浅水半潜型浮式风机基础概念设计与模型试验研究

目前我国海上风电开发主要集中在近海海域。我国近海海域水深相对较浅,在浅水非线性波浪载荷作用下,浮式基础动力响应呈现显著非线性特性,导致浮式风机基础及其系泊系统设计极具挑战。针对我国近海浅水海域环境条件,基于半潜型浮式风机基础概念SPIC,采用参数化建模与优化方法,开展了42 m水深条件下半潜型浮式风机基础概念设计,并在海洋工程水池开展1∶50缩尺模型试验。模型试验的结果表明：半潜式浮式风机基础概念设计具有稳定性好、动力性能优良等优点,浮式基础纵摇运动、机舱加速度等指标满足规范要求。模型试验结果验证了该概念的可行性。     

基于竖轴漩涡水动力特性的海底矿粒采集方法试验研究

随着新能源等新兴产业的高速发展,金属矿产资源需求激增,国内外争相发展深海采矿技术。基于竖轴漩涡的水动力特性,设计了一种带有4个切向射流喷嘴的吸盘式水力集矿装置,提出应用切向射流在集矿装置内诱导生成竖轴漩涡的新集矿方法。开展水力集矿模型试验,研究竖轴漩涡集矿流场流速分布特征;分析低、中、高3种旋流度流态下,集矿流量对矿粒运动轨迹和采集率的影响。结果表明：矿粒起动轨迹随着旋流度的增加,逐渐从混乱无序转向明显的圆周运动;在特定集矿流态下,矿粒采集率随集矿流量的增加不断提高;当矿粒采集率超过90%时,集矿流量需求随着旋流度的增加而减小。通过采矿车原理样机水池测试,初步验证了集矿装置的集矿性能,可为集矿装备的设计研发与论证提供借鉴。     

均匀流中深水系泊Truss Spar平台涡激运动试验研究

在工程中广泛应用的Truss Spar平台自诞生之初就为涡激运动问题所困扰,对其运动特性及抑制方法的机理性研究始终都在进行。采用截断系泊系统水池模型试验对设计中的Truss Spar平台在均匀流中的涡激运动响应进行了研究,分析了有无侧板平台的运动轨迹以及不同速度及流向角来流对平台运动的平衡位置的影响。在影响平台涡激运动特性的重要因素中,选取折合速度及流向角分别加以研究,分析了幅值在锁定区间中的变化规律,验证了减涡侧板对涡激运动良好的抑制作用,并对热点问题进行了探讨。为进一步研究Spar平台的涡激运动特性奠定了基础。     

Shallow Water Effects on Surge Motion and Load of Soft Yoke Moored FPSO

Much attention should be paid to a large FPSO moored permanently in an oil field with water depth of only about 20 m, since shallow water effects on the hydrodynamics may bring about collision and damage. A 160kDWT FPSO with a permanent soft yoke mooring system is investigated with various shallow water depths and focuses are the low frequency surge motion and mooring load. Computation for the FPSO system is made based on linear 3-D potential fluid theory and time-domain numerical simulation method. Corresponding model test is carried out in the ocean engineering basin of Shanghai Jiao Tong University. It is shown that, in the surge natural period, low frequency surge motion and mooring force increase remarkably with the decrease of water depth. Especially, the smaller the ratio of water depth and draught is, the quicker the increase is. The shallow water effects should be taken into account carefully for determining the design load of a single point mooring system.     

Hybrid Model Testing Technique for Deep-Sea Platforms Based on Equivalent Water Depth Truncation

In this paper,an inner turret moored FPSO which works in the water of 320 m depth,is selected to study the so-called "passively-truncated numerical-simulation" type of hybrid model testing technique while the truncated water depth is 160 m and the model scale λ=80.During the investigation,the optimization design of the equivalent-depth truncated system is performed by using the similarity of the static characteristics between the truncated system and the full depth one as the objective function.According to the truncated system,the corresponding physical test model is made.By adopting the coupling time domain simulation method,the truncated system model test is numerically reconstructed to carefully verify the computer simulation software and to adjust the corresponding hydrodynamic parameters.Based on the above work,the numerical extrapolation to the full depth system is performed by using the verified computer software and the adjusted hydrodynamic parameters.The full depth system model test is then performed in the basin and the results are compared with those from the numerical extrapolation.At last,the implementation procedure and the key technique of the hybrid model testing of the deep-sea platforms are summarized and printed.Through the above investigations,some beneficial conclusions are presented.     

