稳心。本文依据力学平衡理论,选择出最优压载舱;依据船舶静态平衡理论和微积分算法,计算出装货过程中船舶变化的重心和稳心,以及船舶倾斜角度与装载货物的关系。当达到船舶允许的最大倾斜角后,操作者就必须给压载舱注入压载物以避免船舶过度倾斜。利用计算机控制阀门开度可以有效控制压载物的流量。 相似文献
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船舶大型化发展的趋势使得其尺度越来越大,而结构轻量化设计的需求则使高强度钢被大量应用于其结构设计之中,相对于传统的小尺度船舶,相对刚度的下降使得船体梁变得越来越“软”,这将导致大型船舶在波浪中航行时船体结构波激振动特性发生变化。采用模型试验和理论预报的方法,研究某大型工程船在不同船体梁刚度下的低频和高频垂向波浪载荷响应。分段试验模型采用2种横剖面惯性矩的钢质梁,用以分别模拟船舶横剖面原始的和变化后的刚度。采用三维水弹性理论对该船在波浪中的响应进行预报,并与模型试验结果进行比较。结果显示:小刚度的船体梁更易在波浪中发生波激振动;频繁的波激振动将导致结构发生严重的疲劳损伤问题。这种刚度变化对船体梁波激振动的影响规律表明,有必要将刚度作为大型船舶结构优化设计的重要参数之一。 相似文献