【作者】 朱航；

【导师】 欧进萍；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2011， 博士

【摘要】 我国南海油气资源储量丰富,约占中国石油总储量的三分之一。近年来,随着能源需求的增加,海洋石油的开采日益受到人们的重视。但由于我国深水油气开采能力较差,目前国内的海洋石油开发,仅局限于渤海和北部湾等浅海海域,南海深水区域的油气开发接近空白。由于水深的增加导致固定式平台成本的大幅增加而不宜用于深水油气的开发,适用于深水油气开发的浮式平台已成为研究的热点。深水浮式平台的研究和应用始于上个世纪60年代,经过几十年的发展,在发达国家已经形成了完备的技术。而我国深水浮式平台起步较晚,缺乏自主的关键技术。平台技术的落后不仅严重制约了我国深海油气资源的开发,同时也阻碍了我国参与国外深海油气开发。因此,深水浮式平台的研究对我国海洋工业的发展有着重要的意义。本文以半潜式平台为例,对平台在风浪联合作用下平台运动性能,以及平台垂荡响应的控制方案进行了研究。本文的主要研究内容如下:首先,归纳了浮式平台的主要结构型式(包括张力腿平台、Spar平台、FPSO和半潜式平台等),阐述了各平台结构型式的力学特点及其发展过程,并对一些新型的平台结构型式进行了简要介绍。同时,对浮式平台的研究现状进行了综述。第二,对半潜式平台的风荷载及表面风压进行了数值和实验研究。数值研究中基于N-S方程,选择剪切应力运输湍流模型、二阶迎风格式离散方法和三维稳态隐式解法,进行了平台风荷载和表面风压的数值计算。制作了1:100和1:150的实验模型,分别用于测压和测力的风洞实验,并通过风洞实验对研究内容进行了测量。通过对数值和实验结果的分析,得到了各风向角作用下平台的风力系数和风压分布规律,并分析了平台倾角对其风荷载的影响。第三,对半潜式平台在风浪联合作用下的水平运动响应进行了数值和实验研究。数值研究中平台的风荷载采用第二章所得结果,波浪荷载由边界元方法计算确定,锚泊系统的拉力采用分段外推校正法计算确定,在此基础上进行了平台水平响应的数值计算,得到了研究结果。制作了1:100的实验模型,通过风洞浪槽实验对风浪联合作用下平台的水平响应进行了测量。通过数值和实验结果的分析,得到了各种海况条件下平台的水平运动响应时程曲线,并分析了风对平台水平运动响应的影响。第四,对半潜式平台的气隙响应进行了数值和实验研究。数值研究中采用了时域格林函数方法,计算了平台的运动响应及波面时程,并由二者计算得出了平台甲板下表面的气隙响应。采用第三章的实验模型,进行了平台甲板下表面波浪砰击实验。通过数值和实验结果的分析,得到了平台甲板下表面各点的气隙响应时程曲线,确定了平台甲板下表面易受波浪砰击的区域。第五,根据调频质量阻尼器(TMD)的原理,设计了带有活动垂荡板的半潜式(MHS)平台结构型式,提出了这种平台垂荡响应RAO的数值计算方法,优化了平台主体和垂荡板的连接刚度,并通过增大主体下浮体体积的方法,对平台主体的偏转性能进行了改进。最后,参考Truss-spar平台的结构特点,设计了适用于承载风机的Truss-spar-buoy浮式平台结构。通过数值方法,研究了风机对平台的影响,并对平台运动响应进行了频域和时域分析。同时,为了进一步减小平台的运动响应,提出了双锚泊系统的设计方案,对平台的锚泊定位系统进行了改进。更多还原

【Abstract】 The South China Sea is enriched with abundant oil and gas resource, which is over 33% of the total in China. As the demand of oil and gas increase, the exploitation of them in oceans has attracted much attention in the recent years. However, as the lack of the technology, the exploitation of ocean oil and gas in our country only is limited to the Bohai Sea and Beibu Gulf, but can not reach the South China Sea. Because of the great water depth, the fixed platform can’t be economically constructed. The concept of the compliant platform has been introduced, and has become a research focus.The study and application of compliant platform started in the 1960s, and has formed a comprehensive technology in the advanced countries. However, in our country, the development of compliant platform techonology is still in its infancy, which hampers the oil and gas exploitation in deep water. Consequently, study on the compliant platform is very important for the development of China ocean industry, which will produce the enormous economic benefits and social benefit.In this dissertation, the motion performance of the semi-submersible platform subject to wind and wave has been studied, and the methods to decrease the heave motion of the platform have been discussed.The main contents of this dissertation can be demonstrated as follows:Firstly, the main types of the compliant platform used for ocean oil and gas exploitation, such as TLP, Spar, FPSO and semi-submersible platform, have been summarized, their structure feathers and developmental process have been demonstrated, and several new types of the compliant platform have been presented. Meanwhile, the studies on the compliant platform have been reviewed.Secondly, the wind loads and wind pressures acting on the semi-submersible platform have been studied by numerical and experimental simulation. In the numerical simulation, the N-S equation, 3-D steady implicit solver, 2nd order upwind discretization and sst k-ωturbulence model have been chosen for the calculation. Meanwhile, in the experimental simulation, two models, with the scale of 1:100 and 1:150, have been measured for wind loads and wind pressure distribution in wind tunnel respectively. By comparing the numerical and experimental results, the shape factors and wind pressure distribution of the platform have been studied, and the influence of platform pitch (roll) motion on the wind loads has been analysised.Thirdly, the motion performance of the semi-submersible platform subject to wind and waves has been studied by numerical and experimental simulation. In the numerical simulation, the wind loads are got from the results in the second chapter, the wave force is calculated by boundary element method, and the mooring force is calculated by piecewise extrapolating method. In the experimental simulation, the model with the scale of 1:100 has been used in the joint laboratory of wind tunnel and wave flume. By comparing the numerical and experimental results, the horizontal motion of the platform under different conditions has been studied, and the influence of wind loads on platform horizontal motions has been analysised.Fourthly, the air gap response of the semi-submersible platform has been studied by numerical and experimental simulation. In the numerical simulation, the platform motion and wave surface function have been calculated by boundary element method in time domain, and the air gap response of the points on deck downward surface have been calculated. In the experimental simulation, the model and laboratory are the same as them used in the third chapter. By comparing the numerical and experimental results, the air gap response of the points on the deck down surface have been studied, and the deck downward surface, where is possibly slapped by waves, has been analysised.Fifthly, based on the TMD concept, the conceptual design of a moveable heave-plate semi-submersible (MHS) platform has been put forward. The heave motion RAO of MHS platform has been calculated by iteration method, the connect stiffness between MHS hull and heave-plate has been optimized, and the platform pitch (or roll) motion has been decreased by enlarging the pontoon volumn.Lastly, based on the structure feature of Truss-spar platform, the conceptual design of Truss-spar-buoy platform used for wind tubine has been put forward. By numerical simulation, the influence of wind loads on platform has been studied, and the motion performance of the platform has been analysised in time and frequent domain respectively. Meanwile, to decrease the platform motion response, a position system with two groups of mooring line has been put forward.更多还原