不同结构形式张力腿平台水动力参数比较分析

随着张力腿平台(TLP)在深海油气开发领域的广泛应用,在早期传统式(C-TLP)的基础上衍生出了多种结构形式,其中还有延展式(E-TLP)、最小化深海水面式(MOSES)和海之星式(SeaStar)已具备业界建造运营经验。为了体现TLP各类结构形式的性能特点,服务于工程开发方案中平台构型选择,本文基于三维势流理论频域方法,针对现已建造的4种TLP的水动力性能及相关参数进行了对比研究。首先,在质量惯性、结构刚度相似的条件下,完成了各类型平台的主尺度方案;其次,采用SESAM软件分析计算了各方案设计平台的附加质量、势流阻尼和运动响应幅值算子(RAO);最后的结果对比表明,不同结构形式对张力腿平台的固有周期影响很大,分散立柱形式的C-TLP与E-TLP的垂向运动响应更小。     

单立柱张力腿平台水动力性能试验研究

通过耐波性水池进行单立柱张力腿平台(简称SCTLP)在系泊状态下的运动特性,以及张力筋键受力情况的试验研究。试验分别在规则波和不规则波(长峰波和短峰波)中进行,浪向选取180°。根据水池深度,模型试验采用1∶87.5的缩尺比进行全水深模拟,并对风力和流速进行了模拟。通过试验,获得较为丰富的试验数据,能很好地分析SCTLP的运动特性。     

考虑多种非线性因素的张力腿平台动力响应

建立了一种考虑多种非线性因素的张力腿平台(TLP)分析模型,其中包括六自由度有限位移,各自由度之间的耦合,瞬时湿表面,瞬时位置,自由表面效应及粘性力等因素引起的非线性。推导出TLP六自由度非线性运动方程。对某典型张力腿平台ISSC TLP进行了时域上的数值计算,求得该平台在规则波作用下的六自由度运动响应。用退化到线性范围的解与已有解进行了对比,吻合良好。数值结果表明,综合考虑非线性因素后响应明显改变,建议在设计TLP平台的时候,考虑非线性因素的影响。     

海洋平台张力腿非线性动力响应

采用非线性梁模型,充分考虑张力腿轴向与流向的耦合效应及平台运动对张力腿的作用,运用Galerkin法进行分析求解,研究不同的长径比(L/D)情况下,弯曲刚度和非线性耦合效应的影响,以期得到更适用于实际的张力腿简化模型。     

畸形波作用下四立柱张力腿平台动力响应研究

介绍了畸形波生成的方法并对各种线性合成畸形波的效率进行了对比。选用改进的随机波加瞬态波的方法模拟强非线性波———"新年波"的波形。采用微元法对张力腿平台的立柱和浮筒进行离散,编制程序对张力腿平台在强非线性波作用下的耦合动力响应进行了数值模拟,重点比较分析了张力腿平台在随机波及畸形波中所受波浪力、平台动力响应、系泊系统张力特性及浪向角对平台运动的影响。研究表明:在"新年波"作用下,0°浪向时,平台在x和z方向所受波浪力较随机波增长了约1/4,纵荡、垂荡及纵摇响应值分别增加了33%,38%和12%,张力腿张力幅值增加约20%,位于平台四角的张力腿张力有所差异,相邻两根张力腿的张力差别不大,浪向角对平台运动响应、张力腿张力的影响畸形波大于随机波的作用。为今后考虑强非线性波浪影响时张力腿平台的设计提供了借鉴和参考。     

张力腿平台及其基础设计

海洋工程油气开发逐步向深海域进军,资料表明２１世纪深海的石渍、天然气将是主要能源这一。目前主要的深海石油平台形式是张力腿平台,其结构一般由平台本体、张力腿系统和基础系统三部分组成。基础部分不但承受着结构上部及海底的各种载荷,而且为结构提供必要的稳定性和安全性。本文通过对当今世界已建成投产的９座深海张力腿平台及其基础形式进行分析,剖析它们的基础设计思想,为我国深海张力腿平台的设计提供参考。     

张力腿平台研究领域和发展趋势

本文比较全面地阐述了世界上第一个张力腿平台（ＴｅｎｓｉｏｎＬｅｇＰｌａｔｆｏｒｍ,简称ＴＬＰ）——ＨｕｔｏｎＴＬＰ的研究情况,并对ＴＬＰ的关键问题——运动响应和系索（张力腿）问题的研究情况进行了较为详细的介绍。最后,指出了目前ＴＬＰ的研究热点以及今后的发展方向。文中收集了有关文献７３篇,对开展ＴＬＰ的研究有一定参考价值。     

