【作者】 张琳；

【导师】 聂孟喜；

【作者基本信息】 清华大学 ， 水利工程， 2005， 硕士

【摘要】 单锚腿系泊系统是当前海军正在研究并将大量投入使用的一种单点系泊系统,该系统目前主要采用经验公式的方法进行设计。本文在系统分析了国内外对单点系泊系统和石油钻井平台立管研究成果的基础上,采用了时域分析方法初步建立了单锚腿系泊系统在风、浪、流联合作用下的动力计算模型,并编制了一套相应的动力模拟计算程序。本文采用了非线性Stokes五阶波作为系泊系统的波浪外荷输入。在计算过程中通过计入Bernoulli方程中的速度平方项体现波浪二阶力对系泊系统的影响。在本程序中,风向、波浪和海流的方向可以设定为不一致,但通常在初始设计时,都会假定风、浪、流是同方向的。由于单锚腿系泊系统的“风标”特性,以及实际工况中当风、浪、流的方向相同时系统的动力响应最大的特点,本程序计算了当风、浪、流作用在与船纵断面呈0度的方向时船舶的动力响应,发现结果是合理的。立管计算方面采用三维集中质量法,建立了立管的动力方程,立管的张力采用静态方法计算得出。对于浮筒的计算,忽略了风力的影响,其受到的海流力和波浪力计算与立管在此方面的计算方法相似。船舶的荷载利用经验公式计算得出,通过计算船体的纵荡和横荡运动体现其运动响应,系泊力采用静态方法计算。本文在Hamilton型拟变分原理体系下,建立了一种时间子域以五次B样条函数插值的时间子域法,船舶和立管的结构动力计算就是用这种新方法求解的。动力计算的初始条件即为系统零时刻时的状态。为了检验动力模拟计算程序,本文对早期建立的两个单锚腿系泊系统——LOOP SALM系统和Tembungo SALM系统进行了动力计算,与给出的设计值以及试验结果进行了比较,发现计算结果较好地反映了波浪荷载的周期性和二阶力的影响。并与一种用Wilson-θ法作为动力计算方法的程序进行了比较,发现新方法具有误差小、稳定性好等优点。本研究对单锚腿系泊系统设计和建造提供了理论上的依据和指导,为将来单锚腿系泊系统的进一步研究打下一定的基础。更多还原

【Abstract】 Single Anchor Leg Mooring System (SALMS) is currently under studyand will be put into practice in navy programs. It is mostly designed byempirical formula at present. In this paper, a numerical model in time domainis present to predict the dynamic responses of SALMS subject to wind, waveand current, and the relative dynamic simulation calculation programs isprovided. The model is established under the comprehensive study on theachievements of Single Point Mooring Systems and risers of oil drillingplatform.The nonlinear five-order Stokes wave is employed to predict the waveload of SALMS, and second-order wave drift forces are also considered bytaking into account of the square item in Bernoulli equation. In this program,the directions of wind, wave and current can be different, but it is usuallyassumed that wind, wave and current are all from the same direction at theinitial design. Because of the ‘weather vane’ characteristic and the dynamicresponses of SALMS would be maximal when the directions of wind, waveand current are consistent, it calculated the dynamic responses of wind, waveand current acting on the same direction that is the long direction of thevessel. The results are reasonable. 3-D concentrated mass method is adoptedto obtain the riser’s dynamic response equation. The static method isemployed in calculations of riser tension. For buoy, it ignored the effect ofwind load, and the calculations of wave load and current load are similar tothe methods of risers’. The loads acting on vessel are obtained withexperimental equations, and the movement responses effect on surging andswaying. The static method is also employed in calculations of mooringforce.Based on the Hamilton-type quasi-variation principle, a new method isintroduced in this paper which applying the quintic B-spline function asinterpolation to the time sub domain. And it is used to solve the vessel andriser’s dynamical response. The initial values are decided by the initiativeconditions.The dynamic simulation calculating programs serve to two SALMS(LOOP SALMS and Tembungo SALMS), and the calculating results ofseveral cases are compared with design and experimental results, which showfairly good consistency and stability. Then, compared with the Wilson-θapproach, B-spline function method is better at the accuracy and the stability.The research provided the directions in theory for designing andconstructing the SALMS. And it grounded SALMS in next study.更多还原