共查询到20条相似文献,搜索用时 46 毫秒
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针对现有水运规范和手册对锚链设计计算方法不足的问题,进行理论推导和数值解决方法研究。采用悬链线理论推导方法,得出锚链拖地形态基本曲线方程,并进一步列出锚链不拖地情况和锚链中间有沉块情况的补充方程。结果表明,可以采用本方法结合数学软件准确求解锚链拖地、不拖地、中间有沉块等各种工况下的曲线方程,以及起锚角、抛锚距离、锚拉力等各参数。 相似文献
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三维锚泊系统时域计算分析 总被引:5,自引:2,他引:3
通过采用在频域内对浮体运动方程求解并将计算结果转换为时域结果,同时与锚链线运动时域方程耦合求解锚泊浮体在限制工作水深的运动位移与锚链线上的张力.采用一种考虑锚链线上各种受力的三维锚链线模型来计算锚链的位移与受力.通过对计算结果的分析表明,本方法简单、实用,可以提供具有工程精度的锚泊性能预报. 相似文献
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锚泊线一阶运动响应对二阶锚链阻尼的影响 总被引:3,自引:1,他引:2
本文主要研究锚泊线的一阶运动响应对二阶锚链阻尼的影响。在频域内采用摄动方法分析系泊结构物慢漂运动时,锚链二阶方程可分解成非齐次方程和齐次方程。其解分别与锚链的一阶运动响应和浮式结构物的二阶运动有关。为了探讨锚泊线一阶运动的影响,本文通过求解非齐次和齐次方程,分别求得相应的二阶锚链阻尼和二阶锚链力。从计算结果可以看出,尽管由非齐次方程得到的二阶锚链力占总的二阶锚链力成分很小,但其所提供的二阶锚链阻尼却与二阶齐次方程解同量级。故在分析二阶锚链阻尼时,不能忽略非齐次方程解的影响。 相似文献
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基于悬链线方程的相关知识,对南海常见的由下部锚链和上部锚缆连接而成的FPSO锚泊系统,分别建立下部锚链和上部锚缆的数学模型并进行详细的分析.在两种已知条件下求解锚链和锚缆组成的悬链线方程,介绍了锚系姿态和张力的分析计算方法.最后对锚系悬链线方程求解方法在工程中的应用提出了建议. 相似文献
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锚链直径对船舶锚泊能力的影响 总被引:1,自引:0,他引:1
从减轻船总体负担、采用链径更小的海洋系泊链的设计需求出发,以单个链环为微元对锚链在锚泊状态所形成悬链线方程进行推导,建立锚链在典型锚泊状态下的悬链线方程,并以此为基础完成不同链径锚链在抛锚长度、最大可承受环境力、最大抛锚深度等方面的计算分析。结合计算结果和船舶实际使用情况,对采用不同链径锚链的锚泊能力进行综合分析后认为,虽然链径较粗的锚链的理论锚泊能力较强,但若采用霍尔锚等非大抓力锚,或对锚泊水域面积无明确要求、没有在深水中抛锚的特殊需求等,则可以选用链径相对较细的海洋系泊链代替目前规范中规定的电焊锚链。 相似文献
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作者建立了卡锚的数理模型和解析方程,用于求取锚链筒和锚唇的合理参数,可在设计阶段预报或排除揳入卡锚和重力阻锚的隐患。作者通过实船试验提供了解析方程中的摩擦系数 f 和揳入力 P 的值。还发现Иванов重力阻锚的锚链筒直径下限曲线的误差,文中给出了切合实用的新图表。 相似文献
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常微分方程具有一般数学的特点:抽象性、严密性,又具有本身的特点,即与工程技术紧密相连,实用性强.而常数变易法是解线性微分方程行之有效的一种方法。 相似文献
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This paper presents the uncertainty modelling of experimental results for a physical model of a tanker moored to a terminal inside a port. The physical model was built for an oil terminal at the port of Leixões in Portugal. The model incorporates the new modified port layout, as well as a future 300 m extension of the port outer north breakwater to enhance operational conditions. The physical model tests were performed on a scale of 1:80 in the Portuguese Civil Engineering Laboratory (LNEC). A generic mooring system of four mooring lines and two fenders is simulated using a nonlinear spring system. Decay tests are carried out to evaluate the natural periods of the moored model. Then, tests are carried out for the moored model in waves. The major aim of the experimental study is to obtain novel results for the wave elevation and direction at various locations inside the port, the ship motions at six degrees of freedom, and loads on mooring lines and fenders including the modified port layout. As the physical model measurements are subjected to different types of uncertainties, a systematic uncertainty analysis is carried out here, following ITTC guidelines and recommendations, to quantify all possible sources of uncertainties. The results are discussed, and several conclusions are reached. Based on the experimental results, the presented physical model study may replicate the results for waves and motions with uncertainties less than 9% of the significant amplitudes. The assessment of the applied nonlinear spring model reveals load predictions on the moorings, with uncertainties less than 4% of the maximum mooring loads. 相似文献
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麦哲伦(Magellan,Ferdinand),葡萄牙著名航海家和探险家.先后为葡萄牙(1505~1512)和西班牙(1519—1521)作航海探险。5个多世纪以来,人们对麦哲伦崇拜得很,都把他看作是世界英雄,因为他是第一个完成环球航行的航海家。这一创举实际上以无可争辩的事实证明了地圆说。从这个意义上讲,麦哲伦的确是 相似文献
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为优化某船用柴油机的燃烧室的"油-气-室"匹配,降低有害物排放,运用AVL Fire对原型燃烧室改用不同燃烧室进行额定工况模拟.结果表明,高低型双涡流室双缩口燃烧室能在上涡流室形成"飞轮效应",相对于原型燃烧室,不仅能增加功率,而且能降低Nox和SOOT的排放.对高低型双涡流室双缩口燃烧室设置不同的高低涡流室的半径比r/R和喷油夹角进行计算.结果表明:随着r/R从0.3增加到1.3,Nox和SOOT的排放量均先减少后增多;当r/R为0.7时,Nox和SOOT的排放量均最少.当喷油夹角为140°~165°时,随着喷油夹角的增大,Nox的排放量先减少后增加,随后再减少,最后又升高;SOOT排放量先减小后增大,随后再减小. 相似文献
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Characteristics of a bubble jet near a vertical wall 总被引:1,自引:0,他引:1
A numerical model of a coupled bubble jet and wall was built on the assumption of potential flow and calculated by the boundary integral method. A three-dimensional computing program was then developed. Starting with the basic phenomenon of the interaction between a bubble and a wall, the dynamics of bubbles near rigid walls were studied systematically with the program. Calculated results agreed well with experimental results. The relationship between the Bjerknes effect of a wall and characteristic parameters was then studied and the calculated results of various cases were compared and discussed with the Blake criterion based on the Kelvin-impulse theory. Our analyses show that the angle of the jet's direction and the pressure on the rigid wall have a close relationship with collapse force and the bubble's characteristic parameters. From this, the application range of Blake criterion can be determined. This paper aims to provide a basis for future research on the dynamics of bubbles near a wall. 相似文献
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