迎浪规则波中波浪增阻和船体垂向运动的数值预报(英文)

The numerical prediction of added resistance and vertical ship motions of one ITTC (International Towing Tank Conference) S-175 containership in regular head waves by our own in-house unsteady RANS solver naoe-FOAM-SL JTU is presented in this paper. The development of the solver naoe-FOAM-SJTU is based on the open source CFD tool, OpenFOAM. Numerical analysis is focused on the added resistance and vertical ship motions (heave and pitch motions) with four very different wavelengths (0.8Lpp≤λ≤1.5Lpp) in regular head waves. Once the wavelength is near the length of the ship model, the responses of the resistance and ship motions become strongly influenced by nonlinear factors, as a result difficulties within simulations occur. In the paper, a comparison of the experimental results and the nonlinear strip theory was reviewed and based on the findings, the RANS simulations by the solver naoe-FOAM-SJTU were considered competent with the prediction of added resistance and vertical ship motions in a wide range of wave lengths.     

基于边界元方法的二维全非线性数值波浪水槽(英文)

The development of a two dimensional numerical wave tank (NWT) with a rocker or piston type wavemaker based on the high order boundary element method (BEM) and mixed Eulerian-Lagrangian (MEL) is examined. The cauchy principle value (CPV) integral is calculated by a special Gauss type quadrature and a change of variable. In addition the explicit truncated Taylor expansion formula is employed in the time-stepping process. A modified double nodes method is assumed to tackle the corner problem, as well as the damping zone technique is used to absorb the propagation of the free surface wave at the end of the tank. A variety of waves are generated by the NWT, for example; a monochromatic wave, solitary wave and irregular wave. The results confirm the NWT model is efficient and stable.     

高速滑行艇在规则波中运动的RANSE数值模拟(英文)

This paper presents a study on the numerical simulation of planing crafts sailing in regular waves. This allows an accurate estimate of the seas keeping performance of the high speed craft. The simulation set in six-degree of freedom motions is based on the Reynolds averaged Navier Stokes equations volume of fluid (RANSE VOF) solver. The trimming mesh technique and integral dynamic mesh method are used to guarantee the good accuracy of the hydrodynamic force and high efficiency of the numerical simulation. Incident head waves, oblique waves and beam waves are generated in the simulation with three different velocities (Fn =1.0, 1.5, 2.0). The motions and sea keeping performance of the planing craft with waves coming from different directions are indicated in the flow solver. The ship designer placed an emphasis on the effects of waves on sailing amplitude and pressure distribution of planing craft in the configuration of building high speed crafts.     

TLP型风力机的空气动力学影响及发电预测(英文)

This research proposes a new offshore wind energy generation system that uses a tension leg platform (TLP) and describes experiments performed on a TLP type wind turbine in both waves and wind. The following conclusions can be made from the results of this research. 1) In the case of coexisting wave-wind fields, the wind effect stabilizes the pitch motion. 2) The wind effect decreases vibration of the mooring lines when waves and wind coexist. In particular, the springing (2nd or 3rd order force) also decreases in this field. 3) It can be estimated that the reduction in the rate of generation of electrical power can be up to about 6% as a result of the heel angle. In addition, the annual amount of electricity generated was estimated along with the utilization factor based on the experimental results.     

双平面焊接圆管截面DKT节点的中心撑杆鞍点及冠点位置的应力集中系数(英文)