新型张力腿式储油处理平台的动力响应分析

针对目前小油田早期生产中存在的不足,提出一种适用于浅水海域的新型张力腿式储油处理平台,该平台主要由储油箱、浮箱、吸力桩、系泊链和甲板结构构成,具备原油处理和储存功能。应用非线性时域耦合分析法,研究了有义波高、平均波周期、水深对该平台的运动响应和系泊链张力的影响。计算结果表明,波高对平台动力响应有较大影响,有义波高每增加0.4 m,平台水平位移相应增加0.408 m,而系泊链力随有义波高的增加呈准线性增大;波周期对平台水平运动影响显著,平均波周期从6.5 s逐级变化至8.5 s时,最大水平位移自3.760 m渐增至5.467 m,而波周期对系泊链力影响较小,变化率一般小于10%;该新型平台对水深大于20 m的浅水海域有良好的动力特性,而对水深小于20 m的海域却表现异常。因此,该新型张力腿式平台能满足水深不小于20 m浅海区的油田早期生产需要。     

在平台振荡条件下TLP张力腿的涡激非线性响应

给出了预测张力腿涡激横向振动的时域分析,考虑了波浪、海流、张力腿平台的横漂与垂荡诸因素.张力腿平台的垂荡引起张力周期性变化,对张力腿的涡激横向振动起参数激励的作用,使其动力响应更为复杂.讨论了参数激励下涡激响应的共振条件;以尾流振子模型为基础,发展了分析张力腿在动张力作用下的涡激振动的工程方法,并分析了一座TLP实例,给出了在横漂周期内张力腿上质点的相对位移、弯矩、剪力幅值的时间历程.结果表明,平台垂荡使张力腿的涡激响应幅值升高、高频成分增加,因此它对张力腿的疲劳设计是重要的.     

随机波浪中张力腿平台耦合运动及系泊系统特性研究

张力腿平台(TLP)是一种垂直系泊的半顺应半刚度式平台,预报平台的运动响应及锚泊系统的张力是张力腿平台结构设计的重要基础。应用挪威船级社SESAM软件在频域和时域内研究了张力腿平台在随机波浪中的非线性运动响应及系泊系统特性,并在试验室中通过缩尺比为1∶40的模型进行了试验验证。在试验验证的基础上,将仅考虑浪与考虑浪、流联合作用下的张力腿的张力平均值、幅值及标准差作了对比。结果表明,在较低海况时,考虑浪和流时的张力腿与不考虑流的情况变化不大;在较大海况时,流的影响不可忽略,考虑流的张力腿变化幅度要略大于不考虑流的情况。     

NURBS高阶面元法在多体水动力分析中应用

当位于海上的多个浮体距离相近时,它们间将产生显著的水动力相互作用。使用NURBS(非均匀有理B样条)高阶面元法进行多体水动力分析,速度势用任意阶的B样条函数近似,物面用NURBS曲面表示,由于水动力与几何表示相分离,就可以方便地实现计算机辅助设计与水动力分析的集成。对截断圆柱与椭球间的水动力相互作用和半潜式平台与箱型驳船间的水动力相互作用的计算显示此种方法可以对多体间的水动力相互作用给出准确的分析,计算时间和占用内存大幅减少。     

直立浮式柱群波浪荷载计算

为了研究类似张力腿平台（ＴＬＰ）等海洋工程结构物的运动,浮式直立柱群的波浪荷载计算是十分重要的。应用匹配渐进和特征函数展开法得到单柱流场速度势的半解析解,再引入大间距假设,将柱群中某一柱体对其它柱体的扰动作用用平面入射波来代替。同时对该问题进行了非平面波修正,计入柱间水动力相互作用,解决了柱群的绕射问题。应用该方法计算了不同条件下的双柱波浪荷载的幅频特征。     

Influence of wave approach angle on TLP's response

The current study focuses on the response analysis of triangular tension leg platform (TLP) for different wave approach angles varying from 0° through 90° and its influence on the coupled dynamic response of triangular TLPs. Hydrodynamic loading is modeled using Stokes fifth-order nonlinear wave theory along with various other nonlinearities arising caused by change in tether tension and change in buoyancy caused by set down effect. Low frequency surge oscillations and high frequency tension oscillations of tethers are ignored in the analysis. Results show that wave approach angle influences the coupled dynamic response of triangular TLP in all degrees of freedom except heave. Response in roll and sway degrees of freedom are activated which otherwise are not present in TLP's response to unidirectional waves. Pitch and roll responses are highly stochastic in nature indicating high degree of randomness. Variation in surge, sway and heave responses are nonlinear and are not proportional to change in wave height for the same period.     