软刚臂系泊系统水平恢复力特性数值预报

建立软刚臂系泊系统的理论模型以及6自由度静恢复力特性计算分析的数学模型,模拟实际几何关系与力学作用机制。提出基于误差判断的变步长迭代搜索的数值逼近求解方法,以QHD32-6 FPSO软刚臂系泊系统的纵向和横向水平恢复力特性为例进行数值预报,并与国外设计公司计算结果以及模型试验结果进行比较分析。对比显示,该模型的数值计算结果符合良好,而且迭代计算次数少、收敛快、误差小,可用于海上软刚臂系泊系统静恢复力特性的预报。     

An Oscillating Wave Energy Converter with Nonlinear Snap-Through Power-Take-Off Systems in Regular Waves

Floating oscillating bodies constitute a large class of wave energy converters, especially for offshore deployment. Usually the Power-Take-Off (PTO) system is a directly linear electric generator or a hydraulic motor that drives an electric generator. The PTO system is simplified as a linear spring and a linear damper. However the conversion is less powerful with wave periods off resonance. Thus, a nonlinear snap-through mechanism with two symmetrically oblique springs and a linear damper is applied in the PTO system. The nonlinear snap-through mechanism is characteristics of negative stiffness and double-well potential. An important nonlinear parameter is defined as the ratio of half of the horizontal distance between the two springs to the original length of both springs. Time domain method is applied to the dynamics of wave energy converter in regular waves. And the state space model is used to replace the convolution terms in the time domain equation. The results show that the energy harvested by the nonlinear PTO system is larger than that by linear system for low frequency input. While the power captured by nonlinear converters is slightly smaller than that by linear converters for high frequency input. The wave amplitude, damping coefficient of PTO systems and the nonlinear parameter affect power capture performance of nonlinear converters. The oscillation of nonlinear wave energy converters may be local or periodically inter well for certain values of the incident wave frequency and the nonlinear parameter , which is different from linear converters characteristics of sinusoidal response in regular waves.     

浅水不规则波浪中油轮运动研究

本文对一般油轮在浅水不规则波浪中六自由度运动进行了试验分析,并对其碰底情况做了研究。试验时对有流情况下不同波高、不同装载的条件进行了分析比较。模型的六自由度运动是用非接触式六自由度运动测量与分析方法求得。该方法应用位置测量仪（ＰＳＤ）对安置在模型上的红外线发光源（ＬＥＤ）进行测量,然后所编制的软件计算出模型的六个自由度运动情况。     

Investigation on the hydrodynamic performance of an ultra deep turret-moored FLNG system

Hydrodynamic performance of an ultra deep turret-moored Floating Liquefied Natural Gas(FLNG) system is investigated.Hydrodynamic modeling of a turret-moored FLNG system,in consideration of the coupling effects of the vessel and its mooring lines,has been addressed in details.Based on the boundary element method,a 3-D panel model of the FLNG vessel and the related free water surface model are established,and the first-order and second-order mean-drift wave loads and other hydrodynamic coefficients are calculated.A systematic model test program consisting of the white noise wave test,offset test and irregular wave test combined with current and wind,etc.is performed to verify the numerical model.Owing to the depth limit of the water basin,the model test is carried out for the hydrodynamics of the FLNG coupled with only the truncated mooring system.The numerical simulation model features well the hydrodynamic performance of the FLNG system obtained from the model tests.The hydrodynamic characteristics presented in both the numerical simulations and the physical model tests would serve as the guidance for the ongoing project of FLNG system.     

半潜式平台气隙数值预报

气隙预报是半潜平台设计过程中要考虑的关键问题之一.以一座250 m水深半潜式钻井平台为例,对其在5种海况下的气隙响应进行了数值计算,并与相应的模型试验相比较.从比较结果可以看出,一阶数值计算和Stokes二阶统计修正的结果均低估了相对波面升高的极值,且波陡越大,低估越严重.但是,它可以较好地预报危险点的位置,因此,可以用来在进行模型试验之前确定探针的布置位置和试验浪向.