A set of parametric stress analyses was carried out for two-planar tubular DKT-joints under different axial loading conditions.The analysis results were used to present general remarks on the effects of the geometrical parameters on stress concentration factors(SCFs) at the inner saddle,outer saddle,and crown positions on the central brace.Based on results of finite element(FE) analysis and through nonlinear regression analysis,a new set of SCF parametric equations was established for fatigue design purposes.An assessment study of equations was conducted against the experimental data and original SCF database.The satisfaction of acceptance criteria proposed by the UK Department of Energy(UK DoE) was also checked.Results of parametric study showed that highly remarkable differences exist between the SCF values in a multi-planar DKT-joint and the corresponding SCFs in an equivalent uni-planar KT-joint having the same geometrical properties.It can be clearly concluded from this observation that using the equations proposed for uni-planar KT-connections to compute the SCFs in multi-planar DKT-joints will lead to either considerably under-predicting or over-predicting results.Hence,it is necessary to develop SCF formulae specially designed for multi-planar DKT-joints.Good results of equation assessment according to UK DoE acceptance criteria,high values of correlation coefficients,and the satisfactory agreement between the predictions of the proposed equations and the experimental data guarantee the accuracy of the equations.Therefore,the developed equations can be reliably used for fatigue design of offshore structures.     

新建半潜运输船在张力腿平台运输方面的应用研究(英文)

Transportation of tension leg platform(TLP) structures for a long distance has always been associated with the use of a heavy semi-transport vessel.The requirements of this type of vessel are always special,and their availability is limited.To prepare for the future development of South China Sea deepwater projects,the China Offshore Oil Engineering Corporation has recently built a heavy lift transport vessel-Hai Yang Shi You 278.This semi-submersible vessel has a displacement capacity of 50k DWT,and a breath of 42 meters.Understanding the vessel’s applicability and preparing it for use in future deepwater projects are becoming imminent needs.This paper reviews the current critical issues associated with TLP transportation and performs detailed analysis of the designed TLP during load-out and transportation.The newly built COOEC transportation vessel HYSY 278 was applied to dry transport of the TLP structure from the COOEC fabrication yard in Qingdao to an oil field in South China Sea.The entire process included the load-out of the TLP structure from the landsite of the fabrication yard,the offloading and float-on of the platform from the vessel,the dry transport of the TLP over a long distance,and the final offloading of the platform.Both hydrodynamic and structure analysis were performed to evaluate the behavior of the transport vessel and TLP structure.Special attention was paid to critical areas associated with the use of this new vessel,along with any potential limitations.The results demonstrate that HYSY 278 can effectively be used for transporting the structure with proper arrangement and well-prepared operation.The procedure and details were presented on the basis of the study results.Special attention was also given to discussion on future use based on the results from the analysis.     

基于改进的Logvinovich法对带横摇运动非对称楔形体入水砰击力的计算(英文)

The water entry problem of an asymmetric wedge with roll motion was analyzed by the method of a modified Logvinovich model (MLM). The MLM is a kind of analytical model based on the Wagner method, which linearizes the free surface condition and body boundary condition. The difference is that the MLM applies a nonlinear Bernoulli equation to obtain pressure distribution, which has been proven to be helpful to enhance the accuracy of hydrodynamic loads. The Wagner condition in this paper was generalized to solve the problem of the water entry of a wedge body with rotational velocity. The comparison of wet width between the MLM and a fully nonlinear numerical approach was given, and they agree well with each other. The effect of angular velocity on the hydrodynamic loads of a wedge body was investigated.     

风机塔架与叶片相互作用的数值模拟(英文)

Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface(AMI) method were presented.The governing equations were the unsteady Reynolds-averaged Navier-Stokes(RANS) which were solved by the pimpleDyMFoam solver,and the AMI method was employed to handle mesh movements.The National Renewable Energy Laboratory(NREL) phase VI wind turbine in upwind configuration was selected for numerical tests with different incoming wind speeds(5,10,15,and 25 m/s) at a fixed blade pitch and constant rotational speed.Detailed numerical results of vortex structure,time histories of thrust,and pressure distribution on the blade and tower were presented.The findings show that the wind turbine tower has little effect on the whole aerodynamic performance of an upwind wind turbine,while the rotating rotor will induce an obvious cyclic drop in the front pressure of the tower.Also,strong interaction of blade tip vortices with separation from the tower was observed.     