Numerical Study on the 3-D Complex Characteristics of Flow Around the Hull Structure of TLP

Vortex-induced motion is based on the complex characteristics of the flow around the tension leg platform (TLP) hull. By considering the flow field of the South China Sea and the configuration of the platform, three typical flow velocities and three flow directions are chosen to study the numerical simulation of the flow field characteristics around the TLP hull. Reynolds-averaged Navier–Stokes equations combined with the detached eddy simulation turbulence model are employed in the numerical study. The hydrodynamic coefficients of columns and pontoons, the total drag and lift coefficients of the TLP, the formation and development of the wake, and the vorticity iso-surfaces for different inlet velocities and current directions are discussed in this paper. The average value of the drag coefficient of the upstream columns is considerably larger than that of the downstream columns in the inlet direction of 0°. Although the time history of the lift coefficient demonstrates a “beating” behavior, the plot shows regularity in general. The Strouhal number decreases as the inlet velocity increases from the power spectral density plot at different flow velocities. The mean root values of the lift and drag coefficients of the front column decrease as the current direction increases. Under the symmetrical configuration of 45°, the streamwise force on C4 is the smallest, whereas the transverse force is the largest. The broken vortex conditions in current directions of 22.5° and 45° are more serious than that in the current direction of 0°. In addition, turbulence at the bottom of the TLP becomes stronger when the current direction changes from 0° to 45°. However, a high inlet velocity indicates a large region influenced by the broken vortex and shows the emergence of the wake behind the TLP under the same current angle.     

海底沉积物弹性参数计算方法及误差分析

由海底沉积物的纵波速、横波速及湿密度,根据岩土力学原理,整理出一组计算海底沉积物弹性参数的公式;以该公式计算了南海南部海域浅层沉积物的弹性参数,计算结果与已有文献资料数据做了比较,分析了两者误差的原因.     

Wave Defending Effects of V-Type Bottom-Mounted Breakwaters

An analytical method is developed for the study of the wave defending effects of the V-type bottom-mounted breakwater. The breakwater is assumed to be rigid, thin, impermeable and vertically located in water of constant depth. The fluid domain is divided into three sub-regions by an imaginary interface. The velocity potential in each region is expanded by eigenfunctions. By satisfying the corresponding boundary conditions and matching conditions in and between sub-regions, a set of hnear algebraic equations can be obtained to determine the unknown coetfficients for the eigenfunction expansions for each sub-region. The accuracy of the present model is verified by a comparison with existing results for the case of an isolated breakwater. Numerical results, in the form of contour maps of the relative wave amplitude around the breakwater, are presented for a range of wave and breakwater parameters. The results show that the V-type bottommounted breakwater is generally effective in defending against waves. In general, the wave height in the protected area is about 20-50 percent of the incident wave height.     

TLP风机基础二阶动力响应研究

针对概念设计的位于南海的三腿TLP浮式风机基础,应用基于水动力与空气动力耦合的FAST程序在时域内开展了风机基础的动力响应分析。结果表明,风载荷对TLP风机基础六个自由度的动力响应,尤其是纵摇影响显著。由于耦合作用,二阶波浪力进一步增大了基础的纵荡、横摇和艏摇响应。谱密度分析表明,风载荷及二阶波浪力显著地增大了浮式基础水平面内的低频运动。此外,基于风机基础运动时程,应用ORCAFLEX软件开展了时域内筋腱的顶部张力特性分析,结果表明,风载荷和二阶波浪力增大了筋腱顶张力幅值。     

地磁测量参考场计算软件的设计与实现

以IGRF全球地磁位模型为基础,设计地磁测量参考场计算软件,实现地磁场参数长波分量的时间域与空间域离散点计算,为野外磁力测量相关数据采集与仪器配置提供先验信息,使数据采集的作业效率及可靠性大大提高。     

Analytical Research on Wave Diffraction on Arc-Shaped Bottom-Mounted Perforated Breakwaters

An analytical method is developed to study wave diffraction on arc-shaped and bottom-mounted perforated breakwaters.The breakwater is assumed to be rigid,thin,vertical,immovable and located in water of constant depth.The fluid domain is divided into two regions by imaginary interface.The velocity potential in each region is expanded by eigenfunctions.By satisfying the continuity of pressure and normal velocity across the imaginary fluid interface,a set of linear algebraic equations can be obtained to determine the unknown coefficients of eigenfunctions.Numerical results,in the form of contour maps of the relative wave amplitude around the breakwater,are presented for a range of wave and breakwater parameters.Results show that the wave diffraction on the arc-shaped and bottom-mounted perforated breakwater is related to the incident wavelength and the porosity of the breakwater.The porosity of the perforated breakwater may have great effect on the diffracted field.