不同状腿结构的自升式平台对比分析(英文)

The jack-up unit is one of the best drilling platforms in offshore oil fields with water depth shallower than 150 meters.As the most pivotal component of the jack-up unit,the leg system can directly affect the global performance of a jack-up unit.Investigation shows that there are three kinds of leg structure forms in the world now:the reverse K,X,and mixing types.In order to clarify the advantage and defects of each one,as well as their effect on the global performance of the jack-up unit,this paper commenced to study performance targets of a deepwater jack-up unit with different leg systems(X type,reverse K type,and mixing type).In this paper a typical leg scantling dimension and identical external loads were selected,detailed finite element snalysis(FEA) models were built to simulate the jack-up unit’s structural behavior,and the multi-point constraint(MPC) element together with the spring element was used to deal with the boundary condition.Finally,the above problems were solved by comparative analysis of their main performance targets(including ultimate static strength,dynamic response,and weight).     

基于混合迭代法的二维水翼空泡性能分析(英文)

In order to study cavitation characteristics of a 2-D hydrofoil, the method that combines nonlinear cavitation model and mixed-iteration is used to predict and analyze the cavitation performance of hydrofoils. The cavitation elements are nonlinearly disposed based on the Green formula and perturbation potential panel method. At the same time, the method that combines cavity shape for fixed cavity length (CSCL) iteration and cavity shape for fixed cavitation number (CSCN) iteration is used to work out the thickness and length of hydrofoil cavitations. Through analysis of calculation results, it can be concluded that the jump of pressure and velocity potentially exist between cavitation end area and non-cavitations area on suction surface when cavitation occurs on hydrofoil. In certain angles of attack, the cavitation number has a negative impact on the length of cavitations. And under the same angle of attack and cavitation number, the bigger the thickness of the hydrofoil, the shorter the cavitations length.     

系泊Spar平台波浪中耦合运动的数值模拟及模型试验

为了研究恶劣环境载荷引起海洋结构物的非线性运动响应,文章基于三维时域格林函数理论,提出了采用时域物面非线性理论方法直接模拟系泊浮体时域耦合分析所需的水动力,建立了系泊浮体波浪中时域耦合运动的数学模型.该方法充分考虑了每时每刻浮体在瞬态波面下湿表面的变化,并计及平均水线面下瞬时空间位置的改变,系统研究了系泊Spar平台波浪中的耦合运动响应及系泊线张力.最后,将数值模拟结果与模型试验结果进行了比较,计算结果令人满意.     

波浪中气泡运动的数值模拟

通过推板造波方法,应用FLUENT动网格技术(Dynamic Mesh)及UDF(User-defined function)建立数值波浪,从而构建数值水槽。对建立的数值波浪与气泡运动方程耦合求解,分析气泡在波浪中的变形与运动。结果表明,波浪中气泡相对静水中更容易保持稳定的球形,且不易发生聚合。这将为舰船尾流中气泡运动研究提供有价值的参考。     

漂浮式海洋能平台运动响应耦合预报研究

随着海洋工程向远海发展,漂浮式海洋能平台的运动响应预报问题成为研究的热点之一.本文以漂浮式海洋能平台为研究对象,首先基于间接时域法,建立浮式平台时域运动方程,然后基于悬链线理论和全矢量形式的三维集中质量法,建立系泊系统运动方程.在使用自行开发的计算程序对以上方程进行求解获得初值后,以系缆和浮式平台的受力和位移作为2个运动方程的交互输入与输出,建立浮式平台与系泊系统的全耦合计算方法.最后对简化的浮式海洋平台进行计算,分析载体平台的运动响应和系缆受力情况.本文可为解决相关工程问题提供参考和借鉴.     

漂浮式海洋能平台运动响应耦合预报研究

随着海洋工程向远海发展,漂浮式海洋能平台的运动响应预报问题成为研究的热点之一。本文以漂浮式海洋能平台为研究对象,首先基于间接时域法,建立浮式平台时域运动方程,然后基于悬链线理论和全矢量形式的三维集中质量法,建立系泊系统运动方程。在使用自行开发的计算程序对以上方程进行求解获得初值后,以系缆和浮式平台的受力和位移作为2个运动方程的交互输入与输出,建立浮式平台与系泊系统的全耦合计算方法。最后对简化的浮式海洋平台进行计算,分析载体平台的运动响应和系缆受力情况。本文可为解决相关工程问题提供参考和借鉴。     

小水线面双体船在波浪中的运动响应预报

用切片理论方法发展了SWATH船耐波性预报程序，提供了390t方案的油田小水线面交通船计算分析结果，包括规则波中纵向运动频率响应函数的计算及不规则波中各种海况下的运动有义值预报。     

内孤立波作用下潜水器运动响应数值分析

内孤立波会导致海水等密度面大振幅的垂向起伏,影响潜水器的水下适航性,甚至危及安全性.运用CFD方法开展内孤立波数值造波,并将内孤立波数值解与eKdV理论解进行比较,验证数值造波的准确性.在此基础上,模拟了内孤立波作用下处于3种不同潜深的Suboff缩比模型的运动,详细分析了不同潜深下模型在内孤立波作用下的运动响应规律....     

油气爆炸下海洋平台抗爆结构型式数值仿真

海洋平台作为人们开发利用海洋资源的重要基础设施,在其服役期间,常会遭到油气泄漏而引起的爆炸冲击破坏,因此对海洋平台结构进行爆炸载荷下的动态响应分析及抗爆研究十分必要。本文以某海洋平台燃油舱的围壁为研究对象,对其分别进行波纹板和夹层板结构设计。使用非线性瞬态动力学分析软件MSC.Dytran对不同结构型式舱壁下燃油舱的吸能情况进行数值对比研究,从而获得抗爆效果较好的海洋平台舱壁抗爆结构。     

可燃气体爆炸压力下海洋平台防爆墙数值仿真研究

采用等效TNT方法计算了海洋平台复杂结构在油气爆炸冲击波作用下的动态响应,采用多欧拉-拉格朗日耦合方法对三种不同防爆墙结构进行数值模拟研究.模拟结果显示:在油气爆炸冲击波的作用下,平台舱室变形、失效后破裂,冲击波通过破口传入平台其它舱室;对海洋平台爆炸舱室的围壁采用原结构、梯形结构和半椭圆三种防爆墙结构进行数值对比研究,考虑防爆墙的能量吸收和甲板能量吸收这两个方面,半椭圆防爆墙结构具有更好的防爆效果.     

半潜平台内孤立波载荷特性数值模拟

以三类内孤立波理论KdV、e KdV和MCC的适用性条件为依据,采用Navier-Stokes方程为流场控制方程,将内孤立波诱导上下层深度平均水平速度作为入口边界条件,建立了两层流体中内孤立波对半潜平台强非线性作用的数值模拟方法。结果表明,数值模拟所得内孤立波波形及其振幅与相应理论和实验结果一致,并且在内孤立波作用下半潜平台水平力、垂向力及其力矩数值模拟结果与实验结果吻合。研究同时表明,半潜平台内孤立波载荷由波浪压差力、粘性压差力和摩擦力构成,其中摩擦力很小,可以忽略;水平力的主要成分为波浪压差力和粘性压差力,粘性压差力与波浪压差力相比较小却不可忽略,流体粘性的影响较小;垂向力中粘性压差力很小,流体粘性影响可以忽略。此外,半潜平台对内孤立波的波形及其诱导流场的影响很小,因此采用Morison和傅汝德—克雷洛夫力公式计算其内孤立波载荷是可行的。     

基于动态刚度阵法的海洋平台动力响应分析

导管架式海洋平台是人类开发和利用海洋资源的重要工程设施,动态刚度阵法是解决工程中结构振动问题的一个强有力的工具,其可以通过较少的单元数计算出结构固有频率和固有振型,减少结构的自由度数,随着计算频率的升高,DSM法无需进一步细化单元.本文应用DSM法建立导管架式海洋平台模型,将导管架式海洋平台简化成平面刚架结构,计算了